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rev. d information furnished by analog devices is believed to be accurate and reliable. however, no responsibility is assumed by analog devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. no license is granted by implication or otherwise under any patent or patent rights of analog devices. trademarks and registered trademarks are the property of their respective owners. one technology way, p.o. box 9106, norwood, ma 02062-9106, u.s.a. tel: 781/329-4700 www.analog.com fax: 781/326-8703 ? 2004 analog devices, inc. all rights reserved. adm1032 * 1 c remote and local system temperature monitor functional block diagram on-chip temperature sensor a/d converter busy run/standby external diode open-circuit address pointer register conversion rate register remote temperature high limit register configuration register interrupt masking limit comparator remote temperature value register local temperature value register v dd gnd sdata sclk therm alert d+ d remote temperature low limit register local temperature high limit register local temperature low limit register analog mux adm1032 local therm limit register external therm limit register digital mux digital mux status register smbus interface remote offset register features on-chip and remote temperature sensing offset registers for system calibration 0.125 c resolution/1 c accuracy on remote channel 1 c resolution/3 c accuracy on local channel fast (up to 64 measurements per second) 2-wire smbus serial interface supports smbus alert programmable under/overtemperature limits programmable fault queue overtemperature fail-safe therm output programmable therm limits programmable therm hysteresis 170 a operating current 5.5 a standby current 3 v to 5.5 v supply small 8-lead soic and msop packages applications desktop and notebook computers smart batteries industrial controllers telecommunications equipment instrumentation embedded systems product description the adm1032 is a dual-channel digital thermometer and under/ overtemperature alarm intended for use in personal com puters and thermal management systems. the higher 1 c accuracy offered allows systems designers to safely reduce temperature guardband- ing and increase system performance. the device can measure the temperature of a microprocessor using a diode- connected npn or pnp transistor, which may be provided on-chip or can be a low cost discrete device, such as the 2n3906. a novel measurement tech- nique cancels out the absolute value of the transistor? base em itter voltage so that no calibration is required. the second measure ment channel measures the out put of an on-chip temperature sensor to monitor the temperature of the device and its environment. the adm1032 communicates over a 2-wire serial interface compatible with system management bus (smbus) standards. under and overtemperature limits can be programmed into the device over the serial bus, and an alert output signals when the on-chip or remote temperature measurement is out of range. this output can be used as an interrupt or as an smbus alert. the therm output is a comparator output that allows cpu clock throttling or on/off control of a cooling fan. an adm1032-1 is available. the only difference between the adm1032 and the adm1032-1 is the default value of the external therm limit. an adm1032-2 is also available. it has a different smbus address to the adm1032 and the adm1032-1. the smbus address of the adm1032-2 is 0x4d. * patents 5,982,221, 6,097,239, 6,133,753, 6,169,442, 5,867,012.
rev. d e2e adm1032especifications parameter min typ max unit test conditions/comments power supply supply voltage, v dd 3.0 3.30 5.5 v average operating supply current, i cc 170 215 m a 0.0625 conversions/sec rate 1 5.5 10 m a standby mode undervoltage lockout threshold 2.35 2.55 2.8 v v dd input, disables adc, rising edge power-on reset threshold 1 2.4 v temperature-to-digital converter local sensor accuracy 1 3 r c0 t a 100 r c, v cc = 3 v to 3.6 v resolution 1 r c remote diode sensor accuracy 1 r c60 r c t d 100 r c, v cc = 3 v to 3.6 v 3 r c0 r c t d 120 r c resolution 0.125 r c remote sensor source current 230 m ah igh level 2 13 m al ow level 2 conversion time 35.7 142.8 ms from stop bit to conversion complete (both channels) one-shot mode with averaging switched on 5.7 22.8 ms one-shot mode with averaging off (i.e., conversion rate = 32 or 64 conversions per second) open-drain digital outputs ( therm , alert ) output low voltage, v ol 0.4 v i out = e6.0 ma 2 high level output leakage current, i oh 0.1 1 m av out = v dd 2 serial bus timing 2 logic input high voltage, v ih 2.1 v v dd = 3 v to 5.5 v sclk, sdata logic input low voltage, v il 0.8 v v dd = 3 v to 5.5 v hysteresis 500 mv sclk, sdata sdata output low sink current 6 ma sdata forced to 0.6 v alert output low sink current 1 ma alert forced to 0.4 v logic input current, i ih , i il e1 +1 m a input capacitance, sclk, sdata 5 pf clock frequency 400 khz smbus timeout 25 64 ms see note 3 sclk clock low time, t low 1.3 m st low between 10% points sclk clock high time, t high 0.6 m st high between 90% points start condition setup time, t su:sta 600 ns start condition hold time, t hd:sta 600 ns time from 10% of sdata to 90% of sclk stop condition setup time, t su:sto 600 ns time from 90% of sclk to 10% of sdata data valid to sclk rising edge 100 ns time for 10% or 90% of sdata to time, t su:dat 10% of sclk data hold time, t hd:dat 300 ns bus free time, t buf 1.3 m sb etween start/stop condition sclk, sdata rise time, t r 300 ns sclk, sdata fall time, t f 300 ns notes 1 see table vi for information on other conversion rates. 2 guaranteed by design, not production tested. 3 the smbus timeout is a programmable feature. by default, it is not enabled. details on how to enable it are available in the se rial bus interface section of this data sheet. specifications subject to change without notice.
rev. d adm1032 e3e absolute maximum ratings * positive supply voltage (v dd ) to gnd . . . . . . e0.3 v, +5.5 v d+ . . . . . . . . . . . . . . . . . . . . . . . . . . . . e0.3 v to v dd + 0.3 v de to gnd . . . . . . . . . . . . . . . . . . . . . . . . . e0.3 v to +0.6 v sclk, sdata, alert . . . . . . . . . . . . . . . . e0.3 v to +5.5 v therm . . . . . . . . . . . . . . . . . . . . . . . e0.3 v to v dd + 0.3 v input current, sdata, therm . . . . . . . . e1 ma, +50 ma input current, de . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 ma esd rating, all pins (human body model) . . . . . . >1,000 v maximum junction temperature (t j m ax) . . . . . . . . . 150 r c storage temperature range . . . . . . . . . . . . e65 r c to +150 r c ir reflow peak temperature . . . . . . . . . . . . . . . . . . . . 220 r c ir reflow peak temperature for pb-free . . . . . . . . . . 260 r c lead temp (soldering 10 sec) . . . . . . . . . . . . . . . . . . . 300 r c * 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. thermal characteristics 8-lead soic package q ja = 121 r c/w 8-lead msop package q ja = 142 r c/w p s t su:dat t high t f t hd:dat t r t low t su:sto ps sclk sdata t hd:sta t hd:sta t su:sta t buf figure 1. diagram for serial bus timing ordering guide temperature package package smbus external therm m r a amar l r ar c adm1032ar-reel 0 r c to 120 r c 8-lead soic r-8 1032ar 4c 85 c adm1032ar-reel7 0 r c to 120 r c 8-lead soic r-8 1032ar 4c 85 c adm1032arz 1 0 r c to 120 r c 8-lead soic r-8 1032ar 4c 85 c adm1032arz-reel 1 0 r c to 120 r c 8-lead soic r-8 1032ar 4c 85 c adm1032arz-reel7 1 0 r c to 120 r c 8-lead soic r-8 1032ar 4c 85 c adm1032ar-1 0 r c to 120 r c 8-lead soic r-8 1032ar01 4c 108 c ADM1032AR-1REEL 0 r c to 120 r c 8-lead soic r-8 1032ar01 4c 108 c ADM1032AR-1REEL7 0 r c to 120 r c 8-lead soic r-8 1032ar01 4c 108 c adm1032arz-1 1 0 r c to 120 r c 8-lead soic r-8 1032ar 4c 85 c adm1032arz-1reel 1 0 r c to 120 r c 8-lead soic r-8 1032ar 4c 85 c adm1032arz-1reel7 1 0 r c to 120 r c 8-lead soic r-8 1032ar 4c 85 c adm1032arm 0 r c to 120 r c 8-lead msop rm-8 t2a 4c 85 c adm1032arm-reel 0 r c to 120 r c 8-lead msop rm-8 t2a 4c 85 c adm1032arm-reel7 0 r c to 120 r c 8-lead msop rm-8 t2a 4c 85 c adm1032armz 1 0 r c to 120 r c 8-lead msop rm-8 t2a 4c 85 c adm1032armz-reel 1 0 r c to 120 r c 8-lead msop rm-8 t2a 4c 85 c adm1032armz-reel7 1 0 r c to 120 r c 8-lead msop rm-8 t2a 4c 85 c adm1032arm-1 0 r c to 120 r c 8-lead msop rm-8 t1a 4c 108 c adm1032arm-1reel 0 r c to 120 r c 8-lead msop rm-8 t1a 4c 108 c adm1032arm-1reel7 0 r c to 120 r c 8-lead msop rm-8 t1a 4c 108 c adm1032armz-1 1 0 r c to 120 r c 8-lead msop rm-8 t1a 4c 108 c adm1032armz-1reel 1 0 r c to 120 r c 8-lead msop rm-8 t1a 4c 108 c adm1032armz-1reel7 1 0 r c to 120 r c 8-lead msop rm-8 t1a 4c 108 c adm1032armz-2 1 0 r c to 120 r c 8-lead msop rm-8 t1c 4d 85 c adm1032armz-2reel 1 0 r c to 120 r c 8-lead msop rm-8 t1c 4d 85 c adm1032armz-2reel7 1 0 r c to 120 r c 8-lead msop rm-8 t1c 4d 85 c 1 z = pb-free part.
rev. d e4e adm1032 pin configuration top view (not to scale) 8 7 6 5 1 2 3 4 d+ sclk de therm adm1032 v dd gnd alert sdata pin function descriptions pin no. mnemonic description 1v dd positive supply, 3 v to 5.5 v. 2d +p ositive connection to remote temperature sensor. 3d en egative connection to remote temperature sensor. 4 therm therm is an open-drain output that can be used to turn a fan on/off or throttle a cpu clock in the event of an overtemperature condition. requires pull-up to v dd . 5g nd supply ground connection. 6 alert open-drain logic output used as interrupt or smbus alert. 7 sdata logic input/output, smbus serial data. open-drain output. requires pull-up resistor. 8 sclk logic input, smbus serial clock. requires pull-up resistor.
rev. d t ypical performance characteristicseadm1032 e5e leakage resistance e m temperature error e c 010 100 20 16 e16 0 e4 e8 e12 8 4 12 d+ to gnd d+ to v dd tpc 1. temperature error vs. leakage resistance frequency e hz v in = 100mv p-p temperature error e c 10 1m 0 2 4 6 8 10 12 v in = 250mv p-p tpc 4. temperature error vs. power supply noise frequency v in = 50mv p-p frequency e hz temperature error e c 0 2 4 6 8 10 12 100k 1m 10m 100m v in = 100mv p-p v in = 25mv p-p tpc 7. temperature error vs. common-mode noise frequency temperature error e c e0.5 0 0.5 1.0 temperature e c 0204 06080 100 120 tpc 2. temperature error vs. actual temperature using 2n3906 1611 16 21 26 31 18 16 0 temperature error e c 8 6 4 2 12 10 14 36 capacitance e nf tpc 5. temperature error vs. capacitance between d+ and de sclk frequency e khz 1510 25 50 75 100 80 70 0 supply current e a 10 50 40 60 20 30 250 500 750 1000 v dd = 3.3v v dd = 5v tpc 8. standby supply current vs. clock frequency frequency e hz 13 11 e1 100k 100m 1m temperature error e c 10m 7 5 3 1 9 v in = 10mv p-p v in = 40mv p-p tpc 3. temperature error vs. differential mode noise frequency conversion rate e hz 0.01 2.0 0 supply current e a 1.5 0.5 v dd = 5v 0.1 1 10 100 1.0 v dd = 3v tpc 6. operating supply current vs. conversion rate supply voltage e v 0 40 0 standby supply current e a 1.5 2.5 0.5 1.0 3.0 5.0 3.5 4.0 4.5 2.0 35 30 25 20 15 10 5 tpc 9. standby supply current vs. supply voltage
rev. d e6e adm1032 functional description the adm1032 is a local and remote temperature sensor and overtemperature alarm. when the adm1032 is o perating normally, the on-board a/d converter operates in a free- running mode. the analog input multiplexer alternately selects either the on-chip temperature sensor to measure its local tem- p erature or the remote temperature sensor. these signals are digitized by the adc and the results are stored in the local and rem ote temperature value registers. the measurement results are compared with local and remote, high, low, and therm temperature limits stored in nine on- chip registers. out-of-limit comparisons generate flags that are st ored in the status register, and one or more out-of limit results w ill cause the alert output to pull low. exceeding therm temperature limits causes the therm output to assert low. the limit registers can be programmed, and the device con- trolled and configured, via the serial system management bus (smbus). the contents of any register can also be read back via the smbus. control and configuration functions consist of y s witch ing the device between normal operation and standby mode. y masking or enabling the alert output. y selecting the conversion rate. measurement method a si mple method of measuring temperature is to exploit the negative temperature coefficient of a diode, or the base-emitter voltage of a transistor, operated at constant current. unfortu- nately, this technique requires calibration to null out the effect of the absolute value of v be , which varies from device to device. the technique used in the adm1032 is to measure the change in v be when the device is operated at two different currents. this is given by where: k is boltzmann?s constant (1.38 10 e23 ). q is the charge on the electron (1.6 10 e19 coulombs). t is the absolute temperature in kelvins. n is the ratio of the two currents. n f is the ideality factor of the thermal diode. the adm1032 is trimmed for an ideality factor of 1.008. d vn kt q in n be f = () () figure 2 shows the input signal conditioning used to measure the output of an external temperature sensor. this figure shows the exte rnal sensor as a substrate transist or, provided for temperature monitoring on some micr oprocessors, but it could equally well be a discrete transistor. if a discrete tr ansistor is used, the collector will not be grounded and should be linked to the base. to prevent ground noise interfering with the measurement, the more negative terminal of the sensor is not referenced to gr ound but is biased above ground by an internal diode at the de input. if the sensor is operating in a noisy environment, c1 ma y optionally be added as a noise filter. its value is typically 2, 200 pf but should be no more than 3,000 pf. see the sec- tion on layout considerations for more information on c1. to measure d v be , the sensor is switched between the operating currents of i and n i. the resulting waveform is passed through a 65 khz low-p ass filter to remove noise, and t hen to a chopper-stabilized amplifier that performs the functions of am plification and rectification of the waveform to produce a dc voltage proportional to d v be . this voltage is measured by the adc to give a temperature output in twos complement format. to further reduce the effects of noise, digital filtering is per formed by averaging the results of 16 measurement cycles. signal conditioning and measurement of the internal tempera ture sensor is performed in a similar manner. temperature data format one lsb of the adc corresponds to 0.125 r c, so the adc can measure from 0 r c to 127.875 r c. the temperature data format is shown in tables i and ii. the results of the local and remote temperature m easurements are stored in the local and remote temperature value registers a nd are compared with limits programmed into the local and remote high and low limit registers. table i. temperature data format (local temperature and remote temperature high byte) temperature digital output 0 r c0 000 0000 1 r c0 000 0001 10 r c0 000 1010 25 r c0 001 1001 50 r c0 011 0010 75 r c0 100 1011 100 r c0 110 0100 125 r c0 111 1101 127 r c0 111 1111 c1 * d+ de remote sensing transistor in i i bias v dd v out+ to adc v oute bias diode low-pass filter f c = 65khz capacitor c1 is optional and it should only be used in very noisy environments. c1 = 1000pf max. * figure 2. input signal conditioning
rev. d adm1032 e7e status register bit 7 of the status register indicates that the adc is busy con verting when it is high. bits 6 to 3, 1, and 0 are flags that indicate the results of the limit comparisons. bit 2 is set when the remote sensor is open circuit. if the local and/or remote temperature measurement is above the corresponding high temperature limit, or below or equal to the corresponding low temperature limit, one or more of these flags will be set. these five flags (bits 6 to 2) nor?d together, so that if any of them are high, the alert interrupt latch will be set and the alert output will go low. reading the status register will clear the five flag bits, provided that the error conditions that caused the flags to be set have gone away. while a limit compara- tor is tripped due to a value register containing an out-of-limit measurement, or the sensor is open circuit, the corres ponding flag b it cannot be reset. a flag bit can only be reset if the corre- sponding value register contains an in-limit measurement or the sensor is good. the alert interrupt latch is not reset by reading the status register but will be reset when the alert output has been serviced by the master reading the device address, provided the error condition has gone away and the status register flag bits have been reset. when flags 1 and 0 are set, the therm output goes low to i ndi c ate that the temperature measurements are outside the programmed limits. therm output does not need to be reset, unlike the alert output. once the measurements are within the limits, the corresponding status register bits are reset and the therm output goes high. table iv. status register bit assignments bit name function 7 busy 1 when adc converting 6 lhigh * 1 when local high temp limit tripped 5 llow * 1 when local low temp limit tripped 4 rhigh * 1 when remote high temp limit tripped 3 rlow * 1 when remote low temp limit tripped 2 open * 1 when remote sensor open-circuit 1 rthrm 1 when remote therm limit tripped 0 lthrm 1 when local therm limit tripped * these flags stay high until the status register is read or they are reset by por. configuration register two bits of the configuration register are used. if bit 6 is 0, which is the power-on default, the device is in operating mode with the adc converting. if bit 6 is set to 1, the device is in standby mode and the adc does not convert. the smbus does, how ever, remain active in standby mode so values can be read from or written to the smbus. the alert and therm o/ps are also active in standby mode. bit 7 of the configuration register is used to mask the alert output. if bit 7 is 0, which is the power-on default, the output is enabled. if bit 7 is set to 1, the output is disabled. table ii. extended temperature resolution (remote temperature low byte) extended remote temperature resolution low byte 0.000 r c0 000 0000 0.125 r c0 010 0000 0.250 r c0 100 0000 0.375 r c0 110 0000 0.500 r c1 000 0000 0.625 r c1 010 0000 0.750 r c1 100 0000 0.875 r c1 110 0000 adm1032 registers t he adm1032 contains registers that are used to store the results of remote and local temperature measurements and high and low temperature limits and to configure and control the device. a description of these registers follows, and further details are given in tables iii to vii. address pointer register the address pointer register itself does not have, or require, an address, since it is the register to which the first data byte of every write operation is written automatically. this data byte is an address pointer that sets up one of the other registers for the second byte of the write operation or for a subsequent read operation. the power-on default value of the address po inter register is 00 h. so, if a read operation is performed immediately after power- on without first writing to the address pointer, the value of the l ocal temperature will be returned, since its register address is 00h. value registers the adm1032 has three registers to store the results of local and remote temperature measurements. these registers are written to by the adc only and can be read over the smbus. offset register series resistance on the d+ and de lines in processor packages and clock noise can introduce offset errors into the remote tem perature measurement. to achieve the specified accuracy on this channel, these offsets must be removed. the offset value is stored as an 11-bit, twos complement value in registers 11h (high byte) and 12h (low byte, left justified). the value of the offset is negative if the msb of register 11h is 1 and positive if the msb of register 12h is 0. the value is added to the measured value of the remote temperature. the offset register powers up with a default value of 0 r c and will have no effect if nothing is written to them. table iii. sample offset register codes offset value 11h 12h e4 r c1 111 1100 0 000 0000 e1 r c1 111 1111 0 000 0000 e0.125 r c1 111 1111 1 110 0000 0 r c0 000 0000 0 000 0000 +0.125 r c0 000 0000 0 010 0000 +1 r c0 000 0001 0 000 0000 +4 r c0 000 0100 0 000 0000
rev. d e8e adm1032 consecutive alert r t alert t alert t t t t alert r l r mr te mm eralterae amt am tm mh t ara tame etert r cx xxx () =+++ 821 1 consult the smbus 1.1 specification for more information. addressing the device in general, every smbus device has a 7-bit device address (except for some devices that have extended, 10-bit addresses). when the master device sends a device address over the bus, the slave device with that address will respond. the adm1032 and the adm1032-1 are available with one smbus address, which is hex 4c (1001 100). the adm1032-2 is also available with one smbus address; however, that address is hex 4d (1001 101). the serial bus protocol operates as follows: 1. the master initiates data transfer by establishing a start condition, defined as a high-to-low transition on the serial data line sdata, while the serial clock line sclk remains high. this indicates that an address/data stream will follow. all slave peripherals connected to the serial bus respond to the start condition and shift in the next eight bits, con sisting of a 7-bit address (msb first) plus an r/ w bit, which determines the direction of the data transfer, i.e., whether data will be written to or read from the slave device. the peripheral whose address corresponds to the transmitted address responds by pulling the data line low during the low period before the ninth clock pulse, known as the acknowl edge bit. all other devices on the bus now remain idle while the table v. configuration register bit assignments power-on bit name function default 7 mask1 0 = alert enabled 0 1 = alert masked 6 run/stop 0 = run 0 1 = standby 5e0 reserved 0 conversion rate register t he low est four bits of this register are used to program the conversion rate by dividing the internal oscillator clock by 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, or 1,024 to give conversion times from 15.5 ms (code 0ah) to 16 seconds (code 00h). this register can be written to and read back over the smbus. the higher four bits of this register are unused and must be set to zero. use of slower conversion times greatly reduces the device power consumption, as shown in table vi. table vi. conversion rate register codes average supply current data conversion/sec ma typ at v dd = 5.5 v 00h 0.0625 0.17 01h 0.125 0.20 02h 0.25 0.21 03h 0.5 0.24 04h 1 0.29 05h 2 0.40 06h 4 0.61 07h 8 1.1 08h 16 1.9 09h 32 0.73 0ah 64 1.23 0b to ffh reserved limit registers t he adm1032 has nine limit registers to store local and remote, high, low, and therm temperature limits. these registers can be written to and read back over the smbus. the high limit registers perform a > comparison, while the low limit registers perform a < comparison. for example, if the high limit register is programmed with 80 r c, then measuring 81 r c will result in an alarm condition. if the low limit register is programmed with 0 r c, measuring 0 r c or lower will result in an alarm condition. exceeding either the local or remote therm limit asserts therm low. a default hysteresis value of 10 r c is provided, which applies to both channels. this hysteresis may be reprogrammed to any value after power up (reg 0x21h). one-shot register the one-shot r egister is used to initiate a single conv ersion and comparison cycle when the adm1032 is in standby mode, a fter which the device returns to standby. this is not a data register as such, and it is the write operation that causes the one-shot conversion. the data written to this address is irrel- evant and is not stored. the conversion time on a single shot is 96 ms when the conversion rate is 16 conversions per second or less. at 32 conversions per second, the conversion time is 15.3 ms. this is because averaging is disabled at the faster conversion rates (32 and 64 conversions per second).
rev. d adm1032 e9e selected device waits for data to be read from or written to it. if the r/ w bit is a 0, the master will write to the slave device. if the r/ w bit is a 1, the master will read from the slave de vice. 2. data is sent over the serial bus in sequences of nine clock pulses, eight bits of data followed by an acknowledge bit from the slave device. transitions on the data line must occur during the low period of the clock signal and remain stable during the high period, si nce a low-to-h igh tr ansition when the clock is high may be interpreted as a stop signal. the number of data bytes that can be transmitted over the serial bus in a single read or write operation is limited only by what the master and slave devices can handle. 3. when all data bytes have been read or written, stop condi tions are established. in write mode, the master will pull the data line high during the tenth clock pulse to assert a stop con dition. in read mode, the master device will override the acknowledge bit by pulling the data line high during the low period before the ninth clock pulse. this is known as no acknowledge. the master will then take the data line low during the low period before the tenth clock pulse, then high during the tenth clock pulse to assert a stop condition. any number of bytes of data may be transferred over the serial bus in one operation, but it is not possible to mix read and write in one operation because the type of operation is determined at the beginning and cannot subsequently be changed without starting a new operation. in the case of the adm1032, write operations contain either one or two bytes, while read operations contain one byte and per form the following functions. to write data to one of the device data registers or read data from it, the address pointer register must first be set so that the correct data register is addressed. the first byte of a write opera- tion always contains a valid address that is stored in the address pointer register. if data is to be written to the device, the write operation contains a second data byte that is written to the register selected by the address pointer register. this is illustrated in figure 3a. the device address is sent over the bus followed by r/ w set to 0. this is followed by two data byt es. the first data byte is the address of the internal data register to be written to, which is stored in the address pointer register. the second data byte is the data to be written to the internal data register. when reading data from a register, there are two possibilities: 1. if the adm1032?s address pointer register value is unknown or not the desired value, it is first necessary to set it to the correct value before data can be read from the desired data register. this is done by performing a write to the adm1032 as before, but only the data byte containing the register read address is sent, since data is not to be written to the register. this is shown in figure 3b. a read operation is then performed consisting of the serial bus address, r/ w bit set to 1, followed by the data byte read from the data register. this is shown in figure 3c. 2. if the address pointer register is known to be at the desired address already, data can be read from the corresponding data register without first writing to the address pointer register and figure 3b can be omitted. table viii. list of adm1032 registers read address (hex) write address (hex) name power-on default not applicable not app licable address pointer undefined 00 not applicable local temperature value 0000 0000 (00h) 01 not applicable external temperature value high byte 0000 0000 (00h) 02 not applicable status undefined 03 09 configuration 0000 0000 (00h) 04 0a conversion rate 0000 1000 (08h) 05 0b local temperature high limit 0101 0101 (55h) (85 r c) 06 0c local temperature low limit 0000 0000 (00h) (0 r c) 07 0d external temperature high limit high byte 0101 0101 (55h) (85 r c) 08 0e external temperature low limit high byte 0000 0000 (00h) (0 r c) not applicable 0f one-shot 10 not applicable external temperature value low byte 0000 0000 11 11 external temperature offset high byte 0000 0000 12 12 external temperature offset low byte 0000 0000 13 13 external temperature high limit low byte 0000 0000 14 14 external temperature low limit low byte 0000 0000 19 19 external therm limit 0101 0101 (55h) (85 r c) (adm1032) 0110 1100 (6ch) (108 r c) (adm1032-1 ) 20 20 local therm limit 0101 0101 (55h) (85 r c) 21 21 therm hysteresis 0000 1010 (0ah) (10 r c) 22 22 consecutive alert 0000 0001 (01h) fe not applicable manufacturer id 0100 0001 (41h) ff not applicable d ie revision code undefined writing to address 0f causes the adm1032 to perform a single measurement. it is not a data register as such and it does not mat ter what data is written to it.
rev. d e10e adm1032 notes 1. although it is possible to read a data byte from a data register without first writing to the address pointer register, if the address pointer register is already at the correct value, it is not possible to write data to a register without writing to the address pointer register because the first data byte of a write is always written to the address pointer register. alert tt t alert alert r alert t alert malert m malert a a a a a a a r l ata tart mater rame eralarete rame areterreterte t mater a am a am rame atate atate lte a am raarr l ata tart mater a a a a a a a r rame eralarete rame areterreterte t mater a am a am ar l ata a a a a a a a r tart mater rame eralarete rame atatermam t mater a am a am rr am t t alert malert malert mater reee malert matere araarea mma eee tare a tart alert reeare r a eeare t smbalert
rev. d adm1032 e11e 1. smbalert pulled low. 2. master initiates a read operation and sends the alert re sponse address (ara = 0001 100). this is a general call address that must not be used as a specific device address. 3. the device whose alert output is low responds to the alert response address and the master reads its device address. since the device address is seven bits, an lsb of 1 is added. the address of the device is now known and it can be inter rogated in the usual way. 4. if more than one device?s alert output is low, the one with t he lowest device address will have priority in accordance with normal smbus arbitration. 5. o nce the adm1032 has responded to the alert response address, it will reset its alert output, provided that the error condition that caused the alert no longer exists. if the smbalert line remains low, the master will send ara again, and so on until all devices whose alert outputs were low have responded. low power standby mode the adm1032 can be put into a low power standby mode by setting bit 6 of the configuration register. when bit 6 is low, the adm1032 operates normally. when bit 6 is high, the adc is inhibited and any conversion in progress is terminated without writing the result to the corresponding value register. the smbus is still enabled. power consumption in the standby mode is reduced to less than 10 m a if there is no smbus activ ity, or 100 m a if there are clock and data signals on the bus. when the device is in standby mode, it is still possible to initiate a one -shot conversion of both channels by writing xxh to the one-shot register (address 0fh), after which the device will return to standby. it is also possible to write new values to the limit register while it is in standby. if the values stored in the temperatur e value registers are now outside the new limits, an alert is gener ated even though the adm1032 is still in standby. the adm1032 interrupt system t he adm1032 has two interrupt outputs, alert and therm . these have different functions. alert responds to violations of software-programmed temperature limits and is maskable. therm is intended as a fail-safe interrupt output that cannot be masked. if the temperature goes equal to or below the lower temperature limit, the alert pin will be asserted low to indicate an out-of-limit condition. if the temperature is within the programmed low and high temperature limits, no interrupt will be generated. if the temperature exceeds the high temperature limit, the alert pin will be asserted low to indi cate an overtemperature cond ition. a local and remote therm limit may be programmed into the device to set the temperature limit above which the overtemperature therm pin will be asserted low. this temperature limit should be equal to or greater than the high temperature limit programmed. the behavior of the high limit and therm limit is as follows: 1. if either temperature measured exceeds the high temperature limit, the alert output will assert low. 2. if the local or remote temperature continues to increase and either one exceeds the therm limit, the therm output asserts low. this can be used to throttle the cpu clock or switch on a fan. a therm hysteresis value is provided to prevent a cooling fan cycling on and off. the power-on default value is 10 r c, but this may be reprogrammed to any value after power-up. this hyster- esis value applies to both the local and remote channels. using these two limits in this way allows the user to gain maxi- mum performance from the system by only slowing it down should it be at a critical temperature. the therm signal is open drain and requires a pull-up to v dd . the therm signal must always be pulled up to the same power supply as the adm1032, unlike the smbus signals (sdata, sclk, and alert ) that may be pulled to a different power rail, usually that of the smbus controller. 100 c 90 c 80 c 70 c 60 c 50 c 40 c therm local therm limit local therm limit ehysteresis temperature figure 5. operation of the therm t therm h therm h r eraltetet aam t t r a m am t alert tr r am alert
rev. d e12e adm1032 a pplications information factors affecting accuracy remote sensing diode the adm1032 is designed to work with substrate transistors built into processors? cpus or with discrete transistors. sub strate transistors will generally be pnp types with the collector con nected to the substrate. discrete types can be either a pnp or an npn transistor connected as a diode (base shorted to collec tor). if an npn transistor is used, the collector and base are connected to d+ and the emitter to de. if a pnp transistor is used, the col lector and base are connected to de and the emitter to d+. substrate transistors are found in a number of cpus. to reduce the error due to variations in these substrate and discrete transistors, a number of factors should be taken into consideration: 1. the ideality factor, n f , of the transistor. the ideality factor is a measure of the deviation of the thermal diode from the ideal behavior. the adm1032 is trimmed for an n f value of 1.008. the following equation may be used to calculate the error introduced at a temperature t r c when using a transistor whose n f does not equal 1.008. consult the pro cessor data sheet for n f values. d t n kelvin t natural = () + () e. . . 1 008 1 008 273 15 this value can be written to the offset register and is automati- cally added to or subtracted from the temperature measurement. 2. some cpu manufacturers specify the high and low current levels of the substrate transistors. the high current level of the adm1032, i high , is 230 a and the low level current, i low , is 13 a. if the adm1032 current levels do not match the levels of the cpu manufacturers, then it may become necessary to remove an offset. the cpu?s data sheet will advise whether this offset needs to be removed and how to calculate it. this offset may be programmed to the offset register. it is important to note that if accounting for two or more offsets is needed, then the algebraic sum of these offsets must be programmed to the offset register. if a discrete transistor is being used with the adm1032, the best accuracy will be obtained by choosing devices according to the following criteria: y base-emitter voltage greater than 0.25 v at 6 ma, at the highest operating temperature. y base-emitter voltage less than 0.95 v at 100 ma, at the lowest operating temperature. y base resistance less than 100 w . y small variation in h fe (say 50 to 150) that indicates tight control of v be characteristics. transistors such as 2n3904, 2n3906, or equivalents in sot-23 packages are suitable devices to use. thermal inertia and self-heating accuracy depends on the temperature of the remote-sensing diode and/or the internal temperature sensor being at the same temperature as that being measured, and a number of factors can affect this. ideally, the sensor should be in good thermal contact with the part of the system being measured, for example the processor. if it is not, the thermal inertia caused by the mass of the sensor will cause a lag in the response of the sensor to a temperature change. in the case of the remote sensor, this should not be a problem, since it will either be a substrate tran sistor in the processor or a small package device, such as the sot-23, placed in close proximity to it. the on-chip sensor, however, will often be remote from the processor and will only be monitoring the general ambient temperature around the package. the thermal time constant of the soic-8 package in still air is about 140 seconds, and if the ambient air temperature quickly changed by 100 degrees, it would take about 12 minutes (five time constants) for the junc- tion temperature of the adm1032 to settle within one degree of this. in practice, the adm1032 package will be in electrical and there fore thermal contact with a printed circuit board and may also be in a forced airflow. how accurately the temperature of the board and/or the forced airflow reflect the temperature to be measured will also affect the accuracy. self-heating due to the power dissipated in the adm1032 or the remote sensor causes the chip temperature of the device or remote sensor to rise above ambient. however, the current forced through the remote sensor is so small that self-heating is neglig ible. in the case of the adm1032, the worst-case condition occurs when the device is converting at 16 conversions per second while sinking the maximum current of 1 ma at the alert and therm output. in this case, the total power dissipation in the device is about 11 mw. the thermal resistance, q ja , of the soic-8 package is about 121 r c/w. in practice, the package will have electrical and therefore thermal connection to the printed circuit board, so the temperature rise due to self-heating will be negligible. layout considerations digital boards can be electrically noisy environments, and the adm1032 is measuring very small voltages from the remote sensor, so care must be taken to minimize noise induced at the sensor inputs. the following precautions should be taken: 1. place the adm1032 as close as possible to the remote sensing diode. provided that the worst noise sources, i.e., clock gen erators, data/address buses, and crts are avoided, this distance can be four to eight inches. 2. route the d+ and de tracks close together, in parallel, with grounded guard tracks on each side. provide a ground plane under the tracks if possible. 3. use wide tracks to minimize inductance and reduce noise pickup. 10 mil track minimum width and spacing is recommended. 10mil 10mil 10mil 10mil 10mil 10mil 10mil gnd d+ de gnd figure 6. arrangement of signal tracks 4. try to minimize the number of copper/solder joints, which can cause thermocouple effects. where copper/solder joints are used, make sure that they are in both the d+ and de path and at the same temperature.
rev. d adm1032 e13e thermocouple effects should not be a major problem since 1 r c corresponds to about 200 v and thermocouple voltages are about 3 v/ r c of temperature difference. unless there are two thermocouples with a big temperature differential between them, thermocouple voltages should be much less than 200 v. 5. place a 0.1 m f bypass capacitor close to the v dd pin. in very noisy environments, place a 1,000 pf input filter capacitor across d+ and de close to the adm1032. 6. if the distance to the remote sensor is more than eight inches, the use of twisted pair cable is recommended. this will work up to about six feet to twelve feet. 7. for really long distances (up to 100 feet), use shielded twisted pair, such as belden #8451 microphone cable. connect the twisted pair to d+ and de and the shield to gnd close to the adm1032. leave the remote end of the shield unconnected to avoid ground loops. because the measurement technique uses switched current sources, excessive cable and/or filter capacitance can affect the measurement. when using long cables, the filter capacitor may be reduced or removed. cable resistance can also introduce errors. 1 w series resistance introduces about 1 r c error. application circuit figure 7 shows a typical application circuit for the adm1032, using a discrete sensor transistor connected via a shielded, twisted pair cable. the pull-ups on sclk, sdata, and alert are required only if they are not already provided elsewhere i n the system. the sclk and sdata pins of the adm1032 can be inter- faced directly to the smbus of an i/o controller, such as the intel 820 chipset. shield 2n3906 or cpu thermal diode alert gnd therm d+ de adm1032 sclk sdata v dd 3v to 3.6v typ 10k 0.1 f v dd typ 10k fan control circuit 5v or 12v fan enable smbus controller figure 7. typical application circuit
rev. d e14e adm1032 outline dimensions 8-lead standard small outline package [soic] narrow body (r-8) dimensions shown in millimeters and (inches) 0.25 (0.0098) 0.17 (0.0067) 1.27 (0.0500) 0.40 (0.0157) 0.50 (0.0196) 0.25 (0.0099) 45 8 0 1.75 (0.0688) 1.35 (0.0532) seating plane 0.25 (0.0098) 0.10 (0.0040) 85 4 1 5.00 (0.1968) 4.80 (0.1890) 4.00 (0.1574) 3.80 (0.1497) 1.27 (0.0500) bsc 6.20 (0.2440) 5.80 (0.2284) 0.51 (0.0201) 0.31 (0.0122) coplanarity 0.10 controlling dimensions are in millimeters; inch dimensions (in parentheses) are rounded-off millimeter equivalents for reference only and are not appropriate for use in design compliant to jedec standards ms-012aa 8-lead mini small outline package [msop] (rm-8) dimensions shown in millimeters 0.80 0.60 0.40 8 0 85 4 1 4.90 bsc pin 1 0.65 bsc 3.00 bsc seating plane 0.15 0.00 0.38 0.22 1.10 max 3.00 bsc coplanarity 0.10 0.23 0.08 compliant to jedec standards mo-187aa
rev. d adm1032 e15e revision history location page 10/04?data sheet changed from rev. c to rev. d. changes to product description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 changes to absolute maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 changes to ordering guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 changes to addressing the device section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 updated outline dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 3/03?data sheet changed from rev. b to rev. c. edits to specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 10/02?data sheet changed from rev. a to rev. b. edits to the general description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 edits to the ordering guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 edits to table viii . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 outline dimensions updated . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
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