HA16117F Datasheet, PDF (13/31 Pages) Hitachi Semiconductor – CMOS Watchdog Timer

HA16117F Series
6. When P-RUN frequency fluctuates (1)
If there is a double-pulse in P-RUN, the WD filter duty will be decreased and RES will be
output, as shown in the figure below, for example. In this case, the condition for non-output of
the RES signal is a value of 3 or less for the ratio of P-RUN pulse interval minimum value to
maximum value (when f_P-RUN ≤ 20 kHz). This is because the C_R pin charge/discharge current
ratio is 3.
H
P-RUN
L
H
Q
L
H
Q
L
H
A
L
5V
3.6 V
C_F
0.9 V
0V
H
WD
L
5V
3.2 V
C_R
1.6 V
0V
H
B
L
H
C
L
H
RES
L
2 ms
28 ms
20 ms
13