Datasheet

Section 20 Power-On Reset and Low-Voltage Detection Circuits (Optional)

Rev.5.00 Nov. 02, 2005 Page 369 of 500

REJ09B0027-0500

Procedures for Clearing Settings when Using LVDR and LVDI:

To operate or release the low-voltage detection circuit normally, follow the procedure described

below. Figure 20.5 shows the timing for the operation and release of the low-voltage detection

circuit.

1. To operate the low-voltage detection circuit, set the LVDE bit in LVDCR to 1.

2. Wait for 50 µs (t

LVDON

) until the reference voltage and the low-voltage-detection power supply

have stabilized by a software timer, etc. Then, clear the LVDDF and LVDUF bits in LVDSR

to 0 and set the LVDRE, LVDDE, and LVDUE bits in LVDCR to 1, as required.

3. To release the low-voltage detection circuit, start by clearing all of the LVDRE, LVDDE, and

LVDUE bits to 0. Then clear the LVDE bit to 0. The LVDE bit must not be cleared to 0 at the

same timing as the LVDRE, LVDDE, and LVDUE bits because incorrect operation may occur.

LVDRE

LVDDE

LVDUE

LVDO N

LVDE

Figure 20.5 Timing for Operation/Release of Low-Voltage Detection Circuit