Rainbow Electronics MAX6649 - Manual

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
♦ 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
MAX6646/MAX6647/MAX6649
+145°C Precision SMBus-Compatible Remote/
Local Sensors with Overtemperature Alarms
________________________________________________________________ Maxim Integrated Products 1
Ordering Information
V CC
DXP
DXN
10k Ω EACH
CLOCK
TO FAN DRIVER OR
SYSTEM SHUTDOWN
3.3V
DATA
INTERRUPT TO µP
200 Ω 0.1 µF
SDA
SCLK
ALERT
GND
2200pF
µP
MAX6646
MAX6647
MAX6649
OVERT
Typical Operating Circuit
19-2540; Rev 1; 7/03
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.
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
Selector Guide, Pin Configurations, and Functional Diagram
appear at end of data sheet.