TC642B/TC647B
PWM Fan Speed Controllers With Minimum Fan Speed,
Fan Restart and FanSenseв„ў Technology for Fault Detection
Features Description Temperature-Proportional Fan Speed for Acoustic
Noise Reduction and Longer Fan Life Efficient PWM Fan Drive 3.0V to 5.5V Supply Range:
-Fan Voltage Independent of TC642B/TC647B
Supply Voltage
-Supports any Fan Voltage FanSenseв„ў Fault Detection Circuit Protects
Against Fan Failure and Aids System Testing Shutdown Mode for "Green" Systems Supports Low Cost NTC/PTC Thermistors Over-Temperature Indication (TC642B only) Fan Auto-Restart Space-Saving 8-Pin MSOP Package The TC642B/TC647B devices are new versions of the
existing TC642/TC647 fan speed controllers. These
devices are switch mode, fan speed controllers that
incorporate a new fan auto-restart function. Temperature-proportional speed control is accomplished using
pulse width modulation. A thermistor (or other voltage
output temperature sensor) connected to the VIN input
supplies the required control voltage of 1.20V to 2.60V
(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. Applications Personal Computers & Servers
LCD Projectors
Datacom & Telecom Equipment …
