TC624 Microchip Technology Inc., TC624 Datasheet - Page 5

• Manufacturer Part Number: TC624
• Description: Low Cost Single Trip Point Temperature Sensor
• Manufacturer: Microchip Technology Inc.

3.0
3.1
When the temperature of the device exceeds the pro-
grammed temperature trip point, T
OUT outputs are driven into their active states. The
desired trip point temperature is programmed with a
single external resistor connected between the T
input and V
value and the trip point temperature is given by
Equation 3-1.
EQUATION 3-1:
For example, as shown in Figure 3-1, to program the
device to trip at 50°C, the programming resistor is:
FIGURE 3-1:
Values vs. Temperature
© 2006 Microchip Technology Inc.
R
Where:
TRIP
250
200
150
100
50
T = Desired trip temperature in degrees Kelvin.
R
-55
TRIP
= 0.5997 x ((50 + 273.15)
DETAILED DESCRIPTION
Trip Point Programming
-35
CC
= Programming resistor value in Ohms
. The relationship between the resistor
-15
R
TRIP
5
TEMPERATURE (°C)
Programming Resistor
= 0.5997 x T
25
2.1312
45
SET
) = 133.65 kΩ
65
2.1312
, the OUT and
85
105
125
SET
3.2
To prevent output “chattering” at the trip point tempera-
ture, the temperature detector in the TC622/TC624 has
2°C hysteresis (see Figure 3-2). The outputs are driven
active when the temperature crosses the set point
determined by the external resistor. As temperature
declines below the set point, the hysteresis action will
hold the outputs true until the temperature drops 2°C
below the threshold.
FIGURE 3-2:
(Set Point – 2 Degrees C)
Hysteresis
Set Point
OUT
OUT
TC622/TC624
Temperature
TC622/TC624 Hysteresis
DS21440C-page 5