19-2545; Rev 1; 10/02
Precision SMBus-Compatible Remote/Local
Temperature Sensors with Overtemperature Alarms
General Description
Features
The MAX6648/MAX6692 are precise, two-channel digi-
tal 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.
ꢀ Dual Channel: Measures Remote and Local
Temperature
ꢀ 0.125°C Resolution
ꢀ High Accuracy: 0.ꢀ°C ꢁmaꢂx ꢃrom ꢄ25°C to
ꢄ125°C ꢁRemotex, and 2°C ꢁmaꢂx ꢃrom ꢄ+0°C to
ꢄ100°C ꢁLocalx
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).
ꢀ Two Alarm Outputs: ALERT and OVERT
ꢀ Two Deꢃault OVERT Thresholds Available
MAX++4ꢀ: ꢄ110°C
MAX++92: ꢄꢀ5°C
ꢀ Programmable Conversion Rate
ꢀ SMBus-Compatible Interꢃace
ꢀ SMBus Timeout
The MAX6648/MAX6692 provide two system alarms:
ALERT and OVERT. ALERT asserts when any of four tem-
perature conditions are violated: local overtemperature,
remote overtemperature, local undertemperature, or
remote undertemperature. OVERT asserts when the tem-
perature 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.
ꢀ Programmable Under/Overtemperature Alarm
Thresholds
Ordering Information
PIN-
MEASURED
PART
TEMP RANGE
PACKAGE TEMP RANGE
Measurements can be done autonomously, with the
conversion rate programmed by the user, or in a single-
shot mode. The adjustable conversion rate allows the
user to optimize supply current and temperature
update rate to match system needs.
MAX6648MUA -55ꢀC to +125ꢀC 8 µMAX
MAX6692MUA -55ꢀC to +125ꢀC 8 µMAX
MAX6692MSA -55ꢀC to +125ꢀC 8 SO
0ꢀC to +125ꢀC
0ꢀC to +125ꢀC
0ꢀC to +125ꢀC
Remote accuracy is ±±.8ꢀC maꢁimum error between
+25ꢀC and +125ꢀC with no calibration needed. The
MAX6648/MAX6692 operate from -55ꢀC to +125ꢀC, and
measure temperatures between ±ꢀC and +125ꢀC. The
MAX6648 is available in an 8-pin µMAX package, and the
MAX6692 is available in 8-pin µMAX and SO packages.
Typical Operating Circuit
3.3V
0.1µF
200Ω
Applications
V
CC
10kΩ EACH
Desktop Computers
Notebook Computers
Servers
DXP
DATA
SDA
MAX6648
MAX6692
CLOCK
SCLK
Thin Clients
ALERT
INTERRUPTED TO µP
DXN
2200pF
Workstations
OVERT
TO FAN DRIVER OR
SYSTEM SHUTDOWN
GND
µP
Test and Measurement
Multichip Modules
Pin Configuration and Functional Diagram appear at end of
data sheet.
SMBus is a trademark of Intel Corp.
________________________________________________________________ Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.