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MAX6646 Datasheet, PDF (1/16 Pages) Maxim Integrated Products – +145°C Precision SMBus-Compatible Remote/ Local Sensors with Overtemperature Alarms | |||
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19-2540; Rev 1; 7/03
+145°C Precision SMBus-Compatible Remote/
Local Sensors with Overtemperature Alarms
General Description
The MAX6646/MAX6647/MAX6649 are precise, two-
channel digital temperature sensors. The devices accu-
rately 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 junc-
tion 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 man-
agement 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 MAX6646/MAX6647/MAX6649
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 MAX6646/MAX6647/MAX6649 provide two system
alarms: ALERT and OVERT. ALERT asserts when any of
four temperature conditions are violated: local overtem-
perature, remote overtemperature, local undertempera-
ture, 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, at the pro-
grammed conversion rate, or in a single-shot mode. The
adjustable conversion rate allows optimizing supply cur-
rent and temperature update rate to match system needs.
Remote accuracy is ±1°C maximum error between +60°C
and +145°C with no calibration needed. The
MAX6646/MAX6647/MAX6649 operate from -55°C to
+125°C, and measure temperatures between 0°C and
+145°C. The MAX6646/MAX6647/MAX6649 are available
in an 8-pin µMAX package.
Applications
Graphics Processors
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 ±1°C (max) from +60°C to +145°C
(Remote), and ±2°C (max) from +60°C to +100°C
(Local)
o Measures High-Ideality Thermal Diodes Up to
+170°C (Apparent)
+145°C (Real)
o Two Alarm Outputs: ALERT and OVERT
o Programmable Under/Overtemperature Alarm
Temperature Thresholds
o Programmable Conversion Rate
o SMBus-Compatible Interface
o SMBus Timeout
Ordering Information
PART
TEMP RANGE
PIN-
PACKAGE
MEASURED
TEMP RANGE
MAX6646MUA -55°C to +125°C 8 µMAX 0°C to +145°C
MAX6647MUA -55°C to +125°C 8 µMAX 0°C to +145°C
MAX6649MUA -55°C to +125°C 8 µMAX 0°C to +145°C
Typical Operating Circuit
0.1µF
3.3V
200â¦
VCC
DXP MAX6646 SDA
MAX6647
MAX6649 SCLK
DXN
2200pF
ALERT
OVERT
µP
GND
10k⦠EACH
DATA
CLOCK
INTERRUPT TO µP
TO FAN DRIVER OR
SYSTEM SHUTDOWN
Selector Guide, Pin Configurations, and Functional Diagram
appear at end of data sheet.
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maximâs website at www.maxim-ic.com.
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