UPD78F0411GA-GAM-AX Datasheet, PDF (491/564 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

CHAPTER 22 LOW-VOLTAGE DETECTOR
(3) Port mode register 12 (PM12)
When using the P120/EXLVI/INTP0 pin for external low-voltage detection potential input, set PM120 to 1. At this
time, the output latch of P120 may be 0 or 1.
PM12 can be set by a 1-bit or 8-bit memory manipulation instruction.
Reset signal generation sets PM12 to FFH.
Figure 22-4. Format of Port Mode Register 12 (PM12)
Address: FF2CH After reset: FFH R/W
Symbol
7
6
5
4
3
2
1
PM12
1
1
1
1
1
1
1
0
PM120
PM120
0
1
P120 pin I/O mode selection
Output mode (output buffer on)
Input mode (output buffer off)
22.4 Operation of Low-Voltage Detector
The low-voltage detector can be used in the following two modes.
(1) Used as reset (LVIMD = 1)
• If LVISEL = 0, compares the supply voltage (VDD) and detection voltage (VLVI), generates an internal reset
signal when VDD < VLVI, and releases internal reset when VDD ≥ VLVI.
• If LVISEL = 1, compares the input voltage from external input pin (EXLVI) and detection voltage (VEXLVI = 1.21
V (TYP.)), generates an internal reset signal when EXLVI < VEXLVI, and releases internal reset when EXLVI ≥
VEXLVI.
(2) Used as interrupt (LVIMD = 0)
• If LVISEL = 0, compares the supply voltage (VDD) and detection voltage (VLVI). When VDD drops lower than
VLVI (VDD < VLVI) or when VDD becomes VLVI or higher (VDD ≥ VLVI), generates an interrupt signal (INTLVI).
• If LVISEL = 1, compares the input voltage from external input pin (EXLVI) and detection voltage (VEXLVI = 1.21
V (TYP.)). When EXLVI drops lower than VEXLVI (EXLVI < VEXLVI) or when EXLVI becomes VEXLVI or higher
(EXLVI ≥ VEXLVI), generates an interrupt signal (INTLVI).
While the low-voltage detector is operating, whether the supply voltage or the input voltage from an external input
pin is more than or less than the detection level can be checked by reading the low-voltage detection flag (LVIF: bit 0
of LVIM).
Remark LVIMD: Bit 1 of low-voltage detection register (LVIM)
LVISEL: Bit 2 of LVIM
User’s Manual U18698EJ1V0UD
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