HA16103 Datasheet, PDF (8/21 Pages) Hitachi Semiconductor – Watchdog Timer

HA16103 FPJ/FPK
Low Voltage Monitoring Function
The system contains a circuit to send a control signal to the microcomputer when the output voltage drops.
The circuit includes the following features.
• Two-point monitoring of output voltage (V_NMI and V_STBY)
• Availability of fine adjustment of Vth1 (V_NMI) and Vth2 (V_STBY)
• Output of control signal in standby mode of microcomputer
Figure 5 shows the timing chart of control signals when the output voltage drops.
If the output voltage drops below Vth1 (4.60 V), the NMI signal rises to request the microcomputer to issue
the NMI interrupt signal. The RES signal falls t_RES seconds after the NMI signal rises. If the output voltage
drops further to below Vth2 (3.2 V), the STBY signal rises to enable the micro-computer to enter standby
mode.
V_BATT
V_O
4.70 V
4.60 V
4.70 V 4.60 V
3.20 V
NMI
Power on reset signal
ton
RES
toff
t RH t RL ^{t RES}
tr
t RES
Automatic reset signal
STBY
P-RUN
System runaway
Figure 5 Timing Chart for Low Voltage Monitoring
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