FAN7389_13 Datasheet, PDF (15/17 Pages) Fairchild Semiconductor – 3-Phase Half-Bridge Gate-Drive IC

INx
OUTx
t_FLTIN
t_INPUT
t_OUTPUT
Figure 46 shows the characteristics of the input filters
while receiving narrow ON and OFF pulses. If input
signal pulse duration, PW_IN, is less than input filter time,
t_FLTIN; the output pulse, PW_OUT, is zero. The input signal
is rejected by input filter. Once the input signal pulse
duration, PW_IN, exceeds input filter time, t_FLTIN, the
output pulse durations, PW_OUT, matches the input pulse
durations, PW_IN. FAN7389 input filter time, t_FLTIN, is
about 250 ns for the high- and low-side outputs.
INx
t_FLTIN
t_INPUT
OUTx
tOUTPUT _{Output duration is}
same as input duration
Figure 44. Input Noise Filter Definition
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
(t_FLTIN), the output does not change states.
Example A and B of the Figure 45 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 46.Input Filter Characteristic of Narrow ON
Figure 45.Noise Rejecting Input Filter Definition
© 2010 Fairchild Semiconductor Corporation
FAN7389 • Rev. 1.0.3
15
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