User’s Manual U16899EJ2V0UD404CHAPTER 22 POWER-ON-CLEAR CIRCUIT22.1 Functions of Power-on-Clear CircuitThe 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 signalwhen V DD < 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. The supply voltage is V DD = 2.0 to 5.5 V when the Ring-OSC clock or subsystem clock is used,but be sure to use the product in a voltage range of 2.2 to 5.5 V because the detection voltage(VPOC) of the POC circuit is 2.1 V ±0.1 V.Remark This product incorporates multiple hardware functions that generate an internal reset signal. A flag thatindicates the reset cause is located in the reset control flag register (RESF) for when an internal resetsignal is generated by the watchdog timer (WDT), low-voltage-detection (LVI) circuit, or clock monitor.RESF is not cleared to 00H and the flag is set to 1 when an internal reset signal is generated by WDT,LVI, or the clock monitor.For details of the RESF, refer to CHAPTER 20 RESET FUNCTION.
