UPD78F9500MA-CAC-A Datasheet, PDF (206/342 Pages) Renesas Technology Corp – 8-Bit Single-Chip Microcontrollers

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 (VDD) and detection voltage (VPOC = 2.1 V ±0.1 V), and generates internal reset signal
when VDD < VPOC.
• Compares supply voltage (VDD) and detection voltage (VPOC = 2.1 V ±0.1 V), and releases internal reset signal
when VDD ≥ VPOC.
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 (VPOC) 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.
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User’s Manual U18172EJ3V0UD