19-3476; Rev 3; 8/07 KIT ATION EVALU E L B AVAILA 7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor Features 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 (SMBus™) protocols: write byte, read byte, send byte, and receive byte for reading the temperature data and programming the alarm thresholds. ♦ Three Thermal-Diode Inputs and Three Thermistor Inputs ♦ Local Temperature Sensor ♦ 1°C Remote Temperature Accuracy (+60°C to +100°C) ♦ 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 Ordering Information The MAX6698 is specified for an operating temperature range of -40°C to +125°C and is available in 16-pin QSOP and 16-pin TSSOP packages. Applications Desktop Computers Workstations Notebook Computers Servers PINPACKAGE PKG CODE -40°C to +125°C 16 QSOP E16-1 -40°C to +125°C 16 TSSOP U16-1 PART TEMP RANGE MAX6698EE_ _ MAX6698UE_ _ *See the Slave Address section. Pin Configuration appears at end of data sheet. Typical Application Circuit +3.3V 1 DXP1 GND 16 2 DXN1 3 DXP2 SMBDATA 14 4 DXN2 ALERT 13 5 DXP3 VCC 12 6 DXN3 OVERT 11 7 THER3 THER1 10 8 VREF THER2 MAX6698 SMBCLK 15 9 REX3 REX2 RTHER3 RTHER2 REX1 RTHER1 SMBus is a trademark of Intel Corp. ________________________________________________________________ Maxim Integrated Products 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. 1 MAX6698 General Description MAX6698 7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor 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 = +70°C) 16-Pin QSOP (derate 8.3mW/°C above +70°C) ......................666.7mW(E16-1) 16-Pin TSSOP (derate 9.4mW/°C above +70°C)....................754.7mW(U16-1) ESD Protection (all pins, Human Body Model) ................±2000V Operating Temperature Range .........................-40°C to +125°C Junction Temperature ......................................................+150°C Storage Temperature Range .............................-60°C to +150°C Lead Temperature (soldering, 10s) .................................+300°C 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 = -40°C to +125°C, unless otherwise noted. Typical values are at VCC = +3.3V and TA = +25°C.) (Note 1) PARAMETER Supply Voltage SYMBOL CONDITIONS VCC MIN TYP 3.0 Standby Supply Current ISS SMBus static 30 Operating Current ICC During conversion 500 Channel 1 only 11 Other diode channels 8 Temperature Resolution Remote Temperature Accuracy VCC = 3.3V Local Temperature Accuracy VCC = 3.3V UNITS 5.5 V 1000 µA µA Bits TA = TRJ = +60°C to +100°C -1.0 +1.0 TA = TRJ = 0°C to +125°C -3.0 +3.0 DXN_ grounded, TRJ = TA = 0°C to +85°C TA = +60°C to +100°C -2.5 +2.5 TA = 0°C to +125°C -3.5 +3.5 o ±0.2 Remote Channel 1 Conversion Time tCONV1 Remote Channels 2 Through 6 Conversion Time tCONV_ Remote-Diode Source Current IRJ UVLO Resistance cancellation on 95 125 156 Resistance cancellation off 190 250 312 95 125 156 High level 80 100 120 Low level 8 10 12 2.3 2.80 2.95 Falling edge of VCC disables ADC Undervoltage-Lockout Hysteresis 90 Power-On Reset (POR) Threshold VCC falling edge o C o C ±2.5 Supply Sensitivity of Temperature Accuracy Undervoltage-Lockout Threshold MAX 1.2 POR Threshold Hysteresis 2.0 C/V ms ms µA V mV 2.5 90 V mV THERMISTOR CONVERSION Voltage-Measurement Accuracy -1 Conversion Time Thermistor Reference Voltage 2 VREF +1 %Full scale 31 ms 1 V _______________________________________________________________________________________ 7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor (VCC = +3.0V to +5.5V, TA = -40°C to +125°C, unless otherwise noted. Typical values are at VCC = +3.3V and TA = +25°C.) (Note 1) PARAMETER SYMBOL Reference-Load Regulation CONDITIONS MIN TYP 0mA < IREF < 2mA Reference-Supply Rejection MAX UNITS 0.4 % 0.5 %/V ALERT, OVERT Output Low Voltage VOL ISINK = 1mA 0.3 ISINK = 6mA 0.5 Output Leakage Current V 1 µA 0.8 V SMBus INTERFACE (SCL, SDA) Logic-Input Low Voltage Logic-Input High Voltage VIL VIH VCC = 3.0V 2.2 V VCC = 5.0V 2.4 V Input Leakage Current -1 Output Low Voltage VOL Input Capacitance CIN +1 ISINK = 6mA 0.3 5 µA V pF SMBus-COMPATIBLE TIMING (Figures 3 and 4) (Note 2) Serial Clock Frequency Bus Free Time Between STOP and START Condition fSCL tBUF START Condition Setup Time Repeat START Condition Setup Time tSU:STA START Condition Hold Time tHD:STA STOP Condition Setup Time tSU:STO Clock Low Period tLOW Clock High Period tHIGH Data Hold Time tHD:DAT Data Setup Time tSU:DAT Receive SCL/SDA Rise Time Receive SCL/SDA Fall Time Pulse Width of Spike Suppressed SMBus Timeout Note 1: Note 2: Note 3: Note 4: tR (Note 3) 400 fSCL = 100kHz 4.7 fSCL = 400kHz 1.6 fSCL = 100kHz 4.7 fSCL = 400kHz 0.6 90% of SCL to 90% of SDA, fSCL = 100kHz 0.6 90% of SCL to 90% of SDA, fSCL = 400kHz 0.6 10% of SDA to 90% of SCL 0.6 90% of SCL to 90% of SDA, fSCL = 100kHz 4 90% of SCL to 90% of SDA, fSCL = 400kHz 0.6 10% to 10%, fSCL = 100kHz 1.3 10% to 10%, fSCL = 400kHz 1.3 90% to 90% 0.6 fSCL = 100kHz 300 µs µs µs µs µs µs µs fSCL = 400kHz (Note 4) 900 fSCL = 100kHz 250 fSCL = 400kHz 100 1 fSCL = 400kHz 0.3 tF tTIMEOUT 300 0 SDA low period for interface reset 25 ns ns fSCL = 100kHz tSP kHz 37 µs ns 50 ns 45 ms All parameters are tested at TA = +25°C. 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 MAX6698 ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (VCC = 3.3V, TA = +25°C, unless otherwise noted.) 350 345 340 335 330 3 2 1 0 0 -1 -2 -3 325 -4 320 4.8 3.3 5.3 3.8 2 1 0 -1 -2 -3 -4 100mVP-P 3 2 1 0 -1 -2 50 75 100 1 0 -1 -2 -5 0.001 0.01 0.1 FREQUENCY (MHz) REMOTE TEMPERATURE ERROR vs. COMMON-MODE NOISE FREQUENCY MAX6698 toc07 5 4 TEMPERATURE ERROR (°C) TEMPERATURE ERROR (°C) 100mVP-P FREQUENCY (MHz) 3 2 1 0 -1 -2 -3 100mVP-P 3 2 1 0 -1 -2 -3 -4 -4 -5 0.001 -5 0.001 0.01 0.1 FREQUENCY (MHz) 1 10 125 1 -4 0.1 100mVP-P 100 2 -4 125 75 3 -3 REMOTE TEMPERATURE ERROR vs. COMMON-MODE NOISE FREQUENCY 4 4 -3 DIE TEMPERATURE (°C) 5 5 MAX6698 toc08 25 50 LOCAL TEMPERATURE ERROR vs. POWER-SUPPLY NOISE FREQUENCY -5 0 25 REMOTE-DIODE TEMPERATURE ERROR vs. POWER-SUPPLY NOISE FREQUENCY 4 TEMPERATURE ERROR (°C) 3 0 REMOTE-DIODE TEMPERATURE (°C) 5 MAX6698 toc04 4 5.3 SUPPLY VOLTAGE (V) SUPPLY VOLTAGE (V) LOCAL TEMPERATURE ERROR vs. DIE TEMPERATURE 4.8 4.3 TEMPERATURE ERROR (°C) 4.3 MAX6698 toc05 3.8 MAX6698 toc03 1 MAX6698 toc06 7 6 5 4 2 TEMPERATURE ERROR (°C) SUPPLY CURRENT (µA) 355 8 3 MAX6698 toc02 360 MAX6698 toc01 STANDBY SUPPLY CURRENT (µA) 12 11 10 9 3.3 4 REMOTE TEMPERATURE ERROR vs. REMOTE-DIODE TEMPERATURE SUPPLY CURRENT vs. SUPPLY VOLTAGE STANDBY SUPPLY CURRENT vs. SUPPLY VOLTAGE TEMPERATURE ERROR (°C) MAX6698 7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor 0.01 0.1 1 10 FREQUENCY (MHz) _______________________________________________________________________________________ 1 7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor -1.5 -2.0 -2.5 -3.0 -3.5 -4.0 VOL = 0.3V 25 20 15 VOL = 0.1V 10 MAX6698 toc11 MAX6698 toc10 -1.0 5 100mVP-P 4 TEMPERATURE ERROR (°C) TEMPERATURE ERROR (°C) -0.5 30 ALERT SINK CURRENT (mA) MAX6698 toc09 0 THERMISTOR ADC ERROR vs. POWER-SUPPLY NOISE FREQUENCY ALERT, OVERT SINK CURRENT vs. TEMPERATURE TEMPERATURE ERROR vs. DXP-DXN CAPACITANCE 3 2 1 0 -1 -2 -3 5 -4 -4.5 -5 0 -5.0 1 100 10 DXP-DXN CAPACITANCE (nF) 0 25 50 75 100 125 0.01 0.1 1 10 100 FREQUENCY (MHz) TEMPERATURE (°C) Pin Description PIN NAME FUNCTION 1 DXP1 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. 2 DXN1 Cathode Input for Channel 1 Remote Diode. Connect the cathode of the channel 1 remote-diodeconnected transistor to DXN1. 3 DXP2 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. 4 DXN2 Cathode Input for Channel 2 Remote Diode. Connect the cathode of the channel 2 remote-diodeconnected transistor to DXN2. 5 DXP3 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. 6 DXN3 Cathode Input for Channel 3 Remote Diode. Connect the cathode of the channel 1 remote-diodeconnected transistor to DXN3. 7 THER3 Thermistor Voltage Sense Input 3. Connect thermistor 3 between THER3 and ground and an external resistor REXT3 between THER3 and VREF. 8 VREF Thermistor Reference Voltage (1V Nominal). VREF is automatically enabled for a thermistor conversion, and is disabled for diode measurements. _______________________________________________________________________________________ 5 MAX6698 Typical Operating Characteristics (continued) (VCC = 3.3V, TA = +25°C, unless otherwise noted.) 7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor MAX6698 Pin Description (continued) PIN NAME FUNCTION 9 THER2 Thermistor Voltage Sense Input 2. Connect thermistor 2 between THER2 and ground and an external resistor REXT3 between THER2 and VREF. 10 THER1 Thermistor Voltage Sense Input 1. Connect thermistor 1 between THER1 and ground and an external resistor REXT3 between THER1 and VREF. 11 OVERT Overtemperature Active-Low, Open-Drain Output. OVERT asserts low when the temperature of channels 1, 4, 5, and 6 exceed the programmed threshold limit. 12 VCC 13 ALERT 14 SMBDATA 15 SMBCLK 16 GND Supply Voltage Input. Bypass to GND with a 0.1µF 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. 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 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 15µA 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. _______________________________________________________________________________________ 7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor 10/100µA DXP1 OVERT MAX6698 DXN1 3-TO-1 MUX DXP3 INPUT BUFFER ALU DP ALERT DXN3 BUF1 VREF ADC CNT COMMAND BYTE COUNTER VREF1 REGISTER BANK REMOTE TEMPERATURES LOCAL TEMPERATURES REXT1 ALERT THRESHOLD OVERT THRESHOLD RTHER1 ALERT RESPONSE ADDRESS SMBus INTERFACE REXT2 3-TO-1 MUX BUF2 RTHER1 REXT1 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 = 0.125°C). All other temperaturemeasurement channels provide 8 bits of temperature data (1 LSB = 1°C). The 8 most significant bits (MSBs) can be read from the local temperature, remote temperature, and thermistor registers. The remaining 3 bits _______________________________________________________________________________________ 7 MAX6698 VCC MAX6698 7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor Write Byte Format S ADDRESS WR ACK COMMAND 7 bits ACK DATA 8 bits Slave Address: equivalent to chip-select line of a 3-wire interface ACK P 8 bits Command Byte: selects which register you are writing to 1 Data Byte: data goes into the register set by the command byte (to set thresholds, configuration masks, and sampling rate) Read Byte Format S ADDRESS WR ACK 7 bits COMMAND ACK ACK DATA /// P 8 bits Slave Address: repeated due to change in dataflow direction Data Byte: reads from the register set by the command byte Receive Byte Format WR 7 bits ACK COMMAND ACK P 8 bits S ADDRESS 7 bits RD ACK DATA /// P 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 Command Byte: sends command with no data, usually used for one-shot command S = Start condition P = Stop condition RD 7 bits Command Byte: selects which register you are reading from Send Byte Format ADDRESS ADDRESS 8 bits Slave Address: equivalent to chip-select line S S Shaded = Slave transmission /// = Not acknowledged 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. 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 Table 1. Thermistor Voltage Data Format VREXT DIGITAL OUTPUT 1.000 1100 1000 0.500 0110 0100 0.250 0011 0010 0.055 0000 1011 0.050 0000 1010 0.005 0000 0001 0.000 0000 0000 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. _______________________________________________________________________________________ 7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor B tLOW C D E F G H tHIGH I J K L MAX6698 A M SMBCLK SMBDATA tSU:STA tHD:STA tSU:STO tSU:DAT 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 F = ACKNOWLEDGE BIT CLOCKED INTO MASTER G = MSB OF DATA CLOCKED INTO SLAVE H = LSB OF DATA CLOCKED INTO SLAVE tBUF I = MASTER PULLS DATA LINE LOW J = ACKNOWLEDGE CLOCKED INTO SLAVE K = ACKNOWLEDGE CLOCK PULSE L = STOP CONDITION M = NEW START CONDITION Figure 3. SMBus Write Timing Diagram A tLOW B C tHIGH D E F G H I J K L M SMBCLK SMBDATA tSU:STA tHD:STA tSU:DAT 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 tHD:DAT tSU:STO tBUF J = ACKNOWLEDGE CLOCKED INTO SLAVE K = ACKNOWLEDGE CLOCK PULSE L = STOP CONDITION M = NEW START CONDITION 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 Figure 4. SMBus Read Timing Diagram Table 2. Main Temperature Register (High Byte) Data Format TEMP (°C) DIGITAL OUTPUT >127 0111 1111 127 0111 1111 126 0111 1110 25 00011001 0.00 0000 0000 <0.00 0000 0000 Diode fault (open) 1111 1111 Diode fault (short) 1111 1111 or 1110 1110 Table 3. Extended Resolution Temperature Register (Low Byte) Data Format TEMP (°C) DIGITAL OUTPUT 0 000X XXXX +0.125 001X XXXX +0.250 010X XXXX +0.375 011X XXXX +0.500 100X XXXX +0.625 101X XXXX +0.725 110X XXXX +0.875 111X XXXX _______________________________________________________________________________________ 9 MAX6698 7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor 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. 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 4°C hysteresis for remote-diode channel 1, or 10 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). ______________________________________________________________________________________ 7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor MAX6698 Table 4. Command Byte Register Bit Assignment ADDRESS (HEX) POR STATE (HEX) READ/ WRITE Local 07 00 R Read local temperature register Remote 1 01 00 R Read channel 1 remote temperature register Remote 2 02 00 R Read channel 2 remote temperature register Remote 3 03 00 R Read channel 3 remote temperature register Thermistor 1 04 00 R Read thermistor 1 voltage register Thermistor 2 05 00 R Read thermistor 2 voltage register Thermistor 3 06 00 R Read thermistor 3 voltage register Configuration 1 41 00 R/W Read/write configuration register 1 Configuration 2 42 00 R/W Read/write configuration register 2 Configuration 3 43 00 R/W Status 1 44 00 R Read status register 1 Status 2 45 00 R Read status register 2 Status 3 46 00 R Local ALERT High Limit 17 5A R/W Read/write local alert high-temperature threshold limit register Remote 1 ALERT High Limit 11 6E R/W Read/write channel 1 remote-diode alert high-temperature threshold limit register Remote 2 ALERT High Limit 12 7F R/W Read/write channel 2 remote-diode alert high-temperature threshold limit register Remote 3 ALERT High Limit 13 64 R/W Read/write channel 3 remote-diode alert high-temperature threshold limit register Thermistor 1 ALERT High Limit 14 64 R/W Read/write thermistor 1 voltage alert high-threshold limit register Thermistor 2 ALERT High Limit 15 64 R/W Read/write thermistor 2 alert high-threshold limit register Thermistor 3 ALERT High Limit 16 64 R/W Read/write thermistor 3 alert high-threshold limit register Remote 1 OVERT High Limit 21 6E R/W Read/write channel 1 remote-diode overtemperature threshold limit register Thermistor 1 OVERT High Limit 24 7F R/W Read/ write thermistor 1 overtemperature threshold limit register Thermistor 2 OVERT High Limit 25 5A R/W Read/write thermistor 2 overtemperature threshold limit register Thermistor 3 OVERT High Limit 26 5A R/W Read/write thermistor3 overtemperature threshold limit register Remote 1 Extended Temperature 09 00 R Read channel 1 remote-diode extended temperature register Manufacturer ID 0A 4D R Read manufacturer ID Device ID and Revision 0E 00 — — REGISTER DESCRIPTION Read/write configuration register 3 Read status register 3 ______________________________________________________________________________________ 11 MAX6698 7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor Table 5. Configuration 1 Register BIT NAME POR STATE 7(MSB) STOP 0 Standby Mode Control Bit. If STOP is set to logic 1, the MAX6698 stops converting and enters standby mode. 6 POR 0 Reset Bit. Set to logic 1 to put the device into its power-on state. This bit is selfclearing. 5 TIMEOUT 0 Timeout Enable Bit. Set to logic 0 to enable SMBus timeout. FUNCTION 4 Fast remote 1 0 Channel 1 Fast Conversion Bit. Set to logic 1 to enable fast conversion of channel 1. 3 Resistance cancellation 0 Resistance Cancellation Bit. When set to logic 1, the MAX6698 cancels series resistance in the channel 1 thermal diode. 2 Reserved 0 — 1 Reserved 0 — 0 Reserved 0 — Table 6. Configuration 2 Register BIT NAME POR STATE FUNCTION 7(MSB) Reserved 0 — 6 Mask Local ALERT 0 Local Alert Mask. Set to logic 1 to mask local channel ALERT. 5 Mask Thermistor 3ALERT 0 Thermistor 3 Alert Mask. Set to logic 1 to mask thermistor 3 ALERT. 4 Mask Thermistor 2ALERT 0 Thermistor 2 Alert Mask. Set to logic 1 to mask thermistor 2 ALERT. 3 Mask Thermistor 1ALERT 0 Thermistor 1 Alert Mask. Set to logic 1 to mask thermistor 1 ALERT. 2 Mask Remote-Diode 3ALERT 0 Remote-Diode 3 Alert Interrupt Mask. Set to logic 1 to mask remote diode 3 ALERT. 1 Mask Remote-Diode 2ALERT 0 Remote-Diode 2 Alert Interrupt Mask. Set to logic 1 to mask remote diode 2 ALERT. 0 Mask Remote-Diode 2ALERT 0 Remote-Diode 1 Alert Interrupt Mask. Set to logic 1 to mask remote diode 1 ALERT. 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. 12 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, ______________________________________________________________________________________ 7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor BIT NAME POR STATE FUNCTION 7(MSB) Reserved 0 — 6 Reserved 0 — 5 Mask Thermistor 3 OVERT 0 Thermistor 3 OVERT Mask Bit. Set to logic 1 to mask thermistor 3 OVERT. 4 Mask Thermistor 2 OVERT 0 Thermistor 2 OVERT Mask Bit. Set to logic 1 to mask thermistor 2 OVERT. 3 Mask Thermistor 1 OVERT 0 Thermistor 1 OVERT Mask Bit. Set to logic 1 to mask thermistor 1 OVERT. 2 Reserved 0 — 1 Reserved 0 — 0 Channel 1 Remote-Diode OVERT Mask Bit. Set to logic 1 to mask channel 1 OVERT. 0 Mask OVERT 1 MAX6698 Table 7. Configuration 3 Register either the measured value must drop below the threshold minus the hysteresis value (4°C or 4 LSBs), or the trip threshold must be set at least 4°C (or 4 LSBs) above the current value. 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 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 × ⎜ NOMINAL ⎟ = TM × ⎜ ⎟ = T (1.00599) ⎝ 1.002 ⎠ M n1 ⎝ ⎠ For a real temperature of +85°C (358.15K), the measured temperature is +82.87°C (356.02K), an error of -2.13°C. 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 ______________________________________________________________________________________ 13 MAX6698 7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor Table 8. Status 1 Register BIT NAME POR STATE FUNCTION 7(MSB) Reserved 0 — 6 Local ALERT 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. 5 Thermistor 3 ALERT 0 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. 4 Thermistor 2 ALERT 0 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. 3 Thermistor 1 ALERT 0 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. 2 Remote-Diode 3 ALERT 0 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. 1 Remote-Diode 2 ALERT 0 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. 0 Remote-Diode 1 ALERT 0 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. 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 100Ω. tions in remote temperature readings of less than ±2°C 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 Unused Diode Channels 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 10µA, and at the lowest expected temperature, the forward voltage must be less than 0.95V at 100µA. Large power transistors must not be used. Also, ensure that the base resistance is less than 10Ω. Tight specifications for forward current gain (50 < ß <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 varia- 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. 14 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. ______________________________________________________________________________________ 7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor BIT NAME POR STATE 7(MSB) Reserved 0 — 6 Reserved 0 — MAX6698 Table 9. Status 2 Register FUNCTION 5 Thermistor 3 OVERT 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. 4 Thermistor 2 OVERT 0 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. 3 Thermistor 1 OVERT 0 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. 2 Reserved 0 — 1 Reserved 0 — 0 Remote 1 OVERT 0 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 Table 10. Status 3 Register BIT NAME POR STATE 7(MSB) Reserved 0 — 6 Reserved 0 — 5 Reserved 0 — 4 Reserved 0 — 3 Diode fault 3 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. 2 Diode fault 2 0 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. 1 Diode fault 1 0 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. 0 Reserved 0 — ______________________________________________________________________________________ 15 MAX6698 7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor Table 11. Remote-Sensors Transistor Manufacturers MANUFACTURER MODEL NO. Central Semiconductor (USA) CMPT3904 Rohm Semiconductor (USA) SST3904 Samsung (Korea) KST3904-TF Siemens (Germany) SMBT3904 Zetex (England) 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 SMBus SLAVE ID MAX6698EE34 0011 010 PIN-PACKAGE 16 QSOP MAX6698EE38 0011 100 16 QSOP MAX6698EE99 1001 100 16 QSOP ADC Noise Filtering MAX6698EE9C 1001 110 16 QSOP MAX6698UE34 0011 010 16 TSSOP MAX6698UE38 0011 100 16 TSSOP MAX6698UE99 1001 100 16 TSSOP MAX6698UE9C 1001 110 16 TSSOP 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=1600Ω. 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 16 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. 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 +30°C error, even with good filtering. ______________________________________________________________________________________ 7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor 5) Use wide traces when practical. 6) When the power supply is noisy, add a resistor (up to 47Ω) in series with VCC. 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- GND 10 mils 10 mils DXP MINIMUM 10 mils DXN 10 mils GND Figure 5. Recommended DXP-DXN PCB Traces 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 1Ω of series resistance the error is approximately +1/2°C. ______________________________________________________________________________________ 17 MAX6698 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 20MΩ leakage path from DXP to ground causes about +1°C 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. MAX6698 7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor Table 13. Temperature vs. Thermistor Channel Data for a Betatherm 103A1 Thermistor and REXT = 1600Ω 18 T (OC) RTHERM VREXT CODE (DECIMAL) BINARY CODE HEX CODE -20 96974 0.016231 3 11000000 3 -19 91525 0.017181 3 11000000 3 -18 86415 0.018179 4 10000000 4 -17 81621 0.019226 4 10000000 4 -16 77121 0.020325 4 10000000 4 -15 72895 0.021478 4 10000000 4 -14 68927 0.022686 5 10100000 5 -13 65198 0.023953 5 10100000 5 -12 61693 0.025279 5 10100000 5 -11 58397 0.026668 5 10100000 5 -10 55298 0.02812 6 11000000 6 -9 52380 0.029641 6 11000000 6 -8 49633 0.03123 6 11000000 6 -7 47047 0.03289 7 11100000 7 -6 44610 0.034625 7 11100000 7 -5 42314.6 0.036434 7 11100000 7 -4 40149.5 0.038324 8 10000000 8 -3 38108.5 0.040294 8 10000000 8 -2 36182.8 0.042347 8 10000000 8 -1 34366.1 0.044486 9 10010000 9 0 32650.8 0.046714 9 10010000 9 1 31030.4 0.049034 10 10100000 A 2 29500.1 0.051447 10 10100000 A 3 28054.2 0.053955 11 10110000 B 4 26687.6 0.056562 11 10110000 B 5 25395.5 0.059269 12 11000000 C 6 24172.7 0.062081 12 11000000 C 7 23016 0.064998 13 11010000 D 8 21921.7 0.068022 14 11100000 E 9 20885.2 0.071158 14 11100000 E 10 19903.5 0.074406 15 11110000 F 11 18973.6 0.07777 16 10000000 10 12 18092.6 0.081249 16 10000000 10 13 17257.4 0.084847 17 10001000 11 14 16465.1 0.088569 18 10010000 12 15 15714 0.092411 18 10010000 12 16 15001.2 0.096379 19 10011000 13 17 14324.6 0.100473 20 10100000 14 18 13682.6 0.104694 21 10101000 15 ______________________________________________________________________________________ 7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor T (OC) RTHERM VREXT CODE (DECIMAL) BINARY CODE HEX CODE 19 13072.8 0.109045 22 10110000 16 20 12493.7 0.113526 23 10111000 17 21 11943.3 0.11814 24 11000000 18 22 11420 0.122888 25 11001000 19 23 10922.7 0.127768 26 11010000 1A 24 10449.9 0.132781 27 11011000 1B 25 10000 0.137931 28 11100000 1C 26 9572 0.143215 29 11101000 1D 27 9164.7 0.148634 30 11110000 1E 28 8777 0.154187 31 11111000 1F 29 8407.7 0.159877 32 10000000 20 30 8056 0.1657 33 10000100 21 31 7720.9 0.171657 34 10001000 22 32 7401.7 0.177744 36 10010000 24 33 7097.2 0.183967 37 10010100 25 34 6807 0.190318 38 10011000 26 35 6530.1 0.1968 39 10011100 27 36 6266.1 0.203404 41 10100100 29 37 6014.2 0.210134 42 10101000 2A 38 5773.7 0.216987 43 10101100 2B 39 5544.1 0.223961 45 10110100 2D 40 5324.9 0.23105 46 10111000 2E 41 5115.6 0.238251 48 11000000 30 42 4915.5 0.245568 49 11000100 31 43 4724.3 0.252992 51 11001100 33 44 4541.6 0.260518 52 11010000 34 45 4366.9 0.268146 54 11011000 36 46 4199.9 0.275867 55 11011100 37 47 4040.1 0.283683 57 11100100 39 48 3887.2 0.291588 58 11101000 3A 49 3741.1 0.299564 60 11110000 3C 50 3601 0.307633 62 11111000 3E 51 3466.9 0.315775 63 11111100 3F 52 3338.6 0.323978 65 10000010 41 53 3215.6 0.332254 66 10000100 42 54 3097.9 0.340578 68 10001000 44 55 2985.1 0.348956 70 10001100 46 56 2876.9 0.35739 71 10001110 47 57 2773.2 0.365865 73 10010010 49 ______________________________________________________________________________________ 19 MAX6698 Table 13. Temperature vs. Thermistor Channel Data for a Betatherm 103A1 Thermistor and REXT = 1600Ω (continued) MAX6698 7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor Table 13. Temperature vs. Thermistor Channel Data for a Betatherm 103A1 Thermistor and REXT = 1600Ω (continued) 20 T (OC) RTHERM VREXT CODE (DECIMAL) BINARY CODE 58 2673.9 0.374365 75 10010110 4B 59 2578.5 0.382913 77 10011010 4D 60 2487.1 0.391476 78 10011100 4E HEX CODE 61 2399.4 0.40006 80 10100000 50 62 2315.2 0.408664 82 10100100 52 63 2234.7 0.417243 83 10100110 53 64 2156.7 0.425906 85 10101010 55 65 2082.3 0.434511 87 10101110 57 66 2010.8 0.443115 89 10110010 59 67 1942.1 0.451709 90 10110100 5A 68 1876 0.460299 92 10111000 5C 69 1812.6 0.468851 94 10111100 5E 70 1751.6 0.477384 95 10111110 5F 71 1693 0.485879 97 11000010 61 72 1636.63 0.494341 99 11000010 63 73 1582.41 0.502764 101 11001010 65 74 1530.28 0.511136 102 11001100 66 75 1480.12 0.51946 104 11010000 68 76 1431.87 0.527727 106 11010100 6A 77 1385.37 0.535947 107 11010110 6B 78 1340.68 0.544092 109 11011010 6D 79 1297.64 0.552173 110 11011100 6E 80 1256.17 0.560191 112 11100000 70 81 1216.23 0.568135 114 11100100 72 82 1177.75 0.576006 115 11100110 73 83 1140.71 0.58379 117 11101010 75 84 1104.99 0.591499 118 11101100 76 85 1070.58 0.599121 120 11110000 78 86 1037.4 0.606658 121 11110010 79 87 1005.4 0.614109 123 11110110 7B 88 974.56 0.621465 124 11111000 7C 89 944.81 0.628731 126 11111100 7E 90 916.11 0.635902 127 11111110 7F 91 888.41 0.642981 129 10000001 81 92 861.7 0.649957 130 10000010 82 ______________________________________________________________________________________ 7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor T (OC) RTHERM VREXT CODE (DECIMAL) BINARY CODE HEX CODE 93 835.93 0.656833 131 10000011 83 94 811.03 0.663617 133 10000101 85 95 786.99 0.6703 134 10000110 86 96 763.79 0.676879 135 10000111 87 97 741.38 0.683358 137 10001001 89 98 719.74 0.689732 138 10001010 8A 99 698.82 0.696009 139 10001011 8B 100 678.63 0.702176 140 10001100 8C 101 659.1 0.708247 142 10001110 8E 102 640.23 0.714212 143 10001111 8F 103 622 0.720072 144 10010000 90 104 604.36 0.725834 145 10010001 91 105 587.31 0.731492 146 10010010 92 106 570.82 0.737049 147 10010011 93 107 554.86 0.742508 149 10010101 95 108 539.44 0.747859 150 10010110 96 109 524.51 0.753115 151 10010111 97 110 510.06 0.758272 152 10011000 98 111 496.08 0.76333 153 10011001 99 112 482.55 0.768289 154 10011010 9A 113 469.45 0.773152 155 10011011 9B 114 456.76 0.777923 156 10011100 9C 115 444.48 0.782595 157 10011101 9D 116 432.58 0.787177 157 10011101 9D 117 421.06 0.791664 158 10011110 9E 118 409.9 0.79606 159 10011111 9F 119 399.08 0.800368 160 10100000 A0 120 388.59 0.80459 161 10100001 A1 121 378.44 0.808718 162 10100010 A2 122 368.59 0.812764 163 10100011 A3 123 359.05 0.816722 163 10100011 A3 124 349.79 0.820601 164 10100100 A4 125 340.82 0.824394 165 10100101 A5 126 332 0.828157 166 10100110 A6 127 323.5 0.831817 166 10100110 A6 ______________________________________________________________________________________ 21 MAX6698 Table 13. Temperature vs. Thermistor Channel Data for a Betatherm 103A1 Thermistor and REXT = 1600Ω (continued) 7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor MAX6698 Pin Configuration Chip Information PROCESS: BiCMOS TOP VIEW DXP1 1 16 GND DXN1 2 15 SMBCLK 14 SMBDATA DXP2 3 DXN2 4 MAX6698 13 ALERT DXP3 5 12 VCC DXN3 6 11 OVERT THER3 7 10 THER1 9 VREF 8 THER2 QSOP 22 ______________________________________________________________________________________ 7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor QSOP.EPS PACKAGE OUTLINE, QSOP .150", .025" LEAD PITCH 21-0055 F 1 1 ______________________________________________________________________________________ 23 MAX6698 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.) 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 MAX6698 7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor 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 © 2007 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.