SMBus-Compatible Temperature Monitor with Automatic PWM Fan-Speed Controller

Industry's Smallest, Single Temperature Sensor and Fan Controller in MSOP Package

Please check latest availability status for a specific part variant.


The MAX6641 temperature sensor and fan controller accurately measures the temperature of its own die and the temperature of a remote pn junction. The device reports temperature values 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.

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 program the alarm thresholds. The temperature data controls a PWM output signal to adjust the speed of a cooling fan, thereby minimizing noise when the system is running cool, but providing maximum cooling when power dissipation increases. The device also features an over-temperature alarm output to generate interrupts, throttle signals, or shut down signals. The MAX6641 operates from supply voltages in the 3.0V to 5.5V range and typically consumes 500µA of supply current.

The MAX6641 is available in a slim 10-pin µMAX® package and is available over the -40°C to +125°C automotive temperature range.
MAX6641: Typical Application Circuit MAX6641: Typical Application Circuit Enlarge+

Key Features

  • Tiny 3mm x 5mm µMAX Package
  • Thermal Diode Input
  • Local Temperature Sensor
  • Open-Drain PWM Output for Fan Drive
  • Programmable Fan Control Characteristics
  • Automatic Fan Spin-Up Ensures Fan Start
  • ±1°C Remote Temperature Accuracy (+60°C to +145°C)
  • Controlled Rate of Change Ensures Unobtrusive Fan-Speed Adjustments
  • Temperature Monitoring Begins at Power-On for Fail-Safe System Protection
  • Active-Low OT Output for Throttling or Shutdown


  • Desktop Computers
  • Industrial
  • Networking Equipment
  • Notebook Computers
  • Servers
  • Workstations

See parametric specs for Fan Controllers (20)

Part NumberSensor TypeFan Cntrl.InterfaceAccuracy
Temp. Thresh.
See Notes
MAX6641 RemotePWM2-Wire/I2C/SMBus1Programmable
$1.46 @1k

Pricing Notes:
This pricing is BUDGETARY, for comparing similar parts. Prices are in U.S. dollars and subject to change. Quantity pricing may vary substantially and international prices may differ due to local duties, taxes, fees, and exchange rates. For volume-specific and version-specific prices and delivery, please see the price and availability page or contact an authorized distributor.
Product Reliability Reports: MAX6641.pdf 
Device   Fab Process   Technology   Sample size   Rejects   FIT at 25°C   FIT at 55°C   Material Composition  

Note : The failure rates are summarized by technology and mapped to the associated material part numbers. The failure rates are highly dependent on the number of units tested.

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