TK11052
Noise Reduction
APPLICATION HINTS (CONT.)
When the thermostat IC is operated in a noisy environment (e.g., motor, fan, etc.), the noise on the signal lines may exceed
the limits of the comparator hysteresis window. This results in erratic comparator output levels. This can be corrected by
adding 0.1 µF capacitors from Pin 1 to GND (or Pin 4), Pin 2 to GND (or Pin 4), and Pin 4 to GND as shown below. The
configuration is determined by the desired comparator output level during power-up in the hysteresis area as described
earlier.
C = 0.1 µF
b
Rb
C = 0.1 µF
d
Rd
VCC
Ra
Rc
1 µF
Vref
Cref = 0.1 µF
V
CC
ROUT1
VCC OUTPUT1
ROUT2
OUTPUT2
July 1999 TOKO, Inc.
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