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.
General Description
The MAX6648/MAX6692 are precise, two-channel digital temperature sensors. They accurately measure the
temperature of their own die and a remote PN junction,
and report the temperature in digital form using a 2-wire
serial interface. The remote PN junction is typically the
emitter-base junction of a common-collector PNP on a
CPU, FPGA, or ASIC.
The 2-wire serial interface accepts standard System
Management Bus (SMBus)™ write byte, read byte,
send byte, and receive byte commands to read the
temperature data and to program the alarm thresholds.
To enhance system reliability, the MAX6648/MAX6692
include an SMBus timeout. A fault queue prevents the
ALERT and OVERT outputs from setting until a fault has
been detected one, two, or three consecutive times
(programmable).
The MAX6648/MAX6692 provide two system alarms:
ALERT and OVERT. ALERT asserts when any of four temperature conditions are violated: local overtemperature,
remote overtemperature, local undertemperature, or
remote undertemperature. OVERT asserts when the temperature rises above the value in either of the two OVERT
limit registers. The OVERT output can be used to activate
a cooling fan, or to trigger a system shutdown.
Measurements can be done autonomously, with the
conversion rate programmed by the user, or in a singleshot mode. The adjustable conversion rate allows the
user to optimize supply current and temperature
update rate to match system needs.
Remote accuracy is ±0.8°C maximum error between
+25°C and +125°C with no calibration needed. The
MAX6648/MAX6692 operate from -55°C to +125°C, and
measure temperatures between 0°C and +125°C. The
MAX6648 is available in an 8-pin µMAX
®
package, and the
MAX6692 is available in 8-pin µMAX and SO packages.
Applications
Desktop Computers
Notebook Computers
Servers
Thin Clients
Workstations
Test and Measurement
Multichip Modules
Features
o Dual Channel Measures Remote and Local
Temperature
o +0.125°C Resolution
o High Accuracy ±0.8°C (max) from +25°C to +125°C
(Remote), and ±2°C (max) from +60°C to +100°C
(Local)
o Two Alarm Outputs: ALERT and OVERT
o Two Default OVERT Thresholds Available
MAX6648: +110°C
MAX6692: +85°C
o Programmable Conversion Rate
o SMBus-Compatible Interface
o SMBus Timeout
o Programmable Under/Overtemperature Alarm
Thresholds
o Compatible with 90nm, 65nm, and 45nm Process
Technology
MAX6648/MAX6692
Precision SMBus-Compatible Remote/Local
Temperature Sensors with Overtemperature Alarms
________________________________________________________________________________________________________________________________
Maxim Integrated Products
1
Ordering Information
V
CC
DXP
DXN
10kΩ EACH
CLOCK
TO FAN DRIVER OR
SYSTEM SHUTDOWN
3.3V
DATA
INTERRUPTED TO μP
200Ω
0.1μF
SDA
SCLK
ALERT
GND
2200pF
μP
OVERT
MAX6648
MAX6692
Typical Operating Circuit
19-2545; Rev 4; 6/08
SMBus is a trademark of Intel Corp.
µMAX is a registered trademark of Maxim Integrated Products, Inc.
Pin Configuration and Functional Diagram appear at end of
data sheet.
Note: All devices operate over the -55°C to +125°C temperature
range.
PART
MAX6648MUA 8 µMAX 0°C to +125°C
MAX6648YMUA 8 µMAX 0°C to +125°C
MAX6692MUA 8 µMAX 0°C to +125°C
MAX6692MSA 8 SO 0°C to +125°C
MAX6692YMUA 8 µMAX 0°C to +125°C
MAX6692YMSA 8 SO 0°C to +125°C
PINPACKAGE
MEASURED
TEMP RANGE
MAX6648/MAX6692
Precision SMBus-Compatible Remote/Local
Temperature Sensors with Overtemperature Alarms
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.
(All voltages referenced to GND.)
V
CC
...........................................................................-0.3V to +6V
DXP.............................................................-0.3V to (V
CC
+ 0.3V)
DXN .......................................................................-0.3V to +0.8V
SCLK, SDA, ALERT, OVERT.....................................-0.3V to +6V
SDA, ALERT, OVERT Current .............................-1mA to +50mA
DXN Current .......................................................................±1mA
Continuous Power Dissipation (T
A
= +70°C)
8-Pin µMAX (derate 5.9mW/°C above +70°C) .............471mW
8-Pin SO (derate 5.9mW/°C above +70°C)..................471mW
ESD Protection (all pins, Human Body Model) ................±2000V
Junction Temperature......................................................+150°C
Operating Temperature Range .........................-55°C to +125°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
ELECTRICAL CHARACTERISTICS
(VCC= 3.0V to 5.5V, TA= -55°C to +125°C, unless otherwise specified. Typical values are at VCC= 3.3V and TA= +85°C.) (Note 1)
Supply Voltage V
Temperature Resolution
Remote Temperature Error
n = 1.008
Local Temperature Error V
Local Temperature Error
(MAX6648Y/MAX6692Y)
Supply Sensitivity of Temperature
Error
Undervoltage Lockout (UVLO)
Threshold
UVLO Hysteresis 90 mV
Power-On-Reset (POR) Threshold VCC falling edge 2.0 V
POR Threshold Hysteresis 90 mV
Standby Supply Current SMBus static 3.5 12 µA
Operating Current During conversion 0.45 0.8 mA
Average Operating Current
Conversion Time t
Conversion Time Error -25 +25 %
DXP and DXN Leakage Current Standby mode 100 nA
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
CC
V
= 3.3V,
CC
= +85°C
T
A
V
= 3.3V,
CC
+60°C ≤ T
+100°C
V
CC
≤ T
CC
V
C C
UVLO Falling edge of V
0.25 conversions per second 40 80
2 conversions per second 250 400
CONV
From stop bit to conversion completion 95 125 156 ms
A
= 3.3V, +0°C
≤ +100°C
A
= 3.3V
= 3.3V
3.0 5.5 V
0.125 °C
10 Bits
T
= +25°C to +125°C -0.8 +0.8
RJ
≤
TRJ = +60°C to +100°C -1.0 +1.0
TRJ = 0°C to +125°C -1.6 +1.6
T
= 0°C to +125°C -3.0 +3.0
RJ
TA = +60°C to +100°C -2.0 +2.0
= 0°C to +125°C -3.0 +3.0
T
A
TA = + 60°C to + 100°C - 4.0
= 0°C to +125°C -4.4
T
A
±0.2 °C/V
disables ADC 2.4 2.7 2.95 V
CC
°C
°C
°C
µA
MAX6648/MAX6692
Precision SMBus-Compatible Remote/Local
Temperature Sensors with Overtemperature Alarms
______________________________________________________________________________________________________________________________________________________________________________
3
ELECTRICAL CHARACTERISTICS (continued)
(VCC= 3.0V to 5.5V, TA= -55°C to +125°C, unless otherwise specified. Typical values are at VCC= 3.3V and TA= +85°C.) (Note 1)
Note 1: All parameters tested at a single temperature. Specifications over temperature are guaranteed by design.
Note 2: Timing specifications guaranteed by design.
Note 3: The serial interface resets when SCLK 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 SCLK’s falling edge.
Remote-Diode Source Current I
ALERT, OVERT
Output Low Voltage
Output High Leakage Current VOH = 5.5V 1 µA
SMBus-COMPATIBLE INTERFACE (SCLK AND SDA)
Logic Input Low Voltage V
Logic Input High Voltage V
Input Leakage Current I
Output Low-Sink Current I
Input Capacitance C
SMBus-COMPATIBLE TIMING (Note 2)
Serial Clock Frequency f
Bus Free Time Between STOP and
START Condition
START Condition Setup Time 4.7 µs
Repeat START Condition Setup
Time
START Condition Hold Time t
STOP Condition Setup Time t
Clock Low Period t
Clock High Period t
Data Setup Time t
Receive SCLK/SDA Rise Time t
Receive SCLK/SDA Fall Time t
Pulse Width of Spike Suppressed t
SMBus Timeout t
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
RJ
IL
IH
LEAK
SINK
IN
SCLK
t
BUF
t
SU:STA
HD:STA
SU:STO
LOW
HIGH
HD:DAT
R
F
SP
TIMEOUT
High level 80 100 120
Low level 8 10 12
I
= 1mA 0.4
SINK
I
= 4mA 0.6
SINK
0.8 V
VCC = 3.0V 2.2
VCC = 5.5V 2.6
VIN = GND or V
V
= 0.6V 6 mA
OL
(Note 3) 100 kHz
90% to 90% 50 ns
10% of SDA to 90% of SCLK 4 µs
90% of SCLK to 90% of SDA 4 µs
10% to 10% 4.7 µs
90% to 90% 4 µs
(Note 4) 250 µs
SDA low period for interface reset 25 37 55 ms
CC
-1 +1 µA
5pF
4.7 µs
1µs
300 ns
050ns
µA
V
V
MAX6648/MAX6692
Precision SMBus-Compatible Remote/Local
Temperature Sensors with Overtemperature Alarms
4
______________________________________________________________________________________________________________________________________________________________________________
Typical Operating Characteristics
(VCC= 3.3V, TA= +25°C, unless otherwise noted.)
STANDBY SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX6648/92 toc01
SUPPLY VOLTAGE (V)
STANDBY SUPPLY CURRENT (μA)
5.04.54.03.5
2.8
3.2
3.6
4.0
2.4
3.0 5.5
OPERATING SUPPLY CURRENT
vs. CONVERSION RATE
MAX6648/92 toc02
CONVERSION RATE (Hz)
OPERATING SUPPLY CURRENT (μA)
4.002.001.000.500.250.13
100
200
300
400
500
600
0
0.63
REMOTE TEMPERATURE ERROR
vs. REMOTE-DIODE TEMPERATURE
MAX6648/92 toc03
TEMPERATURE (°C)
TEMPERATURE ERROR (°C)
100755025
-1.5
-0.5
0.5
1.5
2.5
-2.5
0125
TA = +85°C
FAIRCHILD 2N3906
LOCAL TEMPERATURE ERROR
vs. DIE TEMPERATURE
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1.0
-1.0
MAX6648/92 toc05
TEMPERATURE (°C)
TEMPERATURE ERROR (°C)
1007550250125
REMOTE TEMPERATURE ERROR
vs. 45nm REMOTE DIODE TEMPERATURE
MAX6648/92 toc04
TEMPERATURE (°C)
TEMPERATURE ERROR (°C)
90807060
-4
-2
0
2
4
6
-6
50 100
TEMPERATURE ERROR
vs. POWER-SUPPLY NOISE FREQUENCY
MAX6648/92 toc06
FREQUENCY (Hz)
TEMPERATURE ERROR (°C)
10k1k1 10 100
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
0
0.1 100k
LOCAL ERROR
REMOTE ERROR
VIN = SQUARE WAVE APPLIED TO VCC
WITH NO 0.1μF V
CC
CAPACITOR
-1
0
1
2
3
4
5
6
7
8
9
-2
TEMPERATURE ERROR
vs. COMMON-MODE NOISE FREQUENCY
MAX6648/92 toc07
FREQUENCY (Hz)
TEMPERATURE ERROR (°C)
100k10k10 100 1k1
REMOTE ERROR
LOCAL ERROR
V
IN
= AC-COUPLED TO DXN
V
IN
= 100mV
P-P
-1.5
-1.0
-0.5
0
0.5
1.0
1.5
2.0
-2.0
TEMPERATURE ERROR
vs. DIFFERENTIAL-MODE NOISE FREQUENCY
MAX6648/92 toc08
FREQUENCY (Hz)
TEMPERATURE ERROR (°C)
100k10k10 100 1k1
VIN = 20mV
P-P
SQUARE WAVE
APPLIED TO DXP-DXN
TEMPERATURE ERROR
vs. DXP-DXN CAPACITANCE
MAX6648/92 toc09
DXP-DXN CAPACITANCE (nF)
TEMPERATURE ERROR (°C)
10.0001.000
-5
-4
-3
-2
-1
0
1
-6
0.100 100.000
MAX6648/MAX6692
Precision SMBus-Compatible Remote/Local
Temperature Sensors with Overtemperature Alarms
______________________________________________________________________________________________________________________________________________________________________________
5
Detailed Description
The MAX6648/MAX6692 are temperature sensors
designed to work in conjunction with a microprocessor
or other intelligence in thermostatic, process-control, or
monitoring applications. Communication with the
MAX6648/MAX6692 occurs through the SMBus-compatible serial interface and dedicated alert pins. ALERT
asserts if the measured local or remote temperature is
greater than the software-programmed ALERT high
limit or less than the ALERT low limit. ALERT also
asserts if the remote-sensing diode pins are shorted or
unconnected. The overtemperature alarm, OVERT,
asserts if the software-programmed OVERT limit is
exceeded. OVERT can be connected to fans, a system
shutdown, a clock throttle control, or other thermalmanagement circuitry.
The MAX6648/MAX6692 convert temperatures to digital
data either at a programmed rate or in single conversions. Temperature data is represented as 10 bits plus
sign, with the LSB equal to 0.125°C. The “main” temperature data registers (at addresses 00h and 01h) are 8-bit
registers that represent the data as 7 bits with the final
MSB indicating the diode fault status (Table 1). The
remaining 3 bits of temperature data are available in the
“extended” registers at addresses 11h and 10h (Table 2).
ADC and Multiplexer
The averaging ADC integrates over a 60ms period
(each channel, typically), with excellent noise rejection.
The multiplexer automatically steers bias currents
through the remote and local diodes. The ADC and
associated circuitry measure each diode’s forward voltage and compute the temperature based on this voltage. Both channels are automatically converted once
the conversion process has started, either in free-running or single-shot mode. If one of the two channels is
not used, the device still performs both measurements,
and the user can ignore the results of the unused chan-
Pin Description
Table 1. Main Temperature Data Register
Format (00h, 01h)
PIN NAME FUNCTION
1V
2 DXP
3DXN
4 OVERT
5 GND Ground
6 ALERT
7 SDA SMBus Serial-Data Input/Output, Open Drain
8 SCLK SMBus Serial-Clock Input
CC
Supply Voltage Input, 3V to 5.5V. Bypass V
resistor is recommended but not required for additional noise filtering.
Combined Remote-Diode Current Source and A/D Positive Input for Remote-Diode Channel. DO
NOT LEAVE DXP DISCONNECTED; connect DXP to DXN if no remote diode is used. Place a
2200pF capacitor between DXP and DXN for noise filtering.
Combined Remote-Diode Current Sink and A/D Negative Input. DXN is internally biased to one
diode drop above ground.
Overtemperature Alert/Interrupt Output, Open Drain. OVERT is logic low when the temperature is
above the software-programmed threshold.
SMBus Alert (Interrupt) Output, Open Drain. ALERT asserts when temperature exceeds user-set
limits (high or low temperature). ALERT stays asserted until acknowledged by either reading the
status register or by successfully responding to an alert response address, provided that the fault
condition no longer exists. See the
ALERT
to GND with a 0.1µF capacitor. A 200Ω series
CC
Interrupts section.
TEMP (°C) DIGITAL OUTPUT
130 0 111 1111
127 0 111 1111
126 0 111 1111
25 0 001 1001
0 0 000 0000
<0 0 000 0000
-1 0 000 0000
-25 0 000 0000
Diode fault
(short or open)
1 000 0000