TC642B View Datasheet(PDF) - Microchip Technology

Part Name

Description

Manufacturer

TC642B

PWM Fan Speed Controllers With Minimum Fan Speed, Fan Restart and FanSense™ Technology for Fault Detection

Microchip Technology 

TC642B/TC647B

+5V

R1

237 k

R2

45.3 k

Thermometrics®

100 k @25°C

NHQ104B425R5

8

CB

1 VIN

VDD

0.01 µF

+ CVDD

1.0 µF

FAULT 6

+5V

R4

17.8 k

R3

32.4 k

CB 3 VMIN

0.01 µF

2 CF

CF

1.0 µF

TC647B VOUT 7

SENSE 5

GND

4

R5

10 k

+12V

Panasonic®

Fan 12V, 140 mA

FBA06T12H

Q1

SI2302

or

MGSF1N02E

CSENSE

0.1 µF

RSENSE

3.0

FIGURE 5-13:

Design Example Schematic.

Bypass capacitor CVDD is added to the design to

decouple the bias voltage. This is good to have, espe-

cially when using a MOSFET as the drive device. This

helps to give a localized low-impedance source for the

current required to charge the gate capacitance of Q1.

Two other bypass capacitors, labeled as CB, were also

added to decouple the VIN and VMIN nodes. These

were added simply to remove any noise present that

might cause false triggerings or PWM jitter. R5 is the

pull-up resistor for the FAULT output. The value for this

resistor is system-dependent.

 2002-2013 Microchip Technology Inc.

DS21756C-page 25

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