UPD78F9234MC-5A4-A Datasheet, PDF (258/419 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

CHAPTER 16 POWER-ON-CLEAR CIRCUIT
16.1 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 (TYP.)), and generates internal reset signal
when VDD < VPOC.
• Compares supply voltage (VDD) and detection voltage (VPOC = 2.1 V (TYP.)), 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. Use these products in the following voltage range because the detection voltage (VPOC) of the
POC circuit is the supply voltage range.
Standard product, (A) grade product: 2.2 to 5.5 V, (A2) grade product: 2.26 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 15 RESET FUNCTION.
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User’s Manual U17446EJ5V0UD