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TELCOM SEMICONDUCTOR, INC.

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To prevent output "chattering" when measured tem-

perature is at (or near) the programmed trip point values, the

LOW SET and HIGH SET inputs each have a built-in

hysteresis of – 2

°C max. As a result, the HIGH LIMIT and

LOW LIMIT outputs remain active until the measured tem-

perature falls a maximum of 2

°C below the programmed

HIGH SET and LOW SET thresholds as shown in Figure 3.

The

programmed setting threshold of Figure 3 is user-

programmed temperature trip points of either the LOW SET

or HIGH SET inputs. The LOW LIMIT or HIGH LIMIT output

is driven active when temperature equals the programmed

setpoint value (to within 3

°C). The output remains active

until the temperature falls an additional 2

°C below the

setpoint due to hysteresis.

APPLICATIONS

Mounting

If the TC623 is used to measure the temperature

of another device, it is important that the top surface

of the TC623 package be in intimate contact with the

measured device. Good thermal conductivity and no air

space is critical to accurate temperature measurement in

applications of this type.

Trip Point Programming

The resistance values required for the HIGH SET and

LOW SET inputs are calculated using the formula below:

Where Rtrip = Programming resistor value in Ohms

T = Desired trip temperature in degrees Kelvin.

For example, to program a trip point of 50

°C, the

programming resistor is:

PROGRAMMED SETPOINT

–2

°C HYSTERESIS

HIGH LIMIT OR LOW LIMIT OUTPUT

Figure 3. High Set and Low Set Thresholds

TC623

3V, DUAL TRIP POINT

TEMPERATURE SENSOR