Evaluation Kit
Available
Design
Resources
Tools
and Models
Support
Click here to ask an associate for production status of specific part numbers.
MAX6695/MAX6696
Dual Remote/Local Temperature Sensors with
SMBus Serial Interface
General Description
The MAX6695/MAX6696 are precise, dual-remote, and
local digital temperature sensors. They accurately measure the temperature of their own die and two remote
diode-connected transistors, and report the temperature
in digital form on a 2-wire serial interface. The remote
diode is typically the emitter-base junction of a commoncollector PNP on a CPU, FPGA, GPU, or ASIC.
The 2-wire serial interface accepts standard system
management bus (SMBus) commands such as Write
Byte, Read Byte, Send Byte, and Receive Byte to read
the temperature data and program the alarm thresholds
and conversion rate. The MAX6695/MAX6696 can function autonomously with a programmable conversion rate,
which allows control of supply current and temperature
update rate to match system needs. For conversion rates
of 2Hz or less, the temperature is represented as 10 bits
+ sign with a resolution of +0.125°C. When the conversion
rate is 4Hz, output data is 7 bits + sign with a resolution
of +1°C. The MAX6695/MAX6696 also include an SMBus
timeout feature to enhance system reliability.
Remote temperature sensing accuracy is ±1.5°C between
+60°C and +100°C with no calibration needed. The
MAX6695/MAX6696 measure temperatures from -40°C
to +125°C. In addition to the SMBus ALERT output, the
MAX6695/MAX6696 feature two overtemperature limit
indicators (OT1 and OT2), which are active only while the
temperature is above the corresponding programmable
temperature limits. The OT1 and OT2 outputs are typically
used for fan control, clock throttling, or system shutdown.
Features
● Measure One Local and Two Remote Temperatures
● 11-Bit, +0.125°C Resolution
● High Accuracy ±1.5°C (max) from +60°C to +100°C
(Remote)
● ACPI Compliant
● Programmable Under/Overtemperature Alarms
● Programmable Conversion Rate
● Three Alarm Outputs: ALERT, OT1, and OT2
● SMBus/I2C-Compatible Interface
● Compatible with 65nm Process Technology
(Y Versions)
Ordering Information
PART
PIN-PACKAGE
MAX6695AUB
-40°C to +125°C
10 µMAX
MAX6695YAUB
-40°C to +125°C
10 µMAX
MAX6696AEE
-40°C to +125°C
16 QSOP
MAX6696YAEE
-40°C to +125°C
16 QSOP
Devices are also available in tape-and-reel packages. Specify
tape and reel by adding “T” to the part number when ordering.
+Denotes a lead(Pb)-free/RoHS-compliant package.
Typical Operating Circuit
0.1µF
The MAX6695 has a fixed SMBus address. The MAX6696
has nine different pin-selectable SMBus addresses. The
MAX6695 is available in a 10-pin μMAX® and the MAX6696
is available in a 16-pin QSOP package. Both operate
throughout the -40°C to +125°C temperature range.
47Ω
+3.3V
10kΩ
EACH
CPU
DXP1
VCC
SMBDATA
SMBCLK
MAX6695 ALERT
Applications
●
●
●
●
●
TEMP RANGE
OT1
DXN
Notebook Computers
Desktop Computers
Servers
Workstations
Test and Measurement Equipment
OT2
DXP2
DATA
CLOCK
INTERRUPT
TO µP
TO CLOCK
THROTTLING
TO SYSTEM
SHUTDOWN
GND
GRAPHICS
PROCESSOR
Typical Operating Circuits continued at end of data sheet.
μMAX is a registered trademark of Maxim Integrated Products,
Inc.
Pin Configurations appear at end of data sheet.
19-3183; Rev 4; 6/21
© 2022 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners.
One Analog Way, Wilmington, MA 01887 U.S.A.
|
Tel: 781.329.4700
|
© 2022 Analog Devices, Inc. All rights reserved.
MAX6695/MAX6696
Dual Remote/Local Temperature Sensors with
SMBus Serial Interface
Absolute Maximum Ratings
VCC...........................................................................-0.3V to +6V
DXP1, DXP2.............................................. -0.3V to (VCC + 0.3V)
DXN.......................................................................-0.3V to +0.8V
SMBCLK, SMBDATA, ALERT..................................-0.3V to +6V
RESET, STBY, ADD0, ADD1, OT1, OT2.................-0.3V to +6V
SMBDATA Current.................................................. 1mA to 50mA
DXN Current........................................................................±1mA
Continuous Power Dissipation (TA = +70°C)
10-Pin μMAX (derate 6.9mW/°C above +70°C)........555.6mW
16-Pin QSOP (derate 8.3mW/°C above +70°C).......666.7mW
Operating Temperature Range.......................... -40°C to +125°C
Junction Temperature.......................................................+150°C
Storage Temperature Range............................. -65°C to +150°C
Lead Temperature (soldering, 10s).................................. +300°C
Soldering Temperature (reflow)........................................+260°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 +3.6V, TA = 0°C to +125°C, unless otherwise noted. Typical values are at VCC = +3.3V and TA = +25°C.)
PARAMETER
Supply Voltage
Standby Supply Current
SYMBOL
VCC
Operating Current
Average Operating Current
Remote Temperature Error
(Note 1)
CONDITIONS
SMBus static, ADC in idle state
POR Threshold Hysteresis
Undervoltage Lockout Threshold
UVLO
Undervoltage Lockout Hysteresis
Conversion Time
Remote-Diode Source Current
www.analog.com
IRJ
UNITS
3.6
V
10
µA
mA
0.5
1
Conversion rate = 0.125Hz
35
70
Conversion rate = 1Hz
250
500
Conversion rate = 4Hz
500
1000
TRJ = +25°C to +100°C
(TA = +45°C to +85°C)
-1.5
+1.5
TRJ = 0°C to +125°C (TA = +25°C to +100°C)
-3.0
+3.0
TRJ = -40°C to +125°C (TA = 0°C to +125°C)
-5.0
+5.0
TA = +45°C to +85°C
-2.0
+2.0
-3.0
+3.0
TA = 0°C to +125°C
-4.5
+4.5
µA
°C
+3.0
TA = -40°C to +125°C
+3.0
TA = +25°C to +100°C
-4.0
TA = +45°C to +85°C
-3.8
TA = 0°C to +125°C
-4.2
TA = -40°C to +125°C
Power-On Reset Threshold
MAX
Interface inactive, ADC active
TA = +25°C to +100°C
Local Temperature Error
(MAX6695Y/MAX6696Y)
TYP
3.0
TRJ = -40°C to +125°C (TA = -40°C)
Local Temperature Error
MIN
°C
°C
-4.4
VCC, falling edge (Note 2)
1.3
Falling edge of VCC disables ADC
2.2
1.45
1.6
500
2.8
V
mV
2.95
90
V
mV
Channel 1 rate ≤4Hz, channel 2 / local rate
≤2Hz (conversion rate register ≤05h)
112.5
125
137.5
Channel 1 rate ≥8Hz, channel 2 / local rate
≥4Hz (conversion rate register ≥06h)
56.25
62.5
68.75
High level
80
100
120
Low level
8
10
12
ms
µA
Analog Devices │ 2
MAX6695/MAX6696
Dual Remote/Local Temperature Sensors with
SMBus Serial Interface
Electrical Characteristics (continued)
(VCC = +3.0V to +3.6V, TA = 0°C to +125°C, unless otherwise noted. Typical values are at VCC = +3.3V and TA = +25°C.)
PARAMETER
ALERT, OT1, OT2
SYMBOL
Output Low Sink Current
Logic Input Low Voltage
VIL
INPUT PIN, RESET, STBY (MAX6696)
Logic Input High Voltage
Input Leakage Current
VIH
Logic Input Low Voltage
VIL
VIH
Input Leakage Current
Output Low Sink Current
Input Capacitance
VIL
ILEAK
IOL
CIN
UNITS
6
mA
1
µA
0.3
V
V
0.8
V
+1
µA
0.8
V
±1
µA
6
mA
2.1
ILEAK
VIH
MAX
2.9
SMBus INTERFACE (SMBCLK, SMBDATA, STBY)
Logic Input High Voltage
TYP
VOH = 3.6V
INPUT PIN, ADD0, ADD1 (MAX6696)
Logic Input Low Voltage
MIN
VOL = 0.4V
Output High Leakage Current
Logic Input High Voltage
CONDITIONS
V
-1
2.1
V
VIN = GND or VCC
VOL = 0.6V
5
pF
SMBus-COMPATIBLE TIMING (Figures 4 and 5) (Note 2)
Serial Clock Frequency
fSCL
10
Bus Free Time Between STOP
and START Condition
tBUF
4.7
µs
Repeat START Condition Setup
Time
tSU:STA
90% of SMBCLK to 90% of SMBDATA
4.7
µs
tHD:STA
10% of SMBDATA to 90% of SMBCLK
4
µs
90% of SMBCLK to 90% of SMBDATA
4
µs
10% to 10%
4.7
µs
90% to 90%
4
µs
250
ns
START Condition Hold Time
STOP Condition Setup Time
Clock Low Period
Clock High Period
Data Setup Time
Data Hold Time
SMB Rise Time
SMB Fall Time
SMBus Timeout
tSU:STO
tLOW
tHIGH
tSU:DAT
tHD:DAT
100
300
ns
tR
tF
1
SMBDATA low period for interface reset
20
kHz
30
µs
300
ns
40
ms
Note 1: Based on diode ideality factor of 1.008.
Note 2: Specifications are guaranteed by design, not production tested.
www.analog.com
Analog Devices │ 3
MAX6695/MAX6696
Dual Remote/Local Temperature Sensors with
SMBus Serial Interface
Typical Operating Characteristics
(VCC = 3.3V, TA = +25°C, unless otherwise noted.)
AVERAGE OPERATING SUPPLY CURRENT
vs. CONVERSION RATE CONTROL REGISTER VALUE
4
3
2
1
3.2
3.3
3.4
3.5
MAX6695 toc03
-3
-4
1
0
2
3
4
5
6
7
-50
-25
0
25
50
75
100
125
-1
-2
-3
2
REMOTE CHANNEL2
1
0
REMOTE CHANNEL1
-1
3
TEMPERATURE ERROR (°C)
0
3
-2
-25
0
25
50
75
100
-3
125
1
10
VIN = 10mVP-P
REMOTE CHANNEL2
2
1
0
REMOTE CHANNEL1
-1
-2
-3
100
MAX6695 toc06
TEMPERATURE ERROR
vs. DIFFERENTIAL NOISE FREQUENCY
-4
0.001
0.01
0.1
1
10
100
DXP-DXN CAPACITANCE (nF)
FREQUENCY (MHz)
REMOTE TEMPERATURE ERROR
vs. POWER-SUPPLY NOISE FREQUENCY
LOCAL TEMPERATURE ERROR
vs. POWER-SUPPLY NOISE FREQUENCY
TEMPERATURE ERROR
vs. COMMON-MODE NOISE FREQUENCY
REMOTE CHANNEL2
1
0
REMOTE CHANNEL1
-1
-2
0.001
0.01
0.1
1
FREQUENCY (MHz)
www.analog.com
10
100
100mVP-P
2
1
0
-1
-2
-3
0.001
0.01
0.1
1
FREQUENCY (MHz)
10
100
3
TEMPERATURE ERROR (°C)
2
3
TEMPERATURE ERROR (°C)
100mVP-P
MAX6695 toc08
DIE TEMPERATURE (°C)
MAX6695 toc07a
TEMPERATURE ERROR (°C)
REMOTE CHANNEL2
-2
TEMPERATURE ERROR
vs. DXP-DXN CAPACITANCE
1
-3
0
-1
LOCAL TEMPERATURE ERROR
vs. DIE TEMPERATURE
2
-50
1
-5
MAX6695 toc07b
TEMPERATURE ERROR (°C)
3.6
REMOTE CHANNEL1
2
REMOTE TEMPERATURE (°C)
3
3
100
3
CONVERSION RATE CONTROL REGISTER VALUE (hex)
4
-5
200
4
SUPPLY VOLTAGE (V)
MAX6695 toc04
5
3.1
300
MAX6695 toc05
3.0
400
0
TEMPERATURE ERROR (°C)
0
500
TEMPERATURE ERROR
vs. REMOTE-DIODE TEMPERATURE
5
TEMPERATURE ERROR (°C)
5
600
MAX6695 toc02
MAX6695 toc01
STANDBY SUPPLY CURRENT (µA)
6
OPERATING SUPPLY CURRENT (µA)
STANDBY SUPPLY CURRENT
vs. SUPPLY VOLTAGE
10mVP-P
2
REMOTE CHANNEL2
1
0
REMOTE CHANNEL1
-1
-2
-3
0.001
0.01
0.1
1
10
100
FREQUENCY (Hz)
Analog Devices │ 4
MAX6695/MAX6696
Dual Remote/Local Temperature Sensors with
SMBus Serial Interface
Pin Description
PIN
MAX6695
MAX6696
1
2
NAME
FUNCTION
VCC
Supply Voltage Input, +3V to +3.6V. Bypass to GND with a 0.1µF capacitor. A
47Ω series resistor is recommended but not required for additional noise filtering.
See Typical Operating Circuit.
2
3
DXP1
Combined Remote-Diode Current Source and A/D Positive Input for RemoteDiode Channel 1. DO NOT LEAVE DXP1 UNCONNECTED; connect DXP1 to
DXN if no remote diode is used. Place a 2200pF capacitor between DXP1 and
DXN for noise filtering.
3
4
DXN
Combined Remote-Diode Current Sink and A/D Negative Input. DXN is internally
biased to one diode drop above ground.
Combined Remote-Diode Current Source and A/D Positive Input for RemoteDiode Channel 2. DO NOT LEAVE DXP2 UNCONNECTED; connect DXP2 to
DXN if no remote diode is used. Place a 2200pF capacitor between DXP2 and
DXN for noise filtering.
4
5
DXP2
5
10
OT1
Overtemperature Active-Low Output, Open Drain. OT1 is asserted low only when
the temperature is above the programmed OT1 threshold.
6
8
GND
Ground
7
9
SMBCLK
SMBus Serial-Clock Input
SMBus Alert (Interrupt) Active-Low Output, Open-Drain. Asserts when
temperature exceeds user-set limits (high or low temperature) or when a remote
sensor opens. Stays asserted until acknowledged by either reading the status
register or by successfully responding to an alert response address. See the
ALERT Interrupts section.
8
11
ALERT
9
12
SMBDATA
10
13
OT2
Overtemperature Active-Low Output, Open Drain. OT2 is asserted low only when
temperature is above the programmed OT2 threshold.
—
1, 16
N.C.
No Connect
—
6
ADD1
SMBus Slave Address Select Input (Table 10). ADD0 and ADD1 are sampled
upon power-up.
—
7
RESET
Reset Input. Drive RESET high to set all registers to their default values (POR
state). Pull RESET low for normal operation.
—
14
ADD0
SMBus Slave Address Select Input (Table 10). ADD0 and ADD1 are sampled
upon power-up.
—
15
STBY
Hardware Standby Input. Pull STBY low to put the device into standby mode.
All registers’ data are maintained.
www.analog.com
SMBus Serial-Data Input/Output, Open Drain
Analog Devices │ 5
MAX6695/MAX6696
Dual Remote/Local Temperature Sensors with
SMBus Serial Interface
Detailed Description
The MAX6695/MAX6696 are temperature sensors
designed to work in conjunction with a microprocessor or
other intelligence in temperature monitoring, protection, or
control applications. Communication with the MAX6695/
MAX6696 occurs through the SMBus serial interface and
dedicated alert pins. The overtemperature alarms OT1
and OT2 are asserted if the software-programmed temperature thresholds are exceeded. OT1 and OT2 can be
connected to a fan, system shutdown, or other thermalmanagement circuitry.
The MAX6695/MAX6696 convert temperatures to digital
data continuously at a programmed rate or by selecting a single conversion. At the highest conversion rate,
temperature conversion results are stored in the “main”
temperature data registers (at addresses 00h and 01h)
as 7-bit + sign data with the LSB equal to +1°C. At
slower conversion rates, 3 additional bits are available at
addresses 11h and 10h, providing +0.125°C resolution.
See Table 2, Table 3, and Table 4 for data formats.
ADC and Multiplexer
The MAX6695/MAX6696 averaging ADC (Figure 1) integrates over a 62.5ms or 125ms period (each channel,
typ), depending on the conversion rate (see Electrical
Characteristics table). The use of an averaging ADC
attains excellent noise rejection.
The MAX6695/MAX6696 multiplexer (Figure 1) automatically steers bias currents through the remote and local
diodes. The ADC and associated circuitry measure each
diode’s forward voltages and compute the temperature
based on these voltages. If a remote channel is not
used, connect DXP_ to DXN. Do not leave DXP_ and
DXN unconnected. When a conversion is initiated, all
channels are converted whether they are used or not.
The DXN input is biased at one VBE above ground by an
internal diode to set up the ADC inputs for a differential
measurement. Resistance in series with the remote diode
causes about +1/2°C error per ohm.
A/D Conversion Sequence
A conversion sequence consists of a local temperature
measurement and two remote temperature measurements. Each time a conversion begins, whether initiated
automatically in the free-running autoconvert mode (RUN/
STOP = 0) or by writing a one-shot command, all three
channels are converted, and the results of the three
measurements are available after the end of conversion.
Because it is common to require temperature measurements to be made at a faster rate on one of the remote
channels than on the other two channels, the conversion
www.analog.com
sequence is Remote 1, Local, Remote 1, Remote 2.
Therefore, the Remote 1 conversion rate is double that of
the conversion rate for either of the other two channels.
A BUSY status bit in status register 1 (see Table 7 and the
Status Byte Functions section) shows that the device is
actually performing a new conversion. The results of the
previous conversion sequence are always available when
the ADC is busy.
Remote-Diode Selection
The MAX6695/MAX6696 can directly measure the die
temperature of CPUs and other ICs that have on-board
temperature-sensing diodes (see the Typical Operating
Circuit) or they can measure the temperature of a discrete
diode-connected 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 MAX6695/MAX6696 (not the
MAX6695Y/MAX6696Y) are optimized for n = 1.008. A
thermal diode on the substrate of an IC is normally a PNP
with its collector 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 will be 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 T ACTUAL ×
n NOMINAL
where temperature is measured in Kelvin and nNOMIMAL
for the MAX6695/MAX6696 is 1.008.
As an example, assume you want to use the MAX6695 or
MAX6696 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 ×
TM × (1.00599)
=
n
1.002
1
For a real temperature of +85°C (358.15K), the measured
temperature is +82.87°C (356.02K), an error of -2.13°C.
Effect of Series Resistance
Series resistance (RS) with a sensing diode contributes
additional error. For nominal diode currents of 10μA
Analog Devices │ 6
MAX6695/MAX6696
VCC
Dual Remote/Local Temperature Sensors with
SMBus Serial Interface
(RESET)
RESET/
UVLO
CIRCUITRY
3
MUX
DXP1
REMOTE1
REMOTE2
DXN
DXP2
DIODE FAULT
SMBus
8
ALERT
Q
(STBY)
CONTROL
LOGIC
ADC
LOCAL
S
8
R
REGISTER BANK
READ
SMBDATA
WRITE
SMBCLK
7
COMMAND BYTE
REMOTE TEMPERATURES
OT1
Q
S
R
LOCAL TEMPERATURES
(ADD0)
ADDRESS
DECODER
(ADD1)
ALERT THRESHOLD
ALERT RESPONSE ADDRESS
OT2
OT1 THRESHOLDS
Q
S
R
OT2 THRESHOLDS
() ARE FOR MAX6696 ONLY.
Figure 1. MAX6695/MAX6696 Functional Diagram
and 100μA, the change in the measured voltage due to
series resistance is:
ΔVM = (100μA − 10μA) × RS = 90μA × RS
Since 1°C corresponds to 198.6μV, series resistance contributes a temperature offset of:
µV
Ω = 0.453 °C
µV
Ω
198.6
°C
90
Assume that the sensing diode being measured has a
series resistance of 3Ω. The series resistance contributes
a temperature offset of:
3Ω × 0.453
°C
= +1.36°C
Ω
The effects of the ideality factor and series resistance are
additive. If the diode has an ideality factor of 1.002 and
series resistance of 3Ω, the total offset can be calculated
by adding error due to series resistance with error due to
ideality factor:
1.36°C - 2.13°C = -0.77°C
for a diode temperature of +85°C.
www.analog.com
Analog Devices │ 7
MAX6695/MAX6696
Dual Remote/Local Temperature Sensors with
SMBus Serial Interface
In this example, the effect of the series resistance and the
ideality factor partially cancel each other.
Discrete Remote Diodes
When the remote-sensing diode is a discrete transistor, its
collector and base must be connected together. Table 1
lists examples of discrete transistors that are appropriate
for use with the MAX6695/MAX6696.
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 100Ω. Tight specifications for
forward current gain (50 < ß
工商网监
湘ICP备2023018690号
