Chapter 23 Power-On-Clear Circuit; Functions Of Power-On-Clear Circuit - NEC 78K0 Series User Manual

23.1 Functions of Power-on-Clear Circuit

The power-on-clear circuit (POC) has the following functions.
• Generates internal reset signal at power on.
In the 1.59 V POC mode (option byte: POCMODE = 0), the reset signal is released when the supply voltage
) exceeds 1.59 V ±0.15 V.
(V
DD
In the 2.7 V/1.59 V POC mode (option byte: POCMODE = 1), the reset signal is released when the supply
) exceeds 2.7 V ±0.2 V.
voltage (V
DD
• Compares supply voltage (V
when V < V , and releases reset when V
DD POC
Caution If an internal reset signal is generated in the POC circuit, the reset control flag register (RESF)
is cleared to 00H.
Remark This product incorporates multiple hardware functions that generate an internal reset signal. A flag
that indicates the reset source 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-detector (LVI). 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 22 RESET FUNCTION.
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CHAPTER 23 POWER-ON-CLEAR CIRCUIT

) and detection voltage (V
DD
≥ V
DD POC
Preliminary User's Manual U17260EJ3V1UD
= 1.59 V ±0.15 V), generates internal reset signal
POC
.