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 (SMBus™) 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 -40°C to +125°C and is available in 16-pin
QSOP and 16-pin TSSOP packages.
Applications
Desktop Computers Workstations
Notebook Computers Servers
Features
♦ 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 Fail-
Safe 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
7-Channel Precision Remote-Diode, Thermistor,
and Local Temperature Monitor
________________________________________________________________ Maxim Integrated Products 1
Ordering Information
16
+3.3V
15
14
13
12
11
10
9
1
2
3
4
5
6
R
EX3
R
THER3
7
8
GND
SMBCLK
SMBDATA
DXN2
DXP2
DXN1
DXP1
V
CC
THER1
THER2VREF
THER3
DXN3
DXP3
MAX6698
ALERT
OVERT
R
EX2
R
THER2
R
EX1
R
THER1
Typical Application Circuit
19-3476; Rev 3; 8/07
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.
EVALUATION KIT
AVAILABLE
PART TEMP RANGE
PINPACKAGE
PKG
CODE
MAX6698EE_ _
-40°C to +125°C
16 QSOP
E16-1
MAX6698UE_ _
-40°C to +125°C
16 TSSOP
U16-1
SMBus is a trademark of Intel Corp.
Pin Configuration appears at end of data sheet.
*See the Slave Address section.
MAX6698
7-Channel Precision Remote-Diode, Thermistor,
and Local Temperature Monitor
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
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.
VCC, SCL, SDA, ALERT, OVERT to GND ................-0.3V to +6V
DXP_ to GND..............................................-0.3V to (V
CC
+ 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 (T
A
= +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
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
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Supply Voltage V
CC
3.0 5.5 V
Standby Supply Current I
SS
SMBus static 30 µA
Operating Current I
CC
During conversion
µA
Channel 1 only 11
Temperature Resolution
Other diode channels 8
Bits
TA = T
RJ
= 0°C to +125°C
Remote Temperature Accuracy VCC = 3.3V
DXN_ grounded,
T
RJ
= TA = 0°C to +85°C
o
C
TA = +60°C to +100°C
Local Temperature Accuracy VCC = 3.3V
T
A
= 0°C to +125°C
o
C
Supply Sensitivity of Temperature
Accuracy
o
C/V
Resistance cancellation on 95
Remote Channel 1 Conversion
Time
t
CONV1
Resistance cancellation off
ms
Remote Channels 2 Through 6
Conversion Time
t
CONV_
95
ms
High level 80
Remote-Diode Source Current I
RJ
Low level 8 10 12
µA
Undervoltage-Lockout Threshold
UVLO Falling edge of V
CC
disables ADC 2.3
V
Undervoltage-Lockout Hysteresis
90 mV
Power-On Reset (POR) Threshold
VCC falling edge 1.2 2.0 2.5 V
POR Threshold Hysteresis 90 mV
THERMISTOR CONVERSION
Voltage-Measurement Accuracy
-1 +1
%Full
scale
Conversion Time 31 ms
Thermistor Reference Voltage V
REF
1V
500 1000
TA = T
= +60°C to +100°C -1.0 +1.0
RJ
-3.0 +3.0
-2.5 +2.5
-3.5 +3.5
±0.2
125 156
190 250 312
125 156
100 120
2.80 2.95
±2.5
MAX6698
7-Channel Precision Remote-Diode, Thermistor,
and Local Temperature Monitor
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(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
CONDITIONS
MIN
TYP
MAX
UNITS
Reference-Load Regulation 0mA < I
REF
< 2mA 0.4 %
Reference-Supply Rejection 0.5 %/V
ALERT, OVERT
I
SINK
= 1mA 0.3
Output Low Voltage V
OL
I
SINK
= 6mA 0.5
V
Output Leakage Current 1µA
SMBus INTERFACE (SCL, SDA)
Logic-Input Low Voltage V
IL
0.8 V
VCC = 3.0V 2.2 V
Logic-Input High Voltage V
IH
VCC = 5.0V 2.4 V
Input Leakage Current -1 +1 µA
Output Low Voltage V
OL
I
SINK
= 6mA 0.3 V
Input Capacitance C
IN
5pF
SMBus-COMPATIBLE TIMING (Figures 3 and 4) (Note 2)
Serial Clock Frequency f
SCL
(Note 3)
kHz
f
SCL
= 100kHz 4.7
Bus Free Time Between STOP
and START Condition
t
BUF
f
SCL
= 400kHz 1.6
µs
f
SCL
= 100kHz 4.7
START Condition Setup Time
f
SCL
= 400kHz 0.6
µs
0.6
Repeat START Condition Setup
Time
t
SU:STA
0.6
µs
START Condition Hold Time t
HD:STA
10% of SDA to 90% of SCL 0.6 µs
4
STOP Condition Setup Time t
SU:STO
0.6
µs
10% to 10%, f
SCL
= 100kHz 1.3
Clock Low Period t
LOW
10% to 10%, f
SCL
= 400kHz 1.3
µs
Clock High Period t
HIGH
90% to 90% 0.6 µs
f
SCL
= 100kHz
Data Hold Time t
HD:DAT
f
SCL
= 400kHz (Note 4)
ns
f
SCL
= 100kHz
Data Setup Time t
SU:DAT
f
SCL
= 400kHz
ns
f
SCL
= 100kHz 1
Receive SCL/SDA Rise Time t
R
f
SCL
= 400kHz 0.3
µs
Receive SCL/SDA Fall Time t
F
ns
Pulse Width of Spike Suppressed
t
SP
050ns
SMBus Timeout
SDA low period for interface reset 25 37 45 ms
Note 1: All parameters are tested at TA= +25°C. Specifications over temperature are guaranteed by design.
Note 2: Timing specifications are guaranteed by design.
Note 3: The serial interface resets when SCL is low for more than t
TIMEOUT
.
Note 4: A transition must internally provide at least a hold time to bridge the undefined region (300ns max) of SCL’s falling edge.
t
TIMEOUT
90% of SCL to 90% of SDA, f
90% of SCL to 90% of SDA, f
90% of SCL to 90% of SDA, f
90% of SCL to 90% of SDA, f
= 100kHz
SCL
= 400kHz
SCL
= 100kHz
SCL
= 400kHz
SCL
300
250
100
400
900
300
MAX6698
7-Channel Precision Remote-Diode, Thermistor,
and Local Temperature Monitor
4 _______________________________________________________________________________________
Typical Operating Characteristics
(VCC= 3.3V, TA= +25°C, unless otherwise noted.)
STANDBY SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX6698 toc01
SUPPLY VOLTAGE (V)
STANDBY SUPPLY CURRENT (µA)
5.34.84.3
3.8
1
2
3
4
5
6
7
8
9
10
11
12
0
3.3
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX6698 toc02
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (µA)
5.34.8
3.8 4.3
325
330
335
340
350
345
355
360
320
3.3
-4
-2
-3
0
-1
2
1
3
05025 75 100 125
REMOTE TEMPERATURE ERROR
vs. REMOTE-DIODE TEMPERATURE
MAX6698 toc03
REMOTE-DIODE TEMPERATURE (°C)
TEMPERATURE ERROR (°C)
-4
-3
-2
-1
0
1
2
3
4
0 25 50 75 100 125
LOCAL TEMPERATURE ERROR
vs. DIE TEMPERATURE
MAX6698 toc04
DIE TEMPERATURE (°C)
TEMPERATURE ERROR (°C)
REMOTE-DIODE TEMPERATURE ERROR
vs. POWER-SUPPLY NOISE FREQUENCY
MAX6698 toc05
FREQUENCY (MHz)
TEMPERATURE ERROR (°C)
-4
-3
-2
-1
0
1
2
3
4
5
-5
0.1 1
100mV
P-P
LOCAL TEMPERATURE ERROR
vs. POWER-SUPPLY NOISE FREQUENCY
MAX6698 toc06
FREQUENCY (MHz)
TEMPERATURE ERROR (°C)
0.10.01
-4
-3
-2
-1
0
1
2
3
4
5
-5
0.001 1
100mV
P-P
REMOTE TEMPERATURE ERROR
vs. COMMON-MODE NOISE FREQUENCY
MAX6698 toc07
FREQUENCY (MHz)
TEMPERATURE ERROR (°C)
10.10.01
-4
-3
-2
-1
0
1
2
3
4
5
-5
0.001 10
100mV
P-P
REMOTE TEMPERATURE ERROR
vs. COMMON-MODE NOISE FREQUENCY
MAX6698 toc08
FREQUENCY (MHz)
TEMPERATURE ERROR (°C)
10.10.01
-4
-3
-2
-1
0
1
2
3
4
5
-5
0.001 10
100mV
P-P
MAX6698
_______________________________________________________________________________________ 5
TEMPERATURE ERROR
vs. DXP-DXN CAPACITANCE
MAX6698 toc09
DXP-DXN CAPACITANCE (nF)
TEMPERATURE ERROR (°C)
10
-4.5
-4.0
-3.5
-3.0
-2.5
-2.0
-1.5
-1.0
-0.5
0
-5.0
1 100
MAX6698
7-Channel Precision Remote-Diode, Thermistor,
and Local Temperature Monitor
Typical Operating Characteristics (continued)
(VCC= 3.3V, TA= +25°C, unless otherwise noted.)
0
10
5
20
15
25
30
05025 75 100 125
ALERT, OVERT SINK CURRENT
vs. TEMPERATURE
MAX6698 toc10
TEMPERATURE (°C)
ALERT SINK CURRENT (mA)
VOL = 0.3V
VOL = 0.1V
THERMISTOR ADC ERROR
vs. POWER-SUPPLY NOISE FREQUENCY
MAX6698 toc11
FREQUENCY (MHz)
TEMPERATURE ERROR (°C)
1010.1
-4
-3
-2
-1
0
1
2
3
4
5
-5
0.01 100
100mV
P-P
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 V
CC
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 R
EXT3
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.
MAX6698
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, R
EXT
, 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-
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
6 _______________________________________________________________________________________
Pin Description (continued)
PIN NAME FUNCTION
9 THER2
Thermistor Voltage Sense Input 2. Connect thermistor 2 between THER2 and ground and an external
resistor R
EXT3
between THER2 and VREF.
10 THER1
Thermistor Voltage Sense Input 1. Connect thermistor 1 between THER1 and ground and an external
resistor R
EXT3
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 V
CC
Supply Voltage Input. Bypass to GND with a 0.1µF capacitor.
13 ALERT
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.
14
SMBus Serial-Data Input/Output. Connect to a pullup resistor.
15 SMBCLK SMBus Serial-Clock Input. Connect to a pullup resistor.
16 GND Ground
SMBDATA
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
MAX6698
_______________________________________________________________________________________ 7
DXP1
DXN1
3-TO-1
MUX
INPUT
BUFFER
ADC
10/100µA
V
CC
CNT
COUNTER
VREF
COMMAND BYTE
REMOTE TEMPERATURES
LOCAL TEMPERATURES
REGISTER BANK
ALERT THRESHOLD
OVERT THRESHOLD
ALERT RESPONSE ADDRESS
ALU
DP
VREF1
SMBus
INTERFACE
MAX6698
SCL SDA
OVERT
ALERT
DXP3
DXN3
BUF1
BUF2
3-TO-1
MUX
R
EXT1
R
THER1
R
EXT2
R
THER1
R
EXT1
R
THER1
Figure 1. Internal Block Diagram
7-Channel Precision Remote-Diode, Thermistor,
and Local Temperature Monitor
MAX6698
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.
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
8 _______________________________________________________________________________________
Figure 2. SMBus Protocols
Write Byte Format
Read Byte Format
Send Byte Format
Receive Byte Format
Slave Address: equivalent to chip-select line of
a 3-wire interface
Command Byte: selects which
register you are writing to
Data Byte: data goes into the register
set by the command byte (to set
thresholds, configuration masks, and
sampling rate)
Slave Address: equivalent to chip-select line
Command Byte: selects
which register you are
reading from
Slave Address: repeated
due to change in dataflow direction
Data Byte: reads from
the register set by the
command byte
Command Byte: sends command with no data, usually
used for one-shot command
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
S = Start condition Shaded = Slave transmission
P = Stop condition /// = Not acknowledged
S ADDRESS RD ACK DATA /// P
7 bits 8 bits
WRS ACK COMMAND ACK P
8 bits
ADDRESS
7 bits
P
1
ACKDATA
8 bits
ACKCOMMAND
8 bits
ACKWRADDRESS
7 bits
S
S ADDRESS WR ACK COMMAND ACK S ADDRESS
7 bits8 bits7 bits
RD ACK DATA
8 bits
/// P
Table 1. Thermistor Voltage Data Format
V
REXT
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
DIGITAL OUTPUT
MAX6698
_______________________________________________________________________________________ 9
7-Channel Precision Remote-Diode, Thermistor,
and Local Temperature Monitor
SMBCLK
A = START CONDITION
B = MSB OF ADDRESS CLOCKED INTO SLAVE
C = LSB OF ADDRESS CLOCKED INTO SLAVE
D = R/W BIT CLOCKED INTO SLAVE
AB CDEFG
HIJ
SMBDATA
t
SU:STAtHD:STA
t
LOW
t
HIGH
t
SU:DAT
t
SU:STOtBUF
LMK
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
Figure 3. SMBus Write Timing Diagram
SMBCLK
AB CDEFG HIJ
K
SMBDATA
t
SU:STA
t
HD:STA
t
LOWtHIGH
t
SU:DAT
t
HD:DAT
t
SU:STO
t
BUF
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
L
M
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
J = ACKNOWLEDGE CLOCKED INTO SLAVE
K = ACKNOWLEDGE CLOCK PULSE
L = STOP CONDITION
M = NEW START CONDITION
Figure 4. SMBus Read Timing Diagram
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 2. Main Temperature Register (High
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
Table 3. Extended Resolution
Temperature Register (Low Byte) Data
Format
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.
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 out-
put. 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
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
10 ______________________________________________________________________________________
MAX6698
______________________________________________________________________________________ 11
7-Channel Precision Remote-Diode, Thermistor,
and Local Temperature Monitor
REGISTER
ADDRESS
(HEX)
POR STATE
(HEX)
DESCRIPTION
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 Read/write configuration register 3
Status 1 44 00 R Read status register 1
Status 2 45 00 R Read status register 2
Status 3 46 00 R Read status register 3
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
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 — —
Table 4. Command Byte Register Bit Assignment
READ/
WRITE
Read/write thermistor3 overtemperature threshold limit register
MAX6698
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,
7-Channel Precision Remote-Diode, Thermistor,
and Local Temperature Monitor
12 ______________________________________________________________________________________
BIT NAME
POR
STATE
FUNCTION
7(MSB) STOP 0
Standby Mode Control Bit. If STOP is set to logic 1, the MAX6698 stops
converting and enters standby mode.
6POR0
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.
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 5. Configuration 1 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
0 Thermistor 3 Alert Mask. Set to logic 1 to mask thermistor 3 ALERT.
4
0 Thermistor 2 Alert Mask. Set to logic 1 to mask thermistor 2 ALERT.
3
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.
Table 6. Configuration 2 Register
Mask Thermistor 3ALERT
Mask Thermistor 2ALERT
Mask Thermistor 1ALERT
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 n
NOMINAL
is used to measure the temperature of a diode with a
different ideality factor n1. The measured temperature
T
M
can be corrected using:
where temperature is measured in Kelvin and
n
NOMIMAL
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:
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
TT
n
n
TT
ACTUAL M
NOMINAL
MM
=×
⎛
⎝
⎜
⎞
⎠
⎟
=×
⎛
⎝
⎜
⎞
⎠
⎟
=
1
1 008
1 002
1 00599
.
.
(. )
TT
n
n
M ACTUAL
NOMINAL
=
⎛
⎝
⎜
⎞
⎠
⎟
1
MAX6698
______________________________________________________________________________________ 13
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 Mask OVERT 10
Channel 1 Remote-Diode OVERT Mask Bit. Set to logic 1 to mask channel 1
OVERT.
Table 7. Configuration 3 Register
MAX6698
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.
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 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 VBEcharacteristics. 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-
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.
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.
7-Channel Precision Remote-Diode, Thermistor,
and Local Temperature Monitor
14 ______________________________________________________________________________________
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
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
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
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.
Table 8. Status 1 Register
Thermistor 3 ALERT
Thermistor 2 ALERT
Thermistor 1 ALERT
MAX6698
7-Channel Precision Remote-Diode, Thermistor,
and Local Temperature Monitor
______________________________________________________________________________________ 15
BIT NAME
POR
STATE
FUNCTION
7(MSB) Reserved 0 —
6 Reserved 0 —
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.
Table 9. Status 2 Register
BIT NAME
POR
STATE
FUNCTION
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 V
CC
.
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 V
CC
.
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 V
CC
.
0 Reserved 0 —
Table 10. Status 3 Register
MAX6698
7-Channel Precision Remote-Diode, Thermistor,
and Local Temperature Monitor
16 ______________________________________________________________________________________
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
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.
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 deflec-
tion 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.
MANUFACTURER MODEL NO.
Central Semiconductor (USA) CMPT3904
Rohm Semiconductor (USA) SST3904
Samsung (Korea) KST3904-TF
Siemens (Germany) SMBT3904
Zetex (England) FMMT3904CT-ND
Table 11. Remote-Sensors Transistor
Manufacturers
Note: Discrete transistors must be diode connected (base
shorted to collector).
PART
PIN-PACKAGE
MAX6698EE34 0011 010 16 QSOP
MAX6698EE38 0011 100 16 QSOP
MAX6698EE99 1001 100 16 QSOP
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
Table 12. Slave Address
Table 12 lists the MAX6698 slave addresses.
Slave Addresses
SMBus SLAVE ID
MAX6698
7-Channel Precision Remote-Diode, Thermistor,
and Local Temperature Monitor
______________________________________________________________________________________ 17
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.
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-
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.
10 mils
10 mils
10 mils
MINIMUM
10 mils
GND
DXP
DXN
GND
Figure 5. Recommended DXP-DXN PCB Traces
MAX6698
7-Channel Precision Remote-Diode, Thermistor,
and Local Temperature Monitor
18 ______________________________________________________________________________________
Table 13. Temperature vs. Thermistor Channel Data for a Betatherm 103A1 Thermistor
and R
EXT
= 1600Ω
T (OC) R
THERM
V
REXT
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
MAX6698
7-Channel Precision Remote-Diode, Thermistor,
and Local Temperature Monitor
______________________________________________________________________________________ 19
Table 13. Temperature vs. Thermistor Channel Data for a Betatherm 103A1 Thermistor
and R
EXT
= 1600Ω (continued)
T (OC) R
THERM
V
REXT
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
MAX6698
7-Channel Precision Remote-Diode, Thermistor,
and Local Temperature Monitor
20 ______________________________________________________________________________________
Table 13. Temperature vs. Thermistor Channel Data for a Betatherm 103A1 Thermistor
and R
EXT
= 1600Ω (continued)
T (OC) R
THERM
V
REXT
CODE
(DECIMAL)
BINARY CODE HEX 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
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
MAX6698
7-Channel Precision Remote-Diode, Thermistor,
and Local Temperature Monitor
______________________________________________________________________________________ 21
Table 13. Temperature vs. Thermistor Channel Data for a Betatherm 103A1 Thermistor
and R
EXT
= 1600Ω (continued)
T (OC) R
THERM
V
REXT
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
MAX6698
7-Channel Precision Remote-Diode, Thermistor,
and Local Temperature Monitor
22 ______________________________________________________________________________________
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
DXP1
GND
SMBCLK
SMBDATA
ALERT
V
CC
OVERT
THER1
THER2
TOP VIEW
MAX6698
QSOP
DXN1
DXP2
DXN3
DXN2
DXP3
THER3
VREF
Pin Configuration
Chip Information
PROCESS: BiCMOS
MAX6698
7-Channel Precision Remote-Diode, Thermistor,
and Local Temperature Monitor
______________________________________________________________________________________ 23
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
F
1
1
21-0055
PACKAGE OUTLINE, QSOP .150", .025" LEAD PITCH
MAX6698
7-Channel Precision Remote-Diode, Thermistor,
and Local Temperature Monitor
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.
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
1
1
I
Revision History
Pages changed at Rev 2: 1, 2, 24
Pages changed at Rev 3: 1, 5, 8, 9, 10, 14–17, 24
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