RL78/G15 CHAPTER 17 SELECTABLE POWER-ON-RESET CIRCUIT
R01UH0959EJ0110 Rev.1.10 Page 644 of 765
Mar 7, 2023
CHAPTER 17 SELECTABLE POWER-ON-RESET CIRCUIT
17.1 Functions of Selectable Power-on-reset Circuit
The selectable power-on-reset (SPOR) circuit has the following functions.
●
Generates internal reset signal at power on.
The reset signal is released when the supply voltage (V
DD
) exceeds the detection voltage (V
SPOR
) (V
DD
≥ V
SPOR
).
●
The SPOR circuit compares the supply voltage (V
DD
) with the detection voltage (V
SPDR
), and generates an internal
reset signal when V
DD
< V
SPDR
.
●
The detection level for the power supply detection voltage (V
SPOR
, V
SPDR
) can be selected by using the option byte
(000C1H) as one of 4 levels (for details, see 18.2 Format of User Option Byte).
Bit 0 (SPORF) of the reset control flag register (RESF) is set to 1 if reset occurs. For details of the RESF register, see
CHAPTER 16 RESET FUNCTION.
Caution The values of all flags in the reset control flag register (RESF) are retained until V
DD
reaches data
retention lower limit voltage.
Remark V
SPOR
: SPOR power supply rise detection voltage
V
SPDR
: SPOR power supply fall detection voltage
For details, see 23.6.4 SPOR circuit characteristics and 24.6.4 SPOR circuit characteristics.
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