TC646 View Datasheet(PDF) - Microchip Technology

Part Name

Description

Manufacturer

TC646

PWM Fan Speed Controller with Auto-Shutdown and FanSense™ Technology

Microchip Technology 

TC646

5.0 TYPICAL APPLICATIONS

Designing with the TC646 involves the following:

(1) The temperature sensor network must be

configured to deliver 1.25V to 2.65V on VIN for 0%

to 100% of the temperature range to be regulated.

(2) The auto-shutdown temperature must be set

with a voltage divider on VAS.

(3) The output drive transistor and associated circuitry

must be selected.

(4) The SENSE network, RSENSE and CSENSE, must

be designed for maximum efficiency while

delivering adequate signal amplitude.

(5) If shutdown capability is desired, the drive require-

ments of the external signal or circuit must be

considered.

+5V*

The TC642 demonstration and prototyping board

(TC642DEMO) and the TC642 Evaluation Kit

(TC642EV) provide working examples of TC646 cir-

cuits and prototyping aids. The TC642DEMO is a

printed circuit board optimized for small size and ease

of inclusion into system prototypes. The TC642EV is a

larger board intended for benchtop development and

analysis. At the very least, anyone contemplating a

design using the TC646 should consult the documen-

tation for both TC642EV (DS21403) and TC642DEMO

(DS21401). Figure 5-1 shows the base schematic for

the TC642DEMO.

Shutdown**

R1

NTC

1

VIN

CB

R2

0.01µF

+5V

R3

3 VAS

CB

0.01µF

2

R4

CF

CF

1µF

CB

1µF

8

VDD

6

FAULT

TC646

VOUT 7

GND

4

5

SENSE

+12V

Fan

Thermal

Shutdown

Q1

RBASE

CSENSE

RSENSE

NOTES: *See cautions regarding latch-up considerations in Section 5.0, "Typical Applications".

**Optional. See Section 5.0, "Typical Applications", for details.

FIGURE 5-1:

Typical Application Circuit.

DS21446C-page 10

 2002 Microchip Technology Inc.

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