HA16113FPJ Datasheet, PDF (16/18 Pages) Hitachi Semiconductor – Dual Watchdog Timers

HA16113FPJ
Precautions
If the IC’s ground potential varies suddenly by several volts due to wiring impedance (see figure 7), a false
RES pulse may be output. The reason for this is that potentials in the RES pulse generating circuit change
together with the Vout-GND potential. The reference potential of the comparator in figure 8 and the
potential of the external capacitor have different impedances as seen from the comparator, causing a
momentary inversion. The solution is to stabilize the ground potential. Two ways of stabilizing the IC’s
ground line are:
• Separate the IC’s ground line from high-current ground lines.
• Increase the capacitance (Co) used to smooth the Vout output.
Wiring impedance
SW1
V _IGN
SW2
HA16113FPJ ^Co
R_L
Wiring impedance
Relay or other load
Figure 1 Typical Circuit
Vout
V_CC Vcont
Wiring impedance
C_RES
+
–
RES
GND
Figure 2 RES Comparator
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