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rev. g ad7416/ad7417/ad7418 10-bit digital temperature sensor (ad7416) and four single-channel adcs (ad7417/ad7418) information furnished by analog devices is believed to be accurate and reliable. however, no responsibility is assumed by analog devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. no license is granted by implication or otherwise under any patent or patent rights of analog devices. trademarks and registered trademarks are the property of their respective owners. one technology way, p.o. box 9106, norwood, ma 02062-9106, u.s.a. tel: 781/329-4700 www.analog.com fax: 781/326-8703 ?2004 analog devices, inc. all rights reserved. features 10-bit adc with 15 s and 30 s conversion times single and four single-ended analog input channels on-chip temperature sensor: ?0 c to +125 c on-chip track-and-hold overtemperature indicator automatic power-down at the end of a conversion wide operating supply range: 2.7 v to 5.5 v i 2 c compatible serial interface selectable serial bus address allows connection of up to eight ad7416/ad7417s to a single bus ad7416 is a superior replacement for lm75 applications data acquisition with ambient temperature monitoring industrial process control automotive battery-charging applications personal computers functional block diagrams v dd oti gnd sda scl fault queue counter setpoint comparator t oti setpoint register t hyst setpoint register temperature value register a0 a1 a2 configuration register serial bus interface band gap temperature sensor 10-bit analog-digital converter address pointer register ad7416 control logic a > b ref in v dd oti scl sda a2 a1 a0 convst a in1 a in2 a in3 a in4 + temp sensor sampling capacitor v balance clock a b ref 2.5v charge distribution dac i 2 c interface mux overtemp reg nc nc gnd data out nc = no connect ad7417 control logic a > b v dd oti scl sda a in1 + sampling capacitor v balance clock a b i 2 c interface mux overtemp reg gnd data out temp sensor ref in convst ref 2.5v charge distribution dac ad7418 general description the ad7417 and ad7418 are 10-bit, 4-channel and single- channel adcs with an on-chip temperature sensor that can operate from a single 2.7 v to 5.5 v power supply. the devices contain a 15 s successive approximation converter, a 5-channel multiplexer, a temperature sensor, a clock oscilla- tor, a track-and-hold, and a reference (2.5 v). the ad7416 is a temperature-monitoring only device in an 8-lead package. the temperature sensor on the parts can be accessed via multi- plexer channel 0. when channel 0 is selected and a conversion is initiated, the resulting adc code at the end of the conversion gives a measurement of the ambient temperature ( 1 c @ 25 c). on-chip registers can be programmed with high and low tem- perature limits, and an open-drain overtemperature indicator (oti) output is provided, which becomes active when a pro- grammed limit is exceeded. a configuration register allows programming of the sense of the oti output (active high or active low) and its operating mode (comparator or interrupt). a programmable fault queue counter allows the number of out-of-limit measurements that must occur before triggering the oti output to be set to prevent spurious triggering of the oti output in noisy environments. (continued on page 7)
rev. g e2e ad7416/ad7417/ad7418 (v dd = 2.7 v to 5.5 v, gnd = 0 v, ref in = 2.5 v, unless otherwise noted.) parameter a version b version 1 unit test conditions/comments dc accuracy any channel. resolution 10 10 bits minimum resolution for which no missing codes are guaranteed 10 10 bits relative accuracy 2 1 1l sb max this specification is typical for v dd of 3.6 v to 5.5 v. differential nonlinearity 2 1 1l sb max this specification is typical for v dd of 3.6 v to 5.5 v. gain error 2 3 3l sb max external reference. 10 10 lsb max internal reference. gain error match 2 0.6 0.6 lsb max ad7417 only. offset error 2 4 4lsb max offset error match 0.7 0.7 lsb max ad7417 only. analog inputs input voltage range v ref v ref v max 00 v min input leakage current 3 1 1 a max input capacitance 10 10 pf max temperature sensor 1 measurement error ambient temperature 25 c 2 1 c max t min to t max 3 2 c max temperature resolution 1/4 1/4 c/lsb conversion rate track-and-hold acquisition time 4 400 400 ns max source impedance < 10 . conversion time temperature sensor 30 30 s max typically 27 s. channels 1 to 4 15 15 s max typically 10 s. reference input 5, 6 ref in input voltage range 6 2.625 2.625 v max 2.5 v + 5%. 2.375 2.375 v min 2.5 v C
rev. g ad7416/ad7417/ad7418 e3e notes 1 b version applies to ad7417 only with temperature range of C C C C C C C
rev. g e4e ad7416/ad7417/ad7418 ad7417 pin function description pin no. mnemonic description 1, 16 nc no connection. do not connect anything to this pin. 2 sda digital i/o. serial bus bidirectional data. push-pull output. 3 scl digital input. serial bus clock. 4 oti this is a logic output. the overtemperature indicator (oti) is set if the result of a conversion on chan nel 0 (temperature sensor) is greater than an 8-bit word in the overtemperature register (otr). the signal is reset at the end of a serial read operation. open-drain output. 5 ref in reference input. an external 2.5 v reference can be connected to the ad7417 at this pin. to enable the on-chip reference, the refin pin should be tied to gnd. if an external reference is connected to the ad7417, the internal reference will shut down. 6g nd ground reference for track-and-hold, comparator and capacitor dac, and digital circuitry. 7 C convst sctt convst convst t so nconton soctsso tovw ns ncnoconnct nc s sc ot n n n n nc convst v n n
rev. g ad7416/ad7417/ad7418 e5e ad7416 pin function description pin no. mnemonic description 1 sda digital i/o. serial bus bidirectional data. push-pull output. 2 scl digital input. serial bus clock. 3 oti this is a logic output. the oti is set if the result of a conversion on channel 0 (temperature sensor) is greater that an 8-bit word in the otr. the signal is reset at the end of a serial read operation. open- drain output. 4g nd ground reference for track-and-hold, comparator and capacitor dac, and digital circuitry. 5a 2d igital input. the highest programmable bit of the serial bus address. 6a 1d igital input. the middle programmable bit of the serial bus address. 7a 0d igital input. the lowest programmable bit of the serial bus address. 8v dd positive supply voltage, 2.7 v to 5.5 v. ad7418 pin function description pin no. mnemonic description 1 sda digital i/o. serial bus bidirectional data. push-pull output. 2 scl digital input. serial bus clock. 3 oti this is a logic output. the oti is set if the result of a conversion on channel 0 (temperature sensor) is greater that an 8-bit word in the otr. the signal is reset at the end of a serial read operation. open- drain output. 4g nd ground reference for track-and-hold, comparator and capacitor dac, and digital circuitry. 5a in analog input channel. the input channel is single-ended with respect to gnd. the input channel can convert voltage signals in the range 0 v to v ref . the analog input channel is selected by writing to the configuration register of the ad7418 and choosing channel 4. (see control byte section.) 6 ref in reference input. an external 2.5 v reference can be connected to the ad7418 at this pin. to enable the on-chip reference, the ref in pin should be tied to gnd. if an external reference is connected to the ad7418, the internal reference will shut down. 7v dd positive supply voltage, 2.7 v to 5.5 v. 8 convst sctt convst convst t so nconton socso tovw ns s sc ot n v nconton socso tovw ns s sc ot n convst v n n
rev. g e6e ad7416/ad7417/ad7418 absolute maximum ratings 1 (t a = 25 c, unless otherwise noted.) v dd to agnd . . . . . . . . . . . . . . . . . . . . . . . . . C C C C C C C C C ja thermal impedance . . . . . . . . . . . . . . . . . . . . . 120 c/w lead temperature, soldering . . . . . . . . . . . . . . . . . . 260 c vapor phase (60 sec) . . . . . . . . . . . . . . . . . . . . . . . 215 c infrared (15 sec) . . . . . . . . . . . . . . . . . . . . . . . . . . . 220 c 16-lead soic package, power dissipation . . . . . . . . 450 mw ja thermal impedance . . . . . . . . . . . . . . . . . . . . . 100 c/w lead temperature, soldering vapor phase (60 sec) . . . . . . . . . . . . . . . . . . . . . . . 215 c infrared (15 sec) . . . . . . . . . . . . . . . . . . . . . . . . . . . 220 c 8-lead soic package, power dissipation . . . . . . . . . 450 mw ja thermal impedance . . . . . . . . . . . . . . . . . . . . . 157 c/w lead temperature, soldering vapor phase (60 sec) . . . . . . . . . . . . . . . . . . . . . . . 215 c infrared (15 sec) . . . . . . . . . . . . . . . . . . . . . . . . . . . 220 c msop package, power dissipation . . . . . . . . . . . . . . 450 mw ja thermal impedance . . . . . . . . . . . . . . . . . . . . . 206 c/w lead temperature, soldering vapor phase (60 sec) . . . . . . . . . . . . . . . . . . . . . . . 215 c infrared (15 sec) . . . . . . . . . . . . . . . . . . . . . . . . . . . 220 c notes 1 stresses above those listed under absolute maximum ratings may cause perma- nent damage to the device. this is a stress rating only; functional operation of the device at these or any other conditions above those listed in the operational sections of this specification is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. 2 if the reference input voltage is likely to exceed v dd by more than 0.3 v (e.g., during power-up) and the reference is capable of supplying 30 ma or more, it is recommended to use a clamping diode between the ref in pin and v dd pin. the diagram below shows how the diode should be connected. ref in v dd ad7417 bat81 caution esd (electrostatic discharge) sensitive device. electrostatic charges as high as 4000 v readily accumulate on the human body and test equipment and can discharge without detection. although the ad7416/ad7417/ad7418 features proprietary esd protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. therefore, proper esd precautions are recommended to avoid performance degradation or loss of functionality.
rev. g ad7416/ad7417/ad7418 e7e ordering guide temperature temperature package package model range error description branding option ad7416achips die ad7416ar C C C C C C C C C C C C C C C C C C C C C C C C C C C C C C
rev. g e8e ad7416/ad7417/ad7418 (continued from page 1) an i 2 c compatible serial interface allows the ad7416/ad7417/ ad7418 registers to be written to and read back. the three lsbs of the ad7416/ad7417 C C C convst t t convst t t t c c t t t n v n
rev. g ad7416/ad7417/ad7418 e9e typical connection diagram figure 2 shows a typical connection diagram for the ad7417. using the a0, a1, and a2 pins allows the user to select from up to eight ad7417s on the same serial bus, if desired. an external 2.5 v reference can be connected at the ref in pin. if an exter- nal reference is used, a 10 f capacitor should be connected between ref in and gnd. sda and scl form the 2-wire i 2 c compatible interface. for applications where power consump- tion is of concern, the automatic power-down at the end of a conversion should be used to improve power performance. see operating modes section of this data sheet. v dd a in1 gnd ref in supply 2.7v to 5.5v 0.1 f 10 f 10 f for e xternal r eference optional external reference ad780/ ref-192 0v to 2.5v input convst sda a in2 a in3 a in4 oti scl 2-wire serial interface ad7417 a0 a1 a2 c/ p figure 2. typical connection diagram analog inputs figure 3 shows an equivalent circuit of the analog input struc- ture of the ad7417 and ad7418. the two diodes, d1 and d2, provide esd protection for the analog inputs. care must be taken to ensure that the analog input signal never exceeds the supply rails by more than 200 mv. this will cause these diodes to become forward-biased and start conducting current into the substrate. the maximum current these diodes can conduct without causing irreversible damage to the part is 20 ma. the capacitor c2 in figure 3 is typically about 4 pf and can prima- rily be attributed to pin capacitance. the resistor r1 is a lumped component made up of the on resistance of a multiplexer and a switch. this resistor is typically about 1 k . the capacitor c1 is the adc sampling capacitor and has a capacitance of 3 pf. a in d1 c1 3pf v dd d2 c2 4pf v balance convert phase e switch open track phase e switch closed r1 1k figure 3. equivalent analog input circuit on-chip reference the ad7416/ad7417/ad7418 has an on-chip 1.2 v band gap reference that is gained up by a switched capacitor amplifier to give an output of 2.5 v. the amplifier is only powered up at the start of the conversion phase and is powered down at the end of the conversion. the on-chip reference is selected by connecting the ref in pin to analog ground. this causes sw1 (see figure 4) to open and the reference amplifier to power up during a conver- sion. therefore, the on-chip reference is not available externally. an external 2.5 v reference can be connected to the ref in pin. this has the effect of shutting down the on-chip reference circuitry. 1.2v ref in sw1 2.5v external reference detect buffer 1.2v 26k 24k + + figure 4. on-chip reference temperature measurement a common method of measuring temperature is to exploit the negative temperature coefficient of a diode, or the base-emitter voltage of a transistor, operated at a constant current. unfortu- nately, this technique requires calibration to null out the effect of the absolute value of v be , which varies from device to device. the technique used in the ad7416/ad7417/ad7418 is to measure the current change in v be when the device is operated at two different currents. this is given by vktqnn be = () /1 where: k is boltzmann
rev. g e10e ad7416/ad7417/ad7418 address pointer register the address pointer register is an 8-bit register that stores an address that points to one of the six data registers. the first data byte of every serial write operation to the ad7416/ad7417/ ad7418 is the address of one of the data registers, which is stored in the address pointer register, and selects the data register to which subsequent data bytes are written. only the three lsbs of this register are used to select a data register. table i. address pointer register p7 * p6 * p5 * p4 * p3 * p2 p1 p0 00 00 0 register select * p3 to p7 must be set to 0. table ii. register addresses p2 p1 p0 registers 0 00t emperature value (read-only) 0 01c onfig register (read/write) 0 10t hyst (read/write) 0 11t oti 1 00 adc (ad7417/ad7418 only) 1 01c onfig2 (ad7417/ad7418 only) temperature value register (address 00h) the temperature value register is a 16-bit, read-only register whose 10 msbs store the temperature reading from the adc in 10-bit twos complement format. bits 5 to 0 are unused. table iii. temperature value register d15 d14 d13 d12 d11 d10 d9 d8 d7 d6 msb b8 b7 b6 b5 b4 b3 b2 b1 lsb the temperature data format is shown in table iv. this shows the full theoretical range of the adc from C C C C C C C C v be , the sen- sor (substrate transistor) is switched between operating currents of i and n i. the resulting waveform is passed through a chopper-stabilized amplifier that performs the functions of amplification and rectification of the waveform to produce a dc voltage proportional to v be . this voltage is measured by the adc to give a temperature output in 10-bit twos complement form. the temperature resolution of the adc is 0.25 c, which corre- sponds to 1 lsb of the adc. the adc can theoretically m easure a temperature span of 255 c; the guaranteed temperature range is C C
rev. g ad7416/ad7417/ad7418 e11e configuration register (address 01h) the configuration register is an 8-bit, read/write register that is used to set the operating modes of the ad7416/ad7417/ ad7418. bits d7 to d5 control the channel selection as outlined in table vi. t hese bits should always be 0, 0, 0 for the ad7416. bits d4 and d3 are used to set the length of the fault queue. d2 sets the sense of the oti output. d1 selects the comparator or interrupt mode of operation, and d0 = 1 selects the shutdown mode (default d0 = 0). table v. configuration register d7 d6 d5 d4 d3 d2 d1 d0 channel fault oti cmp/ shut- selection queue polarity int down the ad7416 contains a temperature-only channel, the ad7417 has four analog input channels and a temperature channel, and the ad7418 has two channels, a temperature channel, and an analog input channel. the temperature chan- nel address for all parts is the same, ch0. the address for the analog input chan nel on the ad7418 is ch4. table vi outlines the channel selection on the parts, while table vii shows the fault queue settings. d1 and d2 are explained in the oti out- put section. table vi. channel selection d7 d6 d5 channel selection 00 0t emperature sensor (all parts) 00 1 a in1 (ad7417 only) 01 0 a in2 (ad7417 only) 01 1 a in3 (ad7417 only) 10 0 a in4 (ad7417) and a in (ad7418) table vii. fault queue settings d4 d3 number of faults 00 1 (power-up default) 01 2 10 4 11 6 t hyst setpoint register (address 02h) the t hyst setpoint register is a 16-bit, read/write register w hose nine msbs store the t hyst setpoint in twos complement for- m at equivalent to the nine msbs of the temperature value regis ter. bits 6 to 0 are unused. t oti setpoint register (address 03h) the t oti setpoint register is a 16-bit, read/write register whose nine msbs store the t oti setpoint in twos complement format equivalent to the nine msbs of the temperature value regis ter. bits 6 to 0 are unused. table viii. setpoint registers d15 d14 d13 d12 d11 d10 d9 d8 d7 msb b7 b6 b5 b4 b3 b2 b1 lsb adc value register (address 04h) the adc value register is a 16-bit, read-only register whose 10 msbs store the value produced by the adc in binary for- mat. bits 5 to 0 are unused. table ix shows the adc value register with 10 msbs containing the adc conversion request. table ix. adc value register d15 d14 d13 d12 d11 d10 d9 d8 d7 d6 msb b8 b7 b6 b5 b4 b3 b2 b1 lsb adc transfer function the designed code transitions occur at successive integer lsb values (i.e., 1 lsb, 2 lsb, and so on). the lsb size = vref/ 1024. the ideal transfer function characteristic for the ad7417 and ad7418 adc is shown in figure 7. 111...111 111...110 111...000 011...111 000...010 000...001 000...000 adc code 0v 1/2lsb +vref e 1lsb analog input 1lsb = v ref/1024 figure 7. ideal transfer function characteristic for the ad7417/ad7418 config2 register (address 05h) a second configuration register is included in the ad7417/ ad7418 for the functionality of the convst pin. it is an 8-bit register with bits d5 to d0 being left at 0. bit d7 determines whether the ad7417/ad7418 should be operated in its default mode (d7 = 0), performing conversions every 355 s or in its convst convst t w c tcon c t ssntc c ct ssss c ts s v n
rev. g e12e ad7416/ad7417/ad7418 or the addresses can be set to avoid conflicts with other devices on the bus. the four msbs of this address for the ad 7418 are set to 0101, while the three lsbs are all set to zero. if a serial communication occurs during a conversion operation, the conversion will stop and will restart after the communication. the serial bus protocol operates as follows: 1. the master initiates data transfer by establishing a start condition, defined as a high-to-low transition on the serial data line, sda, while the serial clock line, scl, remains high. this indicates that an address/data stream will follow. all slave peripherals connected to the serial bus respond to the 7-bit address (msb first) plus an r/ w t w w t w tnt wtntot w t n w t ot t st tc s t ot t st t ot t st w w sc s c sto st stt st sssst ssontstt c wsso w sc s c stt st sssst ssontstt c c sto st tt sccontn scontn wss
rev. g ad7416/ad7417/ad7418 e13e the address pointer register, followed by the data byte writ- ten to the selected data register. this is illustrated in figure 9. 3. writing two bytes of data to the t oti or t hyst register. if 9-bit resolution is required for the temperature setpoints, two bytes of data must be written to the t oti and t hyst registers. this consists of the serial bus address, the register address written to the address pointer register, followed by two data bytes written to the selected data register. this is illustrated in figure 10. reading data from the ad7416/ad7417/ad7418 reading data from the ad7416/ad7417/ad7418 is a one or two byte operation. reading back the contents of the configura- tion register is a single byte read operation, as shown in figure 11, the register address previously having been set by a single- byte write operation to the address pointer register. reading data from the temperature value, t oti or t hyst regis- ter, is a two-byte operation, as shown in figure 12. it is also possible to read the most significant bit of a 9-bit/10-bit register in this manner. r/ w 1 scl sda 0 0 1 a2 a1 a0 p7 p6 p5 p4 p3 p2 p1 p0 ack. by ad7416 start by master frame 1 serial bus address byte frame 2 address pointer register byte 191 ack. by ad7416 9 d15 d14 d13 d12 d11 d10 d9 d8 ack. by ad7416 stop by master frame 3 most significant data byte 19 scl (continued) sda (continued) d7 d6 d5 d4 d3 d2 d1 d0 ack. by ad7416 stop by master frame 4 least significant data byte 19 figure 10. writing to the address pointer register followed by two bytes of data to the t oti or t hyst register sda no ack. by master start by master frame 1 serial bus address byte frame 2 single data byte from ad7416 ack. by ad7416 191 9 d7 d6 d5 d4 d3 d2 d1 d0 r/ w a0 a1 a2 1 0 1 scl stop by master 0 figure 11. reading a single byte of data from the configuration register r/ w 1 scl sda 001a2a1a 0 d15 d14 d13 d12 d11 d10 d9 d8 ack. by master start by master frame 1 serial bus address byte frame 2 most significant data byte from ad7416 19 1 ack. by ad7416 9 d7 d6 d5 d4 d3 d2 d1 d0 no ack. by master stop by master frame 3 least significant data byte from ad7416 19 scl (continued) sda (continued) figure 12. reading two bytes of data from the t oti or t hyst register
rev. g e14e ad7416/ad7417/ad7418 please note that when reading back from the adt7416/ adt7417/adt7418, no more than three bytes of data must be read back. a stop command must be inserted at the end of the read communication. if a stop command is not inserted by the master and the adt7416/adt7417/adt7418 receives more scl cycles than the maximum needed for three bytes of data, then the i 2 c interface on the adt7416/adt7417/ adt7418 will pull the sda line low and prevent it from going high again. to recover the adt7416/adt7417/adt7418 interface the part must be powered off and on again. reference the application note, an-686, on the analog devices website for more information on i 2 c interfaces. oti output the oti output has two operating modes, which are selected by bit d1 of the configuration register. in the comparator mode, (d1 = 0), the oti output becomes active when the temperature exceeds t oti and remains active until the tempera- ture falls below t hyst . this mode allows the ad7416/ad7417/ ad7418 to be used as a thermostat, for example, to control the operation of a cooling fan. t oti t hyst oti output comparator mode oti output interrupt mode read * read * read * read * read * read * read * in interrupt mode, a read operation or shutdown resets the oti output; otherwise the oti output remains active indefinitely, once triggered. * figure 13. operation of oti output (shown active low) the open-drain configuration of oti allows the oti outputs of several ad7416/ad7417/ad7418s to be wire-anded together when in active low mode. the oti output is used to indicate that an out-of-limit tem- perature excursion has occurred. oti is an open-drain output that can be programmed to be active low by setting bit d2 of the configuration register to 0 or active high by setting bit d2 of the configuration register to 1. in the interrupt mode (d1 = 1), the oti output becomes active when the temperature exceeds t oti and remains active even if the temperature falls below t hyst , until it is reset by a read opera- tion. once oti has become active by the temperature exceeding t oti , and has then been reset, it will remain inactive even if the temperature remains, or subsequently rises again, above t oti . it will not become active again until the temperature falls below t hyst . it will then remain active until reset by a read opera- tion. once oti has become active by the temperature falling below t hyst and then reset, it will remain inactive even if the temperature remains, or subsequently falls again, below t hyst . oti is also reset when the ad7416/ad7417/ad7418 is placed in shutdown mode by setting bit d0 of the configuration regis- ter to 1. the oti output requires an external pull-up resistor. this can be connected to a voltage different from v dd (for example, to allow interfacing between 5 v and 3.3 v systems) provided that the maximum voltage rating of the oti output is not exceeded. the value of the pull-up resistor depends on the application but should be as large as possible to avoid excessive sink currents at the oti output, which can heat the chip and affect the tempera- ture reading. the maximum value of the pull-up resistor that will meet the output high current specification of the oti out- put is 30 k , but higher values may be used if a lower output current is required. for most applications, a value of 10 k w ill prove suitable. fault queue to avoid false triggering of the ad7416/ad7417/ad7418 in noisy environments, a fault queue counter is provided that can be programmed by bits d3 and d4 of the configuration regis- ter (see table v) to count 1, 2, 4, or 6 fault events before oti becomes active. in order to trigger oti, the faults must occur consecutively. for example, if the fault queue is set to 4, then four consecutive temperature measurements greater than t oti (or less than t hyst ) must occur. any reading that breaks the sequence will reset the fault queue counter, so if there are three readings greater than t oti followed by a reading less than t oti , the fault queue counter will be reset without triggering oti. power-on defaults the ad7416/ad7417/ad7418 always powers up with the following defaults. address pointer pointing to temperature value register com- parator mode t oti = 80 c t hyst = 75 c oti active low fault queue = 1 these default settings allow the ad7416/ad7417/ad7418 to be used as a standalone thermostat without any connection to a serial bus. operating modes the ad7416/ad7417/ad7418 has two possible modes of operation depending on the value of d0 in the configuration register. mode 1 normal operation of the ad7416/ad7417/ad7418 occurs when d0 = 0. in this active mode, a conversion takes place every 400 s. once the conversion has taken place, the part partially powers down, consuming typically 350 a of the current until the next conversion occurs. two situations can arise in this mode on the request of a tempera- ture read. if a read occurs during a conversion, the conversion aborts and a new one starts on the stop/repeat start condition. the temperature value that is read is that of the previous com- pleted conversion. the next conversion will typically occur 400 s after the new conversion has begun. if a read is called between conversions, a conversion is initiated on the stop/repeat start condition. after this conversion, the part returns to performing a conversion every 400 s.
rev. g ad7416/ad7417/ad7418 e15e with a v dd = 3 v, for each 400 s cycle, the ad7416 spends 40 s (or 10% of the time) in conversion mode. it spends 360 s (or 90% of time) in partial power-down mode. thus, the aver- age power dissipated by the ad7416/ad7417/ad7418 is 3011 09 12 mw + = ... mw mw mode 2 for applications where temperature measurements are required at a slower rate, e.g., every second, power consumption of the part can be reduced by writing to the part to go to a full power-down between reads. the current consumption in full power-down is typically 0.2 a and full power-down is initiated when d0 = 1 in the configuration register. when a measurement is required, a write operation can be performed to power-up the part. the part then performs a conversion and is returned to power-down. the temperature value can be read in the full power-down because the i 2 c bus is continuously active. the power dissipation in this mode depends on the rate at w hich reads take place. taking the requirements for a temperature measurement every 100 ms as an example, the optimum power dissipation is achieved by placing the part in full power-down, waking it up every 100 ms, letting it operate for 400 s and putting it into full power-down again. in this case, the average power consumption is calculated as follows. the part spends 40 s (or 0.04% of time) converting with 3 mw dissipation and a 99.96 ms (99.96% of time) in full shutdown with 60 nw dissipa- tion. thus, the average power dissipation is 30 004 60 0 9996 1 2 mw nw w + = ... the fastest throughput rate at which the ad7416/ad7417/ ad7418 can be operated is 2.5 khz (i.e., a read every 400 s conversion period). since t oti and t hyst are 2-byte reads, the read time with the i 2 c operating at 100 kbit/s would be 270 s. if temperature reads are called too often, reads will overlap with conversions, aborting them continuously, which results in invalid readings. convert start mode the ad7417/ad7418 has an extra mode, set by writing to the msb of the config2 register. convst convst convst convst t convst t convst convst convst convst convst convst convst t convst convst ctonsnoton scon t v nt owonst t v v n t t ct c
rev. g e16e ad7416/ad7417/ad7418 fan controller figure 14 shows a simple fan controller that will switch on a cooling fan when the temperature exceeds 80 c and switch it off again when the temperature falls below 75 c. the ad 7416 can be used standalone in this application or with a serial bus interface if different trip temperatures are required. if the ad 7416 is used with a bus interface, the sense of oti can be set to ac tive high, q1 and r1 can be omitted, and oti can be connected directly to the gate of q2 with r2 as the pull-up resistor. v dd 3v to 5.5v ad7416 r1 10k q1 2n3904 or similar r2 10k q2 logic level mosfet rated to suit fan current 12v figure 14. ad7416 used as a fan controller thermostat figure 15 shows the ad7416 used as a thermostat. the heater will be switched on when the temperature falls below t hyst and switched off again when the temperature rises above t oti . for this application and for comparator mode, the oti output should be programmed active low. v dd 3v to 5.5v ad7416 r1 10k q1 2n3904 or similar relay d1 1n4001 heater heater supply rla1 figure 15. ad7416 used as a thermostat system with multiple ad7416s the three lsbs of the ad7416 convst tcs c onvst convst v n cs
rev. g ad7416/ad7417/ad7418 e17e outline dimensions purchase of licensed i 2 c components of analog devices or one of its sublicensed associated companies conveys a license for the purchaser under the phi lips i 2 c patent rights to use these components in an i 2 c system, provided that the system conforms to the i 2 c standard specification as defined by philips. 16-lead standard small outline package [soic] narrow body (r-16) dimensions shown in millimeters and (inches) controlling dimensions are in millimeters; inch dimensions (in parentheses) are rounded-off millimeter equivalents for reference only and are not appropriate for use in design compliant to jedec standards ms-012ac 16 9 8 1 4.00 (0.1575) 3.80 (0.1496) 10.00 (0.3937) 9.80 (0.3858) 1.27 (0.0500) bsc 6.20 (0.2441) 5.80 (0.2283) seating plane 0.25 (0.0098) 0.10 (0.0039) 0.51 (0.0201) 0.31 (0.0122) 1.75 (0.0689) 1.35 (0.0531) 8 0 0.50 (0.0197) 0.25 (0.0098) 1.27 (0.0500) 0.40 (0.0157) coplanarity 0.10 45 0.25 (0.0098) 0.17 (0.0067) 16-lead thin shrink small outline package [tssop] (ru-16) dimensions shown in millimeters 16 9 8 1 pin 1 seating plane 8 0 4.50 4.40 4.30 6.40 bsc 5.10 5.00 4.90 0.65 bsc 0.15 0.05 1.20 max 0.20 0.09 0.75 0.60 0.45 0.30 0.19 coplanarity 0.10 compliant to jedec standards mo-153ab 8-lead standard small outline package [soic] narrow body (r-8) dimensions shown in millimeters and (inches) 0.25 (0.0098) 0.17 (0.0067) 1.27 (0.0500) 0.40 (0.0157) 0.50 (0.0196) 0.25 (0.0099) 45 8 0 1.75 (0.0688) 1.35 (0.0532) seating plane 0.25 (0.0098) 0.10 (0.0040) 85 4 1 5.00 (0.1968) 4.80 (0.1890) 4.00 (0.1574) 3.80 (0.1497) 1.27 (0.0500) bsc 6.20 (0.2440) 5.80 (0.2284) 0.51 (0.0201) 0.31 (0.0122) coplanarity 0.10 controlling dimensions are in millimeters; inch dimensions (in parentheses) are rounded-off millimeter equivalents for reference only and are not appropriate for use in design compliant to jedec standards ms-012aa 8-lead mini small outline package [msop] (rm-8) dimensions shown in millimeters 0.80 0.60 0.40 8 0 85 4 1 4.90 bsc pin 1 0.65 bsc 3.00 bsc seating plane 0.15 0.00 0.38 0.22 1.10 max 3.00 bsc coplanarity 0.10 0.23 0.08 compliant to jedec standards mo-187aa
rev. g e18e ad7416/ad7417/ad7418 revision history location page 8/04?data sheet changed from rev. f to rev. g. changes to figure 12 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 changes to reading data from the ad7416/ad7417/ad7418 section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 changes to power-on-reset section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 7/03edata sheet changed from rev. e to rev. f. updated features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 updated specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 updated absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 updated ordering guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 updated product highlights . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 updated circuit information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 updated temperature measurement section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 10/02edata sheet changed from rev. d to rev. e. edits to specifications headings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 added temperature measurement section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 edits to serial bus address section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 edits to figure 11 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 edits to convst owonst otns
e19e
c01126e0e8/04(g) e20e

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