MAX6646_1207 Datasheet, PDF (1/16 Pages) Maxim Integrated Products – +145°C Precision SMBus-Compatible Remote/ Local Sensors with Overtemperature Alarms

19-2540; Rev 4; 7/12
+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.
Graphics Processors
Desktop Computers
Notebook Computers
Servers
Applications
Thin Clients
Workstations
Test and Measurement
Multichip Modules
Selector Guide, Pin Configurations, and Functional Diagram
appear at end of data sheet.
Features
♦ Dual Channel: Measures Remote and Local
Temperature
♦ 0.125°C Resolution
♦ High Accuracy ±1°C (max) from +60°C to +145°C
(Remote), and ±2°C (max) from +60°C to +100°C
(Local)
♦ Measures High-Ideality Thermal Diodes Up to
+170°C (Apparent)
+145°C (Real)
♦ Two Alarm Outputs: ALERT and OVERT
♦ Programmable Under/Overtemperature Alarm
Temperature Thresholds
♦ Programmable Conversion Rate
♦ SMBus-Compatible Interface
♦ SMBus Timeout
Ordering Information
PART
TEMP PIN-
MEASURED
RANGE PACKAGE 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 _{8 μMAX}
+125°C
0°C to +145°C
+Denotes a lead(Pb)-free/RoHS-compliant package.
Typical Operating Circuit
0.1μF
3.3V
200Ω
V_CC
DXP
MAX6646
MAX6647
SDA
MAX6649
SCLK
DXN
2200pF
ALERT
OVERT
μP
GND
10kΩ EACH
DATA
CLOCK
INTERRUPT TO μP
TO FAN DRIVER OR
SYSTEM SHUTDOWN
μMAX is a registered trademark of Maxim Integrated Products, Inc.
For pricing, delivery, and ordering information, please contact Maxim Direct
1
at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.