 2002 Microchip Technology Inc.

DS21448C-page 9

TC648

5.0

TYPICAL APPLICATIONS

Designing with the TC648 involves the following:

(1) The temperature sensor network must be

to 100% of the temperature range to be regulated.

(2) The auto-shutdown temperature must be set with

(3) The output drive transistor and base resistor must

be selected.

(4) If reset/shutdown capability is desired, the drive

requirements 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 TC648 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 TC648 should consult the documen-

tation for both the TC642EV (DS21403) and

TC642DEMO (DS21401). Figure 5-1 shows the base

schematic for the TC642DEMO.

An Excel-based spreadsheet is also available for

designing the thermistor network for the TC64X fan

controllers. This file (TC64X Therm) is available for

downloading

from

the

Microchip

website

at

www.microchip.com.

FIGURE 5-1:

Typical Application Circuit.

OTF

NC

NTC

GND

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

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

NOTES:

Over-

Temperature

Interrupt

Shutdown**

+12V

+5V*

CF

1 µF

TC648

Fan

0.01 µF

0.01 µF

1 µF

+5V