General Description
●The TC642 is a switch mode fan speed controller for use with brushless DC fans. Temperature proportional speed control is accomplished using pulse width mod ulation (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. Minimum fan
●speed is set by a simple resistor divider on the VMIN input. An integrated Start-up Timer ensures reliable motor start-up at turn-on, coming out of shutdown mode or following a transient fault. A logic low applied to VMIN(Pin 3) causes fan shutdown.
●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 TC642 Supply Voltage
● - Supports any Fan Voltage
●• FanSense™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
●• Over-temperature Indication
●Applications
●• Power Supplies
●• Personal Computers
●• File Servers
●• Telecom Equipment
●• UPSs, Power Amps, etc.
●• General Purpose Fan Speed Control
●Available Tools
●• Fan Controller Demonstration Board (TC642DEMO)
●• Fan Controller Evaluation Kit (TC642EV)
