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iq switch ? proxsense ? series IQS253 datasheet - con?gurable 3 channel dycal tm capacitive sensor with automatic compensation for sensitivity reducing objects unparallelled features: o dycal tm : intelligent hysteresis o internal capacitor implementation (ici) - reference capacitor on-chip o automatic tuning implementation (ati) - automatic adjustment for optimal sensor performance the IQS253 proxsense ? ic is a fully integrated capacitive sensor implementing dynamic cali- bration (dycal tm ) technology: intelligent hysteresis to allow for sensor drift even during sensor activation. main features: o self or projected technology sensors o 3 channels con?gurable as dycal tm /normal output o self: boolean direct output con?gurable through i 2 c o supply voltage: 1 . 8 v to 3 . 6 v o internal voltage regulator o advanced on-chip digital signal processing o i 2 c adjustable settings ? dycal tm settings ? control over ?lter operation ? time-out for stuck key ? proximity and touch sensitivity selections ? low power options ? event mode possible (only communicates if an event is detected) applications: o occupancy sensors o sar complient sensors for tablet pcs o on-ear detection for mobile phones o 3d glasses o personal media players o remote control sleep implementation o gaming controllers o proximity activated backlighting o any applications where a touch and proxim- ity condition can exist for a extended pe- riod of time advantages: o allows for sensor drift in periods of activation and non-activation o improved digital ?ltering to reduce external noise o highly adjustable i 2 c device which only in- terrupts (event mode) when an event is detected copyright ? azoteq IQS253 datasheet v1.04 1of 53
iq switch ? proxsense ? series contents list of figures 4 list of tables 4 revision history 4 list of symbols 5 1 functional overview 6 1.1 applicability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 2 analogue functionality 6 3 digital functionality 7 4 packaging and pin-out 8 4.1 IQS253 self capacitance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 4.2 IQS253 projected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 4.3 power supply and pcb layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 4.4 design rules for harsh emc environments . . . . . . . . . . . . . . . . . . . . . . . 11 5 dycal 12 5.1 operating principle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 6 proxsense module 14 6.1 charge transfer concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 7 prox module setup 14 7.1 self or projected capacitance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 7.2 rate of charge cycles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 7.3 report rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 7.4 active channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 7.5 dycal tm or direct output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 7.6 report order (channel numbers) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 7.7 transfer frequency (f cx ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 7.8 counts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 7.9 long term average (lta) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 7.10 determine touch or prox . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 7.11 ati . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 8 dycal tm 19 8.1 dycal tm channels enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 8.2 dycal tm on touch/prox . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 8.3 lta adapt rates (in and out) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 8.4 block channel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 8.5 dycal tm release threshold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 8.6 dycal tm dynamic touch threshold . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 8.7 10s_ati_block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 8.8 250ms_delay_tm (t dycal ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 8.9 turbo mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 copyright ? azoteq IQS253 datasheet v1.04 2of 53
iq switch ? proxsense ? series 9 communication 22 9.1 ic setup window . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 9.2 event mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 9.3 i 2 c speci?c commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 9.4 i 2 c read and write speci?cs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 10 boolean output 24 10.1 channels for boolean operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 10.2 boolean not . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 10.3 boolean and/or . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 10.4 order of boolean operation: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 11 rf noise 24 11.1 noise immunity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 12 electrical speci?cations 26 12.1 general characteristics (measured at 25 c) . . . . . . . . . . . . . . . . . . . . . . 26 12.2 timing characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 13 mechanical dimensions 29 14 device marking 31 15 ordering information 31 16 device revision history 32 17 errata 32 18 contact information 33 a appendix a 34 b appendix b 36 b.1 IQS253 memory map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 b.2 general implementation hints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 b.3 startup procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 b.4 general i 2 c hints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 references 53 list of figures 4.1 IQS253 pin out. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 4.2 self reference design. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 4.3 projected reference design. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 4.4 emc design choices. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 5.1 dycal overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 7.1 boost power as on cx/crxx. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 7.2 charge cycles as charged in lp modes. . . . . . . . . . . . . . . . . . . . . . . . . . 15 9.1 ic setup window. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 13.1 msop10 package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 13.2 msop10 footprint. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 13.3 msop10 silk screen. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 copyright ? azoteq IQS253 datasheet v1.04 3of 53
iq switch ? proxsense ? series 13.4 dfn-10 package. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 13.5 dfn side view. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 13.6 dfn footprint. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 a.1 dycal output selected on proximity. . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 a.2 dycal output selected on touch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 a.3 filter halt upon touch mode entry. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 list of tables 4.1 IQS253 self capacitive pin-out . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 4.2 IQS253 projected capacitive pin-out . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 7.1 lta halting in non-tm. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 12.1 IQS253 general operating conditions - projected capacitive sensor. . . . . . . . . . 26 12.2 IQS253 general operating conditions - self capacitive sensor. . . . . . . . . . . . . 26 12.3 start-up and shut-down slope characteristics . . . . . . . . . . . . . . . . . . . . . . 27 12.4 debounce employed on IQS253. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 12.5 general timing characteristics for 1.80v vddhi 3.60v . . . . . . . . . . . . . . 27 12.6 IQS253 charging times . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 12.7 IQS253 dycal (output_on_touch = 0) /proximity response times . . . . . . . 28 13.1 msop10 package dimensions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 13.2 msop-10 footprint dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 13.3 msop-10 silk screen dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 13.4 dfn-10 package dimensions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 13.5 dfn-10 side view dimensions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 13.6 dfn-10 footprint dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 revision history rev description date 1.0.1 preliminary sept 2011 1.00 first release jan 2012 1.01 update hc description march 2012 1.02 update dfn-10 footprint april 2012 1.03 include the memory map in the datasheet april 2012 1.04 update self reference schematic with pull-up on boolean output june 2012 copyright ? azoteq IQS253 datasheet v1.04 4of 53
iq switch ? proxsense ? series list of symbols ati automatic tuning implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 bp boost power mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 cs count(s) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13 cx sensor electrode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 emi electromagnetic interference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 esd electro-static discharge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 ftb / eft (electrical) fast transient bursts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 gnd ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 hc halt charge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 lp low power mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 lta long term average . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13 nd noise detect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 ntm non touch mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 p proximity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 rdy ready . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 scl i 2 c clock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 sda i 2 c data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 t time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 t touch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 thr threshold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 tm touch mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 tvs transient voltagesuppression diode - esd protection . . . . . . . . . . . . . . . . . . . . . . . 6 vddhi supply (input) voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 vreg internal regulator output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 wdt watch-dog timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 copyright ? azoteq IQS253 datasheet v1.04 5of 53
iq switch ? proxsense ? series 1 functional overview the IQS253 is a fully integrated three channel capacitive sensor implementing the dycal tm functionality. dynamic calibration (dycal tm ) is an intelligent hysteresis to allow for sensor drift even during sensor activation. all channels can be either con?gured as a dycal tm chan- nel or as a normal direct output channel. the device has an internal voltage regulator and ref- erence capacitor. the regulator is used as ref- erence for the charge transfer circuitry. both circuits reduce the external component count needed. the device automatically tracks slow varying environmental changes via various sig- nal processing algorithms and has an auto- matic tuning (ati) algorithm to calibrate the de- vice to the sense electrode. the charge trans- fer method of capacitive sensing is employed on the IQS253. (the charge transfer principle is thoroughly described in the application note: "azd004 - azoteq capacitive sensing".) the IQS253 can be con?gured as either a self ca- pacitance sensor, where it has a boolean out- put pin available. with the sensor con?gured as a projected capacitance sensor, this pin is con- ?gured as the transmitter electrode. dycal tm settings are highly con?gurable via i 2 c. these settings include: o dycal tm activation with either touch or proximity detection o release threshold o touch mode (tm) entry speed o downward ?lter adaptation rate when in tm o upward ?lter adaptation rate when in tm o ati block after exiting activation o boolean output con?guration the above mentioned con?guration settings do not include regular proxsense ? settings ad- justable via i 2 c. regular settings include: o proximity / touch thresholds o power modes o adaptation rate when not in tm o noise detection activation o ati setup (control over sensitivity and when ati should occur) o redo ati o control over the lta ?lters o wdt enable / disable o ac filter enable / disable o proximity debounce o charge transfer frequency o block channel o event mode enable / disable o setup to wake communication with a partic- ular event 1.1 applicability all speci?cations, except where speci?- cally mentioned otherwise, provided by this datasheet are applicable to the following ranges: o temperature 40 c to + 85 c o supply voltage (vddhi) 1 . 8 v to 3 . 3 v 2 analogue functionality the analogue circuitry measures the capaci- tance of the sense electrodes attached to the cx pins through a charge transfer process that is periodically initiated by the digital circuitry. the measuring process is referred to as a conver- sion and consists of the discharging of cs and cx, the charging of cx and then a series of charge transfers from cx to cs until a trip volt- age is reached. the number of charge transfers required to reach the trip voltage is referred to as counts (cs). the capacitance measurement circuitry makes use of an internal reference ca- pacitor and voltage reference (vreg). the ana- logue circuitry further provides functionality for: copyright ? azoteq IQS253 datasheet v1.04 6of 53
iq switch ? proxsense ? series o power on reset (por) detection. o brown out detection (bod). 3 digital functionality the digital processing functionality is responsi- ble for: o management of bod and wdt events. o initiation of conversions at the selected rate. o processing of cs and execution of algo- rithms. o monitoring and automatic execution of the ati algorithm. o signal processing and digital ?ltering. o detection of prox and touch events. o managing outputs of the device. o managing serial communications. o manage programming of otp options. copyright ? azoteq IQS253 datasheet v1.04 7of 53
iq switch ? proxsense ? series 4 packaging and pin-out the IQS253 ic is available in the msop-10 and dfn-10 package. the pin-outs of the self and projected setup differ with the transmitter (ctx) on the projected con?guration being con?gured as a boolean output (b_out) on the self con?guration. figure 4.1: IQS253 pin out. 4.1 IQS253 self capacitance 4.1.1 pin-out table 4.1: IQS253 self capacitive pin-out pin name type function 1 gnd supply input ground reference 2 cx0 analogue sense electrode 0 3 cx1 analogue sense electrode 1 4 vddhi supply input supply voltage input 5 vreg analogue output internal regulator pin (connect 1 f bypass capacitor) 6 rdy/nd digital out / analogue in i 2 c: rdy data indication output / nd pin 7 sda digital i/o i 2 c: data input / output 8 scl digital input i 2 c: clock input 9 cx2 analogue sense electrode 2 10 b_out digital output boolean output (open drain - requires pull-up resistor) copyright ? azoteq IQS253 datasheet v1.04 8of 53 g n d c x 0 c x 1 v d d h i v r e g b o u t / c t x c x 2 s c l s d a r d y / n d
iq switch ? proxsense ? series 4.1.2 schematic figure 4.2: typical application schematic of IQS253 self capacitive con?guration. 4.2 IQS253 projected table 4.2: IQS253 projected capacitive pin-out pin name type function 1 gnd supply input ground reference 2 cx0 analogue projected charge receiver 0 3 cx1 analogue projected charge receiver 1 4 vddhi supply input supply voltage input 5 vreg analogue output internal regulator pin (connect 1 f bypass capacitor) 6 rdy/nd digital out / analogue in i 2 c: rdy data indication output / nd pin 7 sda digital i/o i 2 c: data input / output 8 scl digital input i 2 c: clock input 9 cx2 analogue projected charge receiver 2 10 ctx analogue charge transmitter copyright ? azoteq IQS253 datasheet v1.04 9of 53 vddhi gnd c1 1uf c2 1uf c4 100pf c3 100pf gnd vddhi sda to mcu scl to mcu rdy to mcu vreg 5 vddhi 4 cx0/ crx0 2 gnd 1 cx1/ crx1 3 rdy/ nd 6 sda 7 b_out/ ctx 10 scl 8 cx2/ crx2 9 IQS253 sda sda scl scl rdy/ nd rdy/ nd r5 10k r6 10k r7 10k r3 470r r2 470r r1 470r bo r8 10k vddhi
iq switch ? proxsense ? series figure 4.3: typical application schematic of IQS253 projected capacitive con?guration. refer to the application note for layout guideline [ 1 ] 4.3 power supply and pcb layout azoteq ics provide a high level of on-chip hardware and software noise ?ltering and esd protection (refer to section 12 ). designing pcbs with better noise immunity against emi, ftb and esd in mind, it is always advisable to keep the critical noise suppression components like the de-coupling capacitors and series resistors in figure 4.2 as close as possible to the ic. always maintain a good ground connection and ground pour underneath the ic. for more guidelines please refer to the relevant application notes as mentioned in section 4.4 . copyright ? azoteq IQS253 datasheet v1.04 10of 53 vddhi gnd c1 1uf c2 1uf c4 100pf c3 100pf gnd vddhi sda to mcu scl to mcu rdy to mcu vreg 5 vddhi 4 cx0/ crx0 2 gnd 1 cx1/ crx1 3 rdy/ nd 6 sda 7 b_out/ ctx 10 scl 8 cx2/ crx2 9 IQS253 sda sda scl scl rdy/ nd rdy/ nd r5 10k r6 10k r7 10k r4 470r r3 470r r2 470r r1 470r
iq switch ? proxsense ? series 4.4 design rules for harsh emc environments figure 4.4: emc design choices. applicable application notes: [ 2 ], [ 3 ], [ 4 ], [ 5 ] copyright ? azoteq IQS253 datasheet v1.04 11of 53 1) determine prox, touch & data requirements 2) choose device radiated rf azd015 ? rx > 1k may be required ? long cx traces not ok ? use rf detection as last resort fast transient bursts azd051 ? rx > 1k may be required ? long cx traces ok ? careful with cx pad size ? grounding very nb electro - static discharge azd013 ? preferably use rx of 470 ? rather use tvs than higher rx to protect ? grounding of tvs nb conducted rf azd052 ? preferably use rx of 470 ? filtering and grounding of supply very nb ? traces < 200mm ok what is the biggest emc threat? start
iq switch ? proxsense ? series 5 dycal figure 5.1: dycal overview. copyright ? azoteq IQS253 datasheet v1.04 12of 53 p thr t thr cs 10 po recallibrate lta cs lta C long term average of cs p thr - derived from lta t thr - derived from lta 1. if touchpad is approached in non-tm: cs goes below lta, if cs goes below p th , out = high & lta will halt (not allowed to track cs), if cs goes below t th , out will stay high & lta will recalibrate device will enter tm (touch mode) & out will stay high tm: touch mode tm non-tm non-tm non-tm: non-touch mode 2. if touchpad is released in tm: lta will track cs as long as cs is below p thr cs goes above lta if cs goes above p thr , lta will halt, if cs goes above rel_t thr , out will go low & lta will recalibrate lta is allowed to track cs lta & lta rate = lta_adapt lta rate = lta_adapt_in lta rate = lta_adapt_out 10 to 10 dycal
iq switch ? proxsense ? series 5.1 operating principle figure 5.1 is a visual representation of the dycal tm functionality. the dycal output is used to indicate the status of a dycal tm event (both a proximity and a touch event). the dycal tm functionality is summarised below. non-touch mode the dycal output is activated on the success- ful detection of a proximity event and will remain activated for the duration of the proximity event, permitting that this event is not longer than the ?lter halt timings. the lta will be halted in this time. as soon as a touch condition is detected (cs below t thr ), the controller will dynamically re-calibrate its lta to the halted lta - t thr . the ic is now in touch mode (tm). touch mode after the re-calibration of the lta, it will follow the cs and be allowed to track slow varying en- vironmental changes. if the cs were to exceed the lta by a release threshold (rel_t thr ) the touch detection will stop and the dycal output will return to its original state. copyright ? azoteq IQS253 datasheet v1.04 13of 53
iq switch ? proxsense ? series 6 proxsense module the IQS253 contains a proxsense ? module that uses patented technology to provide de- tection of prox/touch on numerous sensing lines. the proxsense ? module is a combination of hardware and software, based on the princi- ples of charge transfer. a measurement is taken and used for calculating appropriate outputs. 6.1 charge transfer concepts capacitance measurements are taken with a charge transfer process that is periodically ini- tiated. self capacitive sensing measures the capacitance between the sense electrode (cx) relative to ground. projected capacitance sens- ing measures the capacitance between 2 elec- trodes referred to as the transmitter (ctx) and receiver (crx). the measuring process is re- ferred to as a charge transfer cycle and consists of the following: o discharging of an internal sampling capaci- tor (cs) and the electrode capacitors (self: cx or projected: ctx & crx) on a chan- nel. o charging of cxs / ctxs connected to the channel o and then a series of charge transfers from the cxs / crxs to the internal sampling capacitors (cs), until the trip voltage is reached. the number of charge transfers required to reach the trip voltage on a channel is referred to as counts (cs). the device continuously re- peats charge transfers on the sense electrode connected to the cx pin. for each channel a long term average (lta) is calculated (12 bit unsigned integer values). the counts (12 bit unsigned integer values) are processed and compared to the lta to detect dycal, touch and prox events. for more information re- garding capacitive sensing, refer to the appli- cation note "azd004 - azoteq capacitive sens- ing". please note: attaching a probe to the cx/ctx/crx pin will in?uence the capaci- tance of the sense electrodes and therefore cs. this will have an immediate in?uence on cs. 7 prox module setup 7.1 self or projected capaci- tance the ic can be used in either self or projected capacitance mode. the ic is default in self ca- pacitance mode. this can be changed to pro- jected capacitance mode through either a fg (one time programmable option) bit or in the ?rst communication window with start-up ( use the setup window to set the ic to projected mode ). the user should set the proj bit (bit 7) in the prox_settings1 [0xd2h] register (refer to the device settings the memory map, available in appendix b ) to enable projected ca- pacitance technology. the technology enabled on the ic will be reported in the sysflags [0x10h] register. refer to the IQS253 communi- cation interface application note for more details on the setup window. this setting can only be sent to the IQS253 in the setup-communication- window. please see the section 9.1 for more information regarding this. note that this setup- window is only available once after power-on. the IQS253 will always start-up in event mode (default after por). thus, after the initial setup-window, there will only be communica- tion windows available upon events (ati, prox- imity, etc. refer to the event_mask [0xd9h] register). therefore, if the device is not set to continuous streaming mode (bit 2 in the prox_settings2 [0xd3h] register) during the setup-window, the master controller will have to pull the rdy line low to force a com- munication window to setup additional settings. please refer to application note [ 6 ] for guidelines copyright ? azoteq IQS253 datasheet v1.04 14of 53
iq switch ? proxsense ? series on setting up the IQS253. when using more than one IQS253 device on the same i 2 c bus (especially when sharing a input pin on the master for the rdy lines), it is recommended to use the fg options to set the sensing technology (self or projected) and the individual sub-addresses. 7.2 rate of charge cycles 7.2.1 boost power rate with all 3 channels active and the IQS253 in boost power (bp) mode, the counts (cs) are charged at a ?xed sampling frequency (f sample ) per channel. this is done to en- sure regular samples for processing of results. it is calculated as each channel having a time (t ch annel = charge period (t ch arge ) + compu- tation time) of 9 ms , thus the time between con- secutive samples on a channel (t sample ) will optimally be 27 ms (or 37 hz ). figure 7.1: boost power as on cx / crxx. for every channel disabled, the sampling rate on a channel will reduce with approximately 9ms. 7.2.2 low power rates low current consumption charging modes are available. in any low power (lp) mode, there will be a t lp low power time applicable. this is determined by the low_power register. the value written into this register multiplied by 16ms will yield the lp time (t lp ). please note that this time is only applicable from value 03 h and higher loaded into the low_power reg- ister. the values 01 h and 02 h will have a different time. see table 12.6 for all timings. with the detection of an undebounced proxim- ity event the ic will zoom to bp mode, allow- ing a very fast reaction time for further pos- sible dycal /touch /proximity events. all ac- tive channels will be consecutively charged ev- ery t lp . this succession of charge cycles are succeeded by the charging of cx2 /crx2 as a dummy charge cycle. if a lp rate is selected through register low_power and charging is not in the zoomed in state (bp mode), the lp bit (sysflags register) will be set. 7.2.3 halt charge (hc) setting the hc bit will immediately cause the ic to stop doing conversions (stop measuring ca- pacitance), set the rdy line as an input and enter a sleep mode. to wake up the IQS253, and let it continue with conversions, the rdy line should be pulled low for at least 1.6ms. the rdy line should thereafter be monitored again for communication windows. the hc bit in the memory map will automatically be cleared. figure 7.2: charge cycles as charged in lp modes. copyright ? azoteq IQS253 datasheet v1.04 15of 53 c x 2 / c r x 2 2 2 t s a m p l e c x 1 / c r x 1 1 1 t s a m p l e c x 0 / c r x 0 0 0 t c h a r g e t s a m p l e t c h a n n e l s u c c e s s i o n o f c h a r g e c y c l e s e v e r y t l p c x 0 / c r x 0 0 0 0 c x 0 / c r x 0 t l p 2 2 2 2 t l p 2 2 c x 0 / c r x 0 1 1 1 d u m m y c h a r g e c y c l e d u m m y c h a r g e c y c l e d u m m y c h a r g e c y c l e
iq switch ? proxsense ? series 7.3 report rate the report rate of the device depends on the charge transfer frequency, the number of chan- nels enabled and the length of communications performed by the master device. 7.4 active channels the user has the option to disable channels. this can be done in the active_chan regis- ter. all 3 channels are enabled by default. 7.5 dycal tm or direct output each channel can be con?gured to either give a dycal tm (default) or a direct-output through the dycal_chans register. con?guring a channel as a direct-output channel will yield that the touch and prox indication bits will actively in- dicate whether a channel detects either of these events. the dycal tm function will not be ap- plied to direct-channels and any combination of dycal tm or direct-output channels can be used. 7.6 report order (channel num- bers) the data is reported in the sequence; ch0, ch1, ch2, ch0, ch1, ch2, ch0, etc. the chan- nel number (chan_num) is used to indicate to which channel the rest of the data in the dataset belongs. 7.7 transfer frequency (f cx ) the frequency of the charge transfers can be selected adjusting the xfer_freqx bits. an optimal transfer frequency must be selected for a speci?c application. 7.8 counts capacitive measurements are available in these registers. the data has an ac noise ?lter ap- plied, which helps the device to work in very noisy environments. the ?lter is default en- abled. 7.8.1 disabling ac noise filter the ac noise ?lter can be disabled by setting bit acf_disable in the prox_settings2 reg- ister. this will increase response times, at the expense of noise immunity. 7.9 long term average (lta) the lta ?lter can be seen as the baseline or reference value. the lta is calculated to con- tinuously adapt to any environmental drift. the lta ?lter is calculated from the cs value for each channel. the lta ?lter allows the device to adapt to environmental (slow moving) drift. ac- tuation (dycal, touch or prox) decisions are made by comparing the cs value with the lta reference value. the 12bit lta value is con- tained in the lta_h and lta_l registers. 7.9.1 filter adaptation rates the lta will adapt with different rates depend- ing in which state the ic is in. calculating a new lta value is a function of the old lta and the newly measured cs. the percentage of cs used in this lta calculation is speci?ed as the ?lter adaptation rate. 100% speci?es that there are no ?ltering and lta = cs. a lower percent- age value for the adaptation rate will yield a slower adaptation rate. the IQS253 contains 3 user adjustable adaptation rates. filter adaptation rate in non-tm the lta ?lter will adapt according to the lta_adapt rate if the IQS253 is in non-tm and copyright ? azoteq IQS253 datasheet v1.04 16of 53
iq switch ? proxsense ? series no proximity event is detected. see figure 5.1 for a visual representation. filter adaptation rate in tm the lta will adapt according to the lta_adapt_in rate if ic is in touch mode (tm) and the lta is adjusting towards cs. this rate will apply until lta has reached cs. see figure 5.1 for a visual representation. filter halt in non-tm if |lta-cs| > 16 the lta will adapt according to the lta_adapt_out rate if ic is in touch mode (tm), has reached the cs and o self: cs < lta + 16 o projected: cs > lta - 16 this is the rate at which lta adapts before cs is on its way out of tm. see figure 5.1 for a visual representation. 7.9.2 filter reseed setting the reseed bit in the prox_settings0 register, will reseed lta to: o self: 8 above cs o projected: 8 below cs the ic will stay in the state in which it was before the command was issued. thus, ei- ther non-tm or tm. the bit will automatically be cleared by the ic as soon as the command has been executed. 7.9.3 filter halting lta halt status the status of currently halted channels is displayed in this byte. with the ic in non-tm, it will only show that a channel is halted if it detected a proximity condition. once a touch is detected the halting bit for that channel will be cleared. with the ic in tm, it will show halting bits of channels where: self: cs > lta + 16 projected: cs < lta - 16 force halt setting the force_halt bit will cause all lta values to stop adapting to cs. this bit should be cleared for the ic to start adapting to the envi- ronment again. if the force_halt command was issued while a channel was in non-tm and a touch is made on that channel, it will cause the lta to stay halted but decrease with the touch threshold for that channel. automatic lta halting in non-tm with the ic in non-tm, a proximity event will cause halting of the lta. the halting options are: copyright ? azoteq IQS253 datasheet v1.04 17of 53
iq switch ? proxsense ? series table 7.1: lta halting in non-tm. halt1:halt0 t h alt filter 0 short (default) during prox, ?lter halts for 20s, then reseeds 1 long during prox, ?lter halts for 40s, then reseeds 10 never filter never halts 11 always filter is always halted during a prox detection the halt times given in table 7.1 will be ex- tended when disabling channels. if the halt times in table 7.1 are requried while using less than 3 channels, the reseed command should be used from the master device. automatic lta halting in tm with the ic in tm and lta within 16 counts of cs, no halting will occur. halting will occur once: o self: lta + release threshold < cs > lta + 16 o projected: lta - release threshold < cs < lta - 16 always_halt_dycal = 0: the lta will halt with the same conditions as stated in table 7.1 . always_halt_dycal = 1: the lta will always halt if above conditions apply. the always_halt_dycal bit gives the designer more freedom, allowing different halt- ing conditions for when the ic is in non-tm and in tm. 7.10 determine touch or prox an event is determined by comparing the cs with the lta. since the cs reacts differently when comparing the self with the projected ca- pacitance technology, the user should consider only the conditions for the technology used. o self: cs < lta - threshold o projected: cs > lta + threshold threshold can be either a proximity or touch threshold. 7.10.1 proximity thresholds: proximity thresholds can be adjusted individu- ally for each channel and can be any integer values between 1 and 254. status: the proximity status of the channels are indi- cated in the prox register. the indication bits in this register should only be used if the ap- plicable channel is con?gured into direct mode, otherwise the dycal status bits should be con- sidered. debouncing: by default, 6 consecutive samples should satisfy a proximity detection condition. this debounce can be adjusted to 4 through the prox_debounce bit in the prox_settings3 register. 7.10.2 touch threshold and sta- tus touch thresholds can be adjusted individually for each channel and are calculated as a func- tion of the lta. touchthreshold = ( value /256 lta ) (7.1) where value can be any integer value between 1 and 254. the proximity status of the channels are in- dicated in the touch register. (the indication bits in this register should only be used if the ap- plicable channel is con?gured into direct mode, otherwise the dycal status bits should be con- sidered) 7.11 ati the auto tuning implementation (ati) is a sophisticated technology implemented in copyright ? azoteq IQS253 datasheet v1.04 18of 53
iq switch ? proxsense ? series proxsense ? devices. it allows optimal perfor- mance of the devices for a wide range of sens- ing electrode capacitances, without modi?ca- tion or addition of external components. the ati allows the tuning of two parameters, an ati multiplier and an ati compensation, to adjust the sample value for an attached sensing elec- trode. ati allows the designer to optimise a spe- ci?c design by adjusting the sensitivity and sta- bility of each channel through the adjustment of the ati parameters. partial ati lets the designer specify the multplier parameters instead of an actual base value.see section 7.11.3 . the IQS253 has an automated ati function. the auto-ati function is by default enabled, but can be disabled by setting the ati_off bit. the ati bit in the sysflags register will be set while an ati event is busy. 7.11.1 ati sensitivity the designer can specify the base values for each channel and a global target value for all channels. a rough estimation of sensitivity can be calculated as: sensitivity = target / base (7.2) as can be seen from this equation, the sen- sitivity can be increased by either increasing the target or decreasing the base value. it should, however, be noted that a higher sensi- tivity will yield a higher noise susceptibility. 7.11.2 ati target the target is reached by adjusting the com- pensation bits for each channel. the target value is written into the ati_target register. the value written into this register (0 to 255) multiplied by 8 will yield the new target value. 7.11.3 ati base (multiplier) the following parameters will in?uence the base value: o cs_size : size of sampling capacitor. o proj_bias bits: adjusts the biasing of some analogue parameters in the pro- jected ic. (only applicable in projected mode.) o multiplier bits. the base value used for the ati function can be implemented in 2 ways: 1. ati_partial = 0. ati automatically ad- justs multiplier bits to reach a selected base value . base values are available in the chx_ati_base registers. by us- ing the alt_base bit, an extended list of base values are available. 2. ati_partial = 1. the designer can specify the multiplier settings. these set- tings will give a custom base value from where the compensation bits will be au- tomatically implemented to reach the re- quired target value. the base value is determined by two sets of multiplier bits. sensitivity multipliers which will also scale the compensation to normalise the sensitivity and compensation multipli- ers to adjust the gain. refer to the mem- ory map were the multipliers bits can be set in registers ch0_ati_base (0xc8) to ch2_ati_base (0xca). 7.11.4 re-ati an automatic re-ati event will occur if the cs is outside its re-ati limits. the re-ati limit is cal- culated as the target value divided by 8. for ex- ample: target = 1024 re-ati will occur if cs is outside 1024 128. a re-ati event can also be issued by the master by setting the redo_ati bit. it will clear automatically after the ati event was started. 8 dycal tm the dycal tm technique is explained in section 5 . dycal tm detections are displayed in the dy- copyright ? azoteq IQS253 datasheet v1.04 19of 53
iq switch ? proxsense ? series cal_out register. the IQS253 will also dis- play whether each channel is in tm in the dy- cal_tm register. important factors to consider when designing the dycal tm functionality are: 8.1 dycal tm channels enable explained in section 7.5 . 8.2 dycal tm on touch/prox the dycal tm output bits can either be indicated when a proximity (default) or touch is detected by con?guring the out- put_on_touch bit. 8.3 lta adapt rates (in and out) explained in section 7.9.1 . 8.4 block channel a touch on channel 1 can be used to block (and clear) the other channels outputs. this is useful in event mode as the mcu can remain uninter- rupted from the IQS253 while a touch is present on ch1. o dycal_out if a channel is in dycal tm mode o touch if a channel is in direct-output mode by setting bit block_on_ch1_enable. it should be noted that, if another channel had a dycal tm detection and channel 1 detects a touch event, it will clear the other channels dycal tm outputs. 8.5 dycal tm release threshold the release threshold is relevant for when a channel is released after it was in tm. it is dependent on the selected touch threshold and the setting chosen with bits rel_thr1:rel_thr0. (note: the touch threshold can either be the user selected touch threshold or the dynamic touch thresh- old, whichever is larger) example: technology: self capacitive lta ntm = 1024 (ic in ntm, before detection) lta tm = 850 (ic in tm, after detection) touch thr = lta ntm *30/256 rel thr = 75% * touch thr answer: o the IQS253 detects a touch condition if: cs < lta ntm - touch thr , where touch thr = 1024*30/256 = 120. thus if cs goes below 1024 - 120 = 904. channel is in tm. o the ic will exit tm and clear the dy- cal_out bit if: cs > lta tm + 0.75*120 thus if cs ex- ceeds 850 + 90 = 940 ic will exit tm and clear dycal_out. 8.6 dycal tm dynamic touch threshold the IQS253 calculates a dynamic touch thresh- old. this dynamic threshold enables the ic to calculate more accurately when a user re- leases a button. the lta will reseed to [lta - touch thr ] once a touch is made. using self capacitance as example; the cs will probably go much lower than the value to which the lta reseeded. the IQS253 will only calculate the dynamic touch threshold once the lta is within 16 counts of the cs. 8.7 10s_ati_block after a touch is released and the lta is re- seeded towards the cs, it is highly probable that the lta will be outside the re-ati bound- aries of the ic. this feature helps the channels copyright ? azoteq IQS253 datasheet v1.04 20of 53
iq switch ? proxsense ? series to block the re-ati function for 10 seconds af- ter an actuation has been released. it is also applicable if a channel is con?gured in direct- output mode. the 10seconds block of re-ati after an actuation can be disabled by setting the 10s_ati_block bit. 8.8 250ms_delay_tm (t dycal ) by default, the lta will only reseed to [lta - touch thr ] after t dycal , when entering tm. an option exists to disable this delay, thus the lta will reseed to [lta - touchthr] immediately with the detection of a touch. 8.9 turbo mode the channels are charged in sequence and have a ?xed period. by setting the turbo_mode bit, this period will be shortened to the fastest possible period, negating any dead-time. the ac ?lter will also be disabled for transfers to complete as fast as possible. if dycal is en- abled, the turbo_mode bit will also allow the ic to enter touch mode as fast as possible upon an event. copyright ? azoteq IQS253 datasheet v1.04 21of 53
iq switch ? proxsense ? series 9 communication the IQS253 can communicate on the i 2 c com- patible bus structure. it uses the 2 wire serial interface bus which is i 2 c compatible and an optional rdy pin is available which indicates the communication window. the IQS253 has four available sub addresses, 44h (default) to 47h that is selected upon purchase of the ic. the maximum i 2 c compatible communication speed for the IQS253 is 400kbit/s. please refer to azd062 - IQS253 communication interface guidelines [ 6 ] and the memory map in appendix b for more details. 9.1 ic setup window the IQS253 has a setup window in which the user has the option to write some start-up set- tings before any conversions are done. for example, the setup window can be used to change the ic from self (default) to projected sensing mode. figure 9.1: ic setup window. t start _ up after vddhi was powered, rdy will go low for this setup window. after address- ing the ic, the required settings should be up- dated and only thereafter should a stop bit be issued. the ic will then start with its con- versions. if the setup window is not serviced within t comms , the rdy will go high again (ac- cording to section 9.3.3 ). most settings can be updated at any time on the ic, except switching between self and projected capacitance tech- nology, which can only be done in the setup window. this setting can also be con?gured with a fg which would then not require set- ting up this function via i 2 c commands. as the setup window is only available once after por, applications which do not have control over the IQS253 supply, or have more than one IQS253 on the bus should use the fg option to select between self or projected capacitance. 9.2 event mode IQS253 will in default be con?gured to only communicate with the master if a change in an event occurs (except for the setup win- dow after por). for this reason, it would be highly recommended to use the rdy line when communicating with the IQS253. these com- munication requests are referred to as event mode (only change of events are reported). event mode can be disabled by setting the event_mode_disable bit. the events re- sponsible for resuming communication can be chosen through the event_mask register. by default all events are enabled. the master has the capability to force a communication window at any time, by pulling the rdy line low. the communication window will open directly follow- ing the current conversion. 9.3 i 2 c speci?c commands 9.3.1 reset indication show_reset can be read to determine whether a reset occurred on the device. this bit will be a 1 after a reset. the value of show_reset can be cleared to 0 by writing a 1 in the ack_reset bit. 9.3.2 wdt the wdt is used to reset the ic if a problem (for example a voltage spike) occur during com- munication. the wdt will time-out after t wdt if no valid communication occur for this time. 9.3.3 time-out if no communication is initiated from the mas- ter within the ?rst t comms of the rdy line indicating that data is ready, the ic will re- sume with the next channels charge transfers. this time-out can be disabled by setting the time_out_disable bit. 9.4 i 2 c read and write speci?cs please refer to the memory map and sam- ple code document for the i 2 c read and write copyright ? azoteq IQS253 datasheet v1.04 22of 53 v d d h i r d y t c o m m s t s t a r t _ u p
iq switch ? proxsense ? series speci?cs as implemented on most proxsense ? devices. copyright ? azoteq IQS253 datasheet v1.04 23of 53
iq switch ? proxsense ? series 10 boolean output boolean arithmetic can be applied to one or a combination of channels to get a result. this result is available in the boolean_output bit in the touch register. for the self ca- pacitive IQS253 version, a digital signal output pin (b_out) exists, which corresponds to the boolean output bit. this output pin is to be used for level detection on a master controller, or to be used with a fet for led driving. the pin is not rated to sink or source current. in both the self and projected con?guration, the "event mode" communication could be triggered on a boolean based result. the boolean output will be calculated using: o dycal_out if channel is in dycal tm mode o touch output if channel is in direct-output mode 10.1 channels for boolean oper- ation the channels that should be used to com- pute the boolean output bit is chosen in the boolean_settings register. 10.2 boolean not a boolean not can be applied to any or all channels. 10.3 boolean and/or the boolean and operation will be applied to the chosen channels. the or op- eration can alternatively be applied if the boolean_and_or bit is set. 10.4 order of boolean opera- tion: 1. choose channels for boolean operation 2. should not be applied to a channel? 3. and/or operation? 11 rf noise 11.1 noise immunity the IQS253 has advanced immunity to rf noise sources such as gsm cellular tele- phones, dect, bluetooth and wifi devices. design guidelines should however be followed to ensure the best noise immunity. the design of capacitive sensing applications can encom- pass a large range of situations but as a sum- mary the following should be noted to improve a design: o a ground plane should be placed under the ic, except under the cx line. o all the tracks on the pcb must be kept as short as possible. o the capacitor between vddhi and vss as well as between vreg and vss, must be placed as close as possible to the ic. o a 100 pf capacitor can be placed in paral- lel with the 1uf capacitor between vddhi and vss. another 100 pf capacitor can be placed in parallel with the 1uf capaci- tor between vreg and vss. o when the device is too sensitive for a spe- ci?c application a parasitic capacitor (max 5pf) can be added between the cx line and ground. o proper sense electrode and button design principles must be followed. o unintentional coupling of sense electrode to ground and other circuitry must be lim- ited by increasing the distance to these sources or making use of the driven shield. o in some instances a ground plane some distance from the device and sense elec- trode may provide signi?cant shielding from undesired interference. copyright ? azoteq IQS253 datasheet v1.04 24of 53
iq switch ? proxsense ? series when the capacitance between the sense elec- trode and ground becomes too large the sensi- tivity of the device may be in?uenced. 11.1.1 rf detection in cases of extreme rf interference, the on- chip rf detection is suggested. this detec- tor can be enabled by setting the nd bit in the prox_settings1 register. by connecting a suitable antenna to the rf pin, it allows the de- vice to detect rf noise and notify the master of possible corrupt data. noise affected sam- ples are not allowed to in?uence the lta ?lter, and also do not contribute to dycal, prox or touch detection. with the detection of noise, the noise bit in sysflags will be set. 11.1.2 rf detector sensitivity the sensitivity of the rf detector can be se- lected by setting an appropriate rf detection voltage through the nd_trim bits. please see azd015 for further details regarding this. copyright ? azoteq IQS253 datasheet v1.04 25of 53
iq switch ? proxsense ? series 12 electrical speci?cations absolute maximum speci?cations the following absolute maximum parameters are speci?ed for the device: exceeding these maxi- mum speci?cations may cause damage to the device. o operating temperature 40 c to + 85 c o supply voltage (vddhi - gnd) 3 . 6 v o maximum pin voltage vddhi + 0 . 5 v o maximum continuous current (for speci?c pins) 2 ma o minimum pin voltage gnd - 0 . 5 v o minimum power-on slope 100 v / s o esd protection (hbm) 4 kv o moisture sensitivity level msop-10 msl 1 o moisture sensitivity level dfn-10 msl 3 12.1 general characteristics (measured at 25 c ) table 12.1: IQS253 general operating conditions - projected capacitive sensor. description conditions parameter min typ max unit supply voltage vddhi 1.8 3.3 3.6 v internal regulator output 1.8 vddhi 3.3 vreg 1.62 1.7 1.79 v boost power operating current 1.8 vddhi 3.3 i bp 180 <250 a low_power = 00h low power 32 operating current 1.8 vddhi 3.3 i lp 32 13 <20 a low_power = 20h low power 255 operating current 1.8 vddhi 3.3 i lp 255 4.5 <8 a low_power = ffh table 12.2: IQS253 general operating conditions - self capacitive sensor. description conditions parameter min typ max unit supply voltage vddhi 1.8 3.3 3.6 v internal regulator output 1.8 vddhi 3.3 vreg 1.62 1.7 1.79 v boost power operating current 1.8 vddhi 3.3 i bp 150 <200 a low_power = 00h low power 32 operating current 1.8 vddhi 3.3 i lp 32 11 <15 a low_power = 20h low power 255 operating current 1.8 vddhi 3.3 i lp 255 3.5 <6 a low_power = ffh copyright ? azoteq IQS253 datasheet v1.04 26of 53
iq switch ? proxsense ? series table 12.3: start-up and shut-down slope characteristics description condition parameter min max unit por vddhi slope 100 v / s por 1.2 1.6 v bod bod 1.15 1.55 v table 12.4: debounce employed on IQS253. description conditions value proximity debounce value prox_debounce = 0 6 prox_debounce = 1 4 touch debounce value - 2 12.2 timing characteristics table 12.5: general timing characteristics for 1.80v vddhi 3.60v symbol description typ unit t start up start-up time before the setup win- dow is iniatiated by the IQS253 15 ms t comms time after which communication window will terminate, if not ad- dressed 22 ms f cx ic transfer frequency see xfer_freq in IQS253 mem- ory map mhz t ch arge charge time of channel cs * (1/fcx) ms t ch annel charge time interval 9.01ms t sample sample time of channel active channels * t ch annel ms t bp channel sampling period in bp and turbo_mode = off t sample ms t bp _ turbo channel sampling period in bp and turbo_mode = off active channels * t ch arge ms t lp low power charging time cs*(1/fcx) + t ch arge t wdt wdt time-out while communicating 160 ms t dycal time before switching to tm in dycal tm operation 225 250 275 ms copyright ? azoteq IQS253 datasheet v1.04 27of 53
iq switch ? proxsense ? series table 12.6: IQS253 charging times power mode typical (ms) boost power mode with turbo_mode on 4 boost power mode 9 low power mode 4 64 low power mode 8 128 low power mode 16 256 low power mode 32 512 low power mode 64 1024 low power mode 255 4080 table 12.7: IQS253 dycal (output_on_touch = 0) /proximity response times power mode conditions min** unit boost power mode with turbo_mode on 1 detection with small cs change (prox) and acf off 135 ms detection with large cs change (touch) and acf off 81 release time with acf off 81 ms boost power mode 2 detection with large cs change (touch) and acf off 331 ms release time with acf off 81 ms power modes 3 see example see example ms see example (take 250ms off total time) ms **note: minimum bit set times are dependent on the size of the change in cs caused by the user actuation because the minimum time is a function of the debounce of either the touch / proximity caused. the setting of indication bits are delayed by a charge transfer cycle. with acf = on, detection and release times will dramatically increase due to the cs having to go through a ?ltering process adding a delay lp response time example: low_power = 34h (52d): t lp = 16ms x 52 = 832ms channels active = 2: t sample = 18ms + 9ms for extra channel 2 sampling acf = off: fast respose on cs large cs change: touch debounce = 2 detectiontimelp52 = 27 + 832 + (2 + 1)*27 + 250 = 1.19seconds 1 minimum detection and release times = (debounce +1) x t sample 2 boost power detection and release times = (debounce +1) x t sample + 250ms 3 lp modes = t sample + t lp + (debounce + 1) x t sample + 250m copyright ? azoteq IQS253 datasheet v1.04 28of 53
iq switch ? proxsense ? series 13 mechanical dimensions figure 13.1: msop10 package. table 13.1: msop10 package dimensions. dimension [mm] a min 2.90 a max 3.10 b min 2.90 b max 3.10 h max 1.1 l min 4.75 l max 5.05 t min 0.40 t max 0.80 pitch 0.50 w min 0.17 w max 0.27 figure 13.2: msop10 footprint. table 13.2: msop-10 footprint dimensions dimension mm pitch 0.50 c 4.40 y 1.45 x 0.30 figure 13.3: msop10 silk screen. table 13.3: msop-10 silk screen dimen- sions dimension mm r1 2.30 r2 3.00 figure 13.4: dfn-10 package dimensions. copyright ? azoteq IQS253 datasheet v1.04 29of 53 !" !"#

iq switch ? proxsense ? series table 13.4: dfn-10 package dimensions. dimension [mm] a 3 0.1 b 0.5 c 0.25 d f 3 0.1 l 0.4 p 2.4 q 1.65 figure 13.5: dfn-10 package side view. table 13.5: dfn-10 side view dimensions. dimension mm g 0.05 h 0.65 i 0.7 - 0.8 figure 13.6: dfn-10 footprint. table 13.6: dfn-10 footprint dimensions dimension mm a 2.38 b 1.64 c 0.60 d 0.50 e 0.25 f 2.80 copyright ? azoteq IQS253 datasheet v1.04 30of 53 a b c d e p a c k a g e o u t l i n e f
iq switch ? proxsense ? series 14 device marking pin1 mark on package - bottom left. revision x = ic revision number temperature range t = i 40 c to 85 c (industrial) = c 0 c to 70 c (commercial) ic configuration z = con?guration (hexadecimal) 0 = 44h (self capacitance) 1 = 45h (self capacitance) 2 = 46h (self capacitance) 3 = 47h (self capacitance) 4 = 44h (projected capacitance) 5 = 45h (projected capacitance) 6 = 46h (projected capacitance) 7 = 47h (projected capacitance) date code p = package house ww = week yy = year 15 ordering information orders will be subject to a moq (minimum order quantity) of a full reel. contact the of?cial distrib- utor for sample quantities. a list of the distributors can be found under the "distributors" section of www.azoteq.com. the IQS253 has 4 i 2 c sub-addresses available. the default address is 0x44h. for further enquiries regarding this, please contact azoteq or a local distributor. copyright ? azoteq IQS253 datasheet v1.04 31of 53 i q s 2 5 3 x t z p w w y y r e v i s i o n d a t e c o d e s u b a d d r e s s c o n f i g u r a t i o n t e m p e r a t u r e i q s 2 5 3 z p p b i c n a m e s u b a d d r e s s c o n f i g u r a t i o n b u l k p a c k a g i n g p a c k a g e t y p e
iq switch ? proxsense ? series ic name IQS253 = IQS253 bottom marking z = i 2 c sub address (hexadecimal) package type ms = msop-10 dn = dfn-10 bulk packaging r = reel (msr 4000pcs/reel) - moq = 4000pcs r = reel (dnr 3000pcs/reel) - moq = 3000pcs t = tube (96pcs/tube, special order, ms only) 16 device revision history revision device id package markings comments 0 3114 x3911 projected bias current default 10ua unable to ?oat cx/crx no event mode with boolean output enabled 1 4100 x0112 or later projected bias current default 5ua 17 errata the z ?eld is omitted on the package marking on batch code 21512. the con?guration is 0 on this lot. copyright ? azoteq IQS253 datasheet v1.04 32of 53
iq switch ? proxsense ? series 18 contact information pretoria office paarl office physical address physical address 160 witch hazel avenue 109 main street hazel court 1, 1st floor paarl highveld techno park 7646 centurion, gauteng western cape republic of south africa republic of south africa tel: +27 12 665 2880 tel: +27 21 863 0033 fax: +27 12 665 2883 fax: +27 21 863 1512 postal address postal address po box 16767 po box 3534 lyttelton paarl 0140 7620 republic of south africa republic of south africa the following patents relate to the device or usage of the device: us 6,249,089 b1, us 6,621,225 b2, us 6,650,066 b2, us 6,952,084 b2, us 6,984,900 b1, us 7,084,526 b2, us 7,084,531 b2, us 7,119,459 b2, us 7,265,494 b2, us 7,291,940 b2, us 7,329,970 b2, us 7,336,037 b2, us 7,443,101 b2, us 7,466,040 b2, us 7,498,749 b2, us 7,528,508 b2, us 7,755,219 b2, us 7,772,781, us 7,781,980 b2, us 7,915,765 b2, ep 1 120 018 b1, ep 1 206 168 b1, ep 1 308 913 b1, ep 1 530 178 b1, zl 99 8 14357.x, aus 761094 iq switch ? , proxsense ? , lightsense tm , airbutton ? and the logo are trademarks of azoteq. the information appearing in this datasheet is believed to be accurate at the time of publication. azoteq assumes no liability arising from the use of the information or the product. the applications mentioned herein are used solely for the purpose of illustration and azoteq makes no warranty or representation that such applications will be suitable without further modi?cation, nor recommends the use of its products for application that may present a risk to human life due to malfunction or otherwise. azoteq products are not authorised for use as critical components in life support devices or systems. no licenses to patents are granted, implicitly or otherwise, under any intellectual property rights. azoteq reserves the right to alter its products without prior noti?cation. for the most up-to-date information, please refer to www.azoteq.com. copyright ? azoteq IQS253 datasheet v1.04 33of 53
iq switch ? proxsense ? series a appendix a dycal tm illustrations to view the illustrations in appendix a , the document requires to be opened with adobe reader version 6 or later. note that all illustrations are supplementary, and are not required to use with the datasheet. figure a.1: dycal output selected on proximity, for a projected capacitive ic. note that the ic still only enters tm (touch mode) when the counts exceed the touch threshold, but the dycal output is active after exceeding the proximity threshold. figure a.2: dycal output selected on touch, for a projected capacitive ic. note that the dycal output is only active when the ic enters tm (touch mode) when the counts exceed the touch threshold. copyright ? azoteq IQS253 datasheet v1.04 34of 53
iq switch ? proxsense ? series figure a.3: filter halt upon touch mode entry, for a self capacitive ic. the lta will halt upon proximity detection (regardless on which output dycal was selected). however, when a touch condition is registered, the ?lter will stop halting, to allow the lta to follow the counts. copyright ? azoteq IQS253 datasheet v1.04 35of 53
iq switch ? proxsense ? series b appendix b IQS253 memory map the memory map of the IQS253 is provided in this section, along with a description of each register and instruction. the IQS253 communicates via i 2 c. for an example implementation that provides example code, refer to [ 6 ]. the general proxsense ? memory map is shown below. address access size(bytes) device information 00h-0fh r 16 address access size(bytes) device speci?c data 10h-30h r 32 address access size(bytes) proximity status bytes 31h-34h r 4 address access size(bytes) touch status bytes 35h-38h r 4 address access size(bytes) halt bytes 39h-3ch r 4 address access size(bytes) active bytes (indicate cycle) 3dh-41h r 4 address access size(bytes) counts 42h-82h r 64 address access size(bytes) ltas 83h-c3h r/w 64 address access size(bytes) device settings c4h-fdh r/w 64 note: fe and ff are reserved for other functions in communication. b.1 IQS253 memory map copyright ? azoteq IQS253 datasheet v1.04 36of 53
iq switch ? proxsense ? series b.1.1 device information 00h product number (prod_nr) access bit 7 6 5 4 3 2 1 0 r value 41 (decimal) 01h software number (sw_nr) access bit 7 6 5 4 3 2 1 0 r value sw_nr [00h] prod_nr the product number for the IQS253 is 41 (decimal). [01h] sw_nr the software version number of the device rom can be read in this byte. production version ics sw numbers are 0 for self and projectd. the engineering version numbers are shown below. IQS253 sw nr description 13 (decimal) IQS253 - 3 channel self capacitive sensor version 1 14 (decimal) IQS253 - 3 channel projected sensor version 1 b.1.2 device speci?c data 10h system flags (sysflags) access bit 7 6 5 4 3 2 1 0 name system_ system_ show_ proj_ lp ati_ noise zoom r use use reset mode busy [10h] sysflags bit 7: system_use bit 6: system_use bit 5: show_reset: this bit can be read to determine whether a reset occurred on the device since the ack_reset bit has been set. the value of show_reset can be set to 0 by writing a 1 in the ack_reset bit in the prox_settings_2 byte. bit 4: proj_mode: capacitive sensing technology used 0 = self capacitive sensing 1 = projected capacitive sensing bit 3: lp: if a lp mode is enabled, this bit indicates that charging is currently occurring in a lp rate. 0 = full-speed charging 1 = charging currently occur at a lower rate bit 2: ati_busy: status of automated ati routine 0 = auto ati is not busy 1 = auto ati in progress copyright ? azoteq IQS253 datasheet v1.04 37of 53
iq switch ? proxsense ? series bit 1: noise: this bit indicates the presence of noise interference. 0 = ic has not detected the presence of noise 1 = ic has detected the presence of noise bit 0: zoom: zoom will indicate full-speed charging once an undebounced proximity is detected. in np mode, this will not change the charging frequency. 0 = ic not zoomed in 1 = ic detected undebounced proximity and ic is charging at full-speed b.1.3 proximity status bytes the proximity status of all the channels on the device are shown here. these bits should not be monitored if the ic is in dycal mode. 31h proximity status (prox) access bit 7 6 5 4 3 2 1 0 r name ch2 ch1 ch0 [31h] prox the proximity status of the channels is indicated in this byte. the prox bit of a channel should not be used if a channel is set as a dycal channel. bit 7-3: system_use bit 2: ch2: indicate that a proximity event has been detected on ch2 0 = no proximity event detected 1 = proximity event detected bit 1: ch1: indicate that a proximity event has been detected on ch1 0 = no proximity event detected 1 = proximity event detected bit 0: ch0: indicate that a proximity event has been detected on ch0 0 = no proximity event detected 1 = proximity event detected b.1.4 touch status bytes the touch status of all the channels on the device are shown here. these bits should not be monitored if the ic is in dycal mode. 35h touch status (touch) access bit 7 6 5 4 3 2 1 0 r name boolean_output ch2 ch1 ch0 [35h] touch the touch status of the channels is indicated in this byte. the touch bit of a channel should not be used if a channel is set as a dycal channel. bit 7: boolean_output: a boolean combination can be outputted to this bit. the boolean combination can be con?gured through bytes boolean_settings and boolean_not. this bit will correspond with the output status of the b_out pin of the IQS253 self capacitive ic. 0 = boolean output not active copyright ? azoteq IQS253 datasheet v1.04 38of 53
iq switch ? proxsense ? series 1 = boolean output active bit 6-3: unused bit 2: ch2: indicate that a touch event has been detected on ch2 0 = no touch event detected 1 = touch event detected bit 1: ch1: indicate that a touch event has been detected on ch1 0 = no touch event detected 1 = touch event detected bit 0: ch0: indicate that a touch event has been detected on ch0 0 = no touch event detected 1 = touch event detected b.1.5 dycal touch mode indication 36h dycal tm indication (dycal_tm) bit 7 6 5 4 3 2 1 0 access name ch2 ch1 ch0 r note indicates if channel is in tm [36h] dycal_tm if a channel is con?gured as a dycal channel, these bits will indicate whether tm has been entered. tm is entered once the touch threshold of a channel has been exceeded. bit 7-3: unused bit 2: ch2: ch2 tm indication 0 = channel not in tm 1 = channel in tm bit 1: ch1: ch1 tm indication 0 = channel not in tm 1 = channel in tm bit 0: ch0: ch0 tm indication 0 = channel not in tm 1 = channel in tm b.1.6 dycal output indication 37h dycal output indication (dycal_out) bit 7 6 5 4 3 2 1 0 access name ch2 ch1 ch0 r indicates a dycal detection on a channel [37h] dycal_out if a channel is con?gured as a dycal channel, these bits will indicate whether the dycal output is set. it will default be set with the detection of a proximity, but can be set by a touch by con?guring bit dy- cal_settings:output_on_touch. copyright ? azoteq IQS253 datasheet v1.04 39of 53
iq switch ? proxsense ? series bit 7-3: unused bit 2: ch2: ch2 dycal output 0 = dycal not detected 1 = dycal detected bit 1: ch1: ch1 dycal output 0 = dycal not detected 1 = dycal detected bit 0: ch0: ch0 dycal output 0 = dycal not detected 1 = dycal detected b.1.7 halt bytes the lta ?lter halt status of all the channels are shown here. 39h lta halt status (halt) access bit 7 6 5 4 3 2 1 0 r name ch2 ch1 ch0 [39h] halt indicate the halting state of each channels long term average (lta). if in non-tm, the halt bit of a channel will be set once proximity is detected. once a touch is detected, the ic will enter tm and the halt bit will be cleared. the halting bit will now only be set again if the cs exceeds the lta by 16 in self or if the cs is less than the lta by more than 16 in projected mode. bit 7-3: unused bit 2: ch2: ch2 lta halting state 0 = channels lta adapts to the environment 1 = channels lta halted bit 1: ch1: ch1 halting state 0 = channels lta adapts to the environment 1 = channels lta halted bit 0: ch0: ch0 halting state 0 = channels lta adapts to the environment 1 = channels lta halted b.1.8 channel number 3dh channel number bit 7 6 5 4 3 2 1 0 access value variable (0-2) r note indicates which channels data is currently available [3dh] chan_num the channel number that can be read in this byte indicates which channels data is currently available. copyright ? azoteq IQS253 datasheet v1.04 40of 53
iq switch ? proxsense ? series b.1.9 counts the counts of the current channel is available here. 42h counts (cs_h) bit 7 6 5 4 3 2 1 0 access value variable (high byte) r note counts of active channel (see channel number) 43h counts (cs_h) bit 7 6 5 4 3 2 1 0 access value variable (low byte) r note counts of active channel (see channel number) [42h & 43h] cs_h & cs_l the counts for the current channel can be read in this byte. the high byte and low byte are found in consecutive addresses. b.1.10 long-term averages the long-term average of the current channel is available here to read. 83h long-term average (lta_h) bit 7 6 5 4 3 2 1 0 access value variable (high byte) r note lta of active channel (see channel number) 84h long-term average (lta_l) bit 7 6 5 4 3 2 1 0 access value variable (low byte) r note lta of active channel (see channel number) [83h & 84h] lta_h & lta_l the lta value for the current channel can be read in this byte. the high byte and low byte are found in consecutive addresses. b.1.11 device settings it is attempted that the commonly used settings are situated closer to the top of the memory block. settings that are regarded as more once-off are placed further down. c4h ati target value (ati_target) bit 7 6 5 4 3 2 1 0 access value ati target value (x8 to get real target) r/w default 1 0 0 0 0 0 0 0 note 128 decimal (x8 gives target value = 1024) copyright ? azoteq IQS253 datasheet v1.04 41of 53
iq switch ? proxsense ? series [c4h] ati_target the automated ati target can be set in this byte. the value written to this byte multiplied by 8 will be the target value of all 3 channels. if a new target value is required, the required target (divided by 8) should be written to this byte, where-after a re-ati event should be sent. all 3 channels will now be at the target value once the sysflags_ati_busy ?ag is cleared. ati multiplier and compensation the ati multiplier and ati compensation bits allow the controller to be compatible with a large range of sensors, and in many applications with different environments. ati allows the user to maintain a speci?c sample value on all channels. the ati multiplier parameters would produce the largest changes in sample values and can be thought of as the high bits of ati. the ati compensation bits are used to in?uence the sample values on a smaller scale to provide precision when balancing all channels as close as possible to the target. the ati multiplier parameters are further grouped into two parameters namely ati multiplier- compensation and ati multiplier-sensitivity. ati multiplier-compensation consists of 2 bits and has the biggest effect on the sample value and can be considered as the highest bit of the ati parameters. the ati multiplier-sensitivity can be adjusted with 4 bits for each channel. the value of 1111 would provide the highest cs value and the value of 0000 would provide the lowest. c5h ch0 compensation (comp0) bit 7 6 5 4 3 2 1 0 access value automatically adjusted when ati enabled r/w default 0 c6h ch1 compensation (comp1) bit 7 6 5 4 3 2 1 0 access value automatically adjusted when ati enabled r/w default 0 c7h ch2 compensation (comp2) bit 7 6 5 4 3 2 1 0 access value automatically adjusted when ati enabled r/w default 0 [c5h, c6h, c7h] compensation settings (ch0_comp, ch1_comp, ch2_comp) the compensation settings for each channel are contained in these bytes. the values in these bytes are auto- matically determined if the auto ati function was used. if prox_settings0:ati_off is set, the automatic ati setting is disabled and this byte can be altered to achieve a custom target value. the ati compensation parameter can be con?gured for each channel in a range between 0-255 (decimal). the ati compensation bits can be used to make small adjustments of the sample values of the individual channels. c8h ch0 ati base and multipliers (ch0_ati_base) bit 7 6 5 4 3 2 1 0 access value ch0_ ch0_ mult_ mult_ mult_ mult_ mult_ mult_ base1 base0 comp1 comp0 sense3 sense2 sense1 sense0 r/w gain scale copyright ? azoteq IQS253 datasheet v1.04 42of 53
iq switch ? proxsense ? series c9h ch1 ati base and multipliers (ch1_ati_base) bit 7 6 5 4 3 2 1 0 access ch1_ ch1_ mult_ mult_ mult_ mult_ mult_ mult_ r/w base1 base0 comp1 comp0 sense3 sense2 sense1 sense0 cah ch2 ati base and multipliers (ch2_ati_base) bit 7 6 5 4 3 2 1 0 access ch2_ ch2_ mult_ mult_ mult_ mult_ mult_ mult_ r/w base1 base0 comp1 comp0 sense3 sense2 sense1 sense0 [c8h, c9h, cah] base values and multiplier settings (ch0_base, ch1_base, ch2_base) the base value or multiplier settings of each channel can be set in these bytes. bit 7-6: chx_base1:chx_base0: channel base values alt_base = 0; alt_base = 1 00 = 200; 00 = 150 01 = 50; 01 = 350 10 = 100; 10 = 500 11 = 250; 11 = 700 bit 5-4: mult_comp1:mult_comp0: multiplier compensation setting. 00 = 1:1 (smallest) 01 = 3:1 10 = 1:3 11 = 1:9 bit 3-0: mult_sense3:mult_sense0: multiplier sensitivity setting 0000 = 1 (smallest) 0001 = 2 0010 = 3 0011 = 4 0100 = 5 0101 = 6 0110 = 7 0111 = 8 1000 = 9 1001 = 10 1010 = 11 1011 = 12 1100 = 14 1101 = 14 1110 = 16 1111 = 18 copyright ? azoteq IQS253 datasheet v1.04 43of 53
iq switch ? proxsense ? series cbh proximity sensitivity threshold (prox_thr_ch0) bit 7 6 5 4 3 2 1 0 access name pt_7 pt_6 pt_5 pt_4 pt_3 pt_2 pt_1 pt_0 r/w default 0 0 0 0 0 1 0 0 cch proximity sensitivity threshold (prox_thr_ch1) bit 7 6 5 4 3 2 1 0 access name pt_7 pt_6 pt_5 pt_4 pt_3 pt_2 pt_1 pt_0 r/w default 0 0 0 1 0 0 cdh proximity sensitivity threshold (prox_thr_ch2) bit 7 6 5 4 3 2 1 0 access name pt_7 pt_6 pt_5 pt_4 pt_3 pt_2 pt_1 pt_0 r/w default 0 0 0 1 0 0 [cbh, cch & cdh] proximity sensitivity settings (prox_th_chx) proximity sensitivity thresholds can be anything from 1 to 64. ceh touch sensitivity threshold (touch_thr_ch0) bit 7 6 5 4 3 2 1 0 access name tt_5 tt_5 tt_5 tt_4 tt_3 tt_2 tt_1 tt_0 r/w default 0 0 1 0 0 0 0 0 note touch thr = (value / 256 * lta) cfh touch sensitivity threshold (touch_thr_ch1) bit 7 6 5 4 3 2 1 0 access name tt_5 tt_5 tt_5 tt_4 tt_3 tt_2 tt_1 tt_0 r/w default 0 0 1 0 0 0 0 0 note touch thr = (value / 256 * lta) d0h touch sensitivity threshold (touch_thr_ch2) bit 7 6 5 4 3 2 1 0 access name tt_5 tt_5 tt_5 tt_4 tt_3 tt_2 tt_1 tt_0 r/w default 0 0 1 0 0 0 0 0 note touch thr = (value / 256 * lta) [ceh, cfh & d0h]touch sensitivity settings (touch_th_chx) touch sensitivity thresholds are calculated as a fraction of the lta: touch thr = (touch_thr_chx / 256 * lta). there are 256 possible touch threshold values. copyright ? azoteq IQS253 datasheet v1.04 44of 53
iq switch ? proxsense ? series d1h proxsense module settings 0 (prox_settings0) bit 7 6 5 4 3 2 1 0 access value ati_ ati_ 10s_ati_ redo_ reseed cs_ proj_ proj_ off partial block ati size bias1 bias0 r/w default 0 0 1 0 0 1 1 1 [d1h] prox_settings0 bit 7: auto_ati: disables the automated ati routine. by enabling this bit, the device will not be able to redo ati if the counts are outside their boundaries. 0 = auto ati routine active 1 = ati disabled bit 6: ati_partial: enable partial ati. 0 = if ati occur, it will use the base values as reference 1 = if ati occur, it will use the multiplier_compx and multiplier_sensx as reference bit 5: ati_block: enable the 10 second block of ati after an actuation. 0 = channels will always redo ati if lta is outside boundaries if no actuation is detected 1 = ati will be blocked for 10 seconds after an actuation has occurred. bit 4: redo_auto_ati: force the ati routine to perform. the last written ati_target value will be used as target. 0 = no action 1 = force ati routine to perform. bit 3: reseed: reseed the lta ?lter. this can be used to adapt to an abrupt environment change, where the ?lter is too slow to track this change. note that with the short and long halt selections, an automatic reseed will be performed when the halt time has expired, thus automatically adjusting to the new surroundings. 0 = do not reseed 1 = reseed (this is a global reseed) bit 2: cs: set the size of the internal sampling capacitor. a larger cs capacitor requires more transfers (higher counts) to be charged. 0 = 29.9pf 1 = 59.8pf bit 1-0: proj_bias1:proj_bias0: projected bias current 00 = 1.25ua (smallest) 01 = 2.5ua 10 = 5ua 11 = 10ua d2h proxsense module settings 1 (prox_settings1) bit 7 6 5 4 3 2 1 0 access value proj alt_ turbo_ hc nd nd_ nd_ nd_ base mode trim0 trim0 trim0 r/w default 0 0 0 0 0 0 0 0 [d2] prox_settings1 copyright ? azoteq IQS253 datasheet v1.04 45of 53
iq switch ? proxsense ? series bit 7: proj: use the IQS253 in projected mode. this setting can only be enabled in the setup commu- nications window. alternatively, us the fg option. 0 = IQS253 in self capacitive sensing mode 1 = IQS253 in projected capacitive sensing mode bit 6: alt_base: set this bit to choose the alternative base values 0 = normal base values 1 = alternative base values bit 5: turbo_mode: enable the dycal turbo functionality (if dycal is enabled). by enabling this bit, the device will drastically decrease the time to detect users proximity and touch events. 0 = normal 1 = enable turbo mode bit 4: hc: halt charges. the device will not perform capacitive sensing charge transfers and thus not be able to detect any user events. 0 = charge transfers occur normally 1 = no charge transfers occur bit 3: nd: noise detection enable. this setting is used to enable the on-chip noise detection circuitry. with noise detected, the noise affected samples will be ignored, and have no effect on the prox, touch or lta calculations. the noise bit will appropriately be set as indication of the noise status. 0 = disable noise detection 1 = enable noise detection bit 2-0: nd_trim2:nd_trim0: nd trim values 000 = 19.1mv 001 = 9.65mv 010 = 0mv 011 = -10mv 100 = -19.1mv 101 = -29.8mv 110 = -40.9mv 111 = -57.4mv d3h proxsense module settings 2 (prox_settings2) bit 7 6 5 4 3 2 1 0 access value ack_ comms_ force_ acf_ time_ event_ halt1 halt0 reset wdt_ halt disable out_ mode _ disable disable disable r/w default 0 (w) 0 0 0 0 0 0 0 [d3h] prox_settings2 bit 7: ack_reset: acknowledge show_reset. 0 = nothing 1 = clear the show_reset ?ag (send only once) bit 6: wdt_disable: device watchdog timer (wdt) disable. copyright ? azoteq IQS253 datasheet v1.04 46of 53
iq switch ? proxsense ? series 0 = enabled 1 = disabled bit 5: force_halt: the lta is halted by setting this bit. it will only be allowed to adapt to the environment once it is cleared. 0 = lta adapts to environment until actuation detected. 1 = halt lta. bit 4: acf_disable: disable the ac filter employed on the counts (cs). 0 = enable ac ?lter. 1 = disable ac ?lter. bit 3: time_out_disable: enable i 2 c communication timeout. this bit will enable the ic to resume charge transfers if communication does not commence within 20ms of the rdy indicating that data is ready. 0 = disable time-out. 1 = enable time-out. bit 2: event_mode_disable: enable the ic to stream data continuously. 0 = i 2 c communication will only occur if an event occur (events de?ned in event_mode_mask byte) 1 = continuous streaming mode bit 1-0: halt1:halt0: lta halt timings. 00 = 20s 01 = 40s 10 = never 11 = always d4h proxsense module settings 3 (prox_settings3) bit 7 6 5 4 3 2 1 0 access value lta_ lta_ prox_ xfer_ xfer_ adapt1 adapt0 debounce freq1 freq0 r/w default 0 1 [d4h] prox_settings3 bit 7-6: unused bit 5-4: lta_adapt: rate at which lta adapts to cs when no actuation is detected (non- tm mode). 00 = 3.13% (fastest) 01 = 1.56% 10 = 0.78% 11 = 0.39% (slowest) bit 3: unused bit 2: prox_debounce: number of consecutive cs samples required exceeding proximity threshold to detect a proximity event. 0 = 6 1 = 4 bit 1-0: xfer_freq1:xfer_freq0: charge transfer frequency. copyright ? azoteq IQS253 datasheet v1.04 47of 53
iq switch ? proxsense ? series 00 = 1mhz 01 = 500khz 10 = 250khz 11 = 125khz the charge transfer frequency is a very important parameter. dependant on the design application, the device frequency must be optimised. for example, if keys are to be used in an environment where steam or water droplets could form on the keys, a higher transfer frequency improves immunity. also, if a sensor electrode is a very large object/size, then a slower frequency must be selected since the capacitance of the sensor is large, and a slower frequency is required to allow effective capacitive sensing on the sensor. d5h active channels (active_chan) bit 7 6 5 4 3 2 1 0 access value ch2 ch1 ch0 r/w default 1 1 1 [d5h] active_chan each channel can be individually disabled in this register. bit 7-3: unused bit 2: ch2: setting this bit will disable the channel 0 = active / charging 1 = inactive / not charging bit 1: ch1: setting this bit will disable the channel 0 = active / charging 1 = inactive / not charging bit 0: ch0: setting this bit will disable the channel 0 = active / charging 1 = inactive / not charging d6h low power settings (low_power) bit 7 6 5 4 3 2 1 0 access value lp7 lp6 lp5 lp4 lp3 lp2 lp1 lp0 r/w default normal power default (00h). see note below. note custom value between 1 and 256 value x 16ms lp time [d6h] lp_period byte indicates the sleep time between a burst of conversions. default (00h), a channel is charged every 27ms. the lp time can be set to any custom value between 1 and 256. the time between the conversions will then be the value x 16ms. (note: cx2 does a dummy conversion before the burst of the active channels are executed.) d7h dycal speci?c settings (dycal_settings) bit 7 6 5 4 3 2 1 0 access value 250ms_ always_ beta_ beta_ beta_ output_ rel_ rel_ delay_ halt_ tm_ tm_ tm_in on_ thr1 thr0 tm dycal out1 out0 touch r/w default 0 0 0 0 0 0 0 0 copyright ? azoteq IQS253 datasheet v1.04 48of 53
iq switch ? proxsense ? series [d7h] dycal_settings byte indicates which channels are actively charged. bit 7: 250ms_delay_tm: a 250ms delay is applied on the lta when a touch is detected, before the lta is reseeded to the lta-touch_thr 0 = enabled 1 = disabled bit 6: always_halt_dycal: always halt lta in tm if cs exceeds lta by 16 (self) or if cs is lower than lta by 16 (projected) 0 = halting of lta in tm according to halt1:halt0 settings 1 = always halt lta if above condition is met bit 5-4: lta_adapt_in: rate at which lta adapts after reseed when heading towards the cs in tm 00 = 1.56% 01 = 6.25% (fastest) 10 = 3.13% 11 = 0.78% (slowest) bit 3: lta_adapt_out: rate at which lta adapts after its reached cs, when cs is heading out of tm. 0 = 0.10% (fastest) 1 = 0.01% (slowest) bit 2: output_on_touch: setting this bit will enable the dycal output to change with touch actuation. 0 = dycal on proximity 1 = dycal on touch bit 1-0: release_thr1:release_thr0: release threshold with which cs should exceed lta for lta to reseed back to non-tm. 00 = 75% 01 = 50% 10 = 87.5% 11 = 100% d8h dycal channels enable (dycal_chans) bit 7 6 5 4 3 2 1 0 access name block_on_ch1_enable ch2 ch1 ch0 r/w default 0 1 1 1 [d8h] dycal enable and block channel enable (dycal_chans) channels are default con?gured as dycal channels. clearing a channel bit, will make it a direct output channel. bit 7-4: unused bit 3: ch1_block: setting this bit will make channel 1 a block channel 0 = normal output 1 = ch1 will block the output of the other channels if actuated bit 2: ch2: clearing this bit, will make the channel a direct output channel 0 = direct output channel copyright ? azoteq IQS253 datasheet v1.04 49of 53
iq switch ? proxsense ? series 1 = dycal channel bit 1: ch1: clearing this bit, will make the channel a direct output channel 0 = direct output channel 1 = dycal channel bit 0: ch0: clearing this bit, will make the channel a direct output channel 0 = direct output channel 1 = dycal channel d9h event mode mask (event_mask) bit 7 6 5 4 3 2 1 0 access name ati dycal boolean noise touch prox r/w default 1 1 1 1 1 1 [d9h] event mode mask (event_mask) bit 7-6: unused bit 5: ati: a communication event will occur if an ati or re-ati occurs. 0 = communication event will not occur 1 = communication event will occur bit 4: dycal: a communication event will occur if a dycal state change occurs. 0 = communication event will not occur 1 = communication event will occur bit 3: boolean: a communication event will occur if a boolean state change occurs. 0 = communication event will not occur 1 = communication event will occur bit 2: noise: a communication event will occur if noise is detected. 0 = communication event will not occur 1 = communication event will occur bit 1: touch: a communication event will occur if a proximity state change occurs. should only be used if a channel is in direct mode. 0 = communication event will not occur 1 = communication event will occur bit 0: proximity: a communication event will occur if a proximity state change occurs. should only be used if a channel is in direct mode. 0 = communication event will not occur 1 = communication event will occur dah boolean settings (boolean_settings) bit 7 6 5 4 3 2 1 0 access value bool_ and_or mask_ ch2 mask_ ch1 mask_ ch0 r/w default 0 0 0 0 [dah] boolean_settings copyright ? azoteq IQS253 datasheet v1.04 50of 53
iq switch ? proxsense ? series bit 7-4: unused bit 3: boolean_and_or: boolean and operation on the channels chosen to perform this action on 0 = boolean and operation 1 = boolean or operation bit 2: ch2: use this channel in the boolean operation 0 = no 1 = yes bit 1: ch1: use this channel in the boolean operation 0 = no 1 = yes bit 0: ch0: use this channel in the boolean operation 0 = no 1 = yes dbh boolean not mask (boolean_not) bit 7 6 5 4 3 2 1 0 access name not_ ch2 not_ ch1 not_ ch0 r/w default 0 0 0 [dbh] boolean_not bit 7-3: unused bit 2: ch2: invert this channels polarity (not operation) 0 = no action 1 = not channel (invert channel polarity) bit 1: ch1: invert this channels polarity (not operation) 0 = no action 1 = not channel (invert channel polarity) bit 0: ch0: invert this channels polarity (not operation) 0 = no action 1 = not channel (invert channel polarity) ddh default_comms_pointer access bit 7 6 5 4 3 2 1 0 r/w default 10h (beginning of device speci?c data) [ddh] default comms pointer the value stored in this register will be loaded into the comms pointer at the start of a communication window. for example, if the design only requires the proximity status information each cycle, then the default comms pointer can be set to address 31h. this would mean that at the start of each communication window, the comms pointer would already be set to the proximity status register, simply allowing a read to retrieve the data, without the need of setting up the address. copyright ? azoteq IQS253 datasheet v1.04 51of 53
iq switch ? proxsense ? series b.2 general implementation hints when implementing the communication interface with the IQS253, please refer to the IQS253 datasheet for a detailed description of the i 2 c communication. this section contains some general guidelines and hints regarding the communication interface. b.2.1 i 2 c communication window when communicating via i 2 c, the communication window will automatically close when a stop bit is received by the IQS253. the IQS253 will then proceed to start with a new conversion and the ready line will be pulled low until the new conversion is complete. note that there is no command via i 2 c to initiate a new conversion. to perform multiple read and write commands, the repeated start function of the i 2 c must be used to stack the commands together. b.3 startup procedure after sending initial settings to the IQS253, it is important to execute a reseed. it is suggested to execute an estimated 24 conversions after initial settings before calling for a reseed, to allow the system to stabilise. b.4 general i 2 c hints b.4.1 i 2 c pull-up resistors when implementing i 2 c it is important to remember the pull-up resistors on the data and clock lines. 4.7k is recommended, but for lower clock speeds bigger pull-ups will reduce power consumption. the rdy line is sw od and also requires a pull up resistor (typical 10k). copyright ? azoteq IQS253 datasheet v1.04 52of 53
iq switch ? proxsense ? series references [1] azd008 - design guidelines for touch pads . azoteq, 2011. [2] azd013 - calculating rx for improving esd ratings . azoteq, 2008. [3] azd015 - rf immunity guidelines . azoteq, 2011. [4] azd051 - electrical fast transient burst guidelines . azoteq, 2011. [5] azd052 - conducted rf immunity guidelines . azoteq, 2011. [6] azd062 - IQS253 communication interface guideline . azoteq, 2012. copyright ? azoteq IQS253 datasheet v1.04 53of 53
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