Microchip TC642COA Fan Controller IC 8-Pin, SOIC

The TC642 is a switch mode fan speed controller for use with brushless DC motors. Temperature proportional speed control is accomplished using pulse width modulation. A thermistor (or other voltage output temperature sensor) connected to the VIN input furnishes the required control voltage of 1.25Vto 2.65V (typical) for 0% to 100% PWM duty cycle. Minimum fan speed is set by a simple resistor divider on the VMIN input. An integrated Start-Up Timer ensures reliable motor start-up at turn-on, coming out of Shutdown Mode, or following a transient fault. A logic low applied to VMIN, pin 3, causes fan shutdown.

Temperature Proportional
Fan Speed for Acoustic Control and Longer Fan Life
Efficient PWM Fan Drive
3.0V 5.5V Supply Range
Fan Voltage Independent of TC642 Supply Voltage:
Supports Any Fan Voltage!
FanSense™ Fault Detection Circuits Protect Against Fan Failure and Aid
System Testing
Shutdown Mode for "Green" Systems
Supports Low Cost NTC/PTC Thermistors