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The MAX6643LBBAEE device is an automatic PWM fan speed controller with an overtemperature alarm output.

Main characteristics

Simple, automatic fan speed control

Internal and external temperature detection

Detect fan faults by locking rotor output, tachometer output, or detecting fan power supply current

A variety of output duty cycles with a 1.6% difference achieve low noise when the fan speed changes

Cryogenic fan thresholds can be selected by pin or set at the factory

Automatic start signal to ensure fan start

The fan startup delay reduces the power load during power-on

32Hz PWM output

The controlled duty cycle change rate ensures good noise performance

Temperature measurement accuracy of 2°C

The /FULLSPD/FULLSPD input sets the PWM to 100%

The /OT output threshold that can be selected by pin

16-pin QSOP and 10-pin µMAX packages

Product information

The MAX6643 monitors temperature and automatically adjusts fan speed to ensure optimal cooling while minimizing fan noise. Each device measures two temperature regions.

The MAX6643 generates a PWM waveform to drive the external power transistor, which modulates the power supply to the fan. The MAX6643 monitors the temperature and adjusts the duty cycle of the PWM output waveform to control the fan speed according to the cooling needs of the system. The MAX6643 monitors the temperature of its own core and an optional external transistor.

The MAX6643 has 9 selectable temperature thresholds (rising at 5°C).

All types of devices include an overheat output (/OT). /OT can be used to provide an alarm or to shut down the system. The MAX6643 also has a FULLSPD input, which forces the duty cycle of the PWM to 100%. The MAX6643 also has a /FANFAIL output to indicate fan failure. For a complete list of features for each device, please refer to the selection guide in the Complete data sheet.