TC07 datasheet(4/12 Pages) MICROCHIP

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TC07

DS21674C-page 4

4.0

TYPICAL APPLICATIONS

4.1

Trip Point Programming

The resistor values required to achieve the desired trip

point temperatures on TSET and HSET are calculated

using the formula below:

For example, to program the TC07 outputs to go active

at 50°C and inactive at 30°C, the RT and RH

programming resistors are calculated as follows:

Resistance values for TSET and HSET can be approxi-

mated using Figure 4-1. Care must be taken to ensure

the HSET programming resistor is a smaller value than

the TSET programming resistor. The temperature

programmed on HSET must be at least 5°C lower than

the temperature value programmed by TSET.

FIGURE 4-1:

PROGRAMMING

RESISTOR VALUES VS.

TEMPERATURE

4.2

Cooling and Heating Applications

The TC07 can be used to control a DC fan as shown in

Figure 4-2. The fan turns on when the sensed temper-

ature rises above the temperature set at TSET and

remains on until the temperature falls below the tem-

perature set at HSET. The amount of “cooling"

performed by the fan is dependent on the programmed

hysteresis.

Figure 4-3 shows the TC07 acting as a heater thermo-

stat. Circuit operation is identical to that of the cooling

fan application in Figure 4-2.

FIGURE 4-2:

TC07 AS A FAN

CONTROLLER

RTRIP = 0.6 x T

2.13

Where:

RTRIP = Programming resistor value in Ohms

T = Desired trip point temperature in degrees Kelvin.

RT = 0.6 x ((50 + 273.15)

2.13) = 132.8kΩ

RH = 0.6 x ((30 + 273.15)

2.13) = 115.9kΩ

TEMPERATURE (

°C)

-55

-35

-15

105

125

100

150

200

250

Out

Fan "On"

HSET

TSET

+2.7 to 5.5V +12V

TSET

HSET

GND

VDD

OUT

Logic Level

MOSFET

TC07

OUT

Fan

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