UPD78F1502AGK-GAK-AX Datasheet, PDF (814/1031 Pages) Renesas Technology Corp – 16-Bit Single-Chip Microcontrollers

78K0R/Lx3
CHAPTER 23 POWER-ON-CLEAR CIRCUIT
CHAPTER 23 POWER-ON-CLEAR CIRCUIT
23.1 Functions of Power-on-Clear Circuit
The power-on-clear circuit (POC) is mounted onto all 78K0R/Lx3 microcontroller products.
The power-on-clear circuit has the following functions.
• Generates internal reset signal at power on.
The reset signal is released when the supply voltage (VDD) exceeds 1.61 V ±0.09 V.
Caution If the low-voltage detector (LVI) is set to ON by an option byte by default, the reset signal is not
released until the supply voltage (VDD) exceeds 2.07 V ±0.2 V.
• Compares supply voltage (VDD) and detection voltage (VPDR = 1.59 V ±0.09 V), generates internal reset signal when
VDD < VPDR.
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), low-voltage-detector (LVI), or illegal instruction
execution. 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.
R01UH0004EJ0501 Rev.5.01
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Jun 20, 2011