CHAPTER 11 POWER-ON-CLEAR CIRCUITS
User’s Manual U14826EJ5V0UD
131
(c) Processing to enable LVI interrupt again after LVI interrupt servicing
SET1
LVIMK1;
LVI interrupt disabled
CLR1
LVION1;
LVI operation disabled
SET1
LVION1;
LVI operation enabled
CLR1
LVIMK1;
LVI interrupt enabled
EI
Figure 11-9 shows the LVI circuit operation timing.
Figure 11-9. LVI Circuit Operation Timing
Vectored interrupt
Vectored interrupt does not occur
Power supply voltage (V
DD
)
Detection voltage (V
LVI
)
1.8 V
LVION1
IE
INTLVI1
LVIIF1
LVIMK1
2 ms
Caution The low-voltage detection interrupt request flag (LVIIF1) is set at the rising edge of the LVI
circuit comparator output signal (INTLVI1). Therefore, the power supply voltage (V
DD
) becomes
lower than the detection voltage (V
LVI
) during LVI operation, and if that state continues after
INTLVI1 generation, LVIIF1 is not set. After low-voltage detection, when set as V
DD
> V
LVI
and
then V
DD
< V
LVI
again, LVIIF1 is set.