Chapter 24 Low-Voltage Detector; Functions Of Low-Voltage Detector; Configuration Of Low-Voltage Detector - NEC 78K0 Series User Manual

24.1 Functions of Low-Voltage Detector

The low-voltage detector (LVI) has the following functions.
• Compares supply voltage (V
internal reset signal when V
• Compares a voltage input from an external input pin (EXLVI) with the detection voltage (V
and generates an internal interrupt signal or internal reset signal when EXLVI < V
• The supply voltage (V
• Interrupt or reset function can be selected by software.
• Operable in STOP mode.
When the low-voltage detector is used to reset, bit 0 (LVIRF) of the reset control flag register (RESF) is set to 1 if
reset occurs. For details of RESF, see CHAPTER 22 RESET FUNCTION.

24.2 Configuration of Low-Voltage Detector

The block diagram of the low-voltage detector is shown in Figure 24-1.
EXLVI/P120/
Low-voltage detection level
selection register (LVIS)
536

CHAPTER 24 LOW-VOLTAGE DETECTOR

) and detection voltage (V
DD
< V . Detection levels (16 levels) of supply voltage can be changed by software.
DD LVI
) or voltage input from an external input pin (EXLVI) can be selected by software.
DD
Figure 24-1. Block Diagram of Low-Voltage Detector
N-ch
INTP0
Reference
voltage
source
Internal bus
Preliminary User's Manual U17260EJ3V1UD
), and generates an internal interrupt signal or
LVI
V
DD
+
−
Low-voltage detection register
(LVIM)
= 1.21 V (TYP.)),
EXLVI
.
EXLVI
Internal reset signal
INTLVI