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0.5c accurate, 16-bit digital spi temperature sensor ADT7310 rev. 0 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 ?2009 analog devices, inc. all rights reserved. features 13- or 16-bit user selectable temperature-to-digital converter temperature accuracy 0.5c from ?40c to +105c no temperature calibration/correction required by user power saving 1 sample per second (sps) mode fast first conversion on power-up of 6 ms spi-compatible interface operating temperature from ?55c to +150c operating voltage: 2.7 v to 5.5 v critical overtemperature indicator programmable overtemperature/undertemperature interrupt low power consumption: 700 w typical at 3.3 v shutdown mode for lower power: 7w typical at 3.3 v 8-lead narrow soic rohs-compliant package applications medical equipment environmental control systems computer thermal monitoring thermal protection industrial process control power system monitors hand-held applications general description the ADT7310 is a high accuracy digital temperature sensor in a narrow soic package. it contains a band gap temperature reference and a 13-bit adc to monitor and digitize the temperature to a 0.0625c resolution. the adc resolution, by default, is set to 13 bits (0.0625 c). this can be changed to 16 bits (0.0078 c) by setting bit 7 in the configuration register (register address 0x01). the ADT7310 is guaranteed to operate over supply voltages from 2.7 v to 5.5 v. operating at 3.3 v, the average supply current is typically 210 a. the ADT7310 has a shutdown mode that powers down the device and offers a shutdown current of typically 2 a. the ADT7310 is rated for operation over the ?55c to +150c 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 and ct pins can operate in either comparator or interrupt mode. functional block diagram internal reference 8 7 temperature sensor t high t crit t low internal oscillator filter logic - modulator v dd gnd 6 5 ct int 3 4 1 2 ADT7310 cs spi interface temperature value register configuration and status registers t low register t crit register t hyst register t high register sclk dout din 0 7789-001 figure 1.
ADT7310 rev. 0 | page 2 of 24 table of contents features .............................................................................................. 1 applications ....................................................................................... 1 general description ......................................................................... 1 functional block diagram .............................................................. 1 revision history ............................................................................... 2 specifications ..................................................................................... 3 spi timing specifications ........................................................... 4 absolute maximum ratings ............................................................ 5 esd caution .................................................................................. 5 pin configuration and function descriptions ............................. 6 typical performance characteristics ............................................. 7 theory of operation ........................................................................ 9 circuit information ...................................................................... 9 converter details .......................................................................... 9 temperature measurement ......................................................... 9 one-shot mode .......................................................................... 10 1 sps mode .................................................................................. 10 continuous read mode ............................................................. 12 shutdown ..................................................................................... 12 fault queue ................................................................................. 12 temperature data format ......................................................... 13 temperature conversion formulas ......................................... 13 registers ........................................................................................... 14 status register ............................................................................. 14 configuration register .............................................................. 15 temperature value register ...................................................... 16 id register................................................................................... 16 t crit setpoint register ............................................................... 16 t hyst setpoint register ............................................................... 17 t high setpoint register .............................................................. 17 t low setpoint register ............................................................... 17 serial interface ................................................................................ 18 spi command byte .................................................................... 18 writing data ............................................................................... 19 reading data ............................................................................... 20 interfacing to dsps or microcontrollers ................................. 20 serial interface reset .................................................................. 20 int and ct outputs ...................................................................... 21 undertemperature and overtemperature detection ............ 21 applications information .............................................................. 23 thermal response time ........................................................... 23 supply decoupling ..................................................................... 23 temperature monitoring ........................................................... 23 outline dimensions ....................................................................... 24 ordering guide .......................................................................... 24 revision history 4/09revision 0: initial version
ADT7310 rev. 0 | page 3 of 24 specifications t a = ?55c to +150c; 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 0.5 c t a = ?40c to +105c, v dd = 2.7 v to 3.6 v 0.7 c t a = ?55c to +150c, v dd = 2.7 v to 3.6 v 0.8 c t a = ?40c to +105c, v dd = 4.5 v to 5.5 v 1.0 c t a = ?55c to +150c, v dd = 2.7 v to 5.5 v adc resolution 13 bits twos complement temperature value of sign bit plus 12 adc bits (power-up default resolution) 16 bits twos complement temperature value of sign bit plus 15 adc bits (bit 7 = 1 in the configuration register) temperature resolution 13 bit 0.0625 c 13-bit resolution (sign + 12-bit) 16 bit 0.0078 c 16-bit re solution (sign + 15-bit) temperature conversion time 240 ms continuous conversion and one-shot conversion mode fast temperature conversion time 6 ms first conversion on power-up only 1 sps conversion time 60 ms conversion time for 1 sps mode temperature hysteresis 0.02 c temperature cycle = 25c to 125c, and back to 25c repeatability 0.01 c t a = 25c dc psrr 0.1 c/v t a = 25c digital outputs (open drain) high output leakage current, i oh 0.1 5 a ct and int pins pulled up to 5.5 v output high current 1 ma v oh = 5 .5v output low voltage, v ol 0.4 v i ol = 2 ma @ 5.5 v, i ol = 1 ma @ 3.3 v output high voltage, v oh 0.7 v dd v output capacitance, c out 3 pf digital inputs input current 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 5 10 pf digital output (dout) output high voltage, v oh v oh ? 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 at 3.3 v 210 250 a peak current while converting, spi interface inactive at 5.5 v 230 300 a peak current while converting, spi interface inactive 1 sps current at 3.3v 46 a v dd = 3.3 v, 1 sps mode, t a = 25c at 5.5v 65 a v dd = 5.5 v, 1 sps mode, t a = 25c shutdown current at 3.3 v 2.0 15 a supply current in shutdown mode at 5.5 v 4.4 25 a supply current in shutdown mode power dissipation normal mode 700 w v dd = 3.3 v, normal mode at 25c power dissipation 1 sps 150 w power dissipated for v dd = 3.3 v, t a = 25c 1 accuracy includes lifetime drift.
ADT7310 rev. 0 | page 4 of 24 spi timing specifications t a = ?55c to +150c, 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 at t min , t max (b version) unit conditions/comments t 1 0 ns min cs falling edge to sclk active edge setup time 3 t 2 100 ns min sclk high pulse width t 3 100 ns min sclk low pulse width t 4 30 ns min data valid to sclk edge setup time t 5 25 ns min data valid to sclk edge hold time t 6 0 ns min sclk active edge to data valid delay 3 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 4 10 ns min bus relinquish time after cs inactive edge 80 ns max t 8 0 ns min cs rising edge to sclk edge hold time t 9 0 ns min cs falling 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 dout high 1 sample tested during initial release to ensure compliance. all input signals are specified with t r = t f = 5 ns (10% to 90% of v dd ) and timed from a voltage level of 1.6 v. 2 see figure 2. 3 sclk active edge is falling edge of sclk. 4 this means that the times quoted in the t iming characteristics are the true bus relinqu ish times of the part and, as such, are independent of external bus loading capacitances. 07789-002 cs sclk din dout t 1 1 8 7 msb lsb 23 msb lsb 12 7 8 t 2 t 4 t 5 t 3 t 6 t 7 t 8 t 9 t 10 figure 2. detailed spi timing diagram 1.6v 10pf to output pin i sink (1.6ma with v dd = 5v, 100a with v dd = 3v) i source (200a with v dd =5v, 100a with v dd = 3v) 07789-004 figure 3. load circuit for timing characterization
ADT7310 rev. 0 | page 5 of 24 absolute maximum ratings table 3. parameter rating v dd to gnd C0.3 v to +7 v din input voltage to gnd C0.3 v to v dd + 0.3 v dout voltage to gnd C0.3 v to v dd + 0.3 v sclk input voltage to gnd C0.3 v to v dd + 0.3 v cs input voltage to gnd C0.3 v to v dd + 0.3 v ct and int output voltage to gnd C0.3 v to v dd + 0.3 v esd rating (human body model) 2.0 kv operating temperature range C55c to +150c storage temperature range C65c to +160c maximum junction temperature, t jmax 150c 8-lead soic-n (r-8) power dissipation 1 w max = (t jmax ? t a 2 )/ ja thermal impedance 3 ja , junction-to-ambient (still air) 121c/w jc , junction-to-case 56c/w ir reflow soldering 220c peak temperature (rohs- compliant package) 260c (0c) time at peak temperature 20 sec to 40 sec ramp-up rate 3c/sec maximum ramp-down rate C6c/sec maximum time from 25c to peak temperature 8 minutes maximum 1 values relate to package being used on a standard 2-layer pcb. this gives a worst-case ja and jc . see figure 4 for a plot of maximu m power dissipation vs. ambient temperature (t a ). 2 t a = ambient temperature. 3 junction-to-case resistance is applicable to components featuring a preferential flow direction, for ex ample, components mounted on a heat sink. junction-to-ambient is more useful for air-cooled, pcb-mounted components. stresses above those listed under absolute maximum ratings 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 maximum rating conditions for extended periods may affect device reliability. temperature (c) maximum power dissipation (w) 1.2 0.8 1.0 0.6 0.2 0.4 0 ?55 ?50 ?40 ?30 ?20 ?10 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 max pd = 3.4mw at 150c 0 7789-003 figure 4. soic_n maximum power dissipation vs. temperature esd caution
ADT7310 rev. 0 | page 6 of 24 pin configuration and fu nction descriptions sclk 1 dout 2 din 3 cs 4 v dd 8 gnd 7 ct 6 int 5 ADT7310 top view (not to scale) 07789-005 figure 5. pin configuration table 4. pin function descriptions pin o. nemonic description 1 sclk serial clock input. the serial cl ock is used to clock in and clock out data to and from any register of the ADT7310. 2 dout serial data output. data is clocked out on the sc lk falling edge and is valid on the sclk rising edge. 3 din serial data input. serial data to be loaded to the parts control regist ers 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 selected when this inp ut is low. the device is disabled when this pin is high. 5 int overtemperature and undertemperature indicator. logic o utput. power-up default setting is as an active low comparator interrupt. open-drain configuration. a pull-up resistor is required, typically 10 k. 6 ct critical overtemperature indicator. logic output. po wer-up default polarity is active low. open-drain configuration. a pull-up resistor is required, typically 10 k. 7 gnd analog and digital ground. 8 v dd positive supply voltage (2.7 v to 5.5 v). the supply should be decoupled with a 0.1 f ceramic capacitor to ground.
ADT7310 rev. 0 | page 7 of 24 typical performance characteristics 07789-006 ?60 ?40 ?20 0 20 40 60 80 100 120 140 160 tempe r a ture error (c) temperature (c) ?1.0 ?0.8 ?0.6 ?0.4 ?0.2 0 0.2 0.4 0.6 0.8 1.0 max accuracy limits max accuracy limits 0 0.05 0.10 0.15 0.20 0.25 0.30 ?100 ?50 0 50 100 150 200 i dd ( m a) temperature (c) 3.0v 1sps 5.5v 1sps 5.5v continuous conversion 3.0v continuous conversion 07789-007 figure 6. temperature accuracy at 3 v figure 8. operating supply current vs. temperature 07789-024 ?1.0 ?0.8 ?0.6 ?0.4 ?0.2 0 0.2 0.4 0.6 0.8 1.0 ?60 ?40 ?20 0 20 40 60 80 100 120 140 160 tempe r a ture error (c) temperature (c) max accuracy limits max accuracy limits 3.6v 07789-025 shutdown i dd (a) temperature (c) 0 1 2 3 4 5 6 ?100 ?50 0 50 100 150 200 3.0v 2.7v 4.5v 5.0v 5.5v figure 7. temperature accuracy at 5 v figure 9. shutdown current vs. temperature
ADT7310 rev. 0 | page 8 of 24 0 0.05 0.10 0.15 0.20 0.25 0.30 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 i dd (ma) supply voltage (v) i dd continuous conversion i dd 1sps 07789-008 figure 10. average operating supply current vs. supply voltage at 25c 0 1 2 3 4 5 6 7 8 2.53.03.54.04.55.05.56.0 shutdown i dd (a) supply voltage (v) 0 7789-009 figure 11. shutdown current vs. supply voltage at 25c 0 20 40 60 80 100 120 140 160 04 353025201510 5 temperature (c) time (seconds) 0 07789-011 figure 12. response to thermal shock
ADT7310 rev. 0 | page 9 of 24 theory of operation circuit information the ADT7310 is a 13-bit digital temperature sensor that is extendable to 16-bits for grea ter resolution. an on-board temperature sensor generates a voltage proportional to absolute temperature, which is compared to an internal voltage reference and input to a precision digital modulator. the on-board temperature sensor has excellent accuracy and linearity over the entire rated temperature range without needing correction or calibration by the user. the sensor output is digitized by a sigma-delta (-) modulator, also known as the charge balance type analog-to- digital converter. this type of converter utilizes time-domain oversampling and a high accuracy comparator to deliver 16-bits of resolution in an extremely compact circuit. c onfiguration register functions consist of ? switching between 13-bit and 16-bit resolution ? switching between normal operation and full power-down ? switching between comparator and interrupt event modes on the int and ct pins ? setting the active polarity of the ct and int pins ? setting the number of faults that activate ct and int ? enabling the standard one-shot mode and 1 sps mode converter details the - modulator consists of an input sampler, a summing network, an integrator, a comparator, and a 1-bit dac. this architecture creates a negative feedback loop and minimizes the integrator 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 frequency. this oversampling spreads the quantization noise 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 results in spi temperature data. - ? modulator integrator comparator temperature value register clock generator lpf digital filter 1-bit dac voltage ref and vptat 1-bit 13-bit 0 7789-012 figure 13. -? modulator temperature measurement in normal mode, the ADT7310 runs an automatic conversion sequence. during this automatic conversion sequence, a conver- sion takes 240 ms to complete and the ADT7310 is continuously converting. this means that as soon as one temperature conver- sion is completed, another temperature conversion begins. each temperature conversion result is stored in the temperature value register and is available 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 asserts low. if the temperature exceeds 64c, the int pin asserts 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 read/write register), a high temperature limit (stored in the 16-bit t high setpoint read/write register), and a low temperature limit (stored in the 16-bit t low setpoint read/write register). if the measured value exceeds these limits, the int pin is activated; and if it exceeds the t crit limit, the ct pin is activated. the int and ct pins are programmable for polarity via the configuration register, and the int and ct pins are also programmable for interrupt mode via the configuration register.
ADT7310 rev. 0 | page 10 of 24 din 0x08 0x20 data sclk dout cs wait 240ms minimum for conversion to finish 07789-026 figure 14. typical spi one-shot write to configuration regist er followed by a read from the temperature value register one-shot mode setting bit 5 to 1 and bit 6 to 0 of the configuration register (register address 0x01) enables the one-shot mode. when this mode is enabled, the ADT7310 immediately completes a conversion and then goes into shutdown mode. wait for a minimum of 240 ms after writing to the one-shot bits before reading back the temperature from the temperature value register. this time ensures that the ADT7310 has time to power up and complete a conversion. the one-shot mode is useful when one of the circuit design priorities is to reduce power consumption. 1 sps mode in this mode, the part performs one measurement per second. a conversion takes only 60 ms, and it remains in the idle state for the remaining 940 ms period. this mode is enabled by writing 0 to bit 5 and 1 to bit 6 of the configuration register (register address 0x01).
ADT7310 rev. 0 | page 11 of 24 ct and int operation in one-shot mode see figure 15 for more information on one-shot ct pin operation for t crit overtemperature events when one of the limits is exceeded. note that in interrupt mode, a read from any register resets the int and ct pins. for the int pin in the comparator mode, if the temperature drops below the t high C t hyst value or goes above the t low + t hyst value, a write to the one-shot bits (bit 5 and bit 6 of the configuration register, register a ddress 0x01) resets the int pin. for the ct pin in the comparator mode, if the temperature drops below the t crit C t hyst value, a write to the one-shot bits (bit 5 and bit 6 of the configuration register, register address 0x01) resets the ct pin; see figure 15 . note that when using one-shot mode, ensure that the refresh rate is appropriate to the application being used. tempe r a ture 149c 148c 147c 146c 145c 144c 143c 142c 141c 140c ct pin polarity = active low ct pin polarity = active high t crit t crit ? t hyst time *there is a 240ms delay between writing to the configuration register to start a standard one-shot conversion and the ct pin going active. this is due to the conversion time. the delay is 60ms in the case of a one-shot conversion. write to bit 5 and bit 6 of configuration register.* write to bit 5 and bit 6 of configuration register.* write to bit 5 and bit 6 of configuration register.* 07789- 013 figure 15. one-shot ct pin
ADT7310 rev. 0 | page 12 of 24 continuous read mode when the command byte = 01010100 (0x54), the contents of the temperature value register can be read out without requiring repeated writes to the communications register. by sending 16 sclk clocks to the ADT7310, the contents of the temperature value register are output onto the dout pin. to exit the continuous read mode, the command byte 01010000 (0x50) must be written to the ADT7310. while in continuous read mode, the part monitors activity on the din line so that it can receive the instruction to exit the continuous read mode. additionally, a reset occurs if 32 consecutive 1s are seen on the din pin. therefore, hold din low in continuous read mode until an instruction is to be written to the device. in continuous read mode, the temperature value register cannot be read when a conversion is taking place. if an attempt is made to read the temperature value register while a conversion is taking place, then all 0s are read. this is because the continuous read mode blocks read access to temperature value register during a conversion. shutdown the ADT7310 can be placed in shutdown mode by writing 1 to bit 5 and 1 to bit 6 of the configuration register (register address 0x01). the ADT7310 can be taken out of shutdown mode by writing 0 to bit 5 and 0 to bit 6 of the configuration register (register address 0x01). the ADT7310 typically takes 1 ms (with a 0.1 f decoupling capacitor) to come out of shut- down mode. the conversion result from the last conversion prior to shutdown can still be read from the ADT7310 even when it is in shutdown mode. when the part is taken out of shutdown mode, the internal clock is started and a conversion is initiated. fault queue bit 0 and bit 1 of the configuration register (register address 0x01) are used to set up a fault queue. up to four faults are provided to prevent false tripping of the int and ct pins when the ADT7310 is used in a noisy temperature environ- ment. the number of faults set in the queue must occur consecutively to set the int and ct outputs. for example, if the number of faults set in the queue is four, then four consecutive temperature conversions must occur, with each result exceeding a temperature limit in any of the limit registers, before the int and ct pins are activated. if two consecutive temperature conversions exceed a temperature limit and the third conversion does not, the fault count is reset to zero. 07789-027 din 0x54 sclk dout cs temperature value temperature value temperature value figure 16. continuous read mode
ADT7310 rev. 0 | page 13 of 24 temperature data format one lsb of the adc corresponds to 0.0625c in 13-bit mode. the adc can theoretically measure a temperature range of 255c, but the ADT7310 is guaranteed to measure a low value temperature limit of ?55c to a high value temperature limit of +150c. the temperature measurement result is stored in the 16-bit temperature value register and is compared with the high temperature limits stored in the t crit setpoint register and the t high setpoint register. it 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 setpoint register, and the t low setpoint register are represented by a 13-bit twos complement word. the msb is the temperature sign bit. the three lsbs, bit 0 to bit 2, on power-up, are not part of the temperature c onversion result and are flag bits for t crit , t high , and t low . table 5 shows the 13-bit temperature data format without bit 0 to bit 2. the number of bits in the temperature data-word can be extended to 16 bits, twos complement, by setting bit 7 to 1 in the configuration register (register address 0x01). when using a 16-bit temperature data value, bit 0 to bit 2 are not used as flag bits and are instead the lsb bits of the temperature value. the power-on default setting has a 13-bit temperature data value. reading back the temperature from the temperature value register requires a 2-byte read. designers that use a 9-bit temperature data format can still use the ADT7310 by ignoring the last four lsbs of the 13-bit temperature value. these four lsbs are bit 3 to bit 6 in table 5. table 5. 13-bit temperature data format temperature digital output (binary) bits[ 15:3 ] digital output (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 0x000 +0.0625c 0 0000 0000 0001 0x001 +25c 0 0001 1001 0000 0x190 +50c 0 0011 0010 0000 0x320 +125c 0 0111 1101 0000 0x7d0 +150c 0 1001 0110 0000 0x960 temperature conversion formulas 16-bit temperature data format positive temperature = adc code (dec)/128 negative temperature = ( adc code (dec) C 65,536)/128 where adc code uses all 16 bits of the data byte, including the sign bit. negative temperature = ( adc code (dec) C 32,768)/128 where the msb is removed from the adc code. 13-bit temperature data format positive temperature = adc code (dec)/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) C 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) C 1024)/2 where adc code uses all 10 bits of the data byte, including the sign bit. negative temperature = ( adc code (dec) C 512)/2 where the msb is removed from the adc code. 9-bit temperature data format positive temperature = adc code (dec) negative temperature = adc code (dec) C 512 where adc code uses all nine bits of the data byte, including the sign bit. negative temperature = adc code (dec) C 256 where the msb is removed from the adc code.
ADT7310 rev. 0 | page 14 of 24 registers t he ADT7310 contains eight registers: ? a status register ? a configuration register ? five temperature registers ? an id register the status register, temperature value register, and the id register are read-only. table 6. ADT7310 registers register address description power-on default 0x00 status 0x80 0x01 configuration 0x00 0x02 temperature value 0x0000 0x03 id 0xcx 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 this 8-bit read-only register (register address 0x00) reflects the status of the overtemperature and undertemperature interrupts that can cause the ct and int pins to go active. it also reflects the status of a temperature conversion operation. the interrupt flags in this register are reset by a read operation to the status register and/or when the temperature value returns within the tempera- ture limits including hysterisis. the rdy bit is reset after a read from the temperature value register. in one-shot and 1 sps modes, the rdy bit is reset after a write to the one-shot bits. table 7. status register (register address 0x00) bit default value type name description [0:3] 0000 r unused reads back 0. [4] 0 r t low this bit is set to 1 when the temperature goes below the t low temperature limit. the bit clears to 0 when the status register is read and/or when th e temperature measured goes back above the limit set in the t low + t hyst setpoint registers. [5] 0 r t high this bit is set to 1 when the temperature goes above the t high temperature limit. the bit clears to 0 when the status register is read and/or when th e temperature measured goes back below the limit set in the t high ? t hyst setpoint registers. [6] 0 r t crit this bit is set to 1 when the temperature goes above the t crit temperature limit. this bit clears to 0 when the status register is read and/or when th e temperature measured goes back below the limit set in the t crit ? t hyst setpoint registers. [7] 1 r rdy this bit goes low when the temperature conversion result is written into the temperature value register. it is reset to 1 when the temperature valu e register is read. in one-shot and 1 sps modes, this bit is reset after a write to the one-shot bits.
ADT7310 rev. 0 | page 15 of 24 configuration register this 8-bit read/write register stores various configuration modes for the ADT7310, including shutdown, overtemperature and undertemperature interrupts, one-shot, continuous conversion, interrupt pins polarity, and overtemperature fault queues. table 8. configuration register (register address 0x01) bit default value type name description [0:1] 00 r/ w fault queue these two bits set the number of undertem perature/overtemperature faults that can occur before setting the int and ct pins. this helps to avoid false triggering due to temperature noise. 00 = 1 fault (default). 01 = 2 faults. 10 = 3 faults. 11 = 4 faults. [2] 0 r/ w ct pin polarity this bit selects the output polarity of the ct pin. 0 = active low. 1 = active high. [3] 0 r/ w int pin polarity this bit selects the output polarity of the int pin. 0 = active low. 1 = active high. [4] 0 r/ w int/ct mode this bit selects between comparator mode and interrupt mode. 0 = interrupt mode. 1 = comparator mode. [5:6] 00 r/ w operation mode these two bits set th e operational mode for the ADT7310. 00 = continuous conversion (default). when one conversion is finished, the ADT7310 starts another. 01 = one shot. conversion time is typically 240 ms. 10 = 1 sps mode. conversion time is typically 60 ms. this operational mode reduces the average current consumption. 11 = shutdown. all circuitry except interface circuitry is powered down. [7] 0 r/ w resolution this bit sets up the reso lution of the adc when converting. 0 = 13-bit resolution. sign bit + 12 bits gives a temperature resolution of 0.0625c. 1 = 16-bit resolution. sign bit + 15 bits gives a temperature resolution of 0.0078125c.
ADT7310 rev. 0 | page 16 of 24 temperature value register the temperature value register stores the temperature measured by the internal temperature sensor. the temperature is stored as a 16-bit twos complement format. the temperature is read back from the temperature value register (register address 0x02) as a 16-bit value. bit 2, bit 1, and bit 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, bit 2, bit 1, and bit 0 are no longer used as flag bits and are, instead, used as the lsb bits for the extended digital value. id register this 8-bit read-only register stores the manufacturer id in bit 7 to bit 3 and the silicon revision in bit 2 to bit 0. t crit setpoint register the 16-bit t crit setpoint register (register address 0x04) stores the critical overtemperature limit value. a critical overtemperature 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 overtemperature event occurs. the temperature is stored in twos complement format with the msb being the temperature sign bit. the default setting for the t crit setpoint is 147c. table 9. temperature value register (register address 0x02) bit default value type name description [0] 0 r t low flag/lsb0 flags a t low event if the configuration register, register address 0x01[7] = 0 (13-bit resolution). when the temperature value is below t low, , this bit it set to 1. contains the least significant bit 0 of the 15-bit temperature value if the configuration register, register address 0x01[7] = 1 (16-bit resolution). [1] 0 r t high flag/lsb1 flags a t high event if the configuration register, register address 0x01[7] = 0 (13-bit resolution). when the temperature value is above t high , this bit it set to 1. contains the least significant bit 1 of the 15-bit temperature value if the configuration register, register address 0x01[7] = 1 (16-bit resolution). [2] 0 r t crit flag/lsb2 flags a t crit event if the configuration register, register address 0x01[7] = 0 (13-bit resolution). when the temperature value exceeds t crit , this bit it set to 1. contains the least significant bit 2 of the 15-bit temperature value if the configuration register, register address 0x01[7] = 1 (16-bit resolution). [3:7] 00000 r temp temperature value in twos complement format. [8:14] 0000000 r temp temperature value in twos complement format. [15] 0 r sign sign bit, indicates if the temperature value is negative or positive. table 10. id register (register address 0x03) bit default value type name description [2:0] xxx r revision id contains the silicon revision identification number. [7:3] 11000 r manufacture id contains the manufacturer identification number. table 11. t crit setpoint register (register address 0x04) bit default value type name description [15:0] 0x4980 r/ w t crit 16-bit critical overtemperature limit, stored in twos complement format.
ADT7310 rev. 0 | page 17 of 24 t hyst setpoint register the t hyst setpoint 8-bit register (register address 0x05) stores the temperature hysteresis value for the t high , t low , and t crit temperature limits. the temperature hysteresis value is stored in straight binary format using four lsbs. increments are possible in steps of 1c from 0c to 15c. the value in this register is subtracted from the t high and t crit values and added to the t low value to implement hysteresis. the default setting for the t hyst setpoint is 5c. t high setpoint register the 16-bit t high setpoint register (register address 0x06) stores the overtemperature 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 overtemperature event occurs. the temperature is stored in twos complement format with the most significant bit being the temperature sign bit. the default setting for the t high setpoint is 64c. t low setpoint register the 16-bit t low setpoint register (register address 0x07) stores the undertemperature limit value. an undertemperature 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 undertemperature event occurs. the temperature is stored in twos complement format with the msb being the temperature sign bit. the default setting for the t low setpoint is 10c. table 12. t hyst setpoint register (register address 0x05) bit default value type name description [0:3] 0101 r/w t hyst hysteresis value, from 0c to 15c. stored in st raight binary format. the default setting is 5c. [4:7] 0000 r/w n/a not used. table 13. t high setpoint register (register address 0x06) bit default value type name description [0:15] 0x2000 r/w t high 16-bit overtemperature limit, stored in twos complement format. table 14. t low setpoint register (register address 0x07) bit default value type name description [0:15] 0x0500 r/w t low 16-bit undertemperature limit, stored in twos complement format.
ADT7310 rev. 0 | page 18 of 24 serial interface ADT7310 gnd sclk dout din ct int v dd 10k? 10k ? pull-up v dd 0.1f microcontroller v dd 07789-014 cs figure 17. typical spi interface connection the ADT7310 has a 4-wire serial peripheral interface (spi). the interface has a data input pin (din) for inputting data to the device, a data output pin (dout) for reading data back from the device, and a data clock pin (sclk) for clocking data into and out of the device. a chip select pin ( cs ) enables or disables the serial interface. cs is required for correct operation of the interface. data is clocked out of the ADT7310 on the negative edge of sclk, and data is clocked into the device on the positive edge of sclk. spi command byte all data transactions on the bus begin with the master taking cs from high to low and sending out the command byte. this indicates to the ADT7310 whether the transaction is a read or a write and provides the address of the register for the data transfer. shows the command byte. table 1 5 table 15. command byte c7 c6 c5 c4 c3 c2 c1 c0 0 r/ w register address continuous read 0 0 bit c7 of the command byte must be set to 0 to successfully begin a bus transaction. the spi interface does not work correctly if a 1 is written into this bit. 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. bit c2 activates a continuous read mode on the temperature value register only. when this bit is set, the serial interface is configured so that the temperature value register can be continuously read. when the command word is 01010100 (0x54), the contents of the temperature value register can be read out without requiring repeated writes to set the address bits. simply sending 16 sclk clocks to the ADT7310 clocks the contents of the temperature value register onto the dout pin.
ADT7310 rev. 0 | page 19 of 24 writing data data is written to the ADT7310 in eight 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 ADT7310 clocks the data into the register addressed in the command byte on the positive edge of sclk. the master finishes the write by pulling cs high. figure 18 shows a write to an 8-bit register, and figure 19 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. 07789-028 c3 c2 c5 c4 din c7 c6 c1 d2 d1 d0 c0 8-bit data 5 6 7 8 9 10111213141516 scl k 1234 d5 cs r/w register addr 0 00 cont read d4 d3 d7 d6 8-bit command byte figure 18. 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 sclk 1234 d14 d13 17 cs r/w register addr 0 0 0 cont read d12 d10 d11 d9 d8 d7 d15 8-bit command byte 07789-029 figure 19. writing to a 16-bit register cont read c3 c2 c5 c4 din c7 c6 c1 c0 8-bit data 5 6 7 8 9 10111213141516 sclk 1234 d6 d5 cs r/w register addr 0 0 0 d4 d3 d2 d1 d0 d7 dout 07789-030 8-bit command word figure 20. read from an 8-bit register
ADT7310 rev. 0 | page 20 of 24 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 0 0 cont read d12 d11 d10 d9 d8 d7 d15 dout 07789-031 8-bit command byte figure 21. read from a 16-bit register reading data a read transaction begins when the master writes the command byte to the ADT7310 with the read/write bit set to 1. the master then supplies 8 or 16 clock pulses, depending on the addressed register, and the ADT7310 clocks out data from the addressed register on the dout line. data is clocked out on the first falling edge of sclk following the command byte. the read transaction finishes when the master takes cs high. the master must begin a new read transaction on the bus for every register read. only one register is read per bus transaction. however, in continuous read mode, command byte c2 = 1, and the temperature value register can be read from continuously. the master sends 16 clock pulses on sclk, and the temperature value is clocked out on dout. interfacing to dsps or microcontrollers the ADT7310 can be operated with cs used as a frame syn- chronization signal. this scheme 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 numbers are obeyed. cs can be tied to ground, and the serial interface can be operated in a 3-wire mode. din, dout, and sclk are used to communicate with the ADT7310 in this mode. for microcontroller interfaces, it is recommended that sclk idle high between data transfers. serial interface reset the serial interface can be reset by writing a series of 1s on the din input. if a logic 1 is written to the ADT7310 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 interface gets lost due to a software error or some glitch in the system. reset returns the interface to the state in which it is expecting a write to the communications register. this opera- tion resets the contents of all registers to their power-on values. following a reset, the user should allow a period of 500 s before addressing the serial interface.
ADT7310 rev. 0 | page 21 of 24 int and ct outputs the int and ct pins are open drain outputs, and both pins require a 10 k pull-up resistor to v dd . undertemperature and overtemperature detection the int and ct pins have two undertemperature/over- temperature modes: comparator mode and interrupt mode. the interrupt mode is the default power-up overtemperature mode. the int output pin becomes active when the tempera- ture is greater than the temperature stored in the t high setpoint register or less than the temperature stored in the t low setpoint register. how this pin reacts after this event depends on the overtemperature mode selected. figure 22 illustrates the comparator and interrupt modes for events exceeding the t high limit with both pin polarity settings. figure 23 illustrates the comparator and interrupt modes for events exceeding the t low limit with both pin polarity settings. comparator mode in comparator mode, the int pin returns to its inactive status when the temperature drops below the t high ? t hyst limit or rises above the t low + t hyst limit. putting the ADT7310 into shutdown mode does not reset the int state in comparator mode. interrupt mode in interrupt mode, the int pin goes inactive when any ADT7310 register is read. once the int pin is reset, it goes active again only when the temperature is greater than the temperature stored in the t high setpoint register or less than the temperature stored in the t low setpoint register. placing the ADT7310 into shutdown mode resets the int pin in the interrupt mode. tempe r a ture 82c 81c 80c 79c 78c 77c 76c 75c 74c 73c int pin (comparator mode) polarity = active low int pin (interrupt mode) polarity = 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 07789-020 figure 22. int output temperature response diagram for t high overtemperature events
ADT7310 rev. 0 | page 22 of 24 temper a ture ?13c ?14c ?15c ?16c ?17c ?18c ?19c ?20c ?21c ?22c int pin (comparator mode) polarity = active low int pin (interrupt mode) polarity = active low int pin (interrupt mode) polarity = active high int pin (comparator mode) polarity = active high t low +t hyst t low time read read read 07789-021 figure 23. int output temperature response diagram for t low undertemperature events
ADT7310 rev. 0 | page 23 of 24 applications information thermal response time the time required for a temperature sensor to settle to a specified accuracy is a function of the thermal mass of the sensor and the thermal conductivity between the sensor and the object being sensed. thermal mass is often considered equivalent to capacitance. thermal conductivity is commonly specified using the symbol, q, and can be thought of as thermal resistance. it is commonly specified in units of degrees per watt of power transferred across the thermal joint. the time required for the part to settle to the desired accuracy is dependent on the thermal contact established in that particular application, and the equivalent power of the heat source. in most applications, the settling time is best determined empirically. supply decoupling the ADT7310 should be decoupled with a 0.1 f ceramic capacitor between v dd and gnd. this is particularly important when the ADT7310 is mounted remotely from the power supply. precision analog products, such as the ADT7310, require a well- filtered power source. because the ADT7310 operates from a single supply, it may seem convenient to tap into the digital logic power supply. unfortunately, the logic supply is often a switch-mode design, which generates noise in the 20 khz to 1 mhz range. in addi- tion, fast logic gates can generate glitches hundreds of millivolts in amplitude due to wiring resistance and inductance. if possible, the ADT7310 should be powered directly from the system power supply. this arrangement, shown in figure 24, 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. this decoupling capacitor must be placed as close as possible to the v dd pin of the ADT7310. 0.1f ADT7310 ttl/cmos logic circuits power supply 07789-022 figure 24. use of separate traces to reduce power supply noise temperature monitoring the ADT7310 is ideal for monitoring the thermal environment within hazardous automotive applications. the die accurately reflects the exact thermal conditions that affect nearby integrated circuits. the ADT7310 measures and converts the temperature at the surface of its own semiconductor chip. when the ADT7310 is used to measure the temperature of a nearby heat source, the thermal impedance between the heat source and the ADT7310 must be considered. when the thermal impedance is determined, the temperature of the heat source can be inferred from the ADT7310 output. as much as 60% of the heat transferred from the heat source to the thermal sensor on the ADT7310 die is discharged via the copper tracks and the bond pads. of the pads on the ADT7310, the gnd pad transfers most of the heat. therefore, to measure the temperature of a heat source, it is recommended that the thermal resistance between the ADT7310 gnd pad and the gnd of the heat source be reduced as much as possible.
ADT7310 rev. 0 | page 24 of 24 outline dimensions 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-012-a a 012407-a 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) 4 1 85 5.00 (0.1968) 4.80 (0.1890) 4.00 (0.1574) 3.80 (0.1497) 1.27 (0.0500) bsc 6.20 (0.2441) 5.80 (0.2284) 0.51 (0.0201) 0.31 (0.0122) coplanarity 0.10 figure 25. 8-lead standard small outline package [soic_n] narrow body (r-8) dimensions shown in millimeters and (inches) ordering guide model temperature range temperature accuracy 1 package description package option ADT7310trz 2 C55c to +150c 0.5c 8-lead soic_n r-8 ADT7310trz-reel 2 C55c to +150c 0.5c 8-lead soic_n r-8 ADT7310trz-reel7 2 C55c to +150c 0.5c 8-lead soic_n r-8 eval-ADT7310ebz 2 evaluation board 1 maximum accuracy over the ?40 c to +105c temperature range. 2 z = rohs compliant part. ?2009 analog devices, inc. all rights reserved. trademarks and registered trademarks are the prop erty of their respective owners. d07789-0-4/09(0)

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