Chapter 21 Low-Voltage Detector; Functions Of Low-Voltage Detector; Configuration Of Low-Voltage Detector - NEC 78K0 User Manual

21.1 Functions of Low-Voltage Detector

The low-voltage detector (LVI) has the following functions.
• Compares supply voltage (V
internal reset signal when V
• Detection levels (seven levels)
• Interrupt or reset function can be selected by software.
• Operable in STOP mode.
Note Five levels in the case of (A1) grade products and (A2) grade products.
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, refer to CHAPTER 18 RESET FUNCTION.

21.2 Configuration of Low-Voltage Detector

The block diagram of the low-voltage detector is shown below.
V
DD

CHAPTER 21 LOW-VOLTAGE DETECTOR

) and detection voltage (V
DD
< V .
DD LVI
Note
of supply voltage can be changed by software.
Figure 21-1. Block Diagram of Low-Voltage Detector
V
DD
N-ch
+
−
Detection
voltage source
(V )
LVI
Low-voltage detection level
selection register (LVIS)
Internal bus
User's Manual U16227EJ2V0UD
), and generates an internal interrupt signal or
LVI
Low-voltage detection register
(LVIM)
Internal reset signal
INTLVI
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