Reset Circuit (Watch Dog Timer) - Panasonic KX-FP80C Service Manual

NO. SIGNAL
143 VCL
144 VREFT

6.3.7. RESET CIRCUIT (WATCH DOG TIMER)

The output signal from pin 1 of the voltage detect IC (IC509) is input to the ASIC (IC501) 112 pin.
Then the output signal from pin 109 of the ASIC (IC501) resets the ASIC.
1. During a momentary power interruption, a positive reset pulse of
46~51 msec is generated and the system is reset completely.
2. When pin 108 and 109 of IC501 become low level, they will prohibit
the SRAM (IC504) from changing data.
The SRAM (IC504) will go into the backup mode, when they are
backed up by a lithium battery.
3. The watch dog timer, built-in the ASIC (IC501), is initialized by the
CPU about every 1.5 ms.
When a watch dog error occurs, pin 113 of the ASIC (IC501)
I/O POWER
SUPPLIED
VOLTAGE
A 3.3V
A 3.3V
156
DESCRIPTION
ANALOG PART STANDARD VOLTAGE
SIGNAL
A/D CONVERTER'S FULL SCALE
VOLTAGE OUTPUT