ADM1023 AD | Alldatasheet
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REV.A Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. a ADM1023* Tel: 781/329-4700 World Wide Web Site: http://www.analog.com Fax: 781/326-8703 © Analog Devices, Inc., 2000 FUNCTIONAL BLOCK DIAGRAM ACPI-Compliant High-Accuracy Microprocessor System Temperature Monitor
FEATURES
Next Generation Upgrade to ADM1021 On-Chip and Remote Temperature Sensing Offset Registers for System Calibration 1/H11543C Accuracy and Resolution on Local Channel 0.125/H11543C Resolution/1 /H11543C Accuracy on Remote Channel Programmable Over/Under Temperature Limits Programmable Conversion Rate Supports System Management Bus (SMBus) Alert 2-Wire SMBus Serial Interface 200 /H9262A Max Operating Current (0.25 Conversions/ Seconds) 1 /H9262A Standby Current 3 V to 5.5 V Supply Small 16-Lead QSOP Package
APPLICATIONS
The ADM1023 is a two-channel digital thermometer and under/ over temperature alarm, intended for use in personal computers and other systems requiring thermal monitoring and management. Optimized for the Pentium ® III; the higher accuracy offered 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-con- nected PNP transistor, which may be provided on-chip in the case of the Pentium III or similar processors, or can be a low cost discrete NPN/PNP device such as the 2N 3904/2N3906. 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 tem- perature of the device and its environment. The ADM1023 communicates over a 2-wire serial interface compatible with SMBus standards. Under and over tempera- ture 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. *Patents pending. Pentium is a registered trademark of Intel Corporation. ON-CHIP TEMPERATURE SENSOR A-TO-D CONVERTER BUSY RUN/STANDBY EXTERNAL DIODE OPEN-CIRCUIT ADDRESS POINTER REGISTER ONE-SHOT REGISTER CONVERSION RATE REGISTER OFFSET REGISTERS REMOTE TEMPERATURE HIGH-LIMIT REGISTERS CONFIGURATION REGISTER INTERRUPT MASKING SMBUS INTERFACE LOCAL TEMPERATURE LOW-LIMIT COMPARATOR LOCAL TEMPERATURE HIGH-LIMIT COMPARATOR REMOTE TEMPERATURE LOW-LIMIT COMPARATOR REMOTE TEMPERATURE HIGH-LIMIT COMPARATOR REMOTE TEMPERATURE VALUE REGISTERS LOCAL TEMPERATURE VALUE REGISTER STATUS REGISTER NC V DD GNDNC GND NC NC NC SDATA SCLK ADD0 ADD1 ALERT STBY D– REMOTE TEMPERATURE LOW-LIMIT REGISTERS LOCAL TEMPERATURE HIGH-LIMIT REGISTER LOCAL TEMPERATURE LOW-LIMIT REGISTER ANALOG MUX NC = NO CONNECT ADM1023
–2– REV. A ADM1023–SPECIFICATIONS(TA = TMIN to TMAX 1, VDD = 3.0 V to 3.6 V, unless otherwise noted) Parameter Min Typ Max Unit Test Conditions/Comments POWER SUPPLY AND ADC Temperature Resolution, Local Sensor 1 °C Guaranteed No Missed Codes Temperature Resolution, Remote Sensor 0.125 °C Guaranteed No Missed Codes Temperature Error, Local Sensor –1.5 ± 0.5 +1.5 °CT A = 60°C to 100°C –3 ± 1+ 3 °CT A = 0°C to 120°C Temperature Error, Remote Sensor –1 +1 °CT A, TD = 60°C to 100°C (Note 2) –3 +3 °CT A, TD = 0°C to 120°C (Note 2) Relative Accuracy 0.25 °CT A = 60°C to 100°C Supply Voltage Range 3 3.6 V Note 3 Undervoltage Lockout Threshold 2.55 2.7 2.8 V V DD Input, Disables ADC, Rising Edge Undervoltage Lockout Hysteresis 25 mV Power-On Reset Threshold 0.9 1.7 2.2 V V DD, Falling Edge (Note 4) POR Threshold Hysteresis 50 mV Standby Supply Current 1 5 µAV DD = 3.3 V, No SMBus Activity 4 µA SCLK at 10 kHz Average Operating Supply Current 130 200 µA 0.25 Conversions/Sec Rate Autoconvert Mode, Averaged Over 4 Sec 225 330 µA 2 Conversions/Sec Rate Conversion Time 65 115 170 ms From Stop Bit to Conversion Complete (Both Channels) D+ Forced to D– + 0.65 V Remote Sensor Source Current 120 205 300 µA High Level (Note 4) 71 2 1 6 µA Low Level (Note 4) D-Source Voltage 0.7 V Address Pin Bias Current (ADD0, ADD1) 50 µA Momentary at Power-On Reset SMBus INTERFACE Logic Input High Voltage, V IH 2.2 V V DD = 3 V to 5.5 V STBY, SCLK, SDATA Logic Input Low Voltage, V IL 0.8 V V DD = 3 V to 5.5 V STBY, SCLK, SDATA SMBus 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, IIL –1 +1 µA SMBus Input Capacitance, SCLK, SDATA 5 pF SMBus Clock Frequency 100 kHz SMBus Clock Low Time, t LOW 4.7 µst LOW Between 10% Points SMBus Clock High Time, t HIGH 4n s t HIGH Between 90% Points SMBus Start Condition Setup Time, t SU:STA 4.7 ns SMBus Start Condition Hold Time, t HD:STA 4 ns Time from 10% of SDATA to 90% of SCLK SMBus Stop Condition Setup Time, t SU:STO 4 ns Time from 90% of SCLK to 10% of SDATA SMBus Data Valid to SCLK 250 ns Time for 10% or 90% of Rising Edge Time, t SU:DAT SDATA to 10% of SCLK SMBus Data Hold Time, t HD:DAT 0 µs SMBus Bus Free Time, t BUF 4.7 µs Between Start/Stop Condition SCLK Falling Edge to SDATA 1 µs Master Clocking in Data Valid Time, tVD,DAT SMBus Leakage Current 5 µAV DD = 0 V NOTES 1TMAX = 120°C, TMIN = 0°C. 2TD is temperature of remote thermal diode; T A, TD = 60°C to 100°C. 3Operation at V DD = 5 V guaranteed by design, not production tested. 4Guaranteed by design, not production tested. Specifications subject to change without notice.
conditions for extended periods may affect device reliability. 2V DD Positive supply, 3 V to 5.5 V.
3 D+ Positive connection to remote tem-
4 D– Negative connection to remote tem-
6 ADD1 Three-state logic input, higher bit of
7, 8 GND Supply 0 V connection.
10 ADD0 Three-state logic input, lower bit of
11 ALERT Open-drain logic output used as
12 SDATA L ogic input/output, SMBus serial
14 SCLK Logic input, SMBus serial clock.
15 STBY Logic input selecting normal opera-
tion (high) or standby mode (low). Figure 1. Diagram for Serial Bus Timing
Figure 8. Temperature Error vs. Differential-Mode Noise
5 VOLTS
3.3 VOLTS
Figure 9. Operating Supply Current vs. Conversion Rate, provided for this purpose at addresses 11h and 12h. effect if nothing is written to them. results w ill cause the ALERT output to pull low. tents of any register can also be read back via the SMBus.
- Switching the device between normal operation and standby mode.
- Masking or enabling the ALERT output.
- Selecting the conversion rate. On initial power-up the remote and local temperature values default to –128°C. Since the device normally powers up convert- ing, a measure of local and remote temperature is made and these SUPPLY VOLTAGE – V SUPPLY CURRENT – /H9262A 100 –20
Figure 10. Standby Supply Current vs. Supply Voltage Figure 11. Response to Thermal Shock
∆T n Kelvin T T CTD TD=× + °– . than 1% over the collector current range from 7 µA to 300 µA. Figure 13. Variation of β with Collector Currents ture errors of less than 0.4 °C. mat is shown in Tables I and II. remote high and low limit registers. low temperature limits, and to con figure and control the device. or used for factory test purposes and should not be written to. written to by the ADC and can only be read over the SMBus. Two offset registers are provided at addresses 11h and 12h. introduced by clock noise and PCB track resistance. in Registers 11h (high byte) and 12h (low byte, left-justified). tains a set of example offset values.
–8– REV. A Table IV. Remote Remote Temperature Temperature Offset Registers Offset (Including (Without 11h 12h Value Offset) Offset) 1111 1100 0000 0000 –4°C1 4 °C1 8 °C 1111 1111 0000 0000 –1°C1 7 °C1 8 °C 1111 1111 1110 0000 –0.125°C 17.875 °C1 8 °C 0000 0000 0000 0000 0 °C1 8 °C1 8 °C 0000 0000 0010 0000 +0.125 °C 18.125 °C1 8 °C 0000 0001 0000 0000 +1 °C1 9 °C1 8 °C 0000 0100 0000 0000 +4 °C2 2 °C1 8 °C Status Register Bit 7 of the Status Register indicates that the ADC is busy con- verting when it is high. Bits 6 to 3 are flags that indicate the results of the limit comparisons. If the local and/or remote temperature measurement is above the corresponding high temperature limit, or below the corre- sponding 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 will be set and the ALERT output will go low. Reading the Status Register will clear 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 correspo nding flag bit 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. Table V. 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. 1–0 Reserved. *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. 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. 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. Table III. List of ADM1023 Registers READ Address (Hex) WRITE Address (Hex) Name Power-On Default Not Applicable Not Applicable Address Pointer Unde fined
00 Not Applicable Local Temperature Value 1000 0000 (80h) ( –128°C)
01 Not Applicable Remote Temperature Value High Byte 1000 0000 (80h) ( –128°C)
02 Not Applicable Status Unde fined
03 09 Con figuration 0000 0000 (00h) 04 0A Conversion Rate 0000 0010 (02h) 05 0B Local Temperature High Limit 0111 1111 (7Fh) (+127 °C) 06 0C Local Temperature Low Limit 1100 1001 (C9h) ( –55°C) 07 0D Remote Temperature High Limit High Byte 0111 1111 (7Fh) (+127 °C) 08 0E Remote Temperature Low Limit High Byte 1100 1001 (C9h) ( –55°C) Not Applicable 0F 1 One-Shot
10 Not Applicable Remote Temperature Value Low Byte 0000 0000
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 Unde fined FE Not Applicable Manufacturer Device ID 0100 0001 (41h) FF Not Applicable Die Revision Code 0011 xxxx (3xh) NOTE 1Writing to address 0F causes the ADM1023 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.
–9–REV. A Table VI. 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 5–0 Reserved 0 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 07h) to 16 seconds (Code 00h). 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 zero. Use of slower conversion times greatly reduces the device power consumption, as shown in Table VII. Table VII. Conversion Rate Register Codes Average Supply Current Data Conversion/sec /H9262A Typ at VCC = 3.3 V 00h 0.0625 150 01h 0.125 150 02h 0.25 150 03h 0.5 150 04h 1 150 05h 2 150 06h 4 160 07h 8 180 08h to FFh Reserved 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 per- form 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 will result in an alarm condi- tion. Even though the temperature range is 0 to 127 °C, it is possible to program the Limit Register with negative values. This is for backwards-compatibility with the ADM1021. One-Shot Register 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 conver- sion. The data written to this address is irrelevant and is not stored. 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. 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 will respond. 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/or to avoid conflict with other devices. Although only two address pins are provided, these are three-state, and can be grounded, left unconnected, or tied to V DD, so that a total of nine different addresses are possible, as shown in Table VIII. It should be noted that the state of the address pins is only sampled at power-up, so changing them after power-up will have no effect. Table VIII. Device Addresses ADD0 ADD1 Device Address 0 0 0011 000
0 NC 0011 001
1 NC 1001 101
ADD0, ADD1 sampled at power-up only. The serial bus protocol operates as follows: 1. The master initiates data transfer by establishing a START condi- tion, 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, consisting 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 Acknowledge Bit. All other devices on the bus now remain idle while the 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 device. 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, as 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 condi- tions are established. In WRITE mode, the master will pull the data line high during the 10th clock pulse to assert a STOP condition. 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 10th clock pulse, then high during the 10th 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.
talk, but the SMBALERT function allows them to do so. occurs as illustrated in Figure 17. Figure 17. Use of SMBALERT
- Master initiates a read operation and sends the Alert Response
must not be used as a specific device address.
- The device whose ALERT output is low responds to the Alert
Response Address and the master reads its device address.
- If more than one device ’s ALERT output is low, the one with
with normal SMBus arbitration.
- Once the ADM1023 has responded to the Alert Response
ity, or 100 µA if there are clock and data signals on the bus. so it can be interpreted as a fault condition. surement as a fault condition. are connected to D– and the emitter to D+.
- Base-emitter voltage greater than 0.25 V at 6 µA, at the high-
- Base-emitter voltage less than 0.95 V at 100 µA, at the lowest
- Base resistance less than 100 /H9024.
- Small variation in h fe (say 50 to 150) which indicates tight
control of VBE characteristics. package are suitable devices to use.
package is about 10 seconds. due to self-heating will be negligible.
- Place the ADM1023 as close as possible to the remote sensing
distance can be four to eight inches.
- Route the D+ and D – tracks close together, in parallel, with
under the tracks if possible.
- Use wide tracks to minimize inductance and reduce noise
Figure 18. Arrangement of Signal Tracks
- Try to minimize the number of copper/solder joints, which
path and at the same temperature. them, thermocouple voltages should be much less than 240µV.
- Place a 0.1 µF bypass capacitor close to the V
- If the distance to the remote sensor is more than eight inches,
- For really long distances (up to 100 feet), use shielded twisted
nected to avoid ground loops. only if they are not already provided elsewhere in the system. Figure 19. Typical ADM1023 Application Circuit
2 USB PORTS
2 IDE PORTS
Figure 20. Typical System Using ADM1023 Dimensions shown in inches and (mm).