TC647

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 TC647 Supply Voltage - Supports any Fan Voltage FanSense™ Technology 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 TC647 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 TC647 7 6 5 General Description 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 V MIN (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 th...