MAX6698UE38+ ,7-Channel Precision Remote-Diode, Thermistor, and Local Temperature MonitorELECTRICAL CHARACTERISTICS(V = +3.0V to +5.5V, T = -40°C to +125°C, unless otherwise noted. Typical ..
MAX6698UE99+ ,7-Channel Precision Remote-Diode, Thermistor, and Local Temperature MonitorFeaturesThe MAX6698 precision multichannel temperature sen-♦ Three Thermal-Diode Inputs and Three T ..
MAX6699EE99+ ,5-Channel Precision Temperature MonitorApplications CODEPACKAGEDesktop Computers MAX6699EE_ _ -40°C to +125°C 16 QSOP E16-1MAX6699UE_ _ -4 ..
MAX6699EE99+T ,5-Channel Precision Temperature MonitorELECTRICAL CHARACTERISTICS(V = +3.0V to +5.5V, T = -40°C to +125°C, unless otherwise noted. Typical ..
MAX6699UE34+ ,5-Channel Precision Temperature MonitorFeaturesThe MAX6699 precision multichannel temperature sen-♦ Four Thermal-Diode Inputssor monitors ..
MAX669EUB ,1.8V to 28V Input / PWM Step-Up Controllers in MAXELECTRICAL CHARACTERISTICS (continued)(V = LDO = +5V, R = 200kΩ, T = 0°C to +85°C, unless otherwise ..
MB3771PS ,Power Supply MonitorFUJITSU SEMICONDUCTORDS04-27400-7EDATA SHEETASSP For power supply
MB3771PS ,Power Supply MonitorFUJITSU SEMICONDUCTORDS04-27400-7EDATA SHEETASSP For power supply
MB3773 ,Power Supply Monitor with Watch-Dog TimerFUJITSU SEMICONDUCTORDS04-27401-4EDATA SHEETASSPPower Supply Monitor with Watch-Dog TimerMB3773n DE ..
MB3775 ,SWITCHING REGULATOR CONTROLLERFUJITSU SEMICONDUCTORDS04-27204-3EDATA SHEETASSPSWITCHING REGULATOR CONTROLLERMB3775LOW VOLTAGE DUA ..
MB3775PF , SWITCHING REGULATOR CONTROLLER
MB3776 ,Switching Regulator ControllerFEATURES• Wide supply voltage range: (2 V to 15 V)• Wide oscillation frequency range, high-frequenc ..
MAX6698EE38+-MAX6698UE38+-MAX6698UE99+
7-Channel Precision Remote-Diode, Thermistor, and Local Temperature Monitor
General DescriptionThe MAX6698 precision multichannel temperature sen-
sor 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 over-
temperature thresholds. When the measured tempera-
ture of a channel exceeds the respective threshold, a
status bit is set in one of the status registers. Two open-
drain outputs, OVERTand ALERT, assert correspond-
ing 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 tem-
perature 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.
ApplicationsDesktop Computers Workstations
Notebook ComputersServers
FeaturesThree Thermal-Diode Inputs and Three Thermistor
InputsLocal Temperature Sensor1°C Remote Temperature Accuracy (+60°C to
+100°C)Temperature Monitoring Begins at POR for Fail-
Safe System ProtectionALERT
and OVERTOutputs for Interrupts,
Throttling, and ShutdownSmall 16-Pin QSOP and 16-Pin TSSOP Packages2-Wire SMBus Interface
MAX6698
7-Channel Precision Remote-Diode, Thermistor
and Local Temperature Monitor
Ordering Information+3.3V
REX3
RTHER3
GND
SMBCLK
SMBDATA
DXN2
DXP2
DXN1
DXP1
VCC
THER1
THER2VREF
THER3
DXN3
DXP3
MAX6698
ALERT
OVERT
REX2
RTHER2
REX1
RTHER1
Typical Application Circuit19-3476; Rev 3; 8/07
EVALUATION KIT
AVAILABLE
PARTTEMP RANGEPIN-
PACKAGE
PKG
CODEMAX6698EE_ _-40°C to +125°C16 QSOPE16-1
MAX6698UE_ _-40°C to +125°C16 TSSOPU16-1
SMBus is a trademark of Intel Corp.
Pin Configuration appears at end of data sheet.*See the Slave Addresssection.
MAX6698
7-Channel Precision Remote-Diode, Thermistor,
and Local Temperature Monitor
ABSOLUTE MAXIMUM RATINGSStresses 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, OVERTto 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, OVERTCurrent.............................-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
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)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSSupply VoltageVCC3.05.5V
Standby Supply CurrentISSSMBus static30µA
Operating CurrentICCDuring conversion5001000µA
Channel 1 only11Temperature ResolutionOther diode channels8Bits
TA = TRJ = +60°C to +100°C-1.0+1.0
TA = TRJ = 0°C to +125°C-3.0+3.0Remote Temperature AccuracyVCC = 3.3V
DXN_ grounded,
TRJ = TA = 0°C to +85°C±2.5C
TA = +60°C to +100°C-2.5+2.5Local Temperature AccuracyVCC = 3.3VTA = 0°C to +125°C-3.5+3.5C
Supply Sensitivity of Temperature
Accuracy±0.2oC/V
Resistance cancellation on95125156Remote Channel 1 Conversion
TimetCONV1Resistance cancellation off190250312ms
Remote Channels 2 Through 6
Conversion TimetCONV_95125156ms
High level80100120Remote-Diode Source CurrentIRJLow level81012µA
Undervoltage-Lockout ThresholdUVLOFalling edge of VCC disables ADC2.32.802.95V
Undervoltage-Lockout Hysteresis90mV
Power-On Reset (POR) ThresholdVCC falling edge1.22.02.5V
POR Threshold Hysteresis90mV
THERMISTOR CONVERSIONVoltage-Measurement Accuracy-1+1%Full
scale
Conversion Time31ms
Thermistor Reference VoltageVREF1V
MAX6698
7-Channel Precision Remote-Diode, Thermistor
and Local Temperature Monitor
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)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSReference-Load Regulation0mA < IREF < 2mA0.4%
Reference-Supply Rejection0.5%/V
ALERT, OVERT
ISINK = 1mA0.3Output Low VoltageVOLISINK = 6mA0.5V
Output Leakage Current1µA
SMBus INTERFACE (SCL, SDA)Logic-Input Low VoltageVIL0.8V
VCC = 3.0V2.2VLogic-Input High VoltageVIHVCC = 5.0V2.4V
Input Leakage Current-1+1µA
Output Low VoltageVOLISINK = 6mA0.3V
Input CapacitanceCIN5pF
SMBus-COMPATIBLE TIMING (Figures 3 and 4) (Note 2)Serial Clock FrequencyfSCL(Note 3)400kHz
fSCL = 100kHz4.7Bus Free Time Between STOP
and START ConditiontBUFfSCL = 400kHz1.6µs
fSCL = 100kHz4.7START Condition Setup TimefSCL = 400kHz0.6µs
90% of SCL to 90% of SDA, fSCL = 100kHz0.6Repeat START Condition Setup
TimetSU:STA90% of SCL to 90% of SDA, fSCL = 400kHz0.6µs
START Condition Hold TimetHD:STA10% of SDA to 90% of SCL0.6µs
90% of SCL to 90% of SDA, fSCL = 100kHz4STOP Condition Setup TimetSU:STO90% of SCL to 90% of SDA, fSCL = 400kHz0.6µs
10% to 10%, fSCL = 100kHz1.3Clock Low PeriodtLOW10% to 10%, fSCL = 400kHz1.3µs
Clock High PeriodtHIGH90% to 90%0.6µs
fSCL = 100kHz300Data Hold TimetHD:DATfSCL = 400kHz (Note 4)900ns
fSCL = 100kHz250Data Setup TimetSU:DATfSCL = 400kHz100ns
fSCL = 100kHz1Receive SCL/SDA Rise TimetRfSCL = 400kHz0.3µs
Receive SCL/SDA Fall TimetF300ns
Pulse Width of Spike SuppressedtSP050ns
SMBus TimeouttTIMEOUTSDA low period for interface reset253745ms
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 tTIMEOUT.
Note 4:A transition must internally provide at least a hold time to bridge the undefined region (300ns max) of SCL’s falling edge.
MAX6698
7-Channel Precision Remote-Diode, Thermistor,
and Local Temperature Monitor
Typical Operating Characteristics(VCC= 3.3V, TA= +25°C, unless otherwise noted.)
STANDBY SUPPLY CURRENT
vs. SUPPLY VOLTAGEMAX6698 toc01
SUPPLY VOLTAGE (V)
STANDBY SUPPLY CURRENT (
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX6698 toc02
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (
REMOTE TEMPERATURE ERROR
vs. REMOTE-DIODE TEMPERATURE
MAX6698 toc03
REMOTE-DIODE TEMPERATURE (°C)
TEMPERATURE ERROR (255075100125
LOCAL TEMPERATURE ERROR
vs. DIE TEMPERATUREMAX6698 toc04
DIE TEMPERATURE (°C)
TEMPERATURE ERROR (
REMOTE-DIODE TEMPERATURE ERROR
vs. POWER-SUPPLY NOISE FREQUENCYMAX6698 toc05
FREQUENCY (MHz)
TEMPERATURE ERROR (
100mVP-P
LOCAL TEMPERATURE ERROR
vs. POWER-SUPPLY NOISE FREQUENCYMAX6698 toc06
FREQUENCY (MHz)
TEMPERATURE ERROR (
100mVP-P
REMOTE TEMPERATURE ERROR
vs. COMMON-MODE NOISE FREQUENCYMAX6698 toc07
FREQUENCY (MHz)
TEMPERATURE ERROR (0.10.01
100mVP-P
REMOTE TEMPERATURE ERROR
vs. COMMON-MODE NOISE FREQUENCYMAX6698 toc08
FREQUENCY (MHz)
TEMPERATURE ERROR (0.10.01
100mVP-P
MAX6698
TEMPERATURE ERROR
vs. DXP-DXN CAPACITANCEMAX6698 toc09
DXP-DXN CAPACITANCE (nF)
TEMPERATURE ERROR (
°C)
MAX6698
7-Channel Precision Remote-Diode, Thermistor
and Local Temperature Monitorypical Operating Characteristics (continued)
(VCC= 3.3V, TA= +25°C, unless otherwise noted.)
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 FREQUENCYMAX6698 toc11
FREQUENCY (MHz)
TEMPERATURE ERROR (10.1
100mVP-P
Pin Description
PINNAMEFUNCTIONDXP1
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.DXN1Cathode Input for Channel 1 Remote Diode. Connect the cathode of the channel 1 remote-diode-
connected transistor to DXN1.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.DXN2Cathode Input for Channel 2 Remote Diode. Connect the cathode of the channel 2 remote-diode-
connected transistor to DXN2.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.DXN3Cathode Input for Channel 3 Remote Diode. Connect the cathode of the channel 1 remote-diode-
connected transistor to DXN3.THER3Thermistor Voltage Sense Input 3. Connect thermistor 3 between THER3 and ground and an external
resistor REXT3 between THER3 and VREF.VREFThermistor Reference Voltage (1V Nominal). VREF is automatically enabled for a thermistor
conversion, and is disabled for diode measurements.
MAX6698
Detailed DescriptionThe MAX6698 is a precision multichannel temperature
monitor that features one local, three remote thermal
diode temperature-sensing channels, and three ther-
mistor voltage-sensing channels. All channels have a
programmable alert threshold for each temperature
channel and a programmable overtemperature thresh-
old for channels 1, 4, 5, and 6 (see Figure1).
Communication with the MAX6698 is achieved through
the SMBus serial interface and a dedicated alert
(ALERT)pin. The alarm outputs, OVERTand ALERT,
assert if the software-programmed temperature thresh-
olds are exceeded. ALERTtypically serves as an inter-
rupt, while OVERTcan be connected to a fan, system
shutdown, or other thermal-management circuitry.
Note that thermistor “temperature data” is really the volt-
age 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 SequenceIn 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, ther-
mistor 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 moni-
tored 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, remote-
diode 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 consider-
ably greater in this mode than in the default mode.
Low-Power Standby ModeStandby 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 com-
mands. The timeout is enabled if a start condition is rec-
ognized 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 conver-
sion 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
Pin Description (continued)
PINNAMEFUNCTIONTHER2Thermistor Voltage Sense Input 2. Connect thermistor 2 between THER2 and ground and an external
resistor REXT3 between THER2 and VREF.THER1Thermistor Voltage Sense Input 1. Connect thermistor 1 between THER1 and ground and an external
resistor REXT3 between THER1 and VREF.OVERTOvertemperature Active-Low, Open-Drain Output. OVERT asserts low when the temperature of
channels 1, 4, 5, and 6 exceed the programmed threshold limit.VCCSupply Voltage Input. Bypass to GND with a 0.1µF capacitor.ALERTSMBus Alert (Interrupt), Active-Low, Open-Drain Output. ALERT asserts low when the temperature of
channels 1, 4, 5, and 6 exceed programmed threshold limit.SMBDATASMBus Serial-Data Input/Output. Connect to a pullup resistor.SMBCLKSMBus Serial-Clock Input. Connect to a pullup resistor.GNDGround
SMBus Digital InterfaceFrom a software perspective, the MAX6698 appears as
a series of 8-bit registers that contain temperature mea-
surement 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
(Figure2). 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 Figure4 is the
SMBus read timing diagram.
The remote diode 1 measurement channel provides 11
bits of data (1 LSB = 0.125°C). All other temperature-
measurement 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 tem-
perature, and thermistor registers. The remaining 3 bits
MAX6698DXP1
DXN1
3-TO-1
MUXINPUT
BUFFER
ADC
10/100µA
VCC
CNT
COUNTER
VREFCOMMAND BYTE
REMOTE TEMPERATURES
LOCAL TEMPERATURES
REGISTER BANK
ALERT THRESHOLD
OVERT THRESHOLD
ALERT RESPONSE ADDRESS
ALU
VREF1
SMBus
INTERFACE
MAX6698
SCLSDA
OVERT
ALERTDXP3
DXN3
BUF1
BUF23-TO-1
MUX
REXT1
RTHER1
REXT2
RTHER1
REXT1
RTHER1
Figure1. Internal Block Diagram
7-Channel Precision Remote-Diode, Thermistor
and Local Temperature Monitor
MAX6698for remote diode 1 can be read from the extended tem-
perature 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 updat-
ing continues. Table 1 shows themistor voltage data for-
mat. Table 2 shows the main temperature register (high
byte) data format. Table 3 shows the extended resolu-
tion temperature register (low byte) data format.
Diode Fault DetectionIf 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 OVERTto 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 causeALERTor OVERTto assert, so if a channel will not be
used, disconnect its DXP and DXN inputs.
Alarm Threshold RegistersThere are 11 alarm threshold registers that store over-
temperature ALERTand OVERTthreshold values.
Seven of these registers are dedicated to store one
local alert temperature threshold limit, three remote alert
temperature threshold limits, and three thermistor volt-
age threshold limits (see the ALERTInterrupt Modesec-
tion). 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 OVERTOvertemperature Alarmsection).
Access to these registers is provided through the
SMBusinterface.
7-Channel Precision Remote-Diode, Thermistor,
and Local Temperature MonitorFigure2. SMBus Protocols
Write Byte Format
Read Byte Format
Send Byte FormatReceive Byte FormatSlave Address: equiva-
lent 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: equiva-
lent to chip-select line
Command Byte: selects
which register you are
reading from
Slave Address: repeated
due to change in data-
flow direction
Data Byte: reads from
the register set by the
command byte
Command Byte: sends com-
mand 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 addressS = Start conditionShaded = Slave transmission
P = Stop condition/// = Not acknowledged
ADDRESSRDACKDATA///P7 bits8 bits
SACKCOMMANDACKP8 bits
ADDRESS7 bits
ACKDATA8 bits
ACKCOMMAND8 bits
ACKWRADDRESS7 bits
ADDRESSWRACKCOMMANDACKSADDRESS7 bits8 bits7 bits
ACKDATA8 bits
///P
VREXTDIGITAL OUTPUT1.0001100 1000
0.5000110 0100
0.2500011 0010
0.0550000 1011
0.0500000 1010
0.0050000 0001
0.0000000 0000
Table 1. Thermistor Voltage Data Format
MAX6698
7-Channel Precision Remote-Diode, Thermistor
and Local Temperature MonitorSMBCLK
A = START CONDITION
B = MSB OF ADDRESS CLOCKED INTO SLAVE
C = LSB OF ADDRESS CLOCKED INTO SLAVE
D = R/W BIT CLOCKED INTO SLAVECDEFGHIJ
SMBDATA
tSU:STAtHD:STA
tLOWtHIGH
tSU:DATtSU:STOtBUFK
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
Figure3. SMBus Write Timing Diagram
SMBCLKCDEFGHIJK
SMBDATA
tSU:STAtHD:STA
tLOWtHIGH
tSU:DATtHD:DATtSU:STOtBUF
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 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
Figure4. SMBus Read Timing Diagram
TEMP (°C)DIGITAL OUTPUT>1270111 1111
1270111 1111
1260111 111000011001
0.000000 0000
<0.000000 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 OUTPUT000X XXXX
+0.125001X XXXX
+0.250010X XXXX
+0.375011X XXXX
+0.500100X XXXX
+0.625101X XXXX
+0.725110X XXXX
+0.875111X XXXX
Table 3. Extended Resolution
Temperature Register (Low Byte) Data
Format
MAX6698
ALERTInterrupt ModeAn ALERTinterrupt occurs when the internal or external
temperature reading exceeds a high-temperature limit
(user programmable). The ALERTinterrupt output sig-
nal can be cleared by reading the status register(s)
associated with the fault(s) or by successfully respond-
ing 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 auto-
matic conversions. The ALERToutput is open drain so
that multiple devices can share a common interrupt
line. All ALERTinterrupts can be masked using the
configuration 3 register. The POR state of these regis-
ters is shown in Table4.
ALERTResponse AddressThe 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 Addressessec-
tion). Then, any slave device that generated an inter-
rupt 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 arbitra-
tion rules apply, and the device with the lower address
code wins. The losing device does not generate an
acknowledgment and continues to hold the ALERTline
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.
OVERTOvertemperature AlarmsThe MAX6698 has four overtemperature registers that
store remote alarm threshold data for the OVERTout-
put. OVERTis asserted when a channel’s measured
temperature (voltage in the case of the thermistor chan-
nels) is greater than the value stored in the correspond-
ing threshold register. OVERTremains asserted until
the temperature drops below the programmed thresh-
old 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 cool-
ing fan, send a warning, initiate clock throttling, or trig-
ger a system shutdown to prevent component damage.
See Table 4 for the POR state of the overtemperature
threshold registers.
Command Byte FunctionsThe 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 FunctionsThere are three read-write configuration registers
(Tables 5, 6, 7) that can be used to control the
MAX6698’s operation.
Configuration 1 RegisterThe configuration 1 register (Table5) has several func-
tions. Bit 7(MSB) is used to put the MAX6698 either in
software standby mode (STOP) or continuous conver-
sion 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 con-
versions on channel 1, as described in the ADC
Conversion Sequencesection. Bit 3 enables resistance
cancellation on channel 1. See the Series Resistance
Cancellationsection 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 RegisterThe configuration 2 register functions are described in
Table 6. Bits [6:0] are used to mask the ALERTinterrupt
output. Bit 6 masks the local alert interrupt, bits 5
through 3 mask the remote-diode ALERTinterrupts, and
bits 2 through 0 mask the thermistor alert interrupts. The
power-up state of this register is 0000 0000 (00h).
Configuration 3 RegisterTable7 describes the configuration 3 register. Bits 5, 4,
3, and 0 mask the OVERTinterrupt output for thermistor
channels 1, 2, and 3 and remote-diode channel 1. The
remaining bits, 7, 6, 2, and 1, are reserved. The power-
up state of this register is 0000 0000 (00h).
7-Channel Precision Remote-Diode, Thermistor,
and Local Temperature Monitor
MAX6698
7-Channel Precision Remote-Diode, Thermistor
and Local Temperature Monitor
REGISTERADDRESS
(HEX)
POR STATE
(HEX)
READ/
WRITEDESCRIPTIONLocal0700RRead local temperature register
Remote 10100RRead channel 1 remote temperature register
Remote 20200RRead channel 2 remote temperature register
Remote 30300RRead channel 3 remote temperature register
Thermistor 10400RRead thermistor 1 voltage register
Thermistor 20500RRead thermistor 2 voltage register
Thermistor 30600RRead thermistor 3 voltage register
Configuration 14100R/WRead/write configuration register 1
Configuration 24200R/WRead/write configuration register 2
Configuration 34300R/WRead/write configuration register 3
Status 14400RRead status register 1
Status 24500RRead status register 2
Status 34600RRead status register 3
Local ALERT High Limit175AR/WRead/write local alert high-temperature threshold limit register
Remote 1 ALERT High Limit116ER/WRead/write channel 1 remote-diode alert high-temperature
threshold limit register
Remote 2 ALERT High Limit127FR/WRead/write channel 2 remote-diode alert high-temperature
threshold limit register
Remote 3 ALERT High Limit1364R/WRead/write channel 3 remote-diode alert high-temperature
threshold limit register
Thermistor 1 ALERT High
Limit1464R/WRead/write thermistor 1 voltage alert high-threshold limit
register
Thermistor 2 ALERT High
Limit1564R/WRead/write thermistor 2 alert high-threshold limit register
Thermistor 3 ALERT High
Limit1664R/WRead/write thermistor 3 alert high-threshold limit register
Remote 1 OVERT High Limit216ER/WRead/write channel 1 remote-diode overtemperature threshold
limit register
Thermistor 1 OVERT High
Limit247FR/WRead/ write thermistor 1 overtemperature threshold limit
register
Thermistor 2 OVERT High
Limit255AR/WRead/write thermistor 2 overtemperature threshold limit
register
Thermistor 3 OVERT High
Limit265AR/WRead/write thermistor3 overtemperature threshold limit register
Remote 1 Extended
Temperature0900RRead channel 1 remote-diode extended temperature register
Manufacturer ID0A4DRRead manufacturer ID
Device ID and Revision0E00——
Table 4. Command Byte Register Bit Assignment
MAX6698
Status Registers FunctionsStatus 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 ALERTregisters
for the local or remote-sensing diodes. Status register 2
indicates if the measured temperature has exceeded
the threshold limit set in the OVERTregisters. 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 tem-
perature or an increase in the threshold temperature.
The ALERTinterrupt output follows the status flag bit.
Once the ALERToutput is asserted, it can be deassert-
ed 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 ALERToutput reasserts at the end of the next con-
version. Reading the status 2 register does not clear the
OVERTinterrupt output. To eliminate the fault condition,
7-Channel Precision Remote-Diode, Thermistor,
and Local Temperature Monitor
BITNAMEPOR
STATEFUNCTION7(MSB)STOP0Standby Mode Control Bit. If STOP is set to logic 1, the MAX6698 stops
converting and enters standby mode.
6POR0Reset Bit. Set to logic 1 to put the device into its power-on state. This bit is self-
clearing.TIMEOUT0Timeout Enable Bit. Set to logic 0 to enable SMBus timeout.Fast remote 10Channel 1 Fast Conversion Bit. Set to logic 1 to enable fast conversion of
channel 1.Resistance
cancellation0Resistance Cancellation Bit. When set to logic 1, the MAX6698 cancels series
resistance in the channel 1 thermal diode.Reserved0—Reserved0—Reserved0—
Table 5. Configuration 1 Register
BITNAMEPOR STATEFUNCTION7(MSB)Reserved0—Mask Local ALERT0Local Alert Mask. Set to logic 1 to mask local channel ALERT.Mask Thermistor 3ALERT0Thermistor 3 Alert Mask. Set to logic 1 to mask thermistor 3 ALERT.Mask Thermistor 2ALERT0Thermistor 2 Alert Mask. Set to logic 1 to mask thermistor 2 ALERT.Mask Thermistor 1ALERT0Thermistor 1 Alert Mask. Set to logic 1 to mask thermistor 1 ALERT.Mask Remote-Diode
3ALERT0Remote-Diode 3 Alert Interrupt Mask. Set to logic 1 to mask remote
diode 3 ALERT.Mask Remote-Diode
2ALERT0Remote-Diode 2 Alert Interrupt Mask. Set to logic 1 to mask remote
diode 2 ALERT.Mask Remote-Diode
2ALERT0Remote-Diode 1 Alert Interrupt Mask. Set to logic 1 to mask remote
diode 1 ALERT.
Table 6. Configuration 2 Register
