User’s Manual U18172EJ2V0UD
195
CHAPTER 13 POWER-ON-CLEAR CIRCUIT
13.1 Functions of Power-on-Clear Circuit
The power-on-clear circuit (POC) has the following functions.
•
Generates internal reset signal at power on.
•
Compares supply voltage (V
DD
) and detection voltage (V
POC
= 2.1 V
±
0.1 V), and generates internal reset signal
when V
DD
< V
POC
.
•
Compares supply voltage (V
DD
) and detection voltage (V
POC
= 2.1 V
±
0.1 V), and releases internal reset signal
when V
DD
≥
V
POC
.
Cautions 1. If an internal reset signal is generated in the POC circuit, the reset control flag register
(RESF) is cleared to 00H.
2. Because the detection voltage (V
POC
) of the POC circuit is in a range of 2.1 V
±
0.1 V, use a
voltage in the range of 2.2 to 5.5 V.
Remark
This product incorporates multiple hardware functions that generate an internal reset signal. A flag that
indicates the reset cause is located in the reset control flag register (RESF) for when an internal reset
signal is generated by the watchdog timer (WDT) or low-voltage-detection (LVI) circuit. RESF is not
cleared to 00H and the flag is set to 1 when an internal reset signal is generated by WDT or LVI.
For details of RESF, see
CHAPTER 12 RESET FUNCTION
.