 2002 Microchip Technology Inc.

DS21444C-page 9

TC642

5.0

TYPICAL APPLICATIONS

Designing with the TC642 involves the following:

(1) The temp sensor network must be configured to

temperature range to be regulated.

(3) The output drive transistor and associated circuitry

must be selected.

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.

The TC642 demonstration and prototyping board

(TC642DEMO), and the TC642 Evaluation Kit

(TC642EV), provide working examples of TC642 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 TC642 should consult the documen-

tation for both TC642EV (DS21403) and TC642DEMO

(DS21401).

FIGURE 5-1:

Typical Application Circuit.

5.1

Temperature Sensor Design

voltage in the range of 1.25V to 2.65V (typical) for 0%

to 100% of the temperature range of interest. The

circuit in Figure 5-2 illustrates a convenient way to

provide this signal.

Figure 5-2 shows a simple temperature dependent

temperatures is obtained from the manufacturer’s

specifications. Thermistors are often referred to in

terms of their resistance at 25°C.

FAULT

SENSE

NTC

GND

Thermal

Shutdown

Shutdown

(Optional)

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

+12V

+5V*

1 µF

TC642

Fan

1 µF

0.01 µF

0.01 µF

1

8

6

7

5

4

2

3