PWM Fan Speed Controller
M
Features
• Temperature Proportional Fan Speed for Acoustic Control and Longer Fan Life • Efficient PWM Fan Drive • 3.0...
Description
M
Features
Temperature Proportional Fan Speed for Acoustic Control and Longer Fan Life Efficient PWM Fan Drive 3.0V to 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 Space Saving 8-Pin MSOP Package Over-temperature Indication
TC642
Package Types
SOIC/PDIP/MSOP
VIN CF VMIN GND 1 2 3 4 8 VDD VOUT FAULT SENSE
PWM Fan Speed Controller with FanSense™ Technology
TC642
7 6 5
General Description
The TC642 is a switch mode fan speed controller for use with brushless DC fans. Temperature proportional speed control is accomplished using pulse width modulation (PWM). A thermistor (or other voltage output temperature sensor) connected to the VIN input furnishes the required control voltage of 1.25V to 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. The TC642 also features Microchip Technology's proprietary FanSense™ technology for increasing system reliability. In normal fan operation, a pulse train is present at SENSE (Pin 5). A missing pulse detector monitors this pin during fan operation. A stalled, open ...
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