The TC647 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 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 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 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, indicating normal operation. A Missing-pulse Detector monitors this pin during normal 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 a standard 8-Pin PDIP, MSOP and SOIC packages. Commercial and industrial temperature ranges are available in both package options.

  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?Fault Detection Circuits Protect Against Fan Failure and Aid

  System Testing

  Shutdown Mode for "Green" Systems

  Supports Low Cost NTC/PTC Thermistors