FAN7389 Datasheet, PDF (16/18 Pages) Fairchild Semiconductor – 3-Phase Half-Bridge Gate-Drive IC

3.2. Short-Pulsed Input Noise Rejection Method
The input filter circuitry provides protection against
short-pulsed input signals (HINx, LINx, and EN) on the
input signal lines by applied noise signal.
If the input signal duration is less than input filter time
(tFLT,IN), the output does not change states.
Example A and B of the Figure 44 show the input and
output waveforms with short-pulsed noise spikes with a
duration less than input filter time; the output does not
change states.
Figure 44.Noise Rejecting Input Filter Definition
Figure 45 shows the characteristics of the input filters
while receiving narrow ON and OFF pulses. If input
signal pulse duration, PWIN, is less than input filter
time, tFLT,IN; the output pulse, PWOUT, is zero. The input
signal is rejected by input filter. Once the input signal
pulse duration, PWIN, exceeds input filter time, tFLT,IN,
the output pulse durations, PWOUT, matches the input
pulse durations, PWIN. FAN7389 input filter time, tFLT,IN,
is about 250ns for the high- and low-side outputs.
Figure 45.Input Filter Characteristic of Narrow ON
© 2010 Fairchild Semiconductor Corporation
FAN7389 • Rev. 1.0.0
16
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