 2004 Microchip Technology Inc.

DS21451D-page 7

TC6501/2/3/4

5.0

APPLICATIONS

The TC6501 and TC6503 have open-drain outputs and

are, therefore, intended to interface as microcontroller

reset inputs. Moreover, the combination of these two

devices can be used to implement a temperature

window alarm by wire-ORing the outputs and using an

external pull-up resistor (see Figure 5-1).

FIGURE 5-1:

Over and Under

Temperature Alarm.

The TC6502 can be used to control a DC fan. The fan

turns on when the sensed temperature rises above the

factory-set threshold and remains on until the

temperature falls below threshold minus the hysteresis

selected. An additional fail-safe measure could be

designed by using a second TC6502 with a higher

temperature threshold to alert the user of an impending

thermal shutdown, should the temperature continue to

rise (see Figure 5-2).

FIGURE 5-2:

Fan Control with Over

Temperature Alert.

The TC6504, with its push-pull output, may be used in

a similar fashion to turn on a heater element at cold

temperatures (see Figure 5-3).

FIGURE 5-3:

TC6504 As Heater

Thermostat.

HYST

GND

GND

HYST

+5V

100 k

Ω

GND GND

TC6501

TC6503

HYST

100 pF

Out of Range

100 pF

HYST

GND

GND

HYST

GND GND

TC6501

TC6503

HYST

Temperature

GND

GND

100 pF

HYST

+5V

TC6502PO65

GND

GND

HYST

TC6502PO45

Temperature

Fault

Fan Control

GND

GND

HYST

+5V

TC6502PO65

GND

GND

HYST

TC6502PO45

GND

GND

HYST

+5V

TC6502

GND GND

HYST

TC6502

100 pF

Heater "On"

TC6504

+5V

12V

GND GND HYST

Heater

100 pF

Temperature

Time