The TC648 is a switch mode fan speed controller for use with brushless DC motors. 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. The TC648 can be configured to operate in either Auto-Shutdown or Minimum Speed mode. In Auto-Shutdown mode,fan operation is automatically suspended when measured temperature (VIN) is lower than a user-programmed minimum setting (VAS). The fan is automatically restarted and proportional speed control restored when VIN exceeds VAS (plus hysteresis). Operation in Minimum Speed mode is similar to Auto-Shutdown mode, except the fan is operated at a user-programmed minimum setting when measured temperature is low. An integrated Start-Up Timer ensures reliable motor start-up at turn-on, or when coming out of Shutdown mode.The over-temperature fault (OTF) is asserted when the PWM reaches 100% duty cycle, indicating a possible thermal runaway situation.The TC648 is packaged in a space-saving 8-pin plastic DIP, MSOP or SOIC package and is available in the industrial temperature range.

  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 TC648 Supply Voltage - Supports Any Fan Voltage!

  Over-Temperature Fault Detection

  Automatic Shutdown Mode for "Green" Systems

  Supports Low Cost NTC/PTC Thermistors