TC622/TC624
4.0
4.1
TYPICAL APPLICATIONS
Over-Temperature Shutdown
4.2
Cooling and Heating Applications
The TC622 can be used to create a simple over-tem-
perature shutdown circuit. In this circuit, temperature is
sensed within the system enclosure (internal system
ambient) or at the heatsink itself. When measured
temperature exceeds a preset limit, a fault is indicated
and the system shuts down.
circuit using the TC622 sensor in a single TO-220
package, allowing direct attachment to the heatsink
surface. As shown, the TC622 outputs are driven active
when the heatsink temperature equals the trip point
temperature set by R
TRIP
. When this happens, the
crowbar circuit is activated, causing the supply output
to fold back to zero. The TC622 outputs remain active
until the heatsink temperature falls a minimum of 2°C
(built-in hysteresis) below the trip point temperature, at
which time the device again allows normal supply
operation.
Heatsink
The TC622/TC624 can be used to control a DC fan as
shown in Figure 4-2. The fan turns on when the sensed
temperature rises above T
SET
and remains on until the
temperature falls below T
SET
- 2°C.
thermostat. Circuit operation is identical to that of the
cooling fan application.
Output
Device
TC622
V
CC
Output Device
V
OUT
Circuit Board
TC622 Heatsink Mounting
R
TRIP
Power Good
Signal
TC622
T
SET
V
DD
OUT
GND
OUT
OVERTEMP
Crowbar
Circuit
Heatsink Surface
FIGURE 4-1:
TC622 Power Supply Over-Temperature Shutdown
DS21440C-page 6
©
2006 Microchip Technology Inc.
MICROCHIP [ MICROCHIP TECHNOLOGY ]
