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0.25c accurate, 16 - bit digital spi temperature sensor data sheet adt7320 rev. 0 document feedback 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 res pective owners. one technology way, p.o. box 9106, norwood, ma 02062 - 9106, u.s.a. tel: 781.329.4700 ? 2012 analog devices, inc. all rights reserved. technical support www.analog.com features high performance temperature accuracy 0.20c from ?10c to +85c at 3.0 v 0.25c from ?20c to +105c at 2.7 v to 3.3 v 16- bit temperature resolution: 0.0078c ultralow temperature drift: 0.0073c nist traceable or equivalent fast first tempera ture conversion on power - up of 6 ms easy implementation no temperature calibration/correction required by user no linearity correction required low power power saving 1 sample per second (sps) mode 700 w typical at 3.3 v in normal mode 7 w typical at 3.3 v in shutdown mode wide operating range s t emperature r ange : ? 40c to +150c v oltage r ange : 2.7 v to 5.5 v programmable interrupts cr itical overtemperature interrupt overtemperature/undertemperature interrupt spi - compatible interface 16- lead , rohs - compliant, 4 mm 4 mm lfcsp package applications rtd and t hermistor r eplacement thermocouple cold junction compensation medical e quipment industrial c ontrol and t est food transportation and s torage environmental m onitoring and hvac laser diode temperature control general de sc ription the adt7320 is a high accuracy digital temperature sensor that offer s breakthrough performance over a wide industrial temperature range, housed in a 4 mm 4 mm lfcsp package . it contains a n internal band gap reference , a temperature sensor, and a 1 6- bit analog - to - digital converter ( adc ) to monitor and di gitize the temperature to a resolution of 0.0078 c. the adc resolution , by default , is set to 13 bits (0.06 25c). the adc resolution is a user programmable mode that can be changed through the serial interface. the adt7320 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 adt7320 has a shutdown mode that powers down the device and offers a shutdown current of typically 2 .0 a at 3.3 v . the adt7320 is rated for operation over the ?40 c 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 int pin is also an open - drain output that becomes active when the temperature exceeds a programmable limit. the int pin and ct pin can ope rate in either comparator or interrupt mode. product highlights 1. ease of use, no calibration or correction required by the user. 2. low pow er consumption. 3. excellent long term stability and reliability. 4. high accuracy for industrial, instrumentation, and medica l applications. 5. packaged in a 16 -lead, rohs - compliant, 4 mm 4 mm lfcsp package . functional block dia gram internal reference 12 11 temperature sensor t high t crit t low internal oscillator filter logic - modulator v dd gnd 10 9 ct int adt7320 temperature value register configuration register t hyst register t low register t high register t crit register id register status register 1 2 sclk dout 3 4 din cs spi interface 09012-001 figure 1.
adt7320* product page quick links last content update: 06/09/2017 comparable parts view a parametric search of comparable parts. evaluation kits ? adt7420 evaluation board documentation data sheet ? adt7320: 0.25c accurate, 16-bit digital spi temperature sensor data sheet user guides ? ug-138: evaluating the adt7320/adt7420 temperature sensors tools and simulations ? adt7320 ibis model reference designs ? cn0172 reference materials technical articles ? home is where the heart is design resources ? adt7320 material declaration ? pcn-pdn information ? quality and reliability ? symbols and footprints discussions view all adt7320 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.
adt7320 data sheet rev. 0 | 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 pin configuration and function descriptions ............................. 6 typical performance characteristics ............................................. 7 t heory of operation ........................................................................ 9 circuit information ...................................................................... 9 converter details .......................................................................... 9 continuous conversion mode ................................................... 9 one - shot mode .......................................................................... 10 1 sps mode .................................................................................. 11 s hutdown mode .......................................................................... 11 fault queue ................................................................................. 11 temperature data format ......................................................... 12 temper ature conversion formulas ......................................... 12 registers ........................................................................................... 13 status register ............................................................................. 13 con figuration 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 serial interface reset .................................................................. 19 int and ct outputs ...................................................................... 20 undertemperature and overtemperature detection ............ 20 applications information .............................................................. 22 thermal response time ........................................................... 22 supply decoupling ..................................................................... 22 powering from a switching regulator ..................................... 22 temperature measurement ....................................................... 22 quick guide to measuring temperature ................................ 22 outline dimensions ....................................................................... 23 ordering guide .......................................................................... 23 revision history 12/1 2 rev ision 0 : initial version
data sheet adt7320 rev. 0 | page 3 of 24 specifications t a = ? 40c to +125 c, 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 0.0017 0.20 2 c t a = ? 10c to +8 5c, v dd = 3.0 v 0.25 c t a = ?20c to +105c, v dd = 2.7 v to 3.3 v 0.31 c t a = ?40c to + 105 c, v dd = 3.0 v 0.35 c t a = ?40c to + 105 c, v dd = 2.7 v to 3.3 v 0.50 c t a = ?40c to +125c, v dd = 2.7 v to 3.3 v 0.50 3 c t a = ?10c to +105c, v dd = 4.5 v to 5.5 v 0.66 c t a = ?40c to +125c, v dd = 4.5 v to 5.5 v ? 0.8 5 c t a = + 150c, v dd = 4.5 v to 5.5 v ? 1.0 c t a = + 150c, v dd = 2.7 v to 3.3 v adc resolution 13 bits twos complement t emperature valu e of sign bit plus 12 ad c bits (power - up defa ult resolution) 16 bits twos complement temperature va lue 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 s) 16- bit 0.0078 c 16- bit resolution (s ign + 15 bit s) 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 4 0.002 c temperature cycle = 25c to 125c and back to 25c repeatability 5 0.015 c t a = 25c drift 6 0.0073 c 500 hour stress test at 150c with v dd = 5.0 v dc psrr 0.1 c/v t a = 25c digital outputs ( c t, int ), open drain high output leakage current, i oh 0.1 5 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 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 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 a t 3.3 v 210 2 65 a a t 5.5 v 2 50 300 a 1 sps current 1 sps mode, t a = 25c at 3.3 v 46 a v dd = 3.3 v at 5.5 v 65 a v dd = 5.5 v
adt7320 data sheet rev. 0 | page 4 of 24 parameter min typ max unit test conditions/comments shutdown current supply current in shutdown mode a t 3.3 v 2.0 15 a a t 5.5 v 5.2 25 a power dissipation , normal mode 70 0 w v dd = 3.3 v, normal mode at 25c power dissipation , 1 sps mode 150 w power dissipated for v dd = 3.3 v, t a = 25c 1 accu racy specification includes repeatability. 2 the equivalent 3 limits are 0.15c . this 3 specification is provided to enable comparison with other vendors who use these limits. 3 for higher accuracy at 5 v operation, contact analog devices, inc. 4 temperature h ysteresis does not include repeatability. 5 based on a floating average of 10 readings. 6 drift includes solder heat resistance and life time test performed as per jedec standard jesd22 - a108 . spi timing specifica tions t a = ? 40 c to +150c, v dd = 2.7 v to 5.5 v, unless otherwise noted. all input signals are specified with rise time (t r ) = f all 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 unit descriptions 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 bus relinquish time after cs inactive edge t 8 0 ns min sclk inactive edge to cs rising 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 1 0 ns min sclk inactive edge to dout low 1 sample tested during initial release to ensure compliance. 2 see figure 2 . 3 this means that the times quoted in the timing characteristics in table 2 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 09012-002 figure 2 . detailed spi timing diagram
data sheet adt7320 rev. 0 | page 5 of 24 absolute maximum ratings 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 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 1 ?40c to +150c storage temperature range ?65c to +160c maximum junction temperature, t jmax 150c power dissipation 2 16-lead lfcsp 3 w max = (t jmax ? t a )/ ja thermal impedance 4 ja , junction-to-ambient (still air) 37c/w jc , junction-to-case 33c/w ir reflow soldering 220c peak temperature (rohs-compliant package) 260c (0c/?5c) time at peak temperature 20 sec to 40 sec ramp-up rate 3c/sec maximum ramp-down rate ?6c/sec maximum time from 25c to peak temperature 8 minutes maximum 1 sustained operation abov e 125c results in a shorte r product lifetime. for more information, contact an analog devices, inc., sales representative. 2 values relate to package being used on a standard 2-layer pcb. this gives a worst-case ja and jc . 3 t a = ambient temperature. 4 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 resistance 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. esd caution
adt7320 data sheet rev. 0 | page 6 of 24 pin configuration and fu nction descriptions 12 11 10 1 3 4 v dd 17 epad gnd ct 9 int sclk din 2 dout cs 6 nc 5 nc 7 nc 8 nc 16 nc 15 nc 14 nc 13 nc adt7320 top view (not to scale) notes 1. nc = no connect. do not connect to this pin. the nc pin is not bonded to the die internally. 2. to ensure correct operation, the exposed pad should either be left floating or connected to ground. 09012-003 figure 3. pin configuration table 4. pin function descriptions pin no. mnemonic description 1 sclk serial clock input. the serial clock is used to clock data into and out of any register of the adt7320 . 2 dout serial data output. da ta is clocked out on the sclk falling edge and is valid on the sclk rising edge. 3 din serial data input. serial data to be loaded to the control registers 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 input is low. the device is disabled when this pin is high. 5 nc no connect. do not connect to this pin. the nc pin is not bonded to the die internally. 6 nc no connect. do not connect to this pin. the nc pin is not bonded to the die internally. 7 nc no connect. do not connect to this pin. the nc pin is not bonded to the die internally. 8 nc no connect. do not connect to this pin. the nc pin is not bonded to the die internally. 9 int overtemperature and undertemperature interrupt. 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. 10 ct critical overtemperature interrupt. logic output. po wer-up default polarity is active low. open-drain configuration. a pull-up resistor is required, typically 10 k. 11 gnd analog and digital ground. 12 v dd positive supply voltage (2.7 v to 5.5 v). decouple the supply with a 0.1 f ceramic capacitor to gnd. 13 nc no connect. do not connect to this pin. the nc pin is not bonded to the die internally. 14 nc no connect. do not connect to this pin. the nc pin is not bonded to the die internally. 15 nc no connect. do not connect to this pin. the nc pin is not bonded to the die internally. 16 nc no connect. do not connect to this pin. the nc pin is not bonded to the die internally. 17 epad exposed pad. to ensure correct operation, the exposed pa d should either be left floating or connected to ground.
data sheet adt7320 rev. 0 | page 7 of 24 typical performance characteristics tempe r a ture error (c) ?40 ?60 ?20 0 20 40 temperature (c) 60 80 100 120 140 ?1.00 ?0.50 0 0.50 0.25 ?0.25 0.75 ?0.75 1.00 max accuracy limits max accurac y limits 09012-027 figure 4. temperature accuracy at 3 v tempe r a ture error (c) ?40?60 ?20 0 20 40 temperature (c) 60 80 100 120 140 ?1.00 ?0.50 0 0.50 0.25 ?0.25 0.75 ?0.75 1.00 max accurac y limits max accuracy limits 09012-026 figure 5. temperature accuracy at 5 v ?100 ?50 0 50 100 150 200 i dd ( a) temperature (c) 3.0v 1sps 5.5v 1sps 5.5v continuous conversion 3.0v continuous conversion 09012-028 0 50 100 150 200 250 300 figure 6. operating supply current vs. temperature 3.6v shutdown i dd ( a) temperature (c) 0 5 10 15 20 25 30 ?100 ?50 0 50 100 150 200 3.3v 3.0v 2.7v 4.5v 5.0v 5.5v 09012-032 figure 7. shutdown 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 1sps 09012-029 figure 8. average operating supply current vs. supply voltage 09012-210 0 1 2 3 4 5 6 7 8 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 shutdown i dd (a) supply voltage (v) figure 9. shutdown current vs. supply voltage
adt7320 data sheet rev. 0 | page 8 of 24 0 20 40 60 80 100 120 140 0 5 10 15 25 20 dut tempe r a ture (c) time (s) 125c 105c 85c 0 9012-110 it takes less than 2 seconds for the dut to reach 63.2% of its final temperature span figure 10. thermal response time
data sheet adt7320 rev. 0 | page 9 of 24 theory of operation circuit information the adt7320 is a high accuracy digital temperature 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 rated temperature range without the need for correction or calibration by the user. the sensor output is digitized by a sigma-delta (-) modulator, also known as the 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 compact circuit. converter details 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 integrator output by changing the duty cycle of the comparator output in response to the 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 reference 1-bit 13-/16-bit 09012-012 figure 11. -? modulator the adt7320 can be configured to operate in any one of the following four operating modes: normal mode, one-shot mode, 1 sps mode, and shutdown mode. continuous conversion mode in continuous conversion mode (default power-up mode), the adt7320 runs an automatic conversion sequence. during this automatic conversion sequence, a conversion takes 240 ms to complete and the adt7320 is continuously converting. this means that as soon as one temperature conversion 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 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 register), and a low temperature limit (stored in the 16-bit t low setpoint register). if the measured value exceeds the high or low temperature limits, the int pin is activated; if it exceeds the t crit limit, the ct pin is activated. the polarity of the int and ct pins is programmable for via the configuration register, and the int and ct pins are also programmable for interrupt mode via the configuration register.
adt7320 data sheet rev. 0 | page 10 of 24 din data sclk dout cs wait 240ms minimum for conversion to finish 09012-300 0x08 0x20 figure 12. typical spi one-shot write to configuration register followed by a read from the temperature value register temperature 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.* 0 9012-013 figure 13. one-shot ct pin one-shot mode when one-shot mode is enabled, the adt7320 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 configuration register (register address 0x01) to 01. after writing to the operation mode bits, wait for at least 240 ms before reading back the temperature from the temperature value register. this delay ensures that the adt7320 has adequate time to power up and complete a conversion. to obtain an updated temperature conversion, reset bits[6:5] of the configuration register (register address 0x01) to 01. ct and int operation in one-shot mode see figure 13 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 comparator mode, if the temperature drops below the t high ? t hyst value or goes above the t low + t hyst value, a write to the operation mode bits (bit 5 and bit 6 of the configuration register, register a ddress 0x01) resets the int pin. for the ct pin in comparator mode, if the temperature drops below the t crit ? t hyst value, a write to the operation mode bits (bit 5 and bit 6 of the configuration register, register address 0x01) resets the ct pin (see figure 13 ). when using one-shot mode, ensure that the refresh rate is appropriate to the application being used.
data sheet adt7320 rev. 0 | page 11 of 24 1 sps mode in 1 sps mode, the part performs one measurement per second. a conversion takes 60 ms typically, and the part remains in the idle state for the remaining 940 ms period. this mode is enabled by setting bits[6:5] of the configuration register (register address 0x01) to 10. shutdown mode the adt7320 can be placed in shutdown mode by setting bits[6:5] of the configuration register (register address 0x01) to 11. the adt7320 can be taken out of shutdown mode by setting bits[6:5] of the configuration register (register address 0x01) to 00. the adt7320 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 adt7320 even when it is in shutdown mode. when the part is taken out of shutdown mode, the internal clock restarts 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 adt7320 is used in a noisy temperature environment. 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 set 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.
adt7320 data sheet rev. 0 | page 12 of 24 temperature data format one lsb of the adc corresponds to 0.0625c in 13-bit mode or 0.0078c in 16-bit mode. the adc can theoretically measure a temperature range of 255c, but the adt7320 is guaranteed to measure a low value temperature limit of ?40c 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. on power-up the three lsbs, bit 0 to bit 2, are not part of the temperature conversion 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 adt7320 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] ?40c 1 1101 1000 0000 ?25c 1 1110 0111 0000 ?0.0625c 1 1111 1111 1111 0c 0 0000 0000 0000 +0.0625c 0 0000 0000 0001 +25c 0 0001 1001 0000 +105c 0 0110 1001 0000 +125c 0 0111 1101 0000 +150c 0 1001 0110 0000 temperature conversion 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 (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) ? 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 code (dec) negative temperature = adc code (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 .
data sheet adt7320 rev. 0 | page 13 of 24 registers the adt7320 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. adt7320 registers register address description power-on default 0x00 status 0x80 0x01 configuration 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 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 become 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 temperature limits including hysteresis. 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 operation mode bits in the configuration register. table 7. status register (register address 0x00) bit(s) default value type name description [3:0] 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 is cleared to 0 when the status register is read and/or when the temperature measured rises 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 rises above the t high temperature limit. this bit is cleared to 0 when the status register is read and/or wh en the temperature measured drops 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 rises above the t crit temperature limit. this bit is cleared to 0 when the status register is read and/or when the temperature measured drops 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 to 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 operation mode bits in the configuration register.
adt7320 data sheet rev. 0 | page 14 of 24 configuration register this 8-bit read/write register (register address 0x01) stores various configuration modes for the adt7320 , including shutdown, overtemperature and undertemperature interrupts, one-shot, continuous conversion, interrupt pin polarity, and overtemperature fault queues. table 8. configuration register (register address 0x01) bit(s) default value type name description [1:0] 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 comparator mode or interrupt mode. 0 = interrupt mode. 1 = comparator mode. [6:5] 00 r/ w operation mode these two bits set the operational mode of the adt7320 . 00 = continuous conversion (default). wh en one conversion is finished, the adt7320 begins the next conversion. 01 = one-shot mode. 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 for the interface circuitry is powered down. [7] 0 r/ w resolution this bit sets the resol ution 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 0.0078c.
data sheet adt7320 rev. 0 | page 15 of 24 temperature v alue register the temperature value register stores the temperature measured by the internal temperature sensor. the temperature is stored in 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 , respectively . 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 (regi ster address 0x03) stores the manufacturer id in bit 7 to bit 3 and the silicon revision in bit 2 to bit 0. the default setting for the id register is 0xc3. t crit setpoint register the 16- bit t crit setpoin t register (register address 0x04) stores the crit ical 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(s) default value t ype name description [0] 0 r t low flag/lsb0 flags a t low event if the configuration register, r egister address 0x01[7] = 0 (13 - bit resolution). when the temperature value is below t low , this bit i s set to 1. contains least significant bit 0 of the 15- bit temperature value when 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 i s set to 1. contains least significant bit 1 of the 15 - bit temperature value when 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 configu ration register, register address 0x01[7] = 0 (13 - bit resolution). when the temperature value exceeds t crit , this bit i s set to 1. contains the least significant bit 2 of the 15 - bit temperature value if the config uration register, register address 0x0 1[7] = 1 (16 -b it resolution). [7:3] 00000 r temp temperature value in twos complement format. [14:8] 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(s) default value type name description [2:0] 011 r revision id contains the silicon revision identification number . [7:3] 11000 r manufacture r id contains the manufacturer identificati on number . table 11. t crit setpoint register (register address 0x04) bit(s) default value type name description [15:0] 0x4980 r/ w t crit 16- bit critical overtemperature limit, stored in twos complement format.
adt7320 data sheet rev. 0 | page 16 of 24 t hyst setpoint register the 8-bit t hyst setpoint 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 the 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(s) default value type name description [3:0] 0101 r/ w t hyst hysteresis value, from 0c to 15c. stored in st raight binary format. the default setting is 5c. [7:4] 0000 r/ w n/a n/a = not appl icable. not used. table 13. t high setpoint register (register address 0x06) bit(s) default value type name description [15:0] 0x2000 r/ w t high 16-bit overtemperature limit, stored in twos complement format. table 14. t low setpoint register (register address 0x07) bit(s) default value type name description [15:0] 0x0500 r/ w t low 16-bit undertemperature limit, stored in twos complement format.
data sheet adt7320 rev. 0 | page 17 of 24 serial interface adt7320 gnd sclk dout din ct int v dd 10k ? 10k ? pull-up to v dd 0.1f microcontroller v dd cs 09012-014 figure 14. typical spi interface connection the adt7320 has a 4-wire serial peripheral interface (spi). the interface has a data input pin (din) for writing data to the device, a data output pin (dout) for reading data back from the device, and a serial 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 on the falling edge of sclk, and data is clocked into the device on the rising edge of sclk. adt7320 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. the command byte indicates to the whether the transaction is a read or a write and provides the address of the register for the data transfer. shows the command byte. adt7320 table 15 table 15. 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 interface does not work correctly if a 1 is written into 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.
adt7320 data sheet rev. 0 | page 18 of 24 writing data data is written to the adt7320 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 adt7320 clocks the data into the register addressed in the command byte on the rising edge of sclk. the master finishes the write transaction by pulling cs high. figure 15 shows a write to an 8-bit register, and figure 16 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 09012-128 figure 15. 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 00 0 d12 d10 d11 d9 d8 d7 d15 8-bit command byte 09012-129 figure 16. writing to a 16-bit register
data sheet adt7320 rev. 0 | page 19 of 24 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 8-bit command byte 09012-030 0 figure 17. 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 s clk 1234 d14 d13 17 cs r/w register addr 0 0 0 d12 d11 d10 d9 d8 d7 d15 dout 8-bit command byte 09012-031 0 figure 18. reading from a 16-bit register reading data a read transaction begins when the master writes the command byte to the adt7320 with the read/write bit set to 1. the master then supplies 8 or 16 clock pulses, depending on the addressed register, and the adt7320 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 pulls cs high. interfacing to dsps or microcontrollers the adt7320 can be operated with cs used as a frame synchronization 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 values are obeyed. cs can be tied to ground and the serial interface can operate in a 3-wire mode. din, dout, and sclk are used to communicate with the adt7320 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 adt7320 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 interface is lost due to a software error or a glitch in the system. a reset returns the interface to the state in which it expects a write to a communications register. this operation resets the contents of all registers to their power-on values. following a reset, allow a period of 500 s before addressing the serial interface.
adt7320 data sheet rev. 0 | page 20 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 . the adt7320 must be fully powered up to v dd before reading int and ct data. undertemperature and overtemperature detection the int and ct pins have two undertemperature/overtemperature modes: comparator mode and interrupt mode. the interrupt mode is the default power-up overtemperature mode. the int output pin becomes active 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. how this pin reacts after an undertemperature or overtemperature event depends on the overtemperature mode selected. figure 19 illustrates the comparator and interrupt modes for events exceeding the t high limit with both pin polarity settings. figure 20 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. placing the adt7320 into shutdown mode does not reset the int state in comparator mode. interrupt mode in interrupt mode, the int pin returns to its inactive status when any adt7320 register is read. when the int pin is reset, it becomes 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 adt7320 into shutdown mode resets the int pin 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) 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 09012-020 figure 19. int output te mperature response for t high overtemperature events
data sheet adt7320 rev. 0 | page 21 of 24 temperature ?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 09012-021 figure 20. int output te mperature response for t low undertemperature events
adt7320 data sheet rev. 0 | page 22 of 24 applications information thermal response time powering from a switching regulator 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 that the ic is mounted to. for example, a large pcb containing large amounts of copper tracing can act as a large heat sink and slow the thermal response. for a faster thermal response, it is recommended that the sensor be mounted on a pcb that is as small as possible. precision analog devices such as the adt7320 require a well- filtered power source. if the adt7320 is powered from a switching regulator, noise may be generated above 50 khz that may affect the temperature accuracy specifications. to prevent this, an rc filter should be used between the power supply and adt7320 v dd . the value of the components used should be carefully considered to ensure that the peak value of the supply noise is less than 1 mv. the rc filter should be mounted as far away as possible from the adt7320 to ensure that the thermal mass is kept as low as possible. figure 10 shows the typical response time of less than 2 seconds to reach 63.2% of the temperature span of the dut. the temperature values are the digital bytes read back through the digital interface. the response time includes all delays incurred on chip during signal processing. temperature measurement the adt7320 accurately measures and converts the temperature at the surface of its own semiconductor chip. thermal paths run through the leads, the exposed pad, as well as the plastic package. when the adt7320 is used to measure the temperature of a nearby heat source, the thermal impedance between the heat source and the adt7320 must be considered because this impedance affects the accuracy and thermal response of the measurement. supply decoupling the adt7320 must have a decoupling capacitor connected between v dd and gnd; otherwise, incorrect temperature readings will be 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 pin of the adt7320 . if possible, the adt7320 should be powered directly from the system power supply. this arrangement, shown in figure 21 , 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. for air or surface temperature measurements, take care to isolate the package, leads, and exposed pad from ambient air temperature. use of a thermally conductive adhesive can help to achieve a more accurate surface temperature measurement. quick guide to measuring temperature th e following is a quick guide for measuring temperature in continuous conversion mode (default power-up mode). execute each step sequentially. 0.1f adt7320 ttl/cmos logic circuits power supply 09012-022 1. after power-up, reset the serial interface (load 32 consecutive 1s on din). this ensures all internal circuitry is properly initialized. 2. verify the setup by reading the device id (register address 0x03). it should read 0xc3. 3. after consistent consecutive readings are obtained from step 2, read the configuration register (register address 0x01), t crit (register address 0x04), t high (register address 0x06), and t low (register address 0x07). compare these values with the specified defaults in table 6 . if all the readings match, the interface is operational. figure 21. use of separate traces to reduce power supply noise 4. write to the configuration register to set the adt7320 to the desired configuration. read the temperature value register. it should produce a valid temperature measurement.
data sheet adt7320 rev. 0 | page 23 of 24 outline dimensions 2.70 2.60 sq 2.50 compliant to jedec standards mo-220-wggc. 1 0.65 bsc bottom view top view 16 5 8 9 12 13 4 exposed pad p i n 1 i n d i c a t o r 4.10 4.00 sq 3.90 0.45 0.40 0.35 s eating plane 0.80 0.75 0.70 0.05 max 0.02 nom 0.20 ref 0.20 min coplanarity 0.08 pin 1 indicator 0.35 0.30 0.25 for proper connection of the exposed pad, refer to the pin configuration and function descriptions section of this data sheet. 08-16-2010-c figure 22. 16-lead lead frame chip scale package [lfcsp_wq] 4 mm 4 mm body, very very thin quad (cp-16-17) dimensions shown in millimeters ordering guide model 1 temperature range 2 package description package option adt7320ucpz-r2 ?40c to +150c 16-lead lfcsp_wq cp-16-17 adt7320ucpz-rl7 ?40c to +150c 16-lead lfcsp_wq cp-16-17 EVAL-ADT7X20EBZ evaluation board 1 z = rohs compliant part. 2 operating at extended temperatures over prolonged periods may shorten the lifetime performance of the part.
adt7320 data sheet rev. 0 | page 24 of 24 notes ? 2012 analog devices, inc. all rights reserved. trademarks and registered trademarks are the property of their respective owners. d09012 -0- 12/12(0)

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