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19-3476; Rev 3; 8/07
KIT ATION EVALU BLE AVAILA
7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor
General Description
The MAX6698 precision multichannel temperature sensor monitors its own temperature, the temperatures of three external diode-connected transistors, and the temperatures of three thermistors. All temperature channels have programmable alert thresholds. Channels 1, 4, 5, and 6 also have programmable overtemperature thresholds. When the measured temperature of a channel exceeds the respective threshold, a status bit is set in one of the status registers. Two opendrain outputs, OVERT and ALERT, assert corresponding to these bits in the status register. The 2-wire serial interface supports the standard system management bus (SMBusTM) protocols: write byte, read byte, send byte, and receive byte for reading the temperature data and programming the alarm thresholds. The MAX6698 is specified for an operating temperature range of -40C to +125C and is available in 16-pin QSOP and 16-pin TSSOP packages.
Features
Three Thermal-Diode Inputs and Three Thermistor Inputs Local Temperature Sensor 1C Remote Temperature Accuracy (+60C to +100C) Temperature Monitoring Begins at POR for FailSafe System Protection ALERT and OVERT Outputs for Interrupts, Throttling, and Shutdown Small 16-Pin QSOP and 16-Pin TSSOP Packages 2-Wire SMBus Interface
MAX6698
Ordering Information
PART MAX6698EE_ _ MAX6698UE_ _ TEMP RANGE -40C to +125C -40C to +125C PINPACKAGE 16 QSOP 16 TSSOP PKG CODE E16-1 U16-1
Applications
Desktop Computers Notebook Computers Workstations Servers
*See the Slave Address section. Pin Configuration appears at end of data sheet.
Typical Application Circuit
+3.3V
1 2 3 4 5 6 7 8
DXP1 DXN1 DXP2 DXN2 DXP3 DXN3 THER3 VREF
GND 16
MAX6698
SMBCLK 15 SMBDATA 14 ALERT 13 VCC 12 OVERT 11 THER1 10 THER2 9
REX3
REX2
REX1
RTHER3
RTHER2
RTHER1
SMBus is a trademark of Intel Corp. ________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor MAX6698
ABSOLUTE MAXIMUM RATINGS
VCC, SCL, SDA, ALERT, OVERT to GND ................-0.3V to +6V DXP_ to GND..............................................-0.3V to (VCC + 0.3V) DXN_ to GND ........................................................-0.3V to +0.8V THER_ to GND..........................................................-0.3V to +6V VREF to GND............................................................-0.3V to +6V SDA, ALERT, OVERT Current .............................-1mA to +50mA DXN Current .......................................................................1mA Continuous Power Dissipation (TA = +70C) 16-Pin QSOP (derate 8.3mW/C above +70C) ......................666.7mW(E16-1) 16-Pin TSSOP (derate 9.4mW/C above +70C)....................754.7mW(U16-1) ESD Protection (all pins, Human Body Model) ................2000V Operating Temperature Range .........................-40C to +125C Junction Temperature ......................................................+150C Storage Temperature Range .............................-60C to +150C Lead Temperature (soldering, 10s) .................................+300C
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(VCC = +3.0V to +5.5V, TA = -40C to +125C, unless otherwise noted. Typical values are at VCC = +3.3V and TA = +25C.) (Note 1)
PARAMETER Supply Voltage Standby Supply Current Operating Current Temperature Resolution SYMBOL VCC ISS ICC SMBus static During conversion Channel 1 only Other diode channels TA = TRJ = +60C to +100C Remote Temperature Accuracy VCC = 3.3V TA = TRJ = 0C to +125C DXN_ grounded, TRJ = TA = 0C to +85C TA = +60C to +100C TA = 0C to +125C -2.5 -3.5 0.2 tCONV1 tCONV_ IRJ UVLO High level Low level Falling edge of VCC disables ADC VCC falling edge Resistance cancellation on Resistance cancellation off 95 190 95 80 8 2.3 1.2 125 250 125 100 10 2.80 90 2.0 90 2.5 156 312 156 120 12 2.95 -1.0 -3.0 CONDITIONS MIN 3.0 30 500 11 8 +1.0 +3.0 2.5 +2.5 +3.5
o o o
TYP
MAX 5.5 1000
UNITS V A A Bits
C
Local Temperature Accuracy Supply Sensitivity of Temperature Accuracy Remote Channel 1 Conversion Time Remote Channels 2 Through 6 Conversion Time Remote-Diode Source Current Undervoltage-Lockout Threshold Undervoltage-Lockout Hysteresis Power-On Reset (POR) Threshold POR Threshold Hysteresis THERMISTOR CONVERSION Voltage-Measurement Accuracy Conversion Time Thermistor Reference Voltage VREF
VCC = 3.3V
C
C/V ms ms A V
mV V mV %Full scale ms V
-1 31 1
+1
2
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7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor
ELECTRICAL CHARACTERISTICS (continued)
(VCC = +3.0V to +5.5V, TA = -40C to +125C, unless otherwise noted. Typical values are at VCC = +3.3V and TA = +25C.) (Note 1)
PARAMETER Reference-Load Regulation Reference-Supply Rejection ALERT, OVERT Output Low Voltage Output Leakage Current SMBus INTERFACE (SCL, SDA) Logic-Input Low Voltage Logic-Input High Voltage Input Leakage Current Output Low Voltage Input Capacitance Serial Clock Frequency Bus Free Time Between STOP and START Condition START Condition Setup Time Repeat START Condition Setup Time START Condition Hold Time STOP Condition Setup Time Clock Low Period Clock High Period Data Hold Time Data Setup Time Receive SCL/SDA Rise Time Receive SCL/SDA Fall Time Pulse Width of Spike Suppressed SMBus Timeout tSU:STA tHD:STA tSU:STO tLOW tHIGH tHD:DAT tSU:DAT tR tF tSP tTIMEOUT SDA low period for interface reset 0 25 37 VOL CIN fSCL tBUF (Note 3) fSCL = 100kHz fSCL = 400kHz fSCL = 100kHz fSCL = 400kHz 90% of SCL to 90% of SDA, fSCL = 100kHz 90% of SCL to 90% of SDA, fSCL = 400kHz 10% of SDA to 90% of SCL 90% of SCL to 90% of SDA, fSCL = 100kHz 90% of SCL to 90% of SDA, fSCL = 400kHz 10% to 10%, fSCL = 100kHz 10% to 10%, fSCL = 400kHz 90% to 90% fSCL = 100kHz fSCL = 400kHz (Note 4) fSCL = 100kHz fSCL = 400kHz fSCL = 100kHz fSCL = 400kHz 250 100 1 0.3 300 50 45 4.7 1.6 4.7 0.6 0.6 0.6 0.6 4 0.6 1.3 1.3 0.6 300 900 ISINK = 6mA 5 400 VIL VIH VCC = 3.0V VCC = 5.0V 2.2 2.4 -1 +1 0.3 0.8 V V V A V pF kHz s s s s s s s ns ns s ns ns ms VOL ISINK = 1mA ISINK = 6mA 0.3 0.5 1 V A SYMBOL CONDITIONS 0mA < IREF < 2mA MIN TYP MAX 0.4 0.5 UNITS % %/V
MAX6698
SMBus-COMPATIBLE TIMING (Figures 3 and 4) (Note 2)
Note 1: Note 2: Note 3: Note 4:
All parameters are tested at TA = +25C. Specifications over temperature are guaranteed by design. Timing specifications are guaranteed by design. The serial interface resets when SCL is low for more than tTIMEOUT. A transition must internally provide at least a hold time to bridge the undefined region (300ns max) of SCL's falling edge. _______________________________________________________________________________________ 3
7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor MAX6698
Typical Operating Characteristics
(VCC = 3.3V, TA = +25C, unless otherwise noted.)
STANDBY SUPPLY CURRENT vs. SUPPLY VOLTAGE
12 11 10 9 8 7 6 5 4 3 2 1 0 3.3 3.8 4.3 4.8 5.3 SUPPLY VOLTAGE (V)
MAX6698 toc01
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX6698 toc02
REMOTE TEMPERATURE ERROR vs. REMOTE-DIODE TEMPERATURE
MAX6698 toc03
360 355 SUPPLY CURRENT (A) 350 345 340 335 330 325 320 3.3 3.8 4.3 4.8 5.3 SUPPLY VOLTAGE (V)
3 2 TEMPERATURE ERROR (C) 1 0 -1 -2 -3 -4 0 25 50 75 100
STANDBY SUPPLY CURRENT (A)
125
REMOTE-DIODE TEMPERATURE (C)
LOCAL TEMPERATURE ERROR vs. DIE TEMPERATURE
MAX6698 toc04
REMOTE-DIODE TEMPERATURE ERROR vs. POWER-SUPPLY NOISE FREQUENCY
MAX6698 toc05
LOCAL TEMPERATURE ERROR vs. POWER-SUPPLY NOISE FREQUENCY
4 TEMPERATURE ERROR (C) 3 2 1 0 -1 -2 -3 -4 100mVP-P
MAX6698 toc06
4 3 TEMPERATURE ERROR (C) 2 1 0 -1 -2 -3 -4 0 25 50 75 100
5 4 TEMPERATURE ERROR (C) 3 2 1 0 -1 -2 -3 -4 -5
5
100mVP-P
125
0.1 FREQUENCY (MHz)
1
-5 0.001
0.01
0.1
1
DIE TEMPERATURE (C)
FREQUENCY (MHz)
REMOTE TEMPERATURE ERROR vs. COMMON-MODE NOISE FREQUENCY
MAX6698 toc07
REMOTE TEMPERATURE ERROR vs. COMMON-MODE NOISE FREQUENCY
4 TEMPERATURE ERROR (C) 3 2 1 0 -1 -2 -3 -4 100mVP-P
MAX6698 toc08
5 4 TEMPERATURE ERROR (C) 3 2 1 0 -1 -2 -3 -4
100mVP-P
5
-5 0.001
0.01
0.1 FREQUENCY (MHz)
1
10
-5 0.001
0.01
0.1 FREQUENCY (MHz)
1
10
4
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7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor MAX6698 MAX6698
Typical Operating Characteristics (continued)
(VCC = 3.3V, TA = +25C, unless otherwise noted.)
TEMPERATURE ERROR vs. DXP-DXN CAPACITANCE
MAX6698 toc09
ALERT, OVERT SINK CURRENT vs. TEMPERATURE
MAX6698 toc10
THERMISTOR ADC ERROR vs. POWER-SUPPLY NOISE FREQUENCY
4 TEMPERATURE ERROR (C) 3 2 1 0 -1 -2 -3 -4 100mVP-P
MAX6698 toc11
0 -0.5 TEMPERATURE ERROR (C) -1.0 -1.5 -2.0 -2.5 -3.0 -3.5 -4.0 -4.5 -5.0 1 10 DXP-DXN CAPACITANCE (nF)
30 VOL = 0.3V 25 ALERT SINK CURRENT (mA) 20 15 10 5 0 VOL = 0.1V
5
-5 0 25 50 75 100 125 0.01 0.1 1 FREQUENCY (MHz) 10 100 TEMPERATURE (C)
100
Pin Description
PIN 1 NAME DXP1 FUNCTION Combined Current Source and A/D Positive Input for Channel 1 Remote Diode. Connect to the anode of a remote-diode-connected temperature-sensing transistor. Leave floating or connect to VCC if no remote diode is used. Place a 2200pF capacitor between DXP1 and DXN1 for noise filtering. Cathode Input for Channel 1 Remote Diode. Connect the cathode of the channel 1 remote-diodeconnected transistor to DXN1. Combined Current Source and A/D Positive Input for Channel 2 Remote Diode. Connect to the anode of a remote-diode-connected temperature-sensing transistor. Leave floating or connect to VCC if no remote diode is used. Place a 2200pF capacitor between DXP2 and DXN2 for noise filtering. Cathode Input for Channel 2 Remote Diode. Connect the cathode of the channel 2 remote-diodeconnected transistor to DXN2. Combined Current Source and A/D Positive Input for Channel 3 Remote Diode. Connect to the anode of a remote-diode-connected temperature-sensing transistor. Leave floating or connect to VCC if no remote diode is used. Place a 2200pF capacitor between DXP3 and DXN3 for noise filtering. Cathode Input for Channel 3 Remote Diode. Connect the cathode of the channel 1 remote-diodeconnected transistor to DXN3. Thermistor Voltage Sense Input 3. Connect thermistor 3 between THER3 and ground and an external resistor REXT3 between THER3 and VREF. Thermistor Reference Voltage (1V Nominal). VREF is automatically enabled for a thermistor conversion, and is disabled for diode measurements.
2
DXN1
3
DXP2
4
DXN2
5
DXP3
6 7 8
DXN3 THER3 VREF
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7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor MAX6698
Pin Description (continued)
PIN 9 10 11 12 13 14 15 16 NAME THER2 THER1 OVERT VCC ALERT SMBDATA SMBCLK GND FUNCTION Thermistor Voltage Sense Input 2. Connect thermistor 2 between THER2 and ground and an external resistor REXT3 between THER2 and VREF. Thermistor Voltage Sense Input 1. Connect thermistor 1 between THER1 and ground and an external resistor REXT3 between THER1 and VREF. Overtemperature Active-Low, Open-Drain Output. OVERT asserts low when the temperature of channels 1, 4, 5, and 6 exceed the programmed threshold limit. Supply Voltage Input. Bypass to GND with a 0.1F capacitor. SMBus Alert (Interrupt), Active-Low, Open-Drain Output. ALERT asserts low when the temperature of channels 1, 4, 5, and 6 exceed programmed threshold limit. SMBus Serial-Data Input/Output. Connect to a pullup resistor. SMBus Serial-Clock Input. Connect to a pullup resistor. Ground
Detailed Description
The MAX6698 is a precision multichannel temperature monitor that features one local, three remote thermal diode temperature-sensing channels, and three thermistor voltage-sensing channels. All channels have a programmable alert threshold for each temperature channel and a programmable overtemperature threshold for channels 1, 4, 5, and 6 (see Figure 1). Communication with the MAX6698 is achieved through the SMBus serial interface and a dedicated alert (ALERT) pin. The alarm outputs, OVERT and ALERT, assert if the software-programmed temperature thresholds are exceeded. ALERT typically serves as an interrupt, while OVERT can be connected to a fan, system shutdown, or other thermal-management circuitry. Note that thermistor "temperature data" is really the voltage across the fixed resistor, REXT, in series with the thermistor. This voltage is directly related to temperature, but the data is expressed in percentage of the reference voltage not in C.
version result for each active channel is stored in the corresponding temperature data register. In some systems, one of the remote thermal diodes may be monitoring a location that experiences temperature changes that occur much more rapidly than in the other channels. If faster temperature changes must be monitored in one of the temperature channels, the MAX6698 allows channel 1 to be monitored at a faster rate than the other channels. In this mode (set by writing a 1 to bit 4 of the configuration 1 register), measurements of channel 1 alternate with measurements of the other channels. The sequence becomes remote-diode channel 1, remotediode channel 2, remote-diode channel 1, remote-diode channel 3, remote-diode channel 1, etc. Note that the time required to measure all seven channels is considerably greater in this mode than in the default mode.
Low-Power Standby Mode
Standby mode reduces the supply current to less than 15A by disabling the internal ADC. Enter standby by setting the STOP bit to 1 in the configuration 1 register. During standby, data is retained in memory, and the SMBus interface is active and listening for SMBus commands. The timeout is enabled if a start condition is recognized on the SMBus. Activity on the SMBus causes the supply current to increase. If a standby command is received while a conversion is in progress, the conversion cycle is interrupted, and the temperature registers are not updated. The previous data is not changed and remains available.
ADC Conversion Sequence
In the default conversion mode, the MAX6698 starts the conversion sequence by measuring the temperature on the channel 1 remote diode, followed by the channel 2, remote diode, channel 3 remote diode, and the local channel. Then it measures thermistor channel 1, thermistor channel 2, and thermistor channel 3. The con-
6
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7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor MAX6698
VCC
DXP1
10/100A
DXN1 DXP3 3-TO-1 MUX INPUT BUFFER DP
MAX6698
ALU
OVERT ALERT
DXN3 BUF1 VREF CNT REGISTER BANK COMMAND BYTE COUNTER REMOTE TEMPERATURES LOCAL TEMPERATURES REXT1 ALERT THRESHOLD OVERT THRESHOLD RTHER1 REXT2 3-TO-1 MUX RTHER1 REXT1 BUF2 SMBus INTERFACE ALERT RESPONSE ADDRESS
ADC
VREF1
RTHER1 SCL SDA
Figure 1. Internal Block Diagram
SMBus Digital Interface
From a software perspective, the MAX6698 appears as a series of 8-bit registers that contain temperature measurement data, alarm threshold values, and control bits. A standard SMBus-compatible 2-wire serial interface is used to read temperature data and write control bits and alarm threshold data. The same SMBus slave address also provides access to all functions. The MAX6698 employs four standard SMBus protocols: write byte, read byte, send byte, and receive byte (Figure 2). The shorter receive byte protocol allows quicker transfers, provided that the correct data regis-
ter was previously selected by a read byte instruction. Use caution with the shorter protocols in multimaster systems, since a second master could overwrite the command byte without informing the first master. Figure 3 is the SMBus write timing diagram and Figure 4 is the SMBus read timing diagram. The remote diode 1 measurement channel provides 11 bits of data (1 LSB = 0.125C). All other temperaturemeasurement channels provide 8 bits of temperature data (1 LSB = 1C). The 8 most significant bits (MSBs) can be read from the local temperature, remote temperature, and thermistor registers. The remaining 3 bits
7
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7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor MAX6698
Write Byte Format S ADDRESS 7 bits Slave Address: equivalent to chip-select line of a 3-wire interface Read Byte Format S ADDRESS 7 bits Slave Address: equivalent to chip-select line Send Byte Format S ADDRESS 7 bits WR ACK COMMAND 8 bits Command Byte: sends command with no data, usually used for one-shot command S = Start condition P = Stop condition Shaded = Slave transmission /// = Not acknowledged ACK P WR ACK COMMAND 8 bits Command Byte: selects which register you are reading from ACK S ADDRESS 7 bits Slave Address: repeated due to change in dataflow direction Receive Byte Format S ADDRESS 7 bits RD ACK DATA 8 bits Data Byte: reads data from the register commanded by the last read byte or write byte transmission; also used for SMBus alert response return address /// P RD ACK DATA 8 bits Data Byte: reads from the register set by the command byte /// P WR ACK COMMAND 8 bits Command Byte: selects which register you are writing to ACK DATA 8 bits ACK P 1
Data Byte: data goes into the register set by the command byte (to set thresholds, configuration masks, and sampling rate)
Figure 2. SMBus Protocols
for remote diode 1 can be read from the extended temperature register. If extended resolution is desired, the extended resolution register should be read first. This prevents the most significant bits from being overwritten by new conversion results until they have been read. If the most significant bits have not been read within an SMBus timeout period (nominally 25ms), normal updating continues. Table 1 shows themistor voltage data format. Table 2 shows the main temperature register (high byte) data format. Table 3 shows the extended resolution temperature register (low byte) data format.
Table 1. Thermistor Voltage Data Format
VREXT 1.000 0.500 0.250 0.055 0.050 0.005 0.000 DIGITAL OUTPUT 1100 1000 0110 0100 0011 0010 0000 1011 0000 1010 0000 0001 0000 0000
Diode Fault Detection
If a channel's input DXP_ and DXN_ are left open, the MAX6698 detects a diode fault. An open diode fault does not cause either ALERT or OVERT to assert. A bit in the status register for the corresponding channel is set to 1 and the temperature data for the channel is stored as all 1s (FFh). It takes approximately 4ms for the MAX6698 to detect a diode fault. Once a diode fault is detected, the MAX6698 goes to the next channel in the conversion sequence. Depending on operating conditions, a shorted diode may or may not cause ALERT or OVERT to assert, so if a channel will not be used, disconnect its DXP and DXN inputs.
8
Alarm Threshold Registers
There are 11 alarm threshold registers that store overtemperature ALERT and OVERT threshold values. Seven of these registers are dedicated to store one local alert temperature threshold limit, three remote alert temperature threshold limits, and three thermistor voltage threshold limits (see the ALERT Interrupt Mode section). The remaining four registers are dedicated to remote-diode channel 1, and three thermistor channels 1, 2, and 3 to store overtemperature threshold limits (see the OVERT Overtemperature Alarm section). Access to these registers is provided through the SMBus interface.
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7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor MAX6698
A tLOW B tHIGH C D E F G H I J K L M
SMBCLK
SMBDATA
tSU:STA tHD:STA A = START CONDITION B = MSB OF ADDRESS CLOCKED INTO SLAVE C = LSB OF ADDRESS CLOCKED INTO SLAVE D = R/W BIT CLOCKED INTO SLAVE
tSU:DAT E = SLAVE PULLS SMBDATA LINE LOW F = ACKNOWLEDGE BIT CLOCKED INTO MASTER G = MSB OF DATA CLOCKED INTO SLAVE H = LSB OF DATA CLOCKED INTO SLAVE I = MASTER PULLS DATA LINE LOW J = ACKNOWLEDGE CLOCKED INTO SLAVE K = ACKNOWLEDGE CLOCK PULSE L = STOP CONDITION M = NEW START CONDITION
tSU:STO
tBUF
Figure 3. SMBus Write Timing Diagram
A
tLOW
B
tHIGH
C
D
E
F
G
H
I
J
K
L
M
SMBCLK
SMBDATA tSU:STA tHD:STA tSU:DAT tHD:DAT F = ACKNOWLEDGE BIT CLOCKED INTO MASTER G = MSB OF DATA CLOCKED INTO MASTER H = LSB OF DATA CLOCKED INTO MASTER I = MASTER PULLS DATA LINE LOW
tSU:STO tBUF J = ACKNOWLEDGE CLOCKED INTO SLAVE K = ACKNOWLEDGE CLOCK PULSE L = STOP CONDITION M = NEW START CONDITION
A = START CONDITION B = MSB OF ADDRESS CLOCKED INTO SLAVE C = LSB OF ADDRESS CLOCKED INTO SLAVE D = R/W BIT CLOCKED INTO SLAVE E = SLAVE PULLS SMBDATA LINE LOW
Figure 4. SMBus Read Timing Diagram
Table 2. Main Temperature Register (High Byte) Data Format
TEMP (C) >127 127 126 25 0.00 <0.00 Diode fault (open) Diode fault (short) DIGITAL OUTPUT 0111 1111 0111 1111 0111 1110 00011001 0000 0000 0000 0000 1111 1111 1111 1111 or 1110 1110
Table 3. Extended Resolution Temperature Register (Low Byte) Data Format
TEMP (C) 0 +0.125 +0.250 +0.375 +0.500 +0.625 +0.725 +0.875 DIGITAL OUTPUT 000X XXXX 001X XXXX 010X XXXX 011X XXXX 100X XXXX 101X XXXX 110X XXXX 111X XXXX
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7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor MAX6698
ALERT Interrupt Mode
An ALERT interrupt occurs when the internal or external temperature reading exceeds a high-temperature limit (user programmable). The ALERT interrupt output signal can be cleared by reading the status register(s) associated with the fault(s) or by successfully responding to an alert response address transmission by the master. In both cases, the alert is cleared but is reasserted at the end of the next conversion if the fault condition still exists. The interrupt does not halt automatic conversions. The ALERT output is open drain so that multiple devices can share a common interrupt line. All ALERT interrupts can be masked using the configuration 3 register. The POR state of these registers is shown in Table 4. 4 LSB hysteresis for thermistor channels 1, 2, and 3. An overtemperature output can be used to activate a cooling fan, send a warning, initiate clock throttling, or trigger a system shutdown to prevent component damage. See Table 4 for the POR state of the overtemperature threshold registers.
Command Byte Functions
The 8-bit command byte register (Table 4) is the master index that points to the various other registers within the MAX6698. This register's POR state is 0000 0000.
Configuration Bytes Functions
There are three read-write configuration registers (Tables 5, 6, 7) that can be used to control the MAX6698's operation. Configuration 1 Register The configuration 1 register (Table 5) has several functions. Bit 7(MSB) is used to put the MAX6698 either in software standby mode (STOP) or continuous conversion mode. Bit 6 resets all registers to their power-on reset conditions and then clears itself. Bit 5 disables the SMBus timeout. Bit 4 enables more frequent conversions on channel 1, as described in the ADC Conversion Sequence section. Bit 3 enables resistance cancellation on channel 1. See the Series Resistance Cancellation section for more details. The remaining bits of the configuration 1 register are not used. The POR state of this register is 0000 0000 (00h). Configuration 2 Register The configuration 2 register functions are described in Table 6. Bits [6:0] are used to mask the ALERT interrupt output. Bit 6 masks the local alert interrupt, bits 5 through 3 mask the remote-diode ALERT interrupts, and bits 2 through 0 mask the thermistor alert interrupts. The power-up state of this register is 0000 0000 (00h). Configuration 3 Register Table 7 describes the configuration 3 register. Bits 5, 4, 3, and 0 mask the OVERT interrupt output for thermistor channels 1, 2, and 3 and remote-diode channel 1. The remaining bits, 7, 6, 2, and 1, are reserved. The powerup state of this register is 0000 0000 (00h).
ALERT Response Address
The SMBus alert response interrupt pointer provides quick fault identification for simple slave devices that lack the complex logic needed to be a bus master. Upon receiving an interrupt signal, the host master can broadcast a receive byte transmission to the alert response slave address (see the Slave Addresses section). Then, any slave device that generated an interrupt attempts to identify itself by putting its own address on the bus. The alert response can activate several different slave devices simultaneously, similar to the I2C General Call. If more than one slave attempts to respond, bus arbitration rules apply, and the device with the lower address code wins. The losing device does not generate an acknowledgment and continues to hold the ALERT line low until cleared. (The conditions for clearing an alert vary depending on the type of slave device.) Successful completion of the alert response protocol clears the output latch. If the condition that caused the alert still exists, the MAX6698 reasserts the ALERT interrupt at the end of the next conversion.
OVERT Overtemperature Alarms
The MAX6698 has four overtemperature registers that store remote alarm threshold data for the OVERT output. OVERT is asserted when a channel's measured temperature (voltage in the case of the thermistor channels) is greater than the value stored in the corresponding threshold register. OVERT remains asserted until the temperature drops below the programmed threshold minus 4C hysteresis for remote-diode channel 1, or
10
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7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor
Table 4. Command Byte Register Bit Assignment
REGISTER Local Remote 1 Remote 2 Remote 3 Thermistor 1 Thermistor 2 Thermistor 3 Configuration 1 Configuration 2 Configuration 3 Status 1 Status 2 Status 3 Local ALERT High Limit Remote 1 ALERT High Limit Remote 2 ALERT High Limit Remote 3 ALERT High Limit Thermistor 1 ALERT High Limit Thermistor 2 ALERT High Limit Thermistor 3 ALERT High Limit Remote 1 OVERT High Limit Thermistor 1 OVERT High Limit Thermistor 2 OVERT High Limit Thermistor 3 OVERT High Limit Remote 1 Extended Temperature Manufacturer ID Device ID and Revision ADDRESS (HEX) 07 01 02 03 04 05 06 41 42 43 44 45 46 17 11 12 13 14 15 16 21 24 25 26 09 0A 0E POR STATE (HEX) 00 00 00 00 00 00 00 00 00 00 00 00 00 5A 6E 7F 64 64 64 64 6E 7F 5A 5A 00 4D 00 READ/ WRITE R R R R R R R R/W R/W R/W R R R R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R/W R R -- DESCRIPTION Read local temperature register Read channel 1 remote temperature register Read channel 2 remote temperature register Read channel 3 remote temperature register Read thermistor 1 voltage register Read thermistor 2 voltage register Read thermistor 3 voltage register Read/write configuration register 1 Read/write configuration register 2 Read/write configuration register 3 Read status register 1 Read status register 2 Read status register 3 Read/write local alert high-temperature threshold limit register Read/write channel 1 remote-diode alert high-temperature threshold limit register Read/write channel 2 remote-diode alert high-temperature threshold limit register Read/write channel 3 remote-diode alert high-temperature threshold limit register Read/write thermistor 1 voltage alert high-threshold limit register Read/write thermistor 2 alert high-threshold limit register Read/write thermistor 3 alert high-threshold limit register Read/write channel 1 remote-diode overtemperature threshold limit register Read/ write thermistor 1 overtemperature threshold limit register Read/write thermistor 2 overtemperature threshold limit register Read/write thermistor3 overtemperature threshold limit register Read channel 1 remote-diode extended temperature register Read manufacturer ID --
MAX6698
11
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7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor MAX6698
Table 5. Configuration 1 Register
BIT 7(MSB) 6 5 4 3 2 1 0 NAME STOP POR TIMEOUT Fast remote 1 Resistance cancellation Reserved Reserved Reserved POR STATE 0 0 0 0 0 0 0 0 FUNCTION Standby Mode Control Bit. If STOP is set to logic 1, the MAX6698 stops converting and enters standby mode. Reset Bit. Set to logic 1 to put the device into its power-on state. This bit is selfclearing. Timeout Enable Bit. Set to logic 0 to enable SMBus timeout. Channel 1 Fast Conversion Bit. Set to logic 1 to enable fast conversion of channel 1. Resistance Cancellation Bit. When set to logic 1, the MAX6698 cancels series resistance in the channel 1 thermal diode. -- -- --
Table 6. Configuration 2 Register
BIT 7(MSB) 6 5 4 3 2 1 0 NAME Reserved Mask Local ALERT Mask Thermistor 3ALERT Mask Thermistor 2ALERT Mask Thermistor 1ALERT Mask Remote-Diode 3ALERT Mask Remote-Diode 2ALERT Mask Remote-Diode 2ALERT POR STATE 0 0 0 0 0 0 0 0 -- Local Alert Mask. Set to logic 1 to mask local channel ALERT. Thermistor 3 Alert Mask. Set to logic 1 to mask thermistor 3 ALERT. Thermistor 2 Alert Mask. Set to logic 1 to mask thermistor 2 ALERT. Thermistor 1 Alert Mask. Set to logic 1 to mask thermistor 1 ALERT. Remote-Diode 3 Alert Interrupt Mask. Set to logic 1 to mask remote diode 3 ALERT. Remote-Diode 2 Alert Interrupt Mask. Set to logic 1 to mask remote diode 2 ALERT. Remote-Diode 1 Alert Interrupt Mask. Set to logic 1 to mask remote diode 1 ALERT. FUNCTION
Status Registers Functions
Status registers 1, 2, and 3 (Tables 8, 9, 10) indicate which (if any) temperature thresholds have been exceeded and if there is an open-circuit or short-circuit fault detected with the external sense junctions. Status register 1 indicates if the measured temperature has exceeded the threshold limit set in the ALERT registers for the local or remote-sensing diodes. Status register 2 indicates if the measured temperature has exceeded the threshold limit set in the OVERT registers. Status register 3 indicates if there is a diode fault (open or short) in any of the remote-sensing channels.
Bits in the alert status register clear by a successful read, but set again after the next conversion unless the fault is corrected, either by a drop in the measured temperature or an increase in the threshold temperature. The ALERT interrupt output follows the status flag bit. Once the ALERT output is asserted, it can be deasserted by either reading status register 1 or by successfully responding to an alert response address. In both cases, the alert is cleared even if the fault condition exists, but the ALERT output reasserts at the end of the next conversion. Reading the status 2 register does not clear the OVERT interrupt output. To eliminate the fault condition,
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7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor
Table 7. Configuration 3 Register
BIT 7(MSB) 6 5 4 3 2 1 0 NAME Reserved Reserved Mask Thermistor 3 OVERT Mask Thermistor 2 OVERT Mask Thermistor 1 OVERT Reserved Reserved Mask OVERT 1 POR STATE 0 0 0 0 0 0 0 0 -- -- Thermistor 3 OVERT Mask Bit. Set to logic 1 to mask thermistor 3 OVERT. Thermistor 2 OVERT Mask Bit. Set to logic 1 to mask thermistor 2 OVERT. Thermistor 1 OVERT Mask Bit. Set to logic 1 to mask thermistor 1 OVERT. -- -- Channel 1 Remote-Diode OVERT Mask Bit. Set to logic 1 to mask channel 1 OVERT. FUNCTION
MAX6698
either the measured value must drop below the threshold minus the hysteresis value (4C or 4 LSBs), or the trip threshold must be set at least 4C (or 4 LSBs) above the current value.
different ideality factor n1. The measured temperature TM can be corrected using: n1 TM = TACTUAL nNOMINAL where temperature is measured in Kelvin and nNOMIMAL for the MAX6698 is 1.008. As an example, assume you want to use the MAX6698 with a CPU that has an ideality factor of 1.002. If the diode has no series resistance, the measured data is related to the real temperature as follows:
n 1.008 TACTUAL = TM x NOMINAL = TM x = T (1.00599) 1.002 M n1
Applications Information
Remote-Diode Selection
The MAX6698 directly measures the die temperature of CPUs and other ICs that have on-chip temperaturesensing diodes (see the Typical Application Circuit) or it can measure the temperature of a discrete diodeconnected transistor.
Effect of Ideality Factor
The accuracy of the remote temperature measurements depends on the ideality factor (n) of the remote "diode" (actually a transistor). The MAX6698 is optimized for n = 1.008. A thermal diode on the substrate of an IC is normally a pnp with the base and emitter brought out the collector (diode connection) grounded. DXP_ must be connected to the anode (emitter) and DXN_ must be connected to the cathode (base) of this pnp. If a sense transistor with an ideality factor other than 1.008 is used, the output data is different from the data obtained with the optimum ideality factor. Fortunately, the difference is predictable. Assume a remote-diode sensor designed for a nominal ideality factor nNOMINAL is used to measure the temperature of a diode with a
For a real temperature of +85C (358.15K), the measured temperature is +82.87C (356.02K), an error of -2.13C.
Series Resistance Cancellation
Some thermal diodes on high-power ICs can have excessive series resistance, which can cause temperature measurement errors with conventional remote temperature sensors. Channel 1 of the MAX6698 has a series resistance cancellation feature (enabled by bit 3 of the configuration 1 register) that eliminates the effect of diode series resistance. Set bit 3 to 1 if the series resistance is large enough to affect the accuracy of
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7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor MAX6698
Table 8. Status 1 Register
BIT 7(MSB) 6 5 4 3 NAME Reserved Local ALERT Thermistor 3 ALERT Thermistor 2 ALERT Thermistor 1 ALERT Remote-Diode 3 ALERT POR STATE 0 0 0 0 0 -- Local Channel High-Alert Bit. This bit is set to logic 1 when the local temperature exceeds the temperature threshold limit in the local ALERT high-limit register. Thermistor 3 Alert Bit. This bit is set to logic 1 when the thermistor 3 voltage exceeds the threshold limit in the thermistor 3 ALERT high-limit register. Thermistor 2 Alert Bit. This bit is set to logic 1 when the thermistor 2 voltage exceeds the threshold limit in the thermistor 2 ALERT high-limit register. Thermistor 1 Alert Bit. This bit is set to logic 1 when the thermistor 1 voltage exceeds the threshold limit in the thermistor 1 ALERT high-limit register. Channel 3 Remote-Diode High-Alert Bit. This bit is set to logic 1 when the channel 3 remote-diode temperature exceeds the programmed temperature threshold limit in the remote 3 ALERT high-limit register. Channel 2 Remote-Diode High-Alert Bit. This bit is set to logic 1 when the channel 2 remote-diode temperature exceeds the temperature threshold limit in the remote 2 ALERT high-limit register. Channel 1 Remote-Diode High-Alert Bit. This bit is set to logic 1 when the channel 1 remote-diode temperature exceeds the temperature threshold limit in the remote 1 ALERT high-limit register. FUNCTION
2
0
1
Remote-Diode 2 ALERT
0
0
Remote-Diode 1 ALERT
0
channel 1. The series resistance cancellation function increases the conversion time for channel 1 by 125ms. This feature cancels the bulk resistance of the sensor and any other resistance in series (wire, contact resistance, etc.). The cancellation range is from 0 to 100.
tions in remote temperature readings of less than 2C with a variety of discrete transistors. Still, it is good design practice to verify good consistency of temperature readings with several discrete transistors from any manufacturer under consideration.
Discrete Remote Diodes
When the remote-sensing diode is a discrete transistor, its collector and base must be connected together. Table 11 lists examples of discrete transistors that are appropriate for use with the MAX6698. The transistor must be a small-signal type with a relatively high forward voltage; otherwise, the A/D input voltage range can be violated. The forward voltage at the highest expected temperature must be greater than 0.25V at 10A, and at the lowest expected temperature, the forward voltage must be less than 0.95V at 100A. Large power transistors must not be used. Also, ensure that the base resistance is less than 10. Tight specifications for forward current gain (50 < <150, for example) indicate that the manufacturer has good process controls and that the devices have consistent VBE characteristics. Manufacturers of discrete transistors do not normally specify or guarantee ideality factor. This is normally not a problem since good-quality discrete transistors tend to have ideality factors that fall within a relatively narrow range. We have observed varia14
Unused Diode Channels
If one or more of the remote diode channels is not needed, the DXP and DXN inputs for that channel should either be unconnected, or the DXP input should be connected to VCC. The status register indicates a diode "fault" for this channel and the channel is ignored during the temperature-measurement sequence. It is also good practice to mask any unused channels immediately upon power-up by setting the appropriate bits in the Configuration 2 and Configuration 3 registers. This will prevent unused channels from causing ALERT# or OVERT# to assert.
Thermistor Measurements
The MAX6698 can use three external thermistors to measure temperature. A thermistor's resistance varies as a function of temperature. A negative temperature coefficient (NTC) thermistor can be connected between the thermistor input and ground, with a series resistor, REXT_, connected from the thermistor input to VREF.
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7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor
Table 9. Status 2 Register
BIT 7(MSB) 6 5 NAME Reserved Reserved Thermistor 3 OVERT POR STATE 0 0 0 -- -- Thermistor 3 Overtemperature Status Bit. This bit is set to logic 1 when the thermistor 3 voltage exceeds the threshold limit in the thermistor 3 OVERT high-limit register. Thermistor 2 Overtemperature Status Bit. This bit is set to logic 1 when the thermistor 2 voltage exceeds the threshold limit in the thermistor 2 OVERT high-limit register. Thermistor 1 Overtemperature Status Bit. This bit is set to logic 1 when the thermistor 1 voltage exceeds the threshold limit in the thermistor 1 OVERT high-limit register. -- -- Channel 1 Remote-Diode Overtemperature Status Bit. This bit is set to logic 1 when the channel 1 remote-diode temperature exceeds the temperature threshold limit in the remote 1 OVERT high-limit register. FUNCTION
MAX6698
4
Thermistor 2 OVERT
0
3 2 1 0
Thermistor 1 OVERT Reserved Reserved Remote 1 OVERT
0 0 0 0
Table 10. Status 3 Register
BIT 7(MSB) 6 5 4 3 2 1 0 NAME Reserved Reserved Reserved Reserved Diode fault 3 Diode fault 2 Diode fault 1 Reserved POR STATE 0 0 0 0 0 0 0 0 -- -- -- -- Channel 3 Remote-Diode Fault Bit. This bit is set to 1 when DXP3 and DXN3 are open circuit or when DXP3 is connected to VCC. Channel 2 Remote-Diode Fault Bit. This bit is set to 1 when DXP2 and DXN2 are open circuit or when DXP2 is connected to VCC. Channel 1 Remote-Diode Fault Bit. This bit is set to 1 when DXP1 and DXN1 are open circuit or when DXP1 is connected to VCC. -- FUNCTION
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7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor MAX6698
Table 11. Remote-Sensors Transistor Manufacturers
MANUFACTURER Central Semiconductor (USA) Rohm Semiconductor (USA) Samsung (Korea) Siemens (Germany) Zetex (England) MODEL NO. CMPT3904 SST3904 KST3904-TF SMBT3904 FMMT3904CT-ND
Note: Discrete transistors must be diode connected (base shorted to collector).
Slave Addresses
Table 12 lists the MAX6698 slave addresses.
Table 12. Slave Address
PART MAX6698EE34 MAX6698EE38 MAX6698EE99 MAX6698EE9C MAX6698UE34 MAX6698UE38 MAX6698UE99 MAX6698UE9C SMBus SLAVE ID 0011 010 0011 100 1001 100 1001 110 0011 010 0011 100 1001 100 1001 110 PIN-PACKAGE 16 QSOP 16 QSOP 16 QSOP 16 QSOP 16 TSSOP 16 TSSOP 16 TSSOP 16 TSSOP
with all IC temperature sensors, thermal conductivity between the die and the ambient air is poor by comparison, making air temperature measurements impractical. Because the thermal mass of the PCB is far greater than that of the MAX6698, the device follows temperature changes on the PCB with little or no perceivable delay. When measuring the temperature of a CPU or other IC with an on-chip sense junction, thermal mass has virtually no effect; the measured temperature of the junction tracks the actual temperature within a conversion cycle. When measuring temperature with discrete remote transistors, the best thermal response times are obtained with transistors in small packages (i.e., SOT23 or SC70). Take care to account for thermal gradients between the heat source and the sensor, and ensure that stray air currents across the sensor package do not interfere with measurement accuracy. Self-heating does not significantly affect measurement accuracy. Remote-sensor self-heating due to the diode current source is negligible.
ADC Noise Filtering
The integrating ADC has good noise rejection for lowfrequency signals such as power-supply hum. In environments with significant high-frequency EMI, connect an external 2200pF capacitor between DXP_ and DXN_. Larger capacitor values can be used for added filtering, but do not exceed 3300pF because it can introduce errors due to the rise time of the switched current source. High-frequency noise reduction is needed for high-accuracy remote measurements. Noise can be reduced with careful PCB layout as discussed in the PCB Layout section.
VREF supplies a reference voltage (1V nominal) to bias the thermistor/REXT_ voltage-divider. The voltage across REXT is measured by the MAX6698's ADC, resulting in a voltage that is directly proportional to temperature. The data in the thermistor registers gives the voltage across REXT as a fraction of the reference voltage (1LSB = 0.5% of VREF). Because thermistors have nonlinear temperature-resistance functions, and because different thermistors have different functions, it is important to understand the relationship between temperature, REXT, and the voltage across REXT for a given thermistor. Table 13 shows temperature vs. the thermistor channel data for a Betatherm 10k3A1 thermistor and REXT=1600.
PCB Layout
Follow these guidelines to reduce the measurement error when measuring remote temperature: 1) Place the MAX6698 as close as is practical to the remote diode. In noisy environments, such as a computer motherboard, this distance can be 4in to 8in (typ). This length can be increased if the worst noise sources are avoided. Noise sources include CRTs, clock generators, memory buses, and PCI buses. 2) Do not route the DXP-DXN lines next to the deflection coils of a CRT. Also, do not route the traces across fast digital signals, which can easily introduce +30C error, even with good filtering.
Thermal Mass and Self-Heating
When sensing local temperature, the MAX6698 measures the temperature of the printed-circuit board (PCB) to which it is soldered. The leads provide a good thermal path between the PCB traces and the die. As
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7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor
3) Route the DXP and DXN traces in parallel and in close proximity to each other. Each parallel pair of traces should go to a remote diode. Route these traces away from any higher voltage traces, such as +12VDC. Leakage currents from PCB contamination must be dealt with carefully since a 20M leakage path from DXP to ground causes about +1C error. If high-voltage traces are unavoidable, connect guard traces to GND on either side of the DXP-DXN traces (Figure 5). 4) Route through as few vias and crossunders as possible to minimize copper/solder thermocouple effects. 5) Use wide traces when practical. 6) When the power supply is noisy, add a resistor (up to 47) in series with VCC.
MAX6698
GND 10 mils 10 mils DXP MINIMUM 10 mils DXN 10 mils GND
Figure 5. Recommended DXP-DXN PCB Traces
Twisted-Pair and Shielded Cables
Use a twisted-pair cable to connect the remote sensor for remote-sensor distances longer than 8in or in very noisy environments. Twisted-pair cable lengths can be between 6ft and 12ft before noise introduces excessive errors. For longer distances, the best solution is a shielded twisted pair like that used for audio microphones. For example, Belden #8451 works well for dis-
tances up to 100ft in a noisy environment. At the device, connect the twisted pair to DXP and DXN and the shield to GND. Leave the shield unconnected at the remote sensor. For very long cable runs, the cable's parasitic capacitance often provides noise filtering, so the 2200pF capacitor can often be removed or reduced in value. Cable resistance also affects remote-sensor accuracy. For every 1 of series resistance the error is approximately +1/2C.
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7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor MAX6698
Table 13. Temperature vs. Thermistor Channel Data for a Betatherm 103A1 Thermistor and REXT = 1600
T (OC) -20 -19 -18 -17 -16 -15 -14 -13 -12 -11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 RTHERM 96974 91525 86415 81621 77121 72895 68927 65198 61693 58397 55298 52380 49633 47047 44610 42314.6 40149.5 38108.5 36182.8 34366.1 32650.8 31030.4 29500.1 28054.2 26687.6 25395.5 24172.7 23016 21921.7 20885.2 19903.5 18973.6 18092.6 17257.4 16465.1 15714 15001.2 14324.6 13682.6 VREXT 0.016231 0.017181 0.018179 0.019226 0.020325 0.021478 0.022686 0.023953 0.025279 0.026668 0.02812 0.029641 0.03123 0.03289 0.034625 0.036434 0.038324 0.040294 0.042347 0.044486 0.046714 0.049034 0.051447 0.053955 0.056562 0.059269 0.062081 0.064998 0.068022 0.071158 0.074406 0.07777 0.081249 0.084847 0.088569 0.092411 0.096379 0.100473 0.104694 CODE (DECIMAL) 3 3 4 4 4 4 5 5 5 5 6 6 6 7 7 7 8 8 8 9 9 10 10 11 11 12 12 13 14 14 15 16 16 17 18 18 19 20 21 BINARY CODE 11000000 11000000 10000000 10000000 10000000 10000000 10100000 10100000 10100000 10100000 11000000 11000000 11000000 11100000 11100000 11100000 10000000 10000000 10000000 10010000 10010000 10100000 10100000 10110000 10110000 11000000 11000000 11010000 11100000 11100000 11110000 10000000 10000000 10001000 10010000 10010000 10011000 10100000 10101000 HEX CODE 3 3 4 4 4 4 5 5 5 5 6 6 6 7 7 7 8 8 8 9 9 A A B B C C D E E F 10 10 11 12 12 13 14 15
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7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor
Table 13. Temperature vs. Thermistor Channel Data for a Betatherm 103A1 Thermistor and REXT = 1600 (continued)
T (OC) 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 RTHERM 13072.8 12493.7 11943.3 11420 10922.7 10449.9 10000 9572 9164.7 8777 8407.7 8056 7720.9 7401.7 7097.2 6807 6530.1 6266.1 6014.2 5773.7 5544.1 5324.9 5115.6 4915.5 4724.3 4541.6 4366.9 4199.9 4040.1 3887.2 3741.1 3601 3466.9 3338.6 3215.6 3097.9 2985.1 2876.9 2773.2 VREXT 0.109045 0.113526 0.11814 0.122888 0.127768 0.132781 0.137931 0.143215 0.148634 0.154187 0.159877 0.1657 0.171657 0.177744 0.183967 0.190318 0.1968 0.203404 0.210134 0.216987 0.223961 0.23105 0.238251 0.245568 0.252992 0.260518 0.268146 0.275867 0.283683 0.291588 0.299564 0.307633 0.315775 0.323978 0.332254 0.340578 0.348956 0.35739 0.365865 CODE (DECIMAL) 22 23 24 25 26 27 28 29 30 31 32 33 34 36 37 38 39 41 42 43 45 46 48 49 51 52 54 55 57 58 60 62 63 65 66 68 70 71 73 BINARY CODE 10110000 10111000 11000000 11001000 11010000 11011000 11100000 11101000 11110000 11111000 10000000 10000100 10001000 10010000 10010100 10011000 10011100 10100100 10101000 10101100 10110100 10111000 11000000 11000100 11001100 11010000 11011000 11011100 11100100 11101000 11110000 11111000 11111100 10000010 10000100 10001000 10001100 10001110 10010010 HEX CODE 16 17 18 19 1A 1B 1C 1D 1E 1F 20 21 22 24 25 26 27 29 2A 2B 2D 2E 30 31 33 34 36 37 39 3A 3C 3E 3F 41 42 44 46 47 49
MAX6698
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7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor MAX6698
Table 13. Temperature vs. Thermistor Channel Data for a Betatherm 103A1 Thermistor and REXT = 1600 (continued)
T (OC) 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 RTHERM 2673.9 2578.5 2487.1 2399.4 2315.2 2234.7 2156.7 2082.3 2010.8 1942.1 1876 1812.6 1751.6 1693 1636.63 1582.41 1530.28 1480.12 1431.87 1385.37 1340.68 1297.64 1256.17 1216.23 1177.75 1140.71 1104.99 1070.58 1037.4 1005.4 974.56 944.81 916.11 888.41 861.7 VREXT 0.374365 0.382913 0.391476 0.40006 0.408664 0.417243 0.425906 0.434511 0.443115 0.451709 0.460299 0.468851 0.477384 0.485879 0.494341 0.502764 0.511136 0.51946 0.527727 0.535947 0.544092 0.552173 0.560191 0.568135 0.576006 0.58379 0.591499 0.599121 0.606658 0.614109 0.621465 0.628731 0.635902 0.642981 0.649957 CODE (DECIMAL) 75 77 78 80 82 83 85 87 89 90 92 94 95 97 99 101 102 104 106 107 109 110 112 114 115 117 118 120 121 123 124 126 127 129 130 BINARY CODE 10010110 10011010 10011100 10100000 10100100 10100110 10101010 10101110 10110010 10110100 10111000 10111100 10111110 11000010 11000010 11001010 11001100 11010000 11010100 11010110 11011010 11011100 11100000 11100100 11100110 11101010 11101100 11110000 11110010 11110110 11111000 11111100 11111110 10000001 10000010 HEX CODE 4B 4D 4E 50 52 53 55 57 59 5A 5C 5E 5F 61 63 65 66 68 6A 6B 6D 6E 70 72 73 75 76 78 79 7B 7C 7E 7F 81 82
20
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7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor
Table 13. Temperature vs. Thermistor Channel Data for a Betatherm 103A1 Thermistor and REXT = 1600 (continued)
T (OC) 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 RTHERM 835.93 811.03 786.99 763.79 741.38 719.74 698.82 678.63 659.1 640.23 622 604.36 587.31 570.82 554.86 539.44 524.51 510.06 496.08 482.55 469.45 456.76 444.48 432.58 421.06 409.9 399.08 388.59 378.44 368.59 359.05 349.79 340.82 332 323.5 VREXT 0.656833 0.663617 0.6703 0.676879 0.683358 0.689732 0.696009 0.702176 0.708247 0.714212 0.720072 0.725834 0.731492 0.737049 0.742508 0.747859 0.753115 0.758272 0.76333 0.768289 0.773152 0.777923 0.782595 0.787177 0.791664 0.79606 0.800368 0.80459 0.808718 0.812764 0.816722 0.820601 0.824394 0.828157 0.831817 CODE (DECIMAL) 131 133 134 135 137 138 139 140 142 143 144 145 146 147 149 150 151 152 153 154 155 156 157 157 158 159 160 161 162 163 163 164 165 166 166 BINARY CODE 10000011 10000101 10000110 10000111 10001001 10001010 10001011 10001100 10001110 10001111 10010000 10010001 10010010 10010011 10010101 10010110 10010111 10011000 10011001 10011010 10011011 10011100 10011101 10011101 10011110 10011111 10100000 10100001 10100010 10100011 10100011 10100100 10100101 10100110 10100110 HEX CODE 83 85 86 87 89 8A 8B 8C 8E 8F 90 91 92 93 95 96 97 98 99 9A 9B 9C 9D 9D 9E 9F A0 A1 A2 A3 A3 A4 A5 A6 A6
MAX6698
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7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor MAX6698
Pin Configuration
PROCESS: BiCMOS
TOP VIEW
DXP1 1 DXN1 2 DXP2 3 DXN2 4 DXP3 5 DXN3 6 THER3 7 VREF 8
Chip Information
16 GND 15 SMBCLK 14 SMBDATA
MAX6698
13 ALERT 12 VCC 11 OVERT 10 THER1 9 THER2
QSOP
22
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7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.)
QSOP.EPS
MAX6698
PACKAGE OUTLINE, QSOP .150", .025" LEAD PITCH
21-0055
F
1 1
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7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor MAX6698
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.)
TSSOP4.40mm.EPS
PACKAGE OUTLINE, TSSOP 4.40mm BODY
21-0066
I
1 1
Revision History
Pages changed at Rev 2: 1, 2, 24 Pages changed at Rev 3: 1, 5, 8, 9, 10, 14-17, 24
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
24 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2007 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.

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