View EVAL-ADT7X10EBZ_8898067.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

automotive, 1c accurate, 16-bit, 175c, digital spi temperature sensor in die form data sheet adt7312 rev. a 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. specifications subject to change without notice. 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: 781.461.3113 ?2012 analog devices, inc. all rights reserved. features qualified for automotive applications high performance temperature accuracy: 1c from ?55c to +175c (2.7 v to 3.3 v) 16-bit temperature resolution: 0.0078c fast first temperature conversion on power-up of 6 ms easy implementation no temperature calibration or correction required no linearity correction required low power power-saving 1 sample per second (sps) mode 880 w typical at 3.6 v in normal mode 9 w typical at 3.6 v in shutdown mode wide operating ranges temperature range: ?55c to +175c voltage range: 2.7 v to 5.5 v programmable interrupts critical overtemperature interrupt overtemperature/undertemperature interrupt spi-compatible interface available in die form only applications automotive high temperature monitoring high temperature thermal protection general description the adt7312 is a 1c accurate digital temperature sensor that operates over a very wide temperature range of ?55c to +175c and is available in die form only. it contains an internal band gap reference, a temperature sensor, and a 16-bit analog- to-digital converter (adc) to monitor and digitize the temper- ature to a resolution of 0.0078c. the default adc resolution is 13 bits (0.0625c). the adc resolution can be changed to 16 bits (0.0078c) using the serial interface. the adt7312 is guaranteed to operate over supply voltages from 2.7 v to 5.5 v. at 3.6 v operation, the average supply current is typically 245 a. the adt7312 has a shutdown mode that powers down the device, resulting in a typical shutdown current of 2.5 a at 3.6 v. the adt7312 is rated for operation over the ?55c to +175c temperature range. the ct pin is an open-drain output that becomes active when the temperature exceeds a programmable critical temperature limit. the default critical temperature limit is 147c. the int pin is also an open-drain output that becomes active when the temperature exceeds a programmable limit. the int pin and the ct pin can operate in either comparator or interrupt mode. product highlights 1. ease of use, no calibration or correction required. 2. low power consumption. 3. excellent long-term stability and reliability. 4. qualified for automotive applications. functional block diagram temperature value register configuration status register id register register t hyst register t low register t high register t crit register internal reference 7 temperature sensor t high t crit t low internal oscillator filter logic - ? modulator gnd 8 gnd 9 v dd 10 v dd 6 5 ct int 3 4 1 2 spi interface adt7312 06791-001 sclk dout din cs figure 1.
adt7312* product page quick links last content update: 02/23/2017 comparable parts view a parametric search of comparable parts. documentation data sheet ? adt7312: automotive, 1c accurate, 16-bit, 175c, digital spi temperature sensor in die form datasheet design resources ? adt7312 material declaration ? pcn-pdn information ? quality and reliability ? symbols and footprints discussions view all adt7312 engineerzone discussions. sample and buy visit the product page to see pricing options. technical support submit a technical question or find your regional support number. document feedback submit feedback for this data sheet. this page is dynamically generated by analog devices, inc., and inserted into this data sheet. a dynamic change to the content on this page will not trigger a change to either the revision number or the content of the product data sheet. this dynamic page may be frequently modified.
adt7312 data sheet rev. a | page 2 of 24 table of contents features .............................................................................................. 1 ? applications ....................................................................................... 1 ? general description ......................................................................... 1 ? product highlights ........................................................................... 1 ? functional block diagram .............................................................. 1 ? revision history ............................................................................... 2 ? specifications ..................................................................................... 3 ? spi timing specifications ........................................................... 4 ? absolute maximum ratings ............................................................ 5 ? esd caution .................................................................................. 5 ? pad configuration and function descriptions ............................ 6 ? die bond pad coordinates .............................................................. 7 ? typical performance characteristics ............................................. 8 ? theory of operation ........................................................................ 9 ? circuit description....................................................................... 9 ? converter architecture ................................................................ 9 ? normal mode (continuous conversion mode) ...................... 9 ? one-shot mode .......................................................................... 10 ? 1 sps mode .................................................................................. 11 ? shutdown mode .......................................................................... 11 ? fault queue ................................................................................. 11 ? temperature data format ......................................................... 12 ? temperature conversion formulas ......................................... 12 ? registers ........................................................................................... 13 ? status register ............................................................................. 13 ? configuration register .............................................................. 14 ? temperature value register ...................................................... 15 ? id register................................................................................... 15 ? t crit setpoint register ............................................................... 15 ? t hyst setpoint register ............................................................... 16 ? t high setpoint register .............................................................. 16 ? t low setpoint register ............................................................... 16 ? serial interface ................................................................................ 17 ? spi command byte .................................................................... 17 ? writing data ............................................................................... 18 ? reading data ............................................................................... 19 ? interfacing to dsps or microcontrollers ................................. 19 ? resetting the serial interface .................................................... 19 ? int and ct outputs ...................................................................... 20 ? undertemperature and overtemperature detection ............ 20 ? redundant critical generator .................................................. 21 ? applications information .............................................................. 22 ? thermal response time ........................................................... 22 ? supply decoupling ..................................................................... 22 ? powering from a switching regulator ..................................... 22 ? temperature monitoring ........................................................... 22 ? quick guide to measuring temperature ................................ 22 ? outline dimensions ....................................................................... 23 ? ordering guide .......................................................................... 23 ? automotive products ................................................................. 23 ? revision history 6/12rev. 0 to rev. a changed high output leakage current, i oh maximum parameter from 5 a to 1 a ....................................................... 3 1/12revision 0: initial version
data sheet adt7312 rev. a | page 3 of 24 specifications t a = ?55c to +175c, v dd = 2.7 v to 5.5 v, unless otherwise noted. table 1. parameter min typ max unit test conditions/comments temperature sensor and adc accuracy 1 1.0 c t a = ?55c to +175c, v dd = 2.7 v to 3.3 v 1.1 c t a = ?55c to +175c, v dd = 3.3 v to 3.6 v 1.2 c t a = +150c to +175c, v dd = 4.5 v to 5.5 v 1.5 c t a = ?55c to +175c, v dd = 4.5 v to 5.5 v adc resolution 13 bits twos complement temperature value of sign bit plus 12 bits (power-on default resolution) 16 bits twos complement temperature value of sign bit plus 15 bits (bit 7 = 1 in the configuration register) temperature resolution 13-bit 0.0625 c 13-bit resolution (sign bit plus 12 bits) 16-bit 0.0078 c 16-bit resolution (sign bit plus 15 bits) temperature conversion time 240 ms co ntinuous and one-shot conversion modes fast temperature conversion time 6 ms first conversion on power-up only 1 sps conversion time 60 ms 1 sps mode temperature hysteresis 0.002 c repeatability 2 0.015 c t a = 25c dc psrr 0.1 c/v t a = 25c digital outputs (ct, int) open-drain outputs high output leakage current, i oh +0.1 1 a ct and int pins pulled up to 5.5 v output low voltage, v ol 0.4 v i ol = 3 ma at 5.5 v, i ol = 1 ma at 3.3 v output high voltage, v oh 0.7 v dd v output capacitance, c out 2 pf digital inputs (din, sclk, cs ) input current, i in 1 a v in = 0 v to v dd input low voltage, v il 0.4 v input high voltage, v ih 0.7 v dd v pin capacitance, c in 5 10 pf digital output (dout) output high voltage, v oh v dd ? 0.3 v i source = i sink = 200 a output low voltage, v ol 0.4 v i ol = 200 a output capacitance, c out 50 pf power requirements supply voltage 2.7 5.5 v supply current peak current while converting; spi interface inactive continuous conversion mode 245 320 a v dd = 3.6 v 275 350 a v dd = 5.5 v 1 sps mode 55 a v dd = 3.6 v, t a = 25c 70 a v dd = 5.5 v, t a = 25c shutdown mode 2.5 40 a v dd = 3.6 v 5.4 50 a v dd = 5.5 v power dissipation power dissipated for v dd = 3.6 v, t a = 25c continuous conversion mode 880 w 1 sps mode 200 w shutdown mode 9 w 1 accuracy includes lifetime drift. 2 based on a floating average of 10 readings.
adt7312 data sheet | p age 4 of 24 spi timing specifications t a = ?55c to +175c, v dd = 2.7 v to 5.5 v, unless otherwise noted. all input signals are specified with rise time (t r ) = fall time (t f ) = 5 ns (10% to 90% of v dd ) and timed from a voltage level of 1.6 v. table 2. parameter 1 , 2 limit a t t min , t max unit description t 1 0 ns min cs falling edge to sclk active edge setup time t 2 100 ns min sclk high pulse width t 3 100 ns min sclk low pulse width t 4 30 ns min data setup time prior to sclk rising edge t 5 25 ns min data hold time after sclk rising edge t 6 5 ns min data access time after sclk falling edge 60 ns max v dd = 4.5 v to 5.5 v 80 ns max v dd = 2.7 v to 3.6 v t 7 3 10 ns min bus relinquish time after cs inactive edge 80 ns max t 8 0 ns min sclk inactive edge to cs rising edge hold time t 9 0 ns min cs f alling edge to dout active time 60 ns max v dd = 4.5 v to 5 .5 v 80 ns max v dd = 2.7 v to 3.6 v t 10 10 ns min sclk inactive edge to do ut low 1 sample tested during initial release to ensure compliance. 2 see figure 2 . 3 the t 7 values are the true bus relinquish times of the part and, as such, are independent of external bus loading capacitances. cs sclk din dout t 1 1 8 7 6 msb lsb 2 3 msb lsb 9 10 23 24 t 2 t 4 t 5 t 3 t 6 t 7 t 8 t 9 t 10 06791-002 figure 2 . detailed spi timing diagram rev. a
data sheet adt7312 | p age 5 of 24 absolute maximum rat ings table 3. parameter rating v dd to gnd ? 0.3 v to +7 v din input voltage to gnd ? 0.3 v to v dd + 0.3 v dout output voltage to gnd ? 0.3 v to v dd + 0.3 v sclk input voltage to gnd ?0.3 v to v dd + 0.3 v cs input voltage to gnd ? 0.3 v to v dd + 0.3 v ct and int output voltage to gnd ? 0.3 v to v dd + 0.3 v esd rating (human body model) 2.0 kv operating temperature range ? 55c to +175c storage temperature range ? 65c to +175c maximum junction temperature, t jmax 175c stresses above those listed under absolute maximum rati ngs may cause permanent damage to the device. this is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. exposure to absolute maxi mum rating conditions for extended periods may affect device reliability. esd caution rev. a
adt7312 data sheet | page 6 of 24 pad configuration and fu nction descriptions 1950m 2350m v dd v dd gnd gnd ct int din dout sclk 06791-004 cs figure 3. metallization picture table 4. pad function descriptions pad no. pad name description 1 sclk serial clock input. the serial clock is used to clock data into an d out of any register of the device. 2 dout serial data output. data is clocked out on the falling edge of sclk and is valid on the rising edge of sclk. 3 din serial data input. data to be loaded into the control regist ers of the part is provided on this input. data is clocked into the registers on the rising edge of sclk. 4 cs chip select input. the device is enabled when this pin is low. the device is disabled when this pin is high. 5 int overtemperature and undertemperature indicator. logic outp ut. when the device is power ed up, this output is an active low interrupt by default. open-drain configuration. a pull-up resistor is required, typically 10 k. 6 ct critical overtemperature indicator. logic output. the de fault power-on polarity is active low. open-drain configuration. a pull-up resistor is required, typically 10 k. 7 gnd analog ground. this pad must be conne cted directly to pad 8 (digital ground). 8 gnd digital ground. this pad must be connected directly to pad 7 (analog ground). 9 v dd analog supply voltage (2.7 v to 5.5 v). this pad must be connected directly to pad 10 (digital supply voltage). the supply should be decoupled with a 0.1 f ceramic capacitor to gnd. 10 v dd digital supply voltage (2.7 v to 5.5 v). this pad must be connected directly to pad 9 (analog supply voltage). the supply should be decoupled with a 0.1 f ceramic capacitor to gnd. rev. a
data sheet adt7312 | p age 7 of 24 di e bond p ad c oordinates the following x and y coordinates refer to the center of the b ond p ad and are referen ced from the center of the die. table 5. bond pad coordinates pad no. pad name x coordinate ( m) y coordinate ( m ) 1 sclk ?8 38 +1020 2 dout ?838 + 831 3 din ?838 ?863 4 cs ?838 ?1011 5 int +838 ?1011 6 ct +838 ?863 7 gnd +838 + 508 8 gnd +838 +702 9 v dd +838 +857 10 v dd +838 +1008 rev. a
adt7312 data sheet | p age 8 of 24 typical performance characteristics ?50?70 ?30 ?10 10 30 50 70 90 110 130 150 170 190 temperature error (oc) temperature (oc) 06791-005 ?0.4 ?0.6 ?0.8 ?0.2 0 0.4 0.2 0.6 0.8 1.0 figure 4 . temperature accuracy at 3 v ?50?70 ?30 ?10 10 30 50 70 90 1 10 130 150 170 190 tempera ture error (oc) tempera ture (oc) 06791-006 ?1.0 ?0.5 0 0.5 1.0 1.5 figure 5 . temperature accuracy at 5 v 350 300 200 250 150 100 50 0 ?60 ?40 ?20 0 20 40 60 80 100 120 140 160 180 i dd (a) temperature (c) 5v continuous conversion 3v continuous conversion 5v 1sps 3v 1sps 06791-007 figure 6 . operating supply current vs. temperature 0 5 10 15 20 25 30 ?60 ?40 ?20 0 20 40 60 80 100 120 140 160 180 shutdown i dd (a) tempera ture (c) 06791-008 v dd = 2.7v v dd = 3.0v v dd = 3.6v v dd = 4.5v v dd = 5.0v v dd = 5.5v figure 7 . s hutdown current vs. temperature 0 50 100 150 200 250 300 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 i dd (a) supply voltage (v) continuous conversion 06791-009 1sps figure 8 . operating supply current vs. supply voltage 0 1 2 3 4 5 6 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 shutdown i dd (a) supply voltage (v) 06791-010 figure 9 . shutdown current vs. supply voltage rev. a
data sheet adt7312 | p age 9 of 24 theory of operation circuit description the adt7312 is a 1c accura te digital tempe rature sensor that uses a 16 - bit adc to monitor and digitize the temperature to a resolution of 0.0078c . by default, the adc resolution is set to 13 bits (0.0625c). an internal temperature sensor generates a voltage proportional to absolute temperature ; this voltage is compared to an internal voltage reference and input into a precision digital modulator. the internal temperature sensor has high accuracy and linearity over the entire r ated temperature range without the need for correction or calibration b y the user. the sensor output is digitized by a sigma - delta ( - ?) modu - lator, also known as a charge balance type adc. this type of converter uses time domain oversampling and a high accuracy comparator to deliver 16 bits of resolution in an extremely comp act circuit. converter architecture the - ? modulator consists of an input sampler, a summing network, an integrator, a comparator, and a 1 - bit digital - to - analog converter ( dac ) . this architecture creates a negative feedback loop and minimizes the integrat or output by changing the duty cycle of the comparator output in response to input voltage changes. the comparator samples the output of the integrator at a much higher rate than the input sampling fre - quency. this oversampling spreads the quantization noi se over a much wider band than that of the input signal, improving overall noise performance and increasing accuracy. the modulated output of the comparator is encoded using a circuit technique that r esults in spi temperature data. - modul at or integr at or com p ar at or tempera ture v alue register clock generat or volt age reference lpf digi tal fi lter 1-bit dac 1 bit 13/16 bits 06791-0 11 figure 10 . - ? modulator the adt7312 can be configured to operate in any one of the follow ing operating modes: ? normal mode (continuous conversion mode ) ? one - shot mode ? 1 sps mode ? shutdown mode normal mode (continuous conversion mode) in normal mode (default power - on mode), the adt7312 runs an automatic conversion sequence. during this automati c con - version sequence, a conver sion typically takes 240 ms to complet e. t he adt7312 is continuously converting : as soon as one tempera - ture conver sion is completed, another temperature conversion begins. each temperature conversion result is stored in the temperature value regi ster (register address 0x02) and is avail - able through the spi interface. in continuous conversion mode, the read operation provides the most recent converted result. on power - up , the first conversion is a fast conversion, taking typically 6 ms. if the temperature exceeds 147c, the ct pin is asserted low . if the temperature exceeds 64c, the int pin is asserted low . fast conversion temperature accuracy is typically within 5c. the conversion clock for the part is generated internally. no external clock is required except when reading from and writing to the serial port. the measured temperature value is compared with a critical temperature limit (stored in the 16 - bit t crit setpoint register), a high temperature limit (stored in the 16 - bit t high setpoint r egister), and a low temperature limit (stored in the 16 - bit t low setpoint register). if the measured value exceeds the t high or t low limit , the int pin is activated; if the measured value exceeds the t crit limit, the ct pin is activated. the polarity of th e int and ct pins is programmable using the configuration register ( register address 0x01) . t he int and ct pins are also programmable for interrupt mode via the configuration register . rev. a
adt7312 data sheet | p age 10 of 24 one - shot mode when one - shot mode is enabled, the adt7312 immediately completes a conversion and then goes into shutdown mode. the one - shot mode is useful when one of the circuit design priorities is to reduce power consumption. to enable one - shot mode, set bits[6:5] of the conf iguration reg - ister (register address 0x01) to 01. after writing to the operation mode bits (bits[6:5]) , wait at least 240 ms before reading back the temperature from the temperature value register (see figure 11 ). this delay ensures that the adt7312 has adequate time to power up and complete a conversion. to obtain an updated temperature conversion, reset bits[6:5] of the configuration register to 01. ct and int op eration in one - shot mode figure 12 illustrates the operation of the ct pin in one - shot mode when the t crit overtemperature limit is exceeded. note that in interrupt mode, a read from any register resets the ct and int pins. (for more information about interrupt mode and comparator mode, see the undertemperature and overtemperature detection section.) if the int pin i s configured for comparator mode and the temperature falls below the t high ? t hyst value or exceeds the t low + t hyst value, a write to the operation mode bits of the configuration register (register address 0x01 , bits[6:5] = 01 ) resets the int pin. if the ct pin is configured for comparator mode and the temperatu re falls below the t crit ? t hyst value, a write to the operation mode bits of the configuration register (register address 0x01, bits[6:5] = 01) resets the ct pin (see figure 12). when using one - shot mode, ensure that the refresh rate is appropriate to the application being used. din 0x08 0x20 dat a sclk dout cs wait 240ms minimum for conversion to finish 06791-012 figure 11 . typical spi one - shot write to configuration register followed by a read from the temperature value register rev. a
data sheet adt7312 | p age 11 of 24 tempera ture 149 c 148 c 147c 146c 145c 144c 143c 142c 141c 140c 139c ct pin polarit y = active low ct pin polarit y = active high t crit ? t hyst t crit time 06791-013 write 01 to bits[6:5] of configur a tion register* write 01 to bits[6:5] of configur a tion register* write 01 to bits[6:5] of configur a tion register* *after writing t o the configur a tion register t o s t art a one-shot conversion, the conversion time is 240ms. therefore, it t akes at least 240ms after the write t o the configur a tion register before the ct pin becomes active. figure 12 . c t pin operation in one - shot mode 1 sps mode in 1 sps mode, the part performs one measurement per second. a conversion takes only 60 ms, and the part remains in the idle state for the remaining 940 ms period. to enable 1 sps mode, set bits[6:5] of the con figuration register (register address 0x01) to 10. shutdown mode the adt7312 can be placed in shutdown mode by setting bits[6:5] of the configuration register (register address 0x01) to 11 . the adt7312 can be taken out of shutdown mode by setting bits[6:5] to 00 in the configuration register. the adt7312 typically takes 1 ms (with a 0.1 f decoupling capacitor) to com e out of shut down mode. the conversion result from the last conversion prior to shutdown can still be read from the adt7312 even when it is in shutdown mode. when the part is taken out of shutdown mode, the i nternal clock is re started and a conversion is initiated. fault queue bit s[1:0] of the configuration register (register address 0x01) are used to configure the fault queue. up to four faults are pro - vided to prevent false tripping of the int and ct pins wh en the adt7312 is used in a noisy temperature environment. the number of faults set in the queue must occur consecutively to se t the int and ct outputs. for example, if the fault queue is set to four, four co nsecutive temperature conversion results must exceed a temperature limit before the int or ct pin i s activated. if two consecutive temperature conversions exceed a temperature limit but the third conversion does not exceed a limit , the fault count is rese t to zero. rev. a
adt7312 data sheet | p age 12 of 24 temperature data for mat one lsb of the adc corresponds to 0.0078c in 16 - bit mode. the adc can theoretically measure a temperature range of 255c, but the adt7312 is guarantee d to measure a low value temper ature limit of ?55c to a high value temperature limit of +175c. the temperature measurement result is stored in the 16- bit temperature value register (register address 0x02) . it is compared with the high temperature limits stored in the t crit setpoint re gister and the t high setpoint register. the temperature measurement result is also compared with the low temperature limit stored in the t low setpoint register. temperature data in the temperature value register, the t crit setpoint register, the t high setp oint register, and the t low setpoint register is represented by a 13 - bit , twos complement word. the msb is the temperature sign bit. when the part is powered up , t he three lsbs, bit s[2: 0] , are not part of the temperature conversion result , but are flag bit s for t crit , t high , and t low . table 6 shows the 13 - bit temperature data format without bits[2:0]. table 6 . 13 - bit temperature data format temperature digital output (bits[ d 15: d 3]) binary hex ?55c 1 1100 1001 0000 0x1c90 ?50c 1 1100 1110 0000 0x1ce0 ?25c 1 1110 0111 0000 0x1e70 ?0.0625c 1 1111 1111 1111 0x1fff 0c 0 0000 0000 0000 0x0000 +0.0625c 0 0000 0000 0001 0x0 001 +25c 0 0001 1001 0000 0x0190 +50c 0 0011 0010 0000 0x0320 +125c 0 0111 1101 0000 0x07d0 +150c 0 1001 0110 0000 0x0960 +175c 0 1010 1111 0000 0x0af0 the number of bits in the temperature data - word can be extended to 16 bits, twos complement, by setting bit 7 of the configuration register (register address 0x01) to 1 . when using a 16 - bit temperature data value, bits[2:0] are the lsbs of the temperature value. the default power - on configuration is a 13- bit temperature data value. reading back the temperature from the temperature value register requires a 2 - byte read. designers who use a 9 - bit temp - erature data format can still use the adt7312 by ignoring the four lsbs of the 13 - bit temperature value. these four lsbs are bits[6:3] in tabl e 6 . temperature conversi on formulas 16- bit temperature data format positive temperature = adc code (dec)/128 negative temperature = ( adc code (dec) ? 65 , 536)/128 where adc code uses all 16 bits of the data byte, including the sign bit. negative temperature = ( adc code (dec) ? 32, 768)/128 where the msb is removed from the adc code. 13- bit temperature data format positive temperature = adc code (d ec)/16 negative temperature = ( adc code (dec) ? 8192)/16 where adc code uses all 13 bits of the data byte, including the sign bit. negative temperature = ( adc code (dec) ? 4096)/16 where the msb is removed from the adc code. 10- bit temperature data format positive temperature = adc code (dec)/2 negative temperature = ( adc code (dec) ? 1024)/2 where adc code uses all 10 bits of the data byte, including the sign bit. negative temperature = ( adc code (dec) ? 512)/2 where the msb is removed from the adc code. 9- bit temperature data format positive temperature = adc cod e (dec) negative temperature = adc cod e (dec) ? 512 where adc code uses all nine bits of the data byte, including the sign bit. negative temperature = adc code (dec) ? 256 where the msb is removed from the adc code. rev. a
data sheet adt7312 | p age 13 of 24 registers the adt7312 contains eight registers. ? s tatus register ? c onfiguration register ? temperature value register ? id register ? four temperature setpoint r egisters the status register, the temperature value register, and the id register are read - only register s. table 7. adt7312 registers register address register name power - on default 0x00 status 0x80 0x01 configuratio n 0x00 0x02 temperature value 0x0000 0x03 id 0xc3 0x04 t crit setpoint 0x4980 (147c) 0x05 t hyst setpoint 0x05 (5c) 0x06 t high setpoint 0x2000 (64c) 0x07 t low setpoint 0x0500 (10c) status register th e 8- bit , read - only status register (register ad dress 0x00) reflects the status of the over temper ature and under temperature interrupts that can activate the ct and int pins. this register also reflects the status of a temperature conversion operation. the interrupt flags in th e status register (bits[6: 4]) are reset by a read of the register or when the temperature value returns within the temperature limits (i ncluding hysteresis ) . the rdy bit (bit 7) is reset to 1 after a read of the temperature value register (register address 0x02) . in one - shot and 1 sps modes, the rdy bit is reset after a write to the operation mode bits of the configuration register (register address 0x01, bits[6:5]) . table 8 . status register (register address 0x00) bits default value type name description 7 1 r rdy this bit is set to 0 when the temperature conversion result is written to the temperature value register. this bit is reset to 1 when the temperature value register is read. in one - shot and 1 sps modes, this bit is reset after a wr ite to the operation mode bits of the configuration register (register address 0x01, bit s[6:5]). 6 0 r t crit this bit is set to 1 when the temperature exceeds the t crit temper ature limit. this bit is cleared to 0 wh en the status register is read or when the measured temperature falls below the limit (t crit ? t hyst ) set in the t crit setpoint and t hyst setpoint registers. 5 0 r t high this bit is set to 1 when the temperature exceeds the t high temperature limit. this b it is cleared to 0 when the status register is read or when the measured temperature falls below the limit (t high ? t hyst ) set in the t high setpoint and t hyst setpoint registers. 4 0 r t low this bit is set to 1 when the temperature goes below the t low tem perature limit. this bit is clear ed to 0 when the status register is read or when the measured temperature rises above the limit (t low + t hyst ) set in the t low setpoint and t hyst registers. [3:0] 0000 r unused reads back 0 000. rev. a
adt7312 data sheet | p age 14 of 24 configuration regist er th e 8- bit , read/write configuration register (register a ddress 0x01) stores configuration values for the adt7312 . configuration values include the adc resolution, the operational mode of the part, interrupt pin mode and polarity, and the depth of the f ault queue for overtemperature and undertemperature event s. table 9 . configuration register (register address 0x01) bits default value type name description 7 0 r/ w resolution this bit sets the resolution of the adc when converting. 0 = 13- bit resolution (default) . the s ign bit plus 12 bits gives a temperature resolution of 0.0625c . 1 = 16- bit resolution. the sign bit plus 15 bits gives a temperature resolution of 0 .0078c. [6:5] 00 r/ w operation mode these two bits set the operational mode for the adt7312 . 00 = continuous conversion mode (default). after one conversion is finished, the adt7312 begins the next conversion. conversion time is 240 ms typical. 01 = o ne - shot mode . conversion time is 240 ms typical. 10 = 1 sps mode. conversion time is 60 ms typical . this operational mode reduces the average curre nt consumption. 11 = s hutdown mode . all circuitry except for the interface circuitry is powered down. 4 0 r/ w int/ct mode this bit selects comparator mode or interrupt mode. 0 = interrupt mode. 1 = comparator mode. 3 0 r/ w int pin polarity this bit selects the output polarity of the int pin. 0 = active low. 1 = active high. 2 0 r/ w ct pin polarity this bit selects the output polarity of the ct pin. 0 = active low. 1 = active high. [1:0] 00 r/ w fault queue these two bits set the number of consecutive undertemperature or overtemper - ature faults that must occur before the int and ct pins are activated . th e fault queue helps to avoid false triggering due to temperature noise. 00 = 1 faul t (default). 01 = 2 faults. 10 = 3 faults. 11 = 4 faults. rev. a
data sheet adt7312 | p age 15 of 24 temperature value re gister the 16- bit , read - only temperature value register (register address 0x02) store s the temperature measured by the internal temperature sensor. the temperature is stored as a 16 - bit , twos complement value . the temperature is read back from the temperature value register as a 16 - bit value. when the adc is configured to convert the temperature to a 13 - bit digital value, bit s[2:0] are event alarm flags for t crit , t high , and t low . when the adc is configured to convert the temperature to a 16 - bit digital value, bits[2:0] are the lsb s of the extended digital value. to configure the adc for 13 - bit or 16 - bit resolution, write to bit 7 of the configuration register (register addr ess 0x01). id register th e 8- bit , read - only id register (register address 0x03) stores the manufacturer id in bit s[7: 3] and the silicon revision in bits[2: 0]. t crit setpoint register the 16 - bit , read/write t crit setpoint register (register address 0x04) s tores the critical overt emperature limit value. a critical overt emperature event occurs when the temperature value stored in the temperature value register exceeds the value stored in this register. the ct pin is activated if a critical over - t emperature event occurs. the temperature is s tored in twos complement format; the msb is the temperature sign bit. the default setting for the t crit setpoint is +147c. table 10 . temperature value register (register address 0x02) bits default value type name description 15 0 r sign sign b it . i ndicates whether the temperature value is negative or positive (0 = positive, 1 = negative) . [14:8] 0000000 r temp temperature value (bits[14:8]) in twos complement format. [7:3] 00000 r temp temperat ure value (bits[7:3]) in twos complement format. 2 0 r t crit flag/lsb 2 if the part is configured for 13 - bit resolution (register address 0x01, bit 7 = 0), this bit f lags a critical overtemperature event. when the temperature value exceeds t crit , this bit is set to 1. if the part is configured for 16 - bit resolution (register address 0x01, bit 7 = 1), this bit is lsb 2 of the 15 - bit temperature value . 1 0 r t high flag/lsb 1 if the part is configured for 13 - bit resolution (register address 0x01, bit 7 = 0), this bit flags an overtemperature event. when the temperature value exceeds t high , this bit is set to 1. if the part is configured for 16 - bit resolution (register address 0x01, bit 7 = 1), this bit is lsb 1 of the 15 - bit temperature value. 0 0 r t low fla g/lsb 0 if the part is configured for 13 - bit resolution (register address 0x01, bit 7 = 0), this bit flags an undertemperature event. when the temperature value falls below t low , this bit is set to 1. if the part is configured for 16 - bit resolution (regist er address 0x01, bit 7 = 1), this bit is lsb 0 of the 15 - bit temperature value. table 11 . id register (register address 0x03) bits default value type name description [7:3] 11000 r manufacture r id contains the manufacturer identification number. [2:0] 011 r revision id contains the silicon revision identification number. table 12 . t crit setpoint register (register address 0x04) bits default value type name description [15:0] 0x4980 r/ w t crit 16- bit critical overtemperature limit, st ored in twos complement format. the default setting is +147c. rev. a
adt7312 data sheet | p age 16 of 24 t hyst setpoint register the 8 - bit , read/write t hyst setpoint register (register address 0x05) stores the temperature hysteresis value for th e t high , t low , and t crit temperature limits. the temperature hysteresis value is stored in straight binary format using the four lsbs. each lsb i ncrements the hysteresis value in steps of 1c from 0c to 15c. t o implement hysteresis, t he value in this reg ister is subtracted from the t high and t crit values and is added to the t low value. the default setting for the t hyst setpoint is +5c. t high setpoint register the 16 - bit, read/write t high setpoint register (register address 0x06) stores th e overtemper atu re limit value. an overtemperature event occurs when the temperature value stored in the temperature value register exceeds the value stored in this register. the int pin is activated if an over - temperature event occurs. the temperature is stored in twos complement format ; the msb is the temperature sign bit. the default setting for the t high setpoint is +64c. t low setpoint register the 16- bit, read/write t low setpoint register (register address 0x07) stores the undertemperature limit value. an under temp erature event occurs when the temperature value stored in the temperature value register is less than the value stored in this register. the int pin is activated if an under - temperature event occurs. the temperature is stored in twos complement format ; the msb is the temperature sign bit. the default setting for the t low setpoint is + 10c. t able 13 . t hyst setpoint register (register address 0x05) bits default value type name description [7:4] 0000 r/ w unused not used. [3:0] 0101 r/ w t hyst hysteresis value, from 0c to +1 5c, s tored in straight binary format. the default setting is +5c. table 14 . t high setpoint register (register address 0x06) bits default value type n ame description [15:0] 0x2000 r/ w t high 16- bit overtemperature limit, stored in twos complement format. the default setting is +64c. table 15 . t low setpoint register (register address 0x07) bits default value t ype name d escription [15:0] 0x0500 r/ w t low 16- bit undertemperature limit, stored in twos complement format. the default setting is +10c. rev. a
data sheet adt7312 | p age 17 of 24 serial interface adt7312 gnd sclk dout din ct int v dd 10k 10k pull-up to v dd 0.1f microcontroller v dd cs 06791-023 figure 13 . typical spi interface connection the adt7312 has a 4 - wire serial peripheral interface (spi). the interface has a data input pin (din) for wri ting data to the device, a data output pin (dout) for reading data back from the device, and a data clo ck pin (sclk) for clocking data into and out of the device. a chip select pin ( cs ) enables or disables the adt7312 . cs is required for correct operation of the ser ial interface. data is clocked out of the adt7312 on the falling edge of sclk ; data is clocked into the device on the rising edge of sclk. spi command byte all data transactions on the bus begin with the mast er taking cs from high to low and s ending out the command byte. the command byte indicates to the adt7312 whether the transaction is a read or a write and provides the address of the reg ister for the data transfer. table 16 shows the command byte. table 16 . command byte c7 c6 c5 c4 c3 c2 c1 c0 0 r/ w register address 0 0 0 bit c7, bit c2, bit c1, and bit c0 of the command byte must all be set to 0 to successfully begin a bus transaction. the spi inter - face does not wo rk correctly if a 1 is written to any of these bits. bit c6 is the read/write bit: 1 indicates a read, and 0 indicates a write. bits[c5:c3] contain the target register address. one register can be read from or written to per bus transaction. rev. a
adt7312 data sheet | page 18 of 24 writing data data is written to the adt7312 in 8 bits or 16 bits, depending on the addressed register. the first byte written to the device is the command byte, with the read/write bit set to 0. the master then supplies the 8-bit or 16-bit input data on the din line. the adt7312 clocks the data into the register addressed in the command byte on the rising edge of sclk. the master ends the write transaction by pulling cs high. figure 14 shows a write to an 8-bit register, and figure 15 shows a write to a 16-bit register. the master must begin a new write transaction on the bus, for every register write. only one register is written to per bus transaction. c3 c2 c5 c4 din c7 c6 c1 d2 d1 d0 c0 8-bit data 5 6 7 8 9 10111213141516 sclk 1234 d5 cs r/w register addr 0 0 00 d4 d3 d7 d6 8-bit command byte 0 6791-015 figure 14. writing to an 8-bit register c3 c2 c5 c4 din c7 c6 c1 d2 d1 d0 c0 16-bit data 5 24 6 7 8 9 10 11 12 13 14 15 16 22 23 s cl k 1234 d14 d13 17 cs r/w register addr 0 00 0 d12 d10 d11 d9 d8 d7 d15 8-bit command byte 06791-016 figure 15. writing to a 16-bit register rev. a
data sheet adt7312 | page 19 of 24 reading data a read transaction begins when the master writes the command byte to the adt7312 with the read/write bit set to 1. the master then supplies 8 or 16 clock pulses, depending on the addressed register, and the adt7312 clocks data out of the addressed reg- ister on the dout line. data is clocked out on the first falling edge of sclk following the command byte. the master ends the read transaction by pulling cs high. figure 16 shows a read from an 8-bit register, and figure 17 shows a read from a 16-bit register. interfacing to dsps or microcontrollers the adt7312 can operate with cs used as a frame synchroniza- tion signal. this setup is useful for dsp interfaces. in this case, the first bit (msb) is effectively clocked out by cs because cs normally occurs after the falling edge of sclk in dsps. sclk can continue to run between data transfers, provided that the timing specifications in table 2 are adhered to. cs can be tied to ground, and the serial interface operated in a 3-wire mode. din, dout, and sclk are used to communicate with the adt7312 in this mode. for microcontroller interfaces, it is recommended that sclk idle high between data transfers. resetting the serial interface the serial interface can be reset by writing a series of 1s on the din input. if a logic 1 is written to the adt7312 din line for at least 32 serial clock cycles, the serial interface is reset. this ensures that the interface can be reset to a known state if the connection is lost due to a software error or a glitch in the system. a reset returns the serial interface to the state in which it waits for a write to one of the registers in the adt7312 . this operation resets the contents of all registers to their power-on default values. following a reset, the user should allow a delay of 500 s before addressing the serial interface. c3 c2 c5 c4 din c7 c6 c1 c0 8-bit data 5 6 78 9 10 11 12 13 14 15 16 sclk 1 23 4 d6 d5 cs r/w register addr 0 0 0 d4 d3 d2 d1 d0 d7 dout 06791-017 0 8-bit command byte figure 16. reading from an 8-bit register c3 c2 c5 c4 din c7 c6 c1 d2 d1 d0 c0 16-bit data 5 24 6 7 8 9 10 11 12 13 14 15 16 22 23 sclk 1234 d14 d13 17 cs r/w register addr 0 0 0 d12 d11 d10 d9 d8 d7 d15 dout 8-bit command byte 06791-018 0 figure 17. reading from a 16-bit register rev. a
adt7312 data sheet | p age 20 of 24 int and ct outputs int an d ct are open - drain outputs. b oth outputs require a 10 k? pull - up resistor to v dd . the adt7312 must be fully powered up to v dd before it can read int and ct data. u ndertemperature and o vertemperature de tection the int and ct pins have two undertemperature/overtemp er - ature modes: comparator mode and interrupt mode. i nterrupt mode is the default power - on mode. the int output becomes active when the temperature is greater than the temperature stored in the t high s etpoint register or less than the temperature stored in the t low setpoint register. how th e int pin reacts after an overtemperature or undertemperature event depends on whether comparator mode or interrupt mode is selected. figure 18 illustrates the comparator and interrupt modes for events exceeding the t high limit with both pin polarity settings. figure 19 illustrates the comparator and interrupt modes for events exceeding the t low lim it with both pin p olarity settings. comparator mode in comparator mode, the int output returns to its inactive stat e when the temperature falls below the t high ? t hyst limit or rises above the t low + t hyst limit. p laci ng the adt7312 into shutdown mode does not reset the int state in comparator mode. interrupt mode in interrupt mode, the int output returns to its ina ctive stat e when any adt7312 register is read. when int is reset, it becomes active again only when the temperature is greater than the temp - erature stored in the t high setpoint register or less than the tempe rature stored in the t low setpoint register. placing the adt7312 into shutdown mode resets the int output in interrupt mode. temperature 82c 81c 80c 79c 78c 77c 76c 75c 74c 73c int pin (comparator mode) polarity = active low int pin (interrupt mode) p olarity = active low int pin (interrupt mode) polarity = active high int pin (comparator mode) polarity = active high t high t high ? t hyst time read read read 06791-020 figure 18 . int output response to t high overtemperatur e events rev. a
data sheet adt7312 | p age 21 of 24 tempera ture ?13c ?14c ?15c ?16c ?17c ?18c ?19c ?20c ?21 c ?22 c int pin (com p ar at or mode) polarit y = active low int pin (interrupt mode) polarit y = active low int pin (interrupt mode) polarit y = active high int pin (com p ar at or mode) polarit y = active high t low + t hyst t low time read read read 06791-021 figure 19 . int output response to t low und ertemperature events redundant critical generator the ct output is normally activated when the actual tempera - ture exceeds the value stored in the t crit setpoint register (de fault value is 147 c + t hyst ). t o prevent the ct output from being de activat ed after the temperature exceeds 175c, the adt7312 incorporates a redundant standalone circuit (redundant critical generator) to spe cifically control the ct output at temperatures above 175c. th is circuit incorporates hysteresis to ensure a safe working temperature. figure 20 shows the redundant critical generator assuming control when the tem perature reaches 180c by acti - va ting th e ct output; this circuit does not de activate the ct output until the temperature reaches 138c. th e redundant critical generator is programmed in production to ensure that all parts are trigger ed at the same tempera tures (180c and 138c). ct output temperature (c) 138 180 v dd 06791-019 figure 20 . ct output response using the redundant critical generator rev. a
adt7312 data sheet | p age 22 of 24 application s information thermal response tim e thermal response is a function of the thermal mass of the temperature sensor, but it is also heavily influenced by the mass of the object th at th e ic is mounted to. for example, a large pcb containing large amounts of copper tracking can act as a large heat sink and slow the thermal response. for a faster thermal response, it is recomme nded that the sensor be mounted on a pcb that is as small as possible. supply decoupling the adt7312 must have a decoupling capacitor connected between v dd and gnd; otherwise, incorrect temperature read - ings are obtained . a 0.1 f decoupling capacitor, such as a high frequency ceramic type, must be used and mounted as close as possible to the v dd pad s of the adt7312 . if possible, the adt7312 should be powered directly from the system power supply (see figure 21 ). this arrangement isolates the analog section from the logic - switching transients. even if a separate power supply trace is not available, generous supply bypassing reduces supply line induced errors. local supply bypassing consisting of a 0.1 f ceramic capacitor is critical for the temperature accuracy specifications to be achieved. 0.1f adt7312 ttl/cmos logic circuits power supply 06791-022 figure 21 . use of separate traces to reduce power supply noise powering from a swit ching regulator precision analog devices such as the adt7312 require a well - filtered power source. if the adt7312 is powered from a switching regulator, noise can be generated above 50 khz that may affect the temperature accuracy specification s . to prevent this, an rc filter should be used between the power supply and the adt7312 v dd pins . the value of the components used should be carefully considered to ensure that the peak value of the supply noise is less than 1 m v. the rc filter should be mounted as far away as possible from the adt7312 to ensure that the thermal m ass is kept as low as possible. temperature monitoring the adt7312 is ideal for monitoring the thermal environment of high temperature au tomotive applications. the adt7312 measures and converts the temperature at the surface of its own semiconductor chip . when the adt7312 is used to measure the tem perature of a nearby heat source, the thermal impedance between the heat source and the adt7312 must be considered. when the thermal impedance is determined, the temperature of the heat source can be inferred from the adt7312 output. most of the heat transferred from the heat source to the thermal sensor on the adt7312 die is routed via the copper trac es, the bond pads , and gnd. therefore, to measure the temperature of a heat source, it is recommended that the thermal resistance between the gnd pads of the adt7312 and the gnd of the heat source be reduced as much as possibl e. quick guide to measuring temperature to measur e temperature in continuous conversion mode (default power - on mode) , follow these steps. 1. after power - up , reset the serial interface (load 32 consecutive 1s on din). this step ensures that all internal circu itry is correctly initialized. 2. verify the setup by reading the device id (register addr ess 0x03). it should read 0xc3. 3. after consistent consecutive readings are obtained from the device id register , read the following registers: ? c onfiguration register ( re gister address 0x01) ? t crit setpoint register ( register address 0x04) ? t high setpoint register ( register address 0x06) ? t low setpoint register ( register address 0x07) 4. compare the values in these registers to the default values listed in table 7 . if all the readings match table 7 , the interface is operational. 5. write to the configuration register (register address 0x01) to set the adt7312 to the des ired configuration. read the temperature value register (register address 0x02) . it should produce a valid temperature measurement. rev. a
data sheet adt7312 | page 23 of 24 outline dimensions 01-14-2010-f 2.350 1.950 0.092 side view circuit side (active side) figure 22. 10-pad bare die [chip] (c-10-1) dimensions shown in millimeters ordering guide model 1, 2 temperature range 3 temperature accuracy 4 package description package option adt7312wcz-pt7 ?55c to +175c 1.0c die in pocket tape c-10-1 EVAL-ADT7X10EBZ evaluation board 1 z = rohs compliant part. 2 w = qualified for auto motive applications. 3 operating at extended temperatures over prolonged periods may shorten the lifetime performance of the part. 4 maximum accuracy over the ?55 c to +175c temperature range (v dd = 2.7 v to 3.3 v). automotive products the adt7312w models are available with controlled manufacturing to support the quality and reliability requirements of automotive applications. note that these automotive models may have specifications that differ from the commercial models; therefore, desi gners should review the specifications section of this data sheet carefully. only the automotive grade products shown are available f or use in automotive applications. contact your local analog devices account representative for specific product ordering information and to obtain the specific automotive reliability reports for these models. rev. a
adt7312 data sheet rev. a | page 24 of 24 notes ?2012 analog devices, inc. all rights reserved. trademarks and registered trademarks are the prop erty of their respective owners. d06791-0-6/12(a)

▲Up To Search▲

Price & Availability of EVAL-ADT7X10EBZ

	To Download EVAL-ADT7X10EBZ Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .