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
· emperature Thresholds
· Programmable Conversion Rate
· SMBus-Compatible Interface
· SMBus TimeoutApplication·Graphics Processors
·Desktop Computers
·Notebook Computers
·Servers
·Thin Clients
·Workstations
·Test and Measurement
·Multichip ModulesSpecificationsAll Voltages Referenced to GND
VCC......................................................................-0.3V to +6V
DXP.........................................................-0.3V to (VCC + 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 (TA = +70°C)
8-Pin MAX (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
DescriptionThe MAX6646/MAX6647/MAX6649 are precise, twochannel digital temperature sensors. The devices 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 of MAX6646 is typically the emitter-base junction of a commoncollector PNP on a CPU, FPGA, or ASIC.
The 2-wire serial interface of MAX6646 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 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 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, at the programmed conversion rate, or in a single-shot mode. The adjustable conversion rate of MAX6646 allows optimizing supply current 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 MAX package.
MAX6646 Data Sheet
