The TC647 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 VIN 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 startup 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 TC647 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 or unconnected fan causes the TC647 to trigger its Start-up Timer once. If the fault persists, the FAULT output goes low and the device is latched in its shutdown mode. The TC647 is available in the 8-pin plastic DIP, SOIC and MSOP packages and is available in the industrial and extended commercial temperature ranges.
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 TC647 Supply Voltage - Supports any Fan Voltage
FanSense™ Technology Fault Detection Circuits Protect Against Fan Failure and Aid System Testing