FC122 datasheet(5/10 Pages) SITI

5 / 10 page

Fan Speed Control IC

Version

：A.002

PAGE 4

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FC122

Functional Description

1. Fan Speed Control:

The output voltage (VOUT) can be controlled by

fan control input (VFC).

VFC ≥ VSTR(FC) : VOUT = ( VFC - ½VDD ) * AOUT + VST

2. Temperature Protection:

Pin-TS connects to an external thermistor

network for monitoring ambient temperature.

The input signal (VTS) will decide the minimum

output voltage (VOUT).

VTS ≥ VSTR(TS) : VOUT = ( VTS - ½VDD ) * AOUT + VST

3. Drive output:

Whenever the fan is started from the off state, it will induce an start-up interval

of 0.3 sec, the Pin-OUT will drive full duty in this period and then continue with

the voltage determined by MAX (VFC, VTS).

4. Fault output:

Pin-FLT is an open collector, and active low signal. It will be pulled to low to

indicate that over-temperature has occurred.

Over-temperature: When VTS exceed VVOT.

VFC

VSTR(FC)

VOUT = (VFC – ½VDD ) * AOUT + VST

VOUT

VDD

VTS

VSTR(TS)

VOUT = (VTS – ½VDD ) * AOUT + VST

VOUT

VDD

FC122 Datasheet(PDF) 5 Page - Silicon Touch Technology Inc.