4500/720 Series 720 Family Models 4513, 4514 Group User's Manual

APPLICATION

2-58

4513/4514 Group User’s Manual

2.8 Voltage drop detection circuit

The built-in voltage drop detection circuit is designed to detect a drop in voltage and to reset the microcomputer

if the supply voltage drops below a set value.

Figure 2.8.1 shows the voltage drop detection reset circuit, and Figure 2.8.2 shows the operation waveform

example of the voltage drop detection circuit.

Fig. 2.8.1 Voltage drop detection reset circuit

Fig. 2.8.2 Voltage drop detection circuit operation waveform

Note: Refer to section “3.1 Electrical characteristics” for the reset voltage of the voltage drop detection

circuit.

Voltage drop detection circuit

Internal reset signal

RESET pin

Watchdog timer output

WEF

Note: The output structure of RESET pin is N-channel open-drain.

VDD

VRST (detection voltage)

Voltage drop detection

circuit output

The microcomputer starts

operation after f(XIN) is counted

16892 to 16895 times.

RESET pin

Notes 1: Pull-up RESET pin externally.

2: Refer to the voltage drop detection circuit in the electrical characteristics

for the rating value of VRST (detection voltage).