ADM1023 ACPI-Compliant, High Accuracy Microprocessor System Temperature Monitor The ADM1023 is a 2−channel digital thermometer and under/overtemperature alarm for use in personal computers and other systems requiring thermal monitoring and management. Optimized for the Pentium® III, the higher accuracy allows systems designers to safely reduce temperature guard banding and increase system performance. The device can measure the temperature of a microprocessor using a diode−connected PNP transistor, which may be provided on−chip with the Pentium III or similar processors; or it can be a low−cost, discrete NPN/PNP device such as the 2N3904/2N3906. A novel measurement technique cancels out the absolute value of the transistor’s base emitter voltage so that no calibration is required. The second measurement channel measures the output of an on−chip temperature sensor to monitor the temperature of the device and its environment. The ADM1023 communicates over a 2−wire serial interface compatible with SMBus standards. Under/overtemperature limits can be programmed into the device over the serial bus, and an ALERT output signals when the on−chip or remote temperature is out of range. This output can be used as an interrupt or as an SMBus ALERT. FEATURES • • • • • • • • • • • • • • Next Generation Upgrade of ADM1021 On−Chip and Remote Temperature Sensing Offset Registers for System Calibration 1°C Accuracy and Resolution on Local Channel 0.125°C Resolution/1°C Accuracy on Remote Channel Programmable Over/Undertemperature Limits Programmable Conversion Rate Supports System Management Bus (SMBus) ALERT 2−Wire SMBus Serial Interface 200 mA Max Operating Current (0.25 Conversions/Second) 1 mA Standby Current 3.0 V to 5.5 V Supply Small 16−Lead QSOP Package Pb−Free Packages are Available http://onsemi.com QSOP−16 CASE 492 MARKING DIAGRAM 1 1023A RQZ #YYWW XXX xxx # YYWW XXX = Specific Device Code = Pb−Free Package = Date Code = Assembly Lot ID NC 1 16 NC VDD 2 15 STBY D+ 3 14 SCLK D– 4 ADM1023 13 NC NC 5 TOP VIEW 12 SDATA ADD1 6 11 ALERT GND 7 10 GND 8 9 ADD0 NC ORDERING INFORMATION See detailed ordering and shipping information in the package dimensions section on page 15 of this data sheet. APPLICATIONS • • • • • • Desktop Computers Notebook Computers Smart Batteries Industrial Controllers Telecomm Equipment Instrumentation © Semiconductor Components Industries, LLC, 2010 May, 2010 − Rev. 9 1 Publication Order Number: ADM1023/D ADM1023 ADDRESS POINTER REGISTER ONE−SHOT REGISTER CONVERSION RATE REGISTER OFFSET REGISTERS ON−CHIP TEMPERATURE SENSOR D+ 3 D– 4 LOCAL TEMPERATURE VALUE REGISTER A−TO−D CONVERTER ANALOG MUX BUSY RUN/STANDBY REMOTE TEMPERATURE VALUE REGISTERS LOCAL TEMPERATURE LOW−LIMIT COMPARATOR LOCAL TEMPERATURE LOW−LIMIT REGISTER LOCAL TEMPERATURE HIGH−LIMIT COMPARATOR LOCAL TEMPERATURE HIGH−LIMIT REGISTER REMOTE TEMPERATURE LOW−LIMIT COMPARATOR REMOTE TEMPERATURE LOW−LIMIT REGISTERS REMOTE TEMPERATURE HIGH−LIMIT COMPARATOR REMOTE TEMPERATURE HIGH−LIMIT REGISTERS CONFIGURATION REGISTER 15 STBY 11 ALERT EXTERNAL DIODE OPEN−CIRCUIT INTERRUPT MASKING STATUS REGISTER ADM1023 SMBus INTERFACE 1 2 5 7 8 9 13 16 12 14 10 6 NC VDD NC GND GND NC NC NC SDATA SCLK ADD0 ADD1 NC = NO CONNECT Figure 1. Functional Block Diagram ABSOLUTE MAXIMUM RATINGS Parameter Positive Supply Voltage (VDD) to GND D+, ADD0, ADD1 Rating Unit −0.3 to +6.0 V −0.3 to VDD +0.3 V D− to GND −0.3 to +0.6 SCLK, SDATA, ALERT, STBY −0.3 to +6.0 V ±50 mA Input Current, D− ±10 mA ESD Rating, All Pins (Human Body Model) 2000 V 650 6.7 mW mW/°C −55 to +125 °C Input Current Continuous Power Dissipation Up to 70°C Derating Above 70°C Operating Temperature Range 150 °C −65 to +150 °C Lead Temperature, Soldering (10 s) 300 °C IR Reflow Peak Temperature 220 °C Maximum Junction Temperature (TJmax) Storage Temperature Range IR Reflow Peak Temperature for Pb−Free 260 °C Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect device reliability. NOTE: This device is ESD sensitive. Use standard ESD precautions when handling. THERMAL CHARACTERISTICS Parameter Rating qJA = 105°C/W, qJC = 39°C/W 16−Lead QSOP Package http://onsemi.com 2 ADM1023 PIN ASSIGNMENT Pin No. Mnemonic Description 1 NC No Connect. 2 VDD Positive Supply, 3.0 V to 5.5 V. 3 D+ Positive Connection to Remote Temperature Sensor. 4 D− Negative Connection to Remote Temperature Sensor. 5 NC No Connect. 6 ADD1 Three−State Logic Input, Higher Bit of Device Address. 7 GND Supply 0 V Connection. 8 GND Supply 0 V Connection. 9 NC 10 ADD0 Three−State Logic Input, Lower Bit of Device Address. 11 ALERT Open−Drain Logic Output Used as Interrupt or SMBus ALERT. 12 SDATA Logic Input/Output, SMBus Serial Data. Open−drain output. 13 NC 14 SCLK Logic Input, SMBus Serial Clock. 15 STBY Logic Input Selecting Normal Operation (High) or Standby Mode (Low). 16 NC No Connect. No Connect. No Connect. ELECTRICAL CHARACTERISTICS (TA = TMIN to TMAX, VDD = 3.0 V to 3.6 V, unless otherwise noted. (Note 1) Parameter Test Conditions / Comments Min Typ Max Unit Power Supply and ADC Temperature Resolution, Local Sensor Guaranteed no missed codes 1.0 °C Temperature Resolution, Remote Sensor Guaranteed no missed codes 0.125 °C Temperature Error, Local Sensor TA = 60°C to 100°C TA = 0°C to 120°C −1.5 −3.0 Temperature Error, Remote Sensor TA, TD = 60°C to 100°C (Note 2) TA, TD = 0°C to 120°C (Note 2) Relative Accuracy +1.5 +3.0 °C −1.0 +1.0 °C −3.0 +3.0 °C 0.25 °C 3.6 V TA = 60°C to 100°C Supply Voltage Range (Note 3) Undervoltage Lockout Threshold 3.0 VDD input, disables ADC, rising edge 2.55 Undervoltage Lockout Hysteresis Power−On Reset Threshold ±0.5 ±1.0 2.7 2.8 25 VDD, falling edge (Note 4) 0.9 POR Threshold Hysteresis 1.7 V mV 2.2 50 V mV Standby Supply Current VDD = 3.3 V, no SMBus activity SCLK at 10 kHz 1.0 4.0 5.0 mA Average Operating Supply Current 0.25 conversions/sec rate 130 200 mA Autoconvert Mode, Averaged Over 4 Sec 2 conversions/sec rate 225 370 mA Conversion Time From stop bit to conversion complete (both channels) D+ forced to D− + 0.65 V 65 115 170 ms Remote Sensor Source Current High level (Note 4) Low level (Note 4) 120 7.0 205 12 300 16 mA D− Source Voltage Address Pin Bias Current (ADD0, ADD1) Momentary at power−on reset http://onsemi.com 3 0.7 V 50 mA ADM1023 ELECTRICAL CHARACTERISTICS (TA = TMIN to TMAX, VDD = 3.0 V to 3.6 V, unless otherwise noted. (Note 1) Parameter Test Conditions / Comments Min Typ Max Unit SMBus Interface (See Figure 2) Logic Input High Voltage, VIH STBY, SCLK, SDATA VDD = 3.0 V to 5.5 V 2.2 Logic Input Low Voltage, VIL STBY, SCLK, SDATA VDD = 3.0 V to 5.5 V SMBus Output Low Sink Current SDATA forced to 0.6 V 6.0 mA ALERT Output Low Sink Current ALERT forced to 0.4 V 1.0 mA 0.8 Logic Input Current, IIH, IIL −1.0 SMBus Input Capacitance, SCLK, SDATA V mA +1.0 5.0 SMBus Clock Frequency pF 400 kHz SMBus Clock Low Time, tLOW tLOW between 10% points 1.3 ms SMBus Clock High Time, tHIGH tHIGH between 90% points 0.6 ms 0.6 ms 0.6 ms SMBus Start Condition Setup Time, tSU:STA 1. 2. 3. 4. V SMBus Start Condition Hold Time, tHD:STA Time from 10% of SDATA to 90% of SCLK SMBus Stop Condition Setup Time, tSU:STO Time from 90% of SCLK to 10% of SDATA 0.6 ms SMBus Data Valid to SCLK Rising Edge Time, tSU:DAT Time for 10% or 90% of SDATA to 10% of SCLK 100 ns SMBus Bus Free Time, tBUF Between start/stop condition 1.3 ms SCLK SDATA Rise Time, tR MAX Master clocking in data 300 ns SCLK SDATA Fall Time, tF MAX VDD = 0 V 300 ns TMAX = 120°C, TMIN = 0°C TD is the temperature of the remote thermal diode; TA, TD = 60°C to 100°C Operation at VDD = 5.0 V guaranteed by design; not production tested Guranteed by design; not production tested tHD;STA tR tLOW tF SCL tHD;DAT tHD;STA tHIGH tSU;STA tSU;DAT tSU;STO SDA tBUF P S S Figure 2. Diagram for Serial Bus Timing http://onsemi.com 4 P ADM1023 TYPICAL CHARACTERISTICS 5 20 15 D+ TO GND 4 TEMPERATURE ERROR (5C) TEMPERATURE ERROR (5C) 10 5 0 –5 –10 D+ TO VDD –15 –20 250mV p−p REMOTE 3 2 100mV p−p REMOTE 1 –25 0 100 –30 1 10 LEAKAGE RESISTANCE (MΩ) 100 Figure 3. Temperature Error vs. Resistance from Track to VDD and GND 1k 10k 100k 1M FREQUENCY (Hz) 10M 100M Figure 4. Remote Temperature Error vs. Supply Noise Frequency 9 3 100mV p−p 8 TEMPERATURE ERROR (5C) TEMPERATURE ERROR (5C) 2 7 6 5 4 3 50mV p−p 2 UPPER SPEC LEVEL 1 0 –1 LOWER SPEC LEVEL –2 1 25mV p−p 0 1 10 100 1k 10k 100k FREQUENCY (Hz) 1M 10M –3 50 100M 70 80 90 100 TEMPERATURE (5C) 110 120 Figure 6. Temperature Error of ADM1023 vs. Pentium III Temperature 14 70 12 60 10 SUPPLY CURRENT (μA) TEMPERATURE ERROR (5C) Figure 5. Temperature Error vs. Common−Mode Noise Frequency 60 8 6 4 2 50 40 VDD = 3.3V 30 20 10 0 VDD = 5V 0 –2 2 4 6 8 10 12 14 16 CAPACITANCE (nF) 18 20 22 24 1 Figure 7. Temperature Error vs. Capacitance Between D+ and D− 5 10 25 50 75 100 250 SCLK FREQUENCY (kHz) 500 750 Figure 8. Standby Supply Current vs. SCLK Frequency http://onsemi.com 5 1000 ADM1023 TYPICAL CHARACTERISTICS 4 550 500 SUPPLY CURRENT (μA) TEMPERATURE ERROR (5C) 450 3 10mV p−p 2 1 400 350 300 250 200 3.3V 150 100 0 100k 1M 10M FREQUENCY (Hz) 100M 5V 50 0.0625 1G Figure 9. Temperature Error vs. Differential−Mode Noise Frequency 0.1250 0.2500 0.5000 1.0000 2.0000 CONVERSION RATE (Hz) 4.0000 8.0000 Figure 10. Operating Supply Current vs. Conversion Rate, VDD = 5.0 V and 3.3 V 100 125 REMOTE TEMPERATURE 100 60 TEMPERATURE (5C) SUPPLY CURRENT (μA) 80 40 20 INT TEMPERATURE 75 50 25 0 0 −20 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 SUPPLY VOLTAGE (V) 4.0 4.5 5.0 0 Figure 11. Standby Supply Current vs. Supply Voltage 1 2 3 4 5 6 TIME (Seconds) 7 8 9 Figure 12. Response to Thermal Shock http://onsemi.com 6 10 ADM1023 Theory of Operation on−chip limit registers. As with the measured value, the local temperature limits are stored as 8−bit values and the remote temperature limits as 11−bit values. Out−of−limit comparisons generate flags that are stored in the status register, and one or more out−of−limit results cause the ALERT output to pull low. Registers can be programmed, and the device controlled 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: • Switching the device between normal operation and standby mode. • Masking or enabling the ALERT output. • Selecting the conversion rate. On initial powerup, the remote and local temperature values default to −128°C. The device normally powers up converting, making a measure of local and remote temperature. These values are then stored before making a comparison with the stored limits. However, if the part is powered up in standby mode (STBY pin pulled low), no new values are written to the register before a comparison is made. As a result, both RLOW and LLOW are tripped in the status register, thus generating an ALERT output. This may be cleared in one of two ways: • Change both the local and remote lower limits to –128°C and read the status register (which in turn clears the ALERT output). • Take the part out of standby and read the status register (which in turn clears the ALERT output). This works only when the measured values are within the limit values. Functional Description The ADM1023 contains a two−channel analog−to−digital converter (ADC) with special input−signal conditioning to enable operation with remote and on−chip diode temperature sensors. When the ADM1023 is operating normally, the ADC operates in a free−running mode. The analog input multiplexer alternately selects either the on−chip temperature sensor to measure its local temperature or the remote temperature sensor. These signals are digitized by the ADC, and the results are stored in the local and remote temperature value registers. Only the eight most significant bits (MSBs) of the local temperature value are stored as an 8−bit binary word. The remote temperature value is stored as an 11−bit binary word in two registers. The eight MSBs are stored in the remote temperature value high byte register at Address 0x01. The three least significant bits (LSBs) are stored, left justified, in the remote temperature value low byte register at Address 0x10. Error sources such as PCB track resistance and clock noise can introduce offset errors into measurements on the remote channel. To achieve the specified accuracy on this channel, these offsets must be removed, and two offset registers are provided for this purpose at Address 0x11 and Address 0x12. An offset value may automatically be added to or subtracted from the measurement by writing an 11−bit, twos complement value to Register 0x11 (high byte) and Register 0x12 (low byte, left−justified). The offset registers default to 0 at powerup and have no effect if nothing is written to them. The measurement results are compared with local and remote, high and low temperature limits, stored in six NyI I VDD IBIAS D+ REMOTE SENSING TRANSISTOR VOUT+ C11 TO ADC BIAS DIODE D– LOW−PASS FILTER fC = 65kHz VOUT– 1CAPACITOR C1 IS OPTIONAL. IT IS ONLY NECESSARY IN NOISY ENVIRONMENTS. C1 = 1000pF MAX. Figure 13. Input Signal Conditioning Measurement Method This technique, however, requires calibration to nullify the effect of the absolute value of VBE, which varies from device to device. The technique used in the ADM1023 is to measure the change in VBE when the device is operated at two different collector currents. A simple method of measuring temperature is to exploit the negative temperature coefficient of a diode, or the base emitter voltage of a transistor, operating at constant current. Thus, the temperature may be obtained from a direct measurement of VBE where: V BE + nKT q 1n ǒICǓ IS (eq. 1) http://onsemi.com 7 ADM1023 This is given by: DV BE + nKT q 1n (N) ADM1023 is optimized for nTYPICAL = 1.008; any deviation on n from this typical value causes a temperature error that is calculated below for the nMIN and nMAX of a Pentium III processor at TTD = 100°C. (eq. 2) where: K is Boltzmann’s constant. q is the charge on the electron (1.6 × 10–19 Coulombs). T is the absolute temperature in Kelvins. N is the ratio of the two collector currents. n is the ideality factor of the thermal diode (TD). To measure DVBE, the sensor is switched between operating currents of I and NI. The resulting waveform is passed through a low−pass filter to remove noise, then to a chopper−stabilized amplifier that performs the functions of amplification and rectification of the waveform to produce a dc voltage proportional to DVBE. This voltage is measured by the ADC, which gives a temperature output in binary format. To further reduce the effects of noise, digital filtering is performed by averaging the results of 16 measurement cycles. Signal conditioning and measurement of the internal temperature sensor are performed in a similar manner. Figure 13 shows the input signal conditioning used to measure the output of an external temperature sensor. This figure shows the external sensor as a substrate PNP transistor, provided for temperature monitoring on some microprocessors, but it could equally well be a discrete transistor. If a discrete transistor is used, the collector is not grounded and should be connected to the base. To prevent ground noise from interfering with the measurement, the more negative terminal of the sensor is not referenced to ground but is biased above ground by an internal diode at the D− input. If the sensor is operating in a noisy environment, C1 may optionally be added as a noise filter. Its value is 1000 pF maximum. See the Layout Considerations section for more information on C1. DT MIN + 1.0057 * 1.008 1.008 ǒ273.15 Kelvin ) 100° CǓ DT MAX + 1.0125 * 1.008 1.008 ǒ273.15 Kelvin ) 100° CǓ + ) 1.67° C (eq. 4) Thus, the temperature error due to variation on n of the thermal diode for a Pentium III processor is about 2.5°C. In general, this additional temperature error of the thermal diode measurement due to deviations on n from its typical value is given by: DT + n * 1.008 1.008 ǒ273.15 Kelvin ) TTDǓ (eq. 5) where TTD is in °C. Beta of Thermal Transistor (b) In Figure 13, the thermal diode is a substrate PNP transistor where the emitter current is forced into the device. The derivation of Equation 2 assumed that the collector currents were scaled by N as the emitter currents were also scaled by N. Thus, this assumes that beta (b) of the transistor is constant for various collector currents. Figure 14 shows typical b variation vs. collector current for Pentium III processors at 100°C. The maximum b is 4.5 and varies less than 1% over the collector current range from 7 mA to 300 mA. bMAX < 4.5 IE nb Sources of Errors on Thermal Transistors Measurement Method; The Effect of Ideality Factor (n) b The effects of ideality factor (n) and beta (b) of the temperature measured by a thermal transistor are described in this section. For a thermal transistor implemented on a submicron process, such as the substrate PNP used on a Pentium III processor, the temperature errors due to the combined effect of the ideality factor and beta are shown to be less than 3°C. Equation 2 is optimized for a substrate PNP transistor (used as a thermal diode) usually found on CPUs designed on submicron CMOS processes such as the Pentium III processor. There is a thermal diode on board each of these processors. The n in Equation 2 represents the ideality factor of this thermal diode. This ideality factor is a measure of the deviation of the thermal diode from ideal behavior. According to Pentium III processor manufacturing specifications, measured values of n at 100°C are: IC = b b+1 IE IC (mA) 7 300 Figure 14. Variation of b with Collector Currents Expressing the collector current in terms of the emitter current. I C + I E ƪbń(b ) 1)] (eq. 6) where: bǒ300 mAǓ + bǒ7 mAǓ(1 ) e) e + D bńb and b + b(7mA) (eq. 7) Rewriting the equation for DVBE, to include the ideality factor, n, and beta, b yields: n MIN + 1.0057 t n TYPICAL + 1.008 t n MAX + 1.0125 + * 0.85° C DV BE + nKT q (eq. 3) ƪ 1n (1 ) e) ǒb ) 1Ǔ (1 ) e ) b ) 1 N ƫ (eq. 8) All b variations of less than 1% (e < 0.01) contribute to temperature errors of less than 0.4°C. The ADM1023 takes this ideality factor into consideration when calculating temperature TTD of the thermal diode. The http://onsemi.com 8 ADM1023 Temperature Data Format Register Functions One LSB of the ADC corresponds to 0.125°C, so the ADM1023 can measure from 0°C to 127.875°C. The temperature data format and extended temperature resolution are shown in Table 1 and Table 2. The ADM1023 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 Table 3 to Table 7. Most of the registers for the ADM1023 are dual−port and have different addresses for read and write operations. Attempting to write to a read address or to read from a write address produces an invalid result. Register addresses above 0x14 are reserved for future use or factory test purposes and should not be written to. Table 1. Temperature Data Format (Local and Remote Temperature High Byte) Temperature (5C) (Note 1) Digital Output 0 0 000 0000 1 0 000 0001 10 0 000 1010 25 0 001 1001 Address Pointer Register 50 0 011 0010 75 0 100 1011 100 0 110 0100 125 0 111 1101 127 0 111 1111 The address pointer register does not have, nor does it require, an address, because it is the register to which the first data byte of every write operation is automatically written. 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. 1. The ADM1023 differs from the ADM1021 in that the temperature resolution of the remote channel is improved from 1°C to 0.125°C, but it cannot measure temperatures below 0°C. If negative temperature measurement is required, the ADM1021 should be used. Value Registers The ADM1023 has three registers to store the results of local and remote temperature measurements. These registers are written to by the ADC and can only be read over the SMBus. The results of the local and remote temperature measurements are stored in the local and remote temperature value registers and are compared with limits programmed into the local and remote high and low limit registers. The Offset Register Two offset registers are provided at Address 0x11 and Address 0x12. These are provided so that the user may remove errors from the measured values of remote temperature. These errors may be introduced by clock noise and PCB track resistance. See Table 4 for an example of offset values. The offset value is stored as an 11−bit, twos complement value in Register 0x11 (high byte) and Register 0x12 (low byte, left justified). The value of the offset is negative if the MSB of Register 0x11 is 1, and it is positive if the MSB of Register 0x11 is 0. This value is added to the remote temperature. These registers default to 0 at powerup and have no effect if nothing is written to them. The offset register can accept values from −128.875°C to +127.875°C. The ADM1023 detects overflow so the remote temperature value register does not wrap around +127°C or −128°C. Table 2. Extended Temperature Resolution (Remote Temperature Low Byte) Extended Resolution (5C) Temperature Low Bits 0.000 0000 0000 0.125 0010 0000 0.250 0100 0000 0.375 0110 0000 0.500 1000 0000 0.625 1010 0000 0.750 1100 0000 0.875 1110 0000 http://onsemi.com 9 ADM1023 Table 3. List of ADM1023 Registers Read Address (Hex) Write Address (Hex) Not applicable Not applicable Address pointer Name Undefined Power−On Default 00 Not applicable Local temperature value 1000 0000 (0x80) (−128°C) 01 Not applicable Remote temperature value high byte 1000 0000 (0x80) (−128°C) 02 Not applicable Status Undefined 03 09 Configuration 0000 0000 (0x00) 04 0A Conversion rate 0000 0010 (0x02) 05 0B Local temperature high limit 0111 1111 (0x7F) (+127°C) 06 0C Local temperature low limit 1100 1001 (0xC9) (−55°C) 07 0D Remote temperature high limit high byte 0111 1111 (0x7F) (+127°C) Remote temperature low limit high byte 1100 1001 (0xC9) (−55°C) 08 0E Not applicable 0F (Note 1) 10 Not applicable Remote temperature value low byte 0000 0000 One−shot 11 11 Remote temperature offset high byte 0000 0000 12 12 Remote temperature offset low byte 0000 0000 13 13 Remote temperature high limit low byte 0000 0000 14 14 Remote temperature low limit low byte 0000 0000 19 Not applicable Reserved 0000 0000 20 21 Reserved Undefined FE Not applicable Manufacturer device ID 0100 0001 (0x41) FF Not applicable Die revision code 0011 xxxx (0x3x) 1. Writing to Address 0F causes the ADM1023 to perform a single measurement. It is not a data register as such; thus, it does not matter what data is written to it. Table 4. Offset Values Offset Registers Remote Temperature 0x11 0x12 Offset Value With Offset Without Offset 1111 1100 0000 0000 −4°C 14°C 18°C 1111 1111 0000 0000 −1°C 17°C 18°C 1111 1111 1110 0000 −0.125°C 17.875°C 18°C 0000 0000 0000 0000 0°C 18°C 18°C 0000 0000 0010 0000 +0.125°C 18.125°C 18°C 0000 0001 0000 0000 +1°C 19°C 18°C 0000 0100 0000 0000 +4°C 22°C 18°C Status Register Reading the status register clears the five flag bits, provided the error conditions that caused the flags to be set have gone away. While a limit comparator is tripped due to a value register containing an out−of−limit measurement or the sensor is open−circuit, the corresponding flag bit cannot be reset. A flag bit can be reset only if the corresponding 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 it resets 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. Bit 7 of the status register (see Table 5) indicates that the ADC is busy converting when it is high. Bit 6 to Bit 3 are flags indicating the results of the limit comparisons. If the local and/or remote temperature measurement is above the corresponding high temperature limit or below the corresponding low temperature limit, one or more of these flags will be set. Bit 2 is a flag that is set if the remote temperature sensor is open−circuit. These five flags are NOR’d together, so that if any of them are high, the ALERT interrupt latch is set, and the ALERT output goes low. http://onsemi.com 10 ADM1023 Table 5. Status Register Bit Assignments Bit Name 7 BUSY 6 LHIGH* Table 7. Conversion Rate Register Code Function Data Conversion/Sec Average Supply Current mA Typ at VCC = 3.3 V At 1 when local high temp limit tripped 0x00 0.0625 150 0.125 150 At 1 when ADC converting 5 LLOW* At 1 when local low temp limit tripped 0x01 4 RHIGH* At 1 when remote high temp limit tripped 0x02 0.25 150 0.5 150 3 RLOW* At 1 when remote low temp limit tripped 0x03 2 OPEN* At 1 when remote sensor open−circuit 0x04 1 150 Reserved 0x05 2 150 0x06 4 160 0x07 8 180 0x08 to 0xFF Reserved 1 to 0 *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 (see Table 6). If Bit 6 is set to 1, the device is in standby mode and the ADC does not convert. Standby mode can also be selected by taking the STBY pin low. In standby mode, the values of remote and local temperature remain at the value they were before the part was placed 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 ALERT output is enabled. If Bit 7 is set to 1, the ALERT output is disabled. Limit Registers The ADM1023 has six limit registers to store local and remote, high and low 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 as a limit of 80°C, measuring 81°C results in an alarm condition. Even though the temperature range is 0 to 127°C, it is possible to program the limit register with negative values. This is for backward−compatibility with the ADM1021. One−Shot Register Table 6. Configuration Register Bit Assignments Name Function 7 MASK1 0 = ALERT Enabled 1 = ALERT Masked 0 6 RUN/STOP 0 = Run 1 = Standby 0 Reserved 0 5 to 0 The one−shot register is used to initiate a single conversion and comparison cycle when the ADM1023 is in standby mode, after 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 irrelevant and is not stored. Power−On Default Bit Serial Bus Interface Control of the ADM1023 is carried out via the serial bus. The ADM1023 is connected to this bus as a slave device, under the control of a master device. Note that the SMBus SDA and SCLK pins are three−stated when the ADM1023 is powered down, and they do not pull down the SMBus. Conversion Rate Register The lowest three bits of this register are used to program the conversion rate by dividing the ADC clock by 1, 2, 4, 8, 16, 32, 64, or 128, to give conversion times from 125 ms (Code 0x07) to 16 seconds (Code 0x00). This register can be written to and read back over the SMBus. The higher five bits of this register are unused and must be set to 0. Use of slower conversion times greatly reduces the device’s power consumption, as shown in Table 7. Address Pins 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 responds. The ADM1023 has two address pins, ADD0 and ADD1, to allow selection of the device address, so that several ADM1023s can be used on the same bus and to avoid conflict with other devices. Although only two address pins are provided, these pins are three−state and can be grounded, left unconnected, or tied to VDD, so that a total of nine different addresses are possible, as shown in Table 8. Note that the state of the address pins is sampled only at powerup, so changing them after powerup has no effect. http://onsemi.com 11 ADM1023 clock pulse, known as the Acknowledge bit. All other devices on the bus remain idle while the selected device waits for data to be read from or written to it. If the R/W bit is 0, the master writes to the slave device. If the R/W bit is 1, the master reads from the slave device. 2. Data is sent over the serial bus in sequences of nine clock pulses, 8 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, because a low−to−high transition 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 conditions are established. In write mode, the master pulls the data line high during the 10th clock pulse to assert a stop condition. In read mode, the master device overrides 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 then takes the data line low during the low period before the 10th clock pulse, then high during the 10th clock pulse to assert a stop condition. Table 8. Device Addresses (Note 1) ADD0 ADD1 Device Address 0 0 0011 000 0 NC 0011 001 0 1 0011 010 NC 0 0101 001 NC NC 0101 010 NC 1 0101 011 1 0 1001 100 1 NC 1001 101 1 1 1001 110 1. ADD0 and ADD1 are sampled at powerup only. 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 8 bits. These bits consist of a 7−bit address (MSB first) plus an R/W bit, which determines the direction of the data transfer, that is, whether data is 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 1 9 1 9 SCLK 0 SDATA 1 0 1 1 A1 A0 D7 R/W START BY MASTER D6 D5 D4 D3 D2 D1 D0 ACK. BY ADM1023 ACK. BY ADM1023 FRAME 2 ADDRESS POINTER REGISTER BYTE FRAME 1 SERIAL BUS ADDRESS BYTE 1 9 SCLK (CONTINUED) D7 SDATA (CONTINUED) D6 D5 D4 D3 D2 D1 D0 ACK. BY ADM1023 STOP BY MASTER FRAME 3 DATA BYTE Figure 15. Writing a Register Address to the Address Pointer Register, then Writing Data to the Selected Register 1 9 9 1 SCLK SDATA 0 1 0 1 1 A1 START BY MASTER A0 D7 R/W D6 D5 D4 D3 D2 D1 FRAME 1 SERIAL BUS ADDRESS BYTE FRAME 2 ADDRESS POINTER REGISTER BYTE Figure 16. Writing to the Address Pointer Register Only http://onsemi.com 12 D0 ACK. BY ADM1023 ACK. BY ADM1023 STOP BY MASTER ADM1023 9 1 9 1 SCLK SDATA A6 A5 A4 A3 A2 A1 A0 R/W D7 D5 D6 D4 D3 D2 D1 D0 STOP BY NO ACK. BY MASTER MASTER ACK. BY ADM1023 START BY MASTER FRAME 1 SERIAL BUS ADDRESS BYTE FRAME 2 DATA BYTE FROM ADM1023 Figure 17. Reading Data from a Previously Selected Register 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. For the ADM1023, write operations contain either one or two bytes, while read operations contain one byte and perform the following functions: To write data to one of the device data registers or read data from it, the address pointer register must be set so that the correct data register is addressed. Data can then be written into that register or read from it. The first byte of a write operation 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 15. The device address is sent over the bus followed by R/W set to 0. This is followed by two data bytes. 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 ADM1023’s address pointer register value is unknown or not the desired value, it is 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 ADM1023 as before, but only the data byte containing the register read address is sent, as data is not to be written to the register. This is shown in Figure 16. 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 17. 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. NOTES: • It is possible to read a data byte from a data register without first writing to the address pointer register. However, it is not possible to write data to a register without writing to the address pointer register even if • the address pointer register is already at the correct value. This is because the first data byte of a write is always written to the address pointer register. Do not forget that ADM1023 registers have different addresses for read and write operations. The write address of a register must be written to the address pointer if data is to be written to that register, but it is not possible to read data from that address. The read address of a register must be written to the address pointer before data can be read from that register. ALERT Output The ALERT output goes low whenever an out−of−limit measurement is detected or if the remote temperature sensor is open−circuit. It is an open drain and requires a 10 kW pull−up to VDD. Several ALERT outputs can be wire−AND’ed together, so that the common line goes low if one or more of the ALERT outputs goes low. The ALERT output can be used as an interrupt signal to a processor, or it may be used as an SMBALERT. Slave devices on the SMBus normally cannot signal to the master that they want to talk, but the SMBALERT function allows them to do so. One or more ALERT outputs are connected to a common SMBALERT line connected to the master. When the SMBALERT line is pulled low by one of the devices, the procedure shown in Figure 18 occurs. MASTER RECEIVES SMBALERT START ALERT RESPONSE ADDRESS MASTER SENDS ARA AND READ COMMAND RD ACK DEVICE ADDRESS NO STOP ACK DEVICE SENDS ITS ADDRESS Figure 18. Use of SMBALERT SMBALERT Process 1. SMBALERT pulled low. 2. Master initiates a read operation and sends the alert response 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 ARA and the master reads its device address. The address of the device is now known, and it can be interrogated in the usual way. http://onsemi.com 13 ADM1023 collector connected to the substrate. Discrete types can be either PNP or NPN, connected as a diode (base−shorted to collector). If an NPN transistor is used, the collector and base are connected to D+ and the emitter to D−. If a PNP transistor is used, the collector and base are connected to D− and the emitter to D+. The user has no choice with substrate transistors, but if a discrete transistor is used, the best accuracy is achieved by choosing devices according to the following criteria: • Base emitter voltage greater than 0.25 V at 6 mA, at the highest operating temperature. • Base emitter voltage less than 0.95 V at 100 mA, at the lowest operating temperature. • Base resistance less than 100 W. • Small variation in hfe (approximately 50 to 150), which indicates tight control of VBE characteristics. Transistors such as 2N3904, 2N3906, or equivalents in SOT−23 packages are suitable devices to use. 4. If more than one device’s ALERT output is low, the one with the lowest device address has priority, in accordance with normal SMBus arbitration. 5. Once the ADM1023 has responded to the ARA, it resets its ALERT output, provided that the error condition that caused the ALERT no longer exists. If the SMBALERT line remains low, the master sends ARA again, and so on until all devices whose ALERT outputs were low have responded. Low Power Standby Modes The ADM1023 can be put into a low power standby mode using hardware or software, that is, by taking the STBY input low or by setting Bit 6 of the configuration register. When STBY is high or Bit 6 is low, the ADM1023 operates normally. When STBY is pulled low or 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 mA if there is no SMBus activity, or 100 mA if there are clock and data signals on the bus. These two modes are similar but not identical. When STBY is low, conversions are completely inhibited. When Bit 6 is set, but STBY is high, a one−shot conversion of both channels can be initiated by writing any data value to the one−shot register (Address 0x0F). 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, such as the processor, for example. If it is not in good thermal contact, the thermal inertia caused by the mass of the sensor causes a lag in the response of the sensor to a temperature change. With the remote sensor, this should not be a problem, as it will be either a substrate transistor in the processor or a small package device, such as SOT−23, placed in close proximity to it. The on−chip sensor, however, is often remote from the processor and monitors only the general ambient temperature around the package. The thermal time constant of the QSOP−16 package is about 10 seconds. In practice, the package has electrical, and hence thermal, connection to the printed circuit board. Therefore, the temperature rise due to self−heating is negligible. Sensor Fault Detection The ADM1023 has a fault detector at the D+ input that detects if the external sensor diode is open−circuit. This is a simple voltage comparator that trips if the voltage at D+ exceeds VCC – 1.0 V (typical). The output of this comparator is checked when a conversion is initiated and sets Bit 2 of the status register if a fault is detected. If the remote sensor voltage falls below the normal measuring range, for example, due to the diode being short−circuited, the ADC outputs –128°C (1000 0000 000). Because the normal operating temperature range of the device extends only down to 0°C, this output code is never seen in normal operation and can be interpreted as a fault condition. In this respect, the ADM1023 differs from, and improves upon, competitive devices that output 0 if the external sensor goes short−circuit. Unlike the ADM1023, these other devices can misinterpret a genuine 0°C measurement as a fault condition. If the external diode channel is not being used and is shorted out, the resulting ALERT may be cleared by writing 0x80 (−128°C) to the low limit register. Layout Considerations Digital boards can be electrically noisy environments, and the ADM1023 is measuring very small voltages from the remote sensor; therefore, care must be taken to minimize noise induced at the sensor inputs. The following precautions are needed: • Place the ADM1023 as close as possible to the remote sensing diode. Provided that the worst noise sources, such as clock generators, data/address buses, and CRTs, are avoided, this distance can be 4 to 8 inches. • Route the D+ and D− tracks close together, in parallel, with grounded guard tracks on each side. Provide a ground plane under the tracks if possible (see Figure 19). Applications Factors Affecting Accuracy, Remote Sensing Diode The ADM1023 is designed to work with substrate transistors built into processors or with discrete transistors. Substrate transistors are generally PNP types with the http://onsemi.com 14 ADM1023 • Use wide tracks to minimize inductance and reduce Application Circuits Figure 20 shows a typical application circuit for the ADM1023, using a discrete sensor transistor connected via a shielded, twisted−pair cable. The pullups on SCLK, SDATA, and ALERT are required only if they are not already provided elsewhere in the system. noise pickup. 10 mil track minimum width and spacing is recommended. 10MIL 10MIL 10MIL VDD 10MIL D– 3V TO 5.5V ADM1023 10MIL 10kΩ 10kΩ 10kΩ IN D+ 1000pF 10MIL GND 0.1μF D– 2N3904 10MIL I/O SHIELD OUT ALERT Figure 19. Arrangement of Signal Tracks SET TO REQUIRED ADDRESS ADD0 • Try to minimize the number of copper/solder joints, GND which can cause thermocouple effects. Where copper/solder joints are used, make sure that they are in both the D+ and D− path and at the same temperature. Thermocouple effects should not be a major problem as 1°C corresponds to about 240 mV, and thermocouple voltages are about 3 mV/°C of temperature difference. Unless there are two thermocouples with a big temperature differential between them, thermocouple voltages should be much less than 240 mV. • Place a 0.1 mF bypass capacitor close to the VDD pin and 1000 pF input filter capacitors across D+, D− close to the ADM1023. • If the distance to the remote sensor is more than 8 inches, the use of twisted pair cable is recommended. This is effective up to approximately 6 to 12 feet. • For longer distances (up to 100 feet), use shielded, twisted−pair cable such as Belden #8451 microphone cable. Connect the twisted pair to D+ and D−, and connect the shield to GND close to the ADM1023. 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. A 1 W series resistance introduces about 1°C error. TO CONTROL CHIP ADD1 Figure 20. Typical Application Circuit The SCLK and SDATA pins of the ADM1023 can be interfaced directly to the SMBus of an I/O chip. Figure 21 shows how the ADM1023 might be integrated into a system using this type of I/O controller. D– ADM1023 PROCESSOR ALERT D+ SCLK D+ SDATA GND SYSTEM BUS DISPLAY SYSTEM MEMORY GMCH DISPLAY CACHE HARD CD ROM DISK 2 IDE PORTS PCI SLOTS ICH I/O CONTROLLER HUB PCI BUS SUPER I/O SMBUS USB USB 2 USB PORTS FWH (FIRMWARE HUB) Figure 21. System Using ADM1023 and I/O Controller ORDERING INFORMATION Device Number Shipping† Temperature Range Package Type Package Option ADM1023ARQZ 0°C to +120°C 16−Lead QSOP RQ−16 98 Tube ADM1023ARQZ−REEL 0°C to +120°C 16−Lead QSOP RQ−16 2500 Tape & Reel ADM1023ARQZ−R7 0°C to +120°C 16−Lead QSOP RQ−16 1000 Tape & Reel †For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging Specifications Brochure, BRD8011/D. *The “Z’’ suffix indicates Pb−Free part. http://onsemi.com 15 ADM1023 PACKAGE DIMENSIONS QSOP16 CASE 492−01 ISSUE O −A− Q R H x 45_ U RAD. 0.013 X 0.005 DP. MAX −B− MOLD PIN MARK NOTES: 1. DIMENSIONING AND TOLERANCING PER ANSI Y14.5M, 1982. 2. CONTROLLING DIMENSION: INCH. 3. THE BOTTOM PACKAGE SHALL BE BIGGER THAN THE TOP PACKAGE BY 4 MILS (NOTE: LEAD SIDE ONLY). BOTTOM PACKAGE DIMENSION SHALL FOLLOW THE DIMENSION STATED IN THIS DRAWING. 4. PLASTIC DIMENSIONS DOES NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 6 MILS PER SIDE. 5. BOTTOM EJECTOR PIN WILL INCLUDE THE COUNTRY OF ORIGIN (COO) AND MOLD CAVITY I.D. INCHES DIM MIN MAX A 0.189 0.196 B 0.150 0.157 C 0.061 0.068 D 0.008 0.012 F 0.016 0.035 G 0.025 BSC H 0.008 0.018 J 0.0098 0.0075 K 0.004 0.010 L 0.230 0.244 M 0_ 8_ N 0_ 7_ P 0.007 0.011 Q 0.020 DIA R 0.025 0.035 U 0.025 0.035 8_ V 0_ RAD. 0.005−0.010 TYP G L 0.25 (0.010) M P T DETAIL E V K C N 8 PL MILLIMETERS MIN MAX 4.80 4.98 3.81 3.99 1.55 1.73 0.20 0.31 0.41 0.89 0.64 BSC 0.20 0.46 0.249 0.191 0.10 0.25 5.84 6.20 0_ 8_ 0_ 7_ 0.18 0.28 0.51 DIA 0.64 0.89 0.64 0.89 0_ 8_ −T− D 16 PL 0.25 (0.010) SEATING PLANE M T B S A S J M F DETAIL E Protected by U.S. Patents 5,195,827; 5,867,012; 5,982,221; 6,097,239; 6,133,753; 6,169,442; other patents pending. Pentium is a registered trademark of Intel Corporation. ON Semiconductor and are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does SCILLC assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages. “Typical” parameters which may be provided in SCILLC data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All operating parameters, including “Typicals” must be validated for each customer application by customer’s technical experts. SCILLC does not convey any license under its patent rights nor the rights of others. SCILLC products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the SCILLC product could create a situation where personal injury or death may occur. Should Buyer purchase or use SCILLC products for any such unintended or unauthorized application, Buyer shall indemnify and hold SCILLC and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that SCILLC was negligent regarding the design or manufacture of the part. SCILLC is an Equal Opportunity/Affirmative Action Employer. This literature is subject to all applicable copyright laws and is not for resale in any manner. PUBLICATION ORDERING INFORMATION LITERATURE FULFILLMENT: Literature Distribution Center for ON Semiconductor P.O. Box 5163, Denver, Colorado 80217 USA Phone: 303−675−2175 or 800−344−3860 Toll Free USA/Canada Fax: 303−675−2176 or 800−344−3867 Toll Free USA/Canada Email: [email protected] N. American Technical Support: 800−282−9855 Toll Free USA/Canada Europe, Middle East and Africa Technical Support: Phone: 421 33 790 2910 Japan Customer Focus Center Phone: 81−3−5773−3850 http://onsemi.com 16 ON Semiconductor Website: www.onsemi.com Order Literature: http://www.onsemi.com/orderlit For additional information, please contact your local Sales Representative ADM1023/D