TC648 Fan Speed Controller with Auto-Shutdown and Over-Temperature Alert Features Package Types Temperature Proportional Fan Speed for Acoustic SOIC/PDIP/MSOP Control and Longer Fan Life V V 18 IN DD Efficient PWM Fan Drive V C27 3.0V to 5.5V Supply Range: OUT F TC648 - Fan Voltage Independent of TC648 V AS36 OTF Supply Voltage GND45 NC - Supports any Fan Voltage Over-temperature Fault Detection Automatic Shutdown Mode for Green Systems General Description Supports Low Cost NTC/PTC Thermistors The TC648 is a switch mode, fan speed controller for Space Saving 8-Pin MSOP Package use with brushless DC fans. Temperature proportional speed control is accomplished using pulse width mod- Applications ulation (PWM). A thermistor (or other voltage output Power Supplies temperature sensor) connected to the V input IN Computers furnishes the required control voltage of 1.25V to 2.65V (typical) for 0% to 100% PWM duty cycle. The TC648 Portable Computers can be configured to operate in either auto-shutdown or Telecom Equipment minimum speed mode. In auto-shutdown mode, fan UPSs, Power Amps operation is automatically suspended when measured General Purpose Fan Speed Control temperature (V ) is lower than a user programmed IN minimum setting (V ). The fan is automatically AS Available Tools restarted, and proportional speed control restored, when V exceeds V (plus hysteresis). Operation in IN AS Fan Controller Demonstration Board (TC642DEMO) minimum speed mode is similar to auto-shutdown Fan Controller Evaluation Kit (TC642EV) mode, with the exception that the fan is operated at a user programmed minimum setting when the mea- sured temperature is low. An integrated Start-up Timer ensures reliable motor start-up at turn-on, and when coming out of shutdown or auto-shutdown mode. The over-temperature fault output (OTF) is asserted when the PWM reaches 100% duty cycle, indicating a possible thermal runaway situation. The TC648 is available in the 8-pin plastic DIP, SOIC and MSOP packages and is available in the industrial and extended commercial temperature ranges. 2001-2012 Microchip Technology Inc. DS21448D-page 1TC648 Functional Block Diagram V IN + V DD V OTF OTF PWM + Control V OUT Logic C F Clock Generator OTF Start-up Timer V AS + SHDN + V TC648 SHDN NC GND DS21448D-page 2 2001-2012 Microchip Technology Inc.