TC646VOA Microchip

DTC646 PWM Fan Speed Controller with Auto-Shutdown and FanSense Technology Features Package Types Temperature Proportional Fan Speed for Acoustic SOIC/PDIP/MSOP Control and Longer Fan Life Efficient PWM Fan Drive V V IN18 DD 3.0V to 5.5V Supply Range: V C27 OUT F TC646 - Fan Voltage Independent of TC646 V AS36 FAULT Supply Voltage - Supports any Fan Voltage GND SENSE 45 FanSense Fault Detection Circuits Protect Against Fan Failure and Aid System Testing General Description Shutdown Mode forGree Systems Supports Low Cost NTC/PTC Thermistors The TC646 is a switch mode, fan speed controller for 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- Applications IN nishes the required control voltage of 1.25V to 2.65V Power Supplies (typical) for 0% to 100% PWM duty cycle. The TC646 Computers automatically suspends fan operation when measured temperature (V ) is below a user programmed File Servers IN minimum setting (V ). An integrated Start-up Timer AS Portable Computers ensures reliable motor start-up at turn-on, coming out Telecom Equipment of shutdown mode, auto-shutdown mode or following a UPS, Power Amps transient fault. General Purpose Fan Speed Control The TC646 features Microchip Technology s proprie- tary FanSense technology for increasing system reli- Available Tools ability. In normal fan operation, a pulse train is present at SENSE (Pin 5). A missing-pulse detector monitors Fan Controller Demonstration Board (TC642DEMO) this pin during fan operation. A stalled, open, or uncon- Fan Controller Evaluation Kit (TC642EV) nected fan causes the TC646 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 Section 5.0, Typical Applications, for more information and system design guidelines. The TC646 is available in the 8-pin plastic DIP, SOIC and MSOP packages and is available in the industrial and extended commercial temperature ranges. 2002-2012 Microchip Technology Inc. DS21446D-page 1TC646 Functional Block Diagram V IN + V DD V OTF OTF PWM + Control V Logic OUT C F 3 x T PWM Timer Clock Generator FAULT Start-up Timer V AS + SHDN Missing Pulse Detect. + TC646 V SHDN SENSE 10k GND 70mV (typ.) DS21446D-page 2 2002-2012 Microchip Technology Inc. +