rev. prc 11/?02 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 which may result from its use. no license is granted by implication or otherwise under any patent or patent rights of analog devices. a ADT7301 preliminary technical data one technology way, p.o. box 9106, norwood, ma 02062-9106, u.s.a. tel: 781/329-4700 www.analog.com fax: 781/326-8703 analog devices, inc., 2002 preliminary technical data 12-bit, 0.5 o c accurate, micropower digital temperature sensor in 6-lead sot-23 functional block diagram features 12-bit temperature-to-digital converter ?55 o c to +125 o c operating temperature range capable of operating up to 150 o c 0.5 o c accuracy operating current of 1 a spi- and dsp-compatible serial interface shutdown mode space-saving sot-23 package applications medical equipment automotive cell phone hard disk drives personal computers electronic test equipment office equipment domestic appliances process control general description the ADT7301 is a complete temperature monitoring system in an sot-23 package. it contains a bandgap temperature sensor and a 12-bit adc to monitor and digitize the temperature reading to a resolution of +0.0625c. the ADT7301 has a flexible serial interface that allows easy interfacing to most microcontrollers. the interface is compatible with spi?, qspi and microwire? pro- tocol and is also compatible with dsps. the part features a standby mode that is controlled via the serial interface. the ADT7301?s wide supply voltage range, low supply current and spi-compatible interface, make it ideal for a variety of applications, including personal computers, office equipment, automotive and domestic appliances. spi is a trademark of motorola, inc. microwire is a trademark of national semiconductor, inc. product highlights 1. the ADT7301 has an on-chip temperature sensor that allows an accurate measurement of the ambient tem- perature. the measurable temperature range is ? 55 c to +125 c. 2. supply voltage of +2.7 v to +5.5 v. 3. space-saving 6-lead sot-23 package. 4. temperature accuracy of 0.5 c. 4. 12-bit temperature reading to +0.0625 c resolution. 5. the ADT7301 features a standby mode that reduces the power consumption to tbd w. serial bus interfa ce ADT7301 v dd cs sclk din dout gnd temperature val ue register 12-bit analog/digital converter bandgap temperature sensor
rev. prc ? 2 ? ADT7301?specifications 1 preliminary technical data parameter min typ max units test conditions/comments temperature sensor and adc accuracy @ v dd = +3.3 v (10%) 0.5 ct a = 0 c to 70 c. 1 ct a = ? 40 c to +85 c. 2 ct a = ? 55 c to +125 c. accuracy @ v dd = +5 v (10%) 0.5 ct a = 0 c to 70 c. 1 ct a = ? 40 c to +85 c. 2 ct a = ? 55 c to +125 c. temperature resolution 0.0625 c autoconversion update rate, t r 1 sec temperature conversion time 208 s supplies supply voltage 2.7 5.5 v for specified performance supply current normal mode @ 3 v 100 200 a normal mode @ 5 v 250 400 a shutdown mode @ 2.7v to 3.3v 0.04 1 a shutdown mode @ 4.5v to 5.5v 1 3 a power dissipation 80 w v dd = +3 v - normal mode power dissipation 1 sps 3 w v dd = +3 v - shutdown mode 10 sps 3.3 w v dd = +3 v - shutdown mode 100 sps 6 w v dd = +3 v - shutdown mode digital input 2 input high voltage, v ih 2.4 v input low voltage, v il 0.8 v input current, i in 1 a v in = 0 v to v dd input capacitance, c in 10 p f all digital inputs digital output 2 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 notes 1 all specifications apply for ? 55 c to +125 c unless otherwise stated. 2 guaranteed by design and characterization, not production tested. specifications subject to change without notice. timing characteristics 1, 2, 3 parameter limit units comments t 1 0 ns min cs cs cs (t a = t min to t max , v dd = +2.7 v to +5.5 v, unless otherwise noted) (t a = t min to t max , v dd = +2.7 v to +5.5 v, unless otherwise noted)
rev. prc ADT7301 ? 3 ? preliminary technical data ordering guide temperature temperature package branding package model range accuracy * description information option ADT7301art ? 55 c to +125 c 0.5 c 6-lead sot-23 rt-6 * temperature accuracy is over 0 c to +70 c temperature range. absolute maximum ratings * v dd to gnd . . . . . . . . . . . . . . . . . . . . . . . . . . ? 0.3 v to +7 v digital input voltage to gnd . . . . . . . ? 0.3 v to v dd + 0.3 v digital output voltage to gnd . . . . . ? 0.3 v to v dd + 0.3 v operating temperature range . . . . . . ? 55 c to +125 c storage temperature range . . . . . . . . ? 65 c to +150 c junction temperature . . . . . . . . . . . . . . . . . . . . . . +150 c sot-23, power dissipation . . . . . . . . . . . . . . . . 450 mw ja thermal impedance . . . . . . . . . . . . . . . . . 240 c/w lead temperature, soldering vapor phase (60 sec) . . . . . . . . . . . . . . . . . . . . . +215 c infrared (15 sec) . . . . . . . . . . . . . . . . . . . . . . . . . +220 c soic package, power dissipation . . . . . . . . . . . . . 450 mw ja thermal impedance . . . . . . . . . . . . . . . . . . . . 206 c/w lead temperature, soldering vapor phase (60 sec) . . . . . . . . . . . . . . . . . . . . . +215 c infrared (15 sec) . . . . . . . . . . . . . . . . . . . . . . . . . +220 c * stresses above those listed under absolute maximum ratings may cause perma- nent damage to the device. this is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. caution esd (electrostatic discharge) sensitive device. electrostatic charges as high as 4000 v readily accumulate on the human body and test equipment and can discharge without detection. although the ADT7301 features proprietary esd protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. there- fore, proper esd precautions are recommended to avoid performance degradation or loss of functionality. figure 1. load circuit for data access time and bus relinquish time +1.6 v i ol 200 a 200 a i oh to output pin c l 50pf warning! esd sensitive device
rev. prc ADT7301 ? 4 ? preliminary technical data pin function description pin sot-23 mnemonic pin no. description g n d 1 analog and digital ground. d i n 2 serial data input. serial data to be loaded to the part ? s control register is provided on this input. data is clocked into the control register on the rising edge of sclk. v dd 3 positive supply voltage, +2.7 v to +5.5 v. sclk 4 serial clock input. this is the clock input for the serial port. the serial clock is used to clock data out of the temperature value register of the ADT7301 and also to clock data into the control register on the part. cs 1 2 3 gnd top view (n ot to scale) 6 5 4 a dt7301 din v dd dout cs scl k
rev. prc ADT7301 ? 5 ? preliminary technical data typical performance curves title 0 0 0 00 0 t i t l e 0000 title 0 0 0 00 0 t i t l e 0000 tpc 1. temperature accuracy @ 3.3 v and 5 v tpc 2. operating supply current vs temperature title 0 0 0 00 0 t i t l e 0000 title 0 0 0 00 0 t i t l e 0000 tpc 3. operating supply current vs supply voltage tpc 4. power-down current vs supply voltage tpc 5. temperature accuracy vs supply ripple frequency title 0 0 0 00 0 t i t l e 0000 title 0 0 0 00 0 t i t l e 0000 tpc 6. response to thermal shock
rev. prc ADT7301 ? 6 ? preliminary technical data circuit information the ADT7301 is a 12-bit digital temperature sensor with a 13 th bit as a sign bit. the part houses an on-chip temperature sensor, a 12-bit a/d converter, a reference and serial interface logic functions in an sot-23 package. the a/d converter section consists of a conventional suc- cessive-approximation co nverter based around a capacitor dac. the parts are capable of running on a +2.7 v to +5.5 v power supply. the on-chip temperature sensor allows an accurate measure- ment of the ambi ent device tem perature to be made. the specified measurement range of the ADT7301 is ? 55 c to +125 c. the ADT7301 is capable of measuring up to 150 c but for limited time periods. the structural integ- rity of the device will start to deteriorate when operated at voltage and temperature maximum specifications. converter details the conversion clock for the part is internally generated so no external clock is required except when reading from and writing to the serial port. in normal mode, an internal clock oscillator runs the automatic conversion sequence. a conversion is initiated every 1 sec. at this time, the part wakes up and performs a temperature conversion. this temperature conversion typically takes 208 s, at which time the analog circuitry of the part automatically shuts down. the analog circuitry powers up again when the 1 sec timer times out and the next conversion begins. the result of the most recent temperature conversion is always available in the serial output register as the serial interface circuitry never shuts down. the ADT7301 can be placed in a shutdown mode, via the control register, in which case, the on-chip oscillator is shut down and no further conversions are initiated until the ADT7301 is taken out of shutdown mode. the conversion result from the last conversion prior to shutdown can still be read from the ADT7301 even when it is in shutdown mode. in the automatic conversion mode, every time read or write operation takes place, the internal clock oscillator is restarted at the end of the read or write operation. the result of the conversion is available, typically 208 s later. similarly, when the part is taken out of shutdown mode, the internal clock oscillator is restarted and the conversion result is available, typically 208 s later. read- ing from the device again before conversion is complete will again provide the same set of data. temperature value register the temperature value register is a 13-bit read-only regis- ter that stores the temperature reading from the adc in 12-bit twos complement format plus a sign bit. the msb (db12) is the sign bit. the adc can theoretically mea- sure a temperature span of 255 c. the internal tempera- ture sensor is guaranteed to a low value limit of -55 c and a high limit of +125 c. the temperature data format is shown in table i. this table shows the temperature measurement range of the device ( ? 55 c to +150 c). a typical performance curve is shown in tpc 1. table i. temperature data format digital output temperature db12 . . . db0 ? 55 c 1, 1100 1001 0000 ? 50 c 1, 1100 1110 0000 ? 40 c 1, 1101 1000 0000 ? 30 c 1, 1110 0010 0000 ? 25 c 1, 1110 0111 0000 ? 10 c 1, 1111 0110 0000 -0.0625 c 1, 1111 1111 1111 0 c 0, 0000 0000 0000 +0.0625 c 0, 0000 0000 0001 +10 c 0, 0000 1010 0000 +25 c 0, 0001 1001 0000 +50 c 0, 0011 0010 0000 +75 c 0, 0100 1011 0000 +100 c 0, 0110 0100 0000 +125 c 0, 0111 1101 0000 +150 c 0, 1001 0110 0000 temperature conversion formula: 1. positive temperature = adc code(d)/16 2. negative temperature = (adc code*(d) - 8192)/16 *using all 12 bits of the data byte plus the sign bit. negative temperature = (adc code(d)* - 4096)/16 *db12 (sign bit) is removed from the adc code d i g i t a l o u t p u t -55c +150c temperature (c) 1, 1100, 1001, 0000 0 , 1001, 0110, 0000 1, 1100, 1001, 0000 0, 0000, 0000, 0001 +0.0625c -0.0625c 1, 1110, 0010, 0000 -30c +75c 0, 0100, 1011, 0000 figure 2. temperature to digital transfer function serial interface the serial interface on the ADT7301 consists of four wires, cs cs cs
rev. prc ADT7301 ? 7 ? preliminary technical data improve synchronisation between the ADT7301 and the master device. the din line is used to write the part into standby mode, if required. the cs cs cs ? t cares while all other bits in the data stream other, than the power-down bit, should be 0 to ensure correct operation of the ADT7301. data is loaded into the control register on the fifteenth falling sclk edge and the data takes effect at this time i.e., if the part is programmed to go into shutdown, it does so at this point. if the cs cs sclk dout din don't care don't care power- down leading ze ro db12 db11 db0 123 4 14 15 16 t 1 t 2 t 3 t 4 t 5 t 6 t 7 t 8 db0 db0 db0 figure 3. serial interface timing diagram microprocessor interfacing the ADT7301 ? s serial interface allows for easy interface to most microcomputers and microprocessors. figures 4 through 7 show some typical interface circuits. the serial interface on the ADT7301 consists of four wires: cs cs cs ADT7301* sclk dout din cs mc68hc11* sclk miso mosi pc1 *additional pins omitted for clarity figure 4. ADT7301 to mc68hc11 interface ADT7301 to 8051 interfacean interface circuit between the ADT7301 and the micro-controller is shown in figure 5. the 8xc51 is configured in its mode 0 serial interface mode. the serial clock line of the 8xc51 (on p3.1) idles high between data transfers. data is transferred to and from the ADT7301 in
rev. prc ADT7301 ? 8 ? preliminary technical data two 8-bit serial data operations. the ADT7301 outputs the msb of its data stream as the first valid bit while the 8xc51 expects the lsb first. thus, the data read into the serial buffer needs to be rearranged before the correct data word from the ADT7301 is available in the accumulator. in the example shown, the ADT7301 is connected to the serial port of the 8051. because the serial interface of the 8xc51 contains only one data line, the din line of the ADT7301 is tied low in the interface example given in figure 5. for applications that require the use of the power-down feature of the ADT7301, the serial interface should be implemented using data port lines on the 8051. this al- lows a full-duplex serial interface to be implemented. the method involves ? bit-banging ? a port line to generate a serial clock while using two other port lines to shift data in and out with the fourth port line connecting to cs cs, ADT7301* sclk dout din cs 8051* p3.1 p3.0 p1.2 p1.3 *additional pins omitted for clarity figure 5. ADT7301 to 8051 interface ADT7301 to pic16c6x/7x interface figure 6 shows an interface circuit between the ADT7301 and the pic16c6x/7x microcontroller. the pic16c6x/ 7x synchronous serial port (ssp) is configured as an spi master with the clock polarity bit set to a logic one. in this mode, the serial clock line of the pic16c6x/7x idles high between data transfers. data is transferred to and from the ADT7301 in two 8-bit serial data operations. in the example shown, port line ra1 is being used to gener- ate the cs ADT7301* sclk dout din cs pic16c6x/7x* sck sdo sdi ra1 *additional pins omitted for clarity figure 6. ADT7301 to pic16c6x/7x interface ADT7301 to adsp-21xx interface figure 7 shows an interface between the ADT7301 and the adsp-21xx dsp processor. to ensure correct opera- tion of the interface the sport control register should be set up as follows: tfsw = rfsw = 1, alternate framing invrfs = invtfs = 1, active low framing signal dtype = 00, right justify data slen = 1111, 16-bit data words isclk = 1, internal serial clock tfsr = rfs = 1, frame every word irfs = 0, rfs configured as input itfs = 1, tfs configured as output the interface requires an inverter between the sclk line of the adsp-21xx and the sclk input of the ADT7301. the adsp-2 1xx has the tfs and rfs of the sport tied together with tfs set as an output and rfs set as an input. the dsp operates in alternate framing mode and the sport control register is set up as described above. ADT7301* sclk dout din cs adsp-21xx* sck dr dt rfs *additional pins omitted for clarity tfs figure 7. ADT7301 to adsp-21xx interface mounting the ADT7301 the ADT7301 can be used for surface or air-temperature sensing applications. if the device is cemented to a surface with thermally conductive adhesive, the die temperature will be within about 0.1 c of the surface temperature, thanks to the device ? s low power consumption. care should be taken to insulate the back and leads of the device from the air, if the ambient air temperature is different from the surface temperature being measured. the ground pin provides the best thermal path to the die, so the temperature of the die will be close to that of the printed circuit ground track. care should be taken to en- sure that this is in good thermal contact with the surface being measured. as with any ic, the ADT7301 and its associated wiring and circuits must be kept free from moisture to prevent leakage and corrosion, particularly in cold conditions where condensation is more likely to occur. water-resis- tant varnishes and conformal c oatings can be used for protection. the small size of the ADT7301 package allows it to be mounted inside sealed metal probes, which provide a safe environment for the device. supply decoupling the ADT7301 should be decoupled with a 0.1 f ce- ramic capacitor between v dd and gnd. this is particu- larly important if the ADT7301 is mounted remote from the power supply.
outline dimensions dimensions shown in inches and (mm). 6-lead plastic surface mount sot-23 (rt-6) 0.122 (3.10) 0.106 (2.70) pin 1 0.118 (3.00) 0.098 (2.50) 0.075 (1.90) bsc 0.037 (0.95) bsc 1 3 4 5 6 2 0.071 (1.80) 0.059 (1.50) 0.009 (0.23) 0.003 (0.08) 0.022 (0.55) 0.014 (0.35) 10 0 0.020 (0.50) 0.010 (0.25) 0.059 (0.15) 0.000 (0.00) 0.051 (1.30) 0.035 (0.90) seating plane 0.057 (1.45) 0.035 (0.90)
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