TC642VUA Microchip

TC642 PWM Fan Speed Controller with FanSense Technology Features Package Types SOIC/PDIP/MSOP Temperature Proportional Fan Speed for Acoustic Control and Longer Fan Life V V IN18 DD Efficient PWM Fan Drive C V 3.0V to 5.5V Supply Range: 27 F OUT TC642 - Fan Voltage Independent of TC642 V MIN36 FAULT Supply Voltage GND45 SENSE - Supports any Fan Voltage Fault Detection Circuits Protect FanSense Against Fan Failure and Aid System Testing General Description Shutdown Mode forGree Systems The TC642 is a switch mode fan speed controller for Supports Low Cost NTC/PTC Thermistors use with brushless DC fans. Temperature proportional Space Saving 8-Pin MSOP Package speed control is accomplished using pulse width mod- Over-temperature Indication ulation (PWM). A thermistor (or other voltage output temperature sensor) connected to the V input fur- IN Applications nishes the required control voltage of 1.25V to 2.65V Power Supplies (typical) for 0% to 100% PWM duty cycle. Minimum fan speed is set by a simple resistor divider on the V Personal Computers MIN input. An integrated Start-up Timer ensures reliable File Servers motor start-up at turn-on, coming out of shutdown Telecom Equipment mode or following a transient fault. A logic low applied UPSs, Power Amps, etc. to V (Pin 3) causes fan shutdown. MIN General Purpose Fan Speed Control The TC642 also features Microchip Technology s pro- prietary FanSense technology for increasing system Available Tools reliability. In normal fan operation, a pulse train is pres- ent at SENSE (Pin 5). A missing pulse detector moni- Fan Controller Demonstration Board (TC642DEMO) tors this pin during fan operation. A stalled, open or Fan Controller Evaluation Kit (TC642EV) unconnected fan causes the TC642 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. FAULT is also asserted if the PWM reaches 100% duty cycle, indicating a possible thermal runaway situation, although the fan continues to run. See Section5.0, Typical Applications, for more information and system design guidelines. The TC642 is available in the standard 8-pin plastic DIP, SOIC and MSOP packages and is available in the commercial, extended commercial and industrial temperature ranges. 2001-2012 Microchip Technology Inc. DS21444D-page 1TC642 Functional Block Diagram + V IN V DD V OTF + OTF SHDN + Control Logic V OUT C F 3 x T PWM Timer Clock Generator FAULT Start-up V Timer MIN + V SHDN Missing Pulse Detect TC642 SENSE 10k GND 70mV (typ.) DS21444D-page 2 2001-2012 Microchip Technology Inc. +