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
⢠FanSenseâ¢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)
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