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micrf112 qwikradio ? uhf ask/fsk transmitter qwikradio is a registered trademark of micrel, inc. micrel inc. ? 2180 fortune drive ? san jose, ca 95131 ? usa ? te l +1 (408) 944-0800 ? fax + 1 (408) 474-1000 ? http://www.micre l.com december 2011 m9999-120911 (408) 944-0800 general description the micrf112 is a high performance, easy to use, single chip ask / fsk transmitter ic for remote wireless applications in the 300 to 450mhz frequency band. this transmitter ic is a true ?data-in, antenna-out? monolithic device. micrf112 is high performance in three areas: power delivery, operating voltage, and operating temperature. in terms of power, the micrf112 is capable of delivering +10 dbm into a 50 ? load. this power level enables a small form factor transmitter (lossy antenna) such as a key fob transmitter to operate near the maximum limit of transmission regulations. in terms of operating voltage, the micrf112 operates from 3.6v to 1.8v. many transmitter ics in the same frequency band stop operating below 2.0v. the micrf112 will work with most batteries to the end of their useful lim its. in terms of operating temperature, the micrf112 operates from -40c to +125c. this wide operating temperature range makes micrf112 an ideal candidate for the demanding applications such as a tire pressure monitoring system. the micrf112 is easy to use. one only needs a reference frequency (rf carrier frequency divided by 32 times) generated from a crystal with a few additional external parts to create a comp lete versatile transmitter. the micrf112 operates with ask/ook (amplitude shift keying/on-off keyed) uhf receiver types from wide-band super-regenerative radios to narrow-band, high performance super-heterodyne receivers. the micrf112?s maximum ask data rate is 50kbps (manchester encoding). it operates with fsk receivers as well. the chip is designed to support narrow band fsk (frequency shift modulation) by switching an external capacitor in parallel with the reference crystal. the micrf112?s maximum fsk data rate is 10kbps. features ? complete uhf transmitter ? frequency range 300mhz to 450mhz ? data rates up to 50kbps ask, 10kbps fsk ? output power to 10dbm ? low external part count ? low standby current <1a ? low voltage operation (down to 1.8v) ? operate with crystals or ceramic resonators applications ? remote keyless en try systems (rke) ? remote control (stb, hvac and appliances) ? garage door opener transmitters ? remote sensor data links ? infrared transmitter replacement ? tire pressure monitor system (tpms) ordering information part number temp. range package micrf112ymm10 ?40c to +125c 10-pin msop
micrel, inc. micrf112 december 2011 2 m9999-120911 (408) 944-0800 typical application figure 1. micrf112 ask key fob design note: values in parenthesis are for 315mhz
micrel, inc. micrf112 december 2011 3 m9999-120911 (408) 944-0800 pin configuration x tal_mod fsk 6 5 1 ask xtlin xtlout vss 10 vdd paout vsspa en 9 8 7 2 3 4 10-pin msop (m) pin description pin number msop-10 pin name pin function 1 ask ask data input 2 xlin reference oscillator input connection. 3 xtlout reference oscillator output connection. 4 vss ground 5 xtal_mod reference oscillation modulation port for fsk operation. 6 fsk fsk data input 7 en chip enable, active high 8 vsspa pa ground 9 pa_out pa output 10 vdd positive power supply
micrel, inc. micrf112 december 2011 4 m9999-120911 (408) 944-0800 absolute maximum ratings (note 1) supply voltage vdd ...................................................+5.0v voltage on paou t......................................................+7.2v voltage on i/o pins ............................ vss?0.3 to vdd+0.3 storage temperature rang e ....................-65c to + 150c lead temperature (soldering, 10 seconds) ............ + 300c esd rating .................................................................note 3 operating ratings (note 2) supply voltage vdd ........................................ 1.8v to 3.6v ambient operating temperat ure (ta) ...... ?40c to +125c programmable transmitter frequency range: ....................................................... 300mhz to 450mhz electrical characteristics (note 4) speci cations apply for vdd = 3.0v, ta = 25c, freq refosc = 13.560mhz, en = vdd. bold values indicate ?40c to 125c unless otherwise noted. 1kbps data rate 50% duty cycle. rl 50ohm load (matched) parameter condition min typ max units power supply standby supply current, iq en = v ss .05 1a a @ 315mhz, p out = +10dbm 11.2 ma mark supply current i on @ 433.92mhz, p out = +10dbm 11.2 ma @ 315mhz 2.7 ma space supply current, i off @ 433.92 mhz 2.7 ma rf output section and modulation limits: @315mhz, note 4 10.5 dbm output power level, p out fsk or ask "mark" @433.92mhz, note 4 10.5 dbm @ 630mhz, note 4 2nd harm. -39 dbc harmonics output for 315 mhz @945mhz, note 4 3rd harm. -53 dbc @ 867.84mhz, note 4 2nd harm. -55 dbc harmonics output for 433.92 mhz @1301.76mhz, note 4 3rd harm. -55 dbc extinction ratio for ask 70 dbc fsk modulation frequency deviation load capacitor = 10pf, crystal type = hc49/u 22 khz data rate 10 kbps ask modulation data rate 50 kbps @315mhz, note 6 <700 khz occupied bandwidth @433.92mhz, note 6 <1000 khz vco section @ 100khz from carrier -76 dbc/hz 315 mhz single side band phase noise @ 1000khz from carrier -79 dbc/hz @ 100khz from carrier -72 dbc/hz 433.92 mhz single side band phase noise @ 1000khz from carrier -81 dbc/hz reference oscillator section xtlin, xtlout, xtlmod pin capacitance 2 pf external capacitance see schematic c17 & c18 18 pf oscillator startup time note 5 crystal: hc49s 300 s digital / control section output blanking stdby transition from low to high 500 s
micrel, inc. micrf112 december 2011 5 m9999-120911 (408) 944-0800 electrical characteristics (cont.) parameter condition min typ max units high (v ih ) 0.8v dd v digital input (en, ask and fsk) low (v il ) 0.2v dd v high (v ih ) 0.05 a digital input leakage current (en, ask and fsk pins) low (v il ) 0.05 a under voltage lock out (uvlo) 1.6 v note 1. exceeding the absolute maximum rating may damage the device. note 2. the device is not guaranteed to function outside its operating rating. note 3. devices are esd sensitive. handling precautions recommended. human body model, 1.5k in series with 100pf. note 4. measured using te st circuit in figure 2. note 5. dependent on crystal note 6. rbw = 100khz, obw measured at -20dbc.
micrel, inc. micrf112 december 2011 6 m9999-120911 (408) 944-0800 test circuit figure 2. micrf112 test circuit with 50 ? output note 1. values without parenthesis are for 433 .92 mhz and values in parenthesis are for 315mhz note 2. c9 = 100pf for external ref-osc note 3. for fsk r1 = 0 ? , r2 = np, r6 = 100k, and r5 = np
micrel, inc. micrf112 december 2011 7 m9999-120911 (408) 944-0800 assembly drawing micrf112 50 ohm test board top layer micrf112 50 ohm test board bottom layer micrf112 50 ohm test board
micrel, inc. micrf112 december 2011 8 m9999-120911 (408) 944-0800 typical characteristics using micrf112, 50 ? test board 315mhz obw, ask = 1khz 315mhz obw, ask = 50khz cw max power @ 3v, 315mhz, ask = 1khz, note 1 rf spectrum 2 nd harmonic; fundamental at 315 mhz rf spectrum 3 rd harmonic; fundamental at 315 mhz 315mhz, power level at space, vdd = 3.0v, ask = 1khz note 1. 1.2db cable loss.
micrel, inc. micrf112 december 2011 9 m9999-120911 (408) 944-0800 315mhz, zero span , ask = 1khz 315mhz, zero span, ask = 50khz 315mhz, phase noise, ask = 1khz, 100khz offset, ?75.59dbc/hz 315mhz, phase noise, ask = 1khz, 1mhz offset, ?78.99dbc/hz 315mhz, phase noise, ask = cw, 100khz offset, ?74.39dbc/hz 315mhz, phase noise, ask = cw, 1mhz offset, ?77.28dbc/hz
micrel, inc. micrf112 december 2011 10 m9999-120911 (408) 944-0800 433.92mhz obw, ask = 1khz 433.92mhz obw, ask = 50khz 433.92mhz, cw max power @ 3v, ask = 1khz, note 1 rf spectrum 2 nd harmonic; fundamental at 433.92 mhz rf spectrum 3 rd harmonic; fundamental at 433.92 mhz 433.92mhz power level at space, vdd = 3.0v, ask = 1khz note 1. 1.3db cable loss.
micrel, inc. micrf112 december 2011 11 m9999-120911 (408) 944-0800 433.92mhz zero span, 1khz 433.92ask zero span at 50khz 433.92mhz phase noise, ask = cw, 100khz offset, ?81.04dbc/hz 433.92mhz phase noise, ask = cw, 1mhz offset, ?78.76dbc/hz 433.92mhz phase noise, ask = 1khz, 100khz offset, ?71.73dbc/hz 433.92mhz phase noise, ask = 1khz, 1mhz offset, ?81.04dbc/hz
micrel, inc. micrf112 december 2011 12 m9999-120911 (408) 944-0800 functional diagram figure 3. functional block diagram micrf112 10 pin ask / fsk version functional description figure 3 shows a functional block diagram of the micrf112 transmitter. the micrf112 can be best described as a phase locked transmitter. the system can be partitioned into six functional blocks; crystal oscillator, pll32, power ampli er, enable control, under voltage detect and open drain switch for fsk operation. crystal oscillator the reference oscillator is crystal-based pierce con guration. it is designed to accept crystals with frequency from 9.375mhz to 14.0625mhz. crystal oscillator parameters for ask operation figure 4 shows a reference oscillator circuit con guration for ask operation. the reference oscillator is capable of driving crystals with esr range from 20 ? to 300 ? . when the esr of crystal is at 20 ? , the crystal parameter limits are: esr 20 ? c par 2 to 10pf c mo 10 to 40ff figure 4. reference oscillator ask operation when the esr of crystal is at 300 ? , the crystal parameter limits are: esr 300 ? c par 2 to 5pf c mo 10 to 40ff c load 10 to 30pf
micrel, inc. micrf112 december 2011 13 m9999-120911 (408) 944-0800 crystal oscillator for fsk operation figure 5 shows reference oscillator circuit con guration for fsk operation. to operate the micrf112 in fsk mode, one additional capacitor is needed between xtalout pin and xtalmod pin. crystal parameters for fsk operation are the same as ask operation except: ? when the esr of crystal is at 20 ? , c fsk + c load not to exceed 70pf. ? when the esr of crystal is at 300 ? , c fsk + c load not to exceed 30pf figure 5. reference oscillator fsk operation pll 32 the function of pll32 is to provide a stable carrier frequency for transmission. it is a ?divided by 32? phase locked oscillator. power amplifier the power amplifier serves two purposes: 1) to buffer the vco from external elements and 2) to amplify the phase locked signal. the power amplifier can produce +10dbm at 3v (typical). enable control enable control gates the ask data. it only allows transmission when lock, amplitude and under voltage detect conditions are valid. under voltage detect ?under voltage detect? block senses operating voltage. if the operating voltage falls below 1.6v, ?under voltage detect? block will send a signal to ?enable control? block to disable the pa. open drain switch open drain switch is used for fsk operation. fsk data is fed into the fsk pin. the fsk pin is connected to the gate of the open drain switch. the open collector is connected to the xtalmod pin. in figure 4, a capacitor is shown connected from xtalmod pin to xtalout. when fsk pin goes high, the capacitor between xtalmod and xtalout pulls the frequency of refosc low .
micrel, inc. micrf112 december 2011 14 m9999-120911 (408) 944-0800 application information figure 6. ask 433.92mhz and 315mhz note: values in parenthesis are for 315mhz the micrf112 is well suited to drive a 50 ohms source, monopole or a loop antenna. figure 6 is an example of a loop antenna configuration. figure 6 also shows both 315mhz and 433.92mhz ask conf igurations for a loop antenna. besides using a different crystal, table 1 lists modified values needed for the listed frequencies. frequency (mhz) l1 (nh) c5 (pf) l4 (nh) c7 (p f) y1 (mhz) 315.0 470 10 150 6.8 9.84375 433.92 680 10 82 4.7 13.5600 table 1 the reference design shown in figure 6 has an antenna optimized for using the matching network as described in table 1. power control using external resistor r7 is used to adjust the rf output levels which may be needed to meet compliance. as an example, the following tables list typical values of conducted rf output levels and corresponding r7 resistor values for the 50 ? test board shown in figur e 2. r7 of the tx112 demo board using the loop antenna can be adjusted for the appropriate radiated field allowed by fcc or etsi compliance. contact micrel for suggested values to meet fcc and etsi compliances. r7, ? output power, dbm idd, ma 0 10 6.7 75 8.5 6.3 100 8.0 6.2 500 1.6 4.13 1000 -3.8 4.87 output power versus external resistor at 315mhz r7, ? output power, dbm idd, ma 0 8.68 7.5 75 8.34 7.33 100 8.02 7.3 500 4.34 6.3 1000 0.42 5.5 output power versus external resistor at 433.92 mhz
micrel, inc. micrf112 december 2011 15 m9999-120911 (408) 944-0800 output matching network part of the function of the output network is to attenuate the second and third harmonics. when matching to a transmit frequency, care must be taken not only to optimize for maximum output power but to attenuate unwanted harmonics. layout issues pcb layout is of primary concern to achieve optimum performance and consistent manufacturing results. care must used on orientation of components to ensure they do not couple or decouple the rf signal. pcb trace length should be short to minimize parasitic inductance, (1 inch ~ 20nh). for example, depending on inductance values, a 0.5 inch trace can change the inductance by as much as 10%. to reduce para sitic inductance, the use of wide traces and a ground plane under signal traces is recommended. vias with low value inductance should be used for components requiring a connection-to-ground. antenna layout directivity is affected by an tenna trace layout. no ground plane should be under the antenna trace. for consistent performance, components should not be placed inside the loop of the antenna. ge rbers for figure 7, with a suggested layout, can be obtained on the micrel web site at: http://www.micrel.com.
micrel, inc. micrf112 december 2011 16 m9999-120911 (408) 944-0800 pcb board assembly drawing micrf112 demo board top layer micrf112 demo board bottom layer micrf112 demo board figure 7. demo board pcb
micrel, inc. micrf112 december 2011 17 m9999-120911 (408) 944-0800 figure 8. tx112-1 demo board schematic note: configuration is for ask operation. values in parenthesis are for 315mhz
micrel, inc. micrf112 december 2011 18 m9999-120911 (408) 944-0800 functional description of tx112-1 evaluation board. figure 7 shows the tx112-1 demo board pcb. figure 8 is a detailed schematic of the tx112-1. note that components labeled as np are to obtain different configurations including fsk mode of operation. table 2 describes each header pin connector used in the demo board. pin function name functional description j1-1 vdd 1.8v to 3.6v j1-2 ground vss j1-3 ask input modulating data input, ask or fsk j2-1 ref-osc external reference input j2-2 ground vss j2-3 enable enable input, active high tx112-1-433.92 ask bill of materials item quantity ref part pcb footprint mfg p/n manufacturer 1 1 c1 10f 0805 grm21br60j106ke01l murata 2 1 c2 100pf 0603 grm1885c1h101ja01d murata 3 1 c5 10pf 0603 grm1885c1h100ja01d murata 4 3 r1,r4,r6 (np) 5 5 c6,c8,c11,c12,c15 (np) 6 1 c7 4.7pf 0603 grm1885c1h4r7ja01d murata 7 1 c10 0.1f 0603 grm188f51h104za01d murata 8 2 c13,c14 18pf 0603 grm1885c1h180ja01d murata 9 2 j1,j2 con3 tshr-114-s-02-a-gt 10 1 l1 680nh 0805 0805cs-680xjb coilcraft 11 1 l4 82nh 0603 0603cs-082nxjb coilcraft 12 1 l5 antenna antenna loop, part of pcb 13 1 r2 100k ? 0603 crcw0603100kfkea vishay 14 6 r3,r5,r7 r8,jpr1,jpr2 0 ? 0603 crc06030000z0ea vishay 13 1 u1 micrf112ymm10 micrf112ym micrel 14 1 y1 13.560mhz xtal sa-13.5600-f-10-c-3-3 hib table 2
micrel, inc. micrf112 december 2011 19 m9999-120911 (408) 944-0800 tx112-1-315mhz ask bill of materials item quantity ref part pcb footprint mfg p/n manufacturer 1 1 c1 10f 0805 grm21br60j106ke01l murata 2 1 c2 100pf 0603 grm1885c1h101ja01d murata 3 1 c5 10pf 0603 grm1885c1h1000ja01d murata 4 3 r1,r4,r6 (np) 5 5 c6,c8,c11,c12,c15 (np) 6 1 c7 4.7pf 0603 grm1885c1h6r8ja01d murata 7 1 c10 0.1f 0603 grm188f51h104za01d murata 8 2 c13,c14 18pf 0603 grm1885c1h180ja01d murata 9 2 j1,j2 con3 tshr-114-s-02-a-gt 10 1 l1 470nh 0805 0805cs-470xjb coilcraft 11 1 l4 150nh 0603 0603cs-r15xjb coilcraft 12 1 l5 antenna antenna loop, part of pcb 13 1 r2 100k ? 0603 crcw0603100kfkea vishay 14 6 r3,r5,r7 r8,jpr1,jpr2 0 ? 0603 crc06030000z0ea vishay 13 1 u1 micrf112ymm10 micrf112ym micrel 14 1 y1 9.84375mhz xtal sa-9.84375-f-10-c-3-3 hib table 3 fsk operation table 2 and 3 describe the ask operat ion for 433.92mhz and 315mhz. table 4 lists the component values t hat change between ask or fsk operation. please note that use of a high fsk data rate may excite parasitic resonant modes with some crys tal types. recommended crystals from table 2 and 3 are good for both ask and fsk. mode r1 r2 r5 r6 jpr1 jpr2 c8 ask np 100k ? 0 ? np 0 ? np np fsk 0 ? np np 100k ? np 0 ? (1)3.3pf (2)10pf notes: 1. c8 = 3.3pf for 1khz using hc49/u or hc49us type crystals. 2. c8= 10pf for 10khz using hc49/u, (high profile) only. table 4: ask and fsk settings r3 r4 constant on 0 ? np external standby control np 100k ? table 5: enable control (shutdown)
micrel, inc. micrf112 december 2011 20 m9999-120911 (408) 944-0800 package information 10-pin msop package type (ymm10) micrel, inc. 2180 fortune drive san jose, ca 95131 usa tel +1 (408) 944-0800 fax +1 (408) 474-1000 web http://www.micrel.com the information furnished by micrel in this data sheet is belie ved to be accurate and reliable. however, no responsibility is a ssumed by micrel for its use. micrel reserves the right to change circuitry and specifications at any time without notification to the customer. micrel products are not designed or authori zed for use as components in life support app liances, devices or systems where malfu nction of a product can reasonably be expected to result in pers onal injury. life support devices or system s are devices or systems that (a) are in tended for surgical implant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significan t injury to the user. a purchaser?s use or sale of micrel products for use in life support appli ances, devices or systems is at purchaser?s own risk an d purchaser agrees to fully indemnify micrel for any damages resulting from such use or sale. ? 2011 micrel, incorporated.

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