NEC 78K0 Series User Manual page 538

(1) Low-voltage detection register (LVIM)
This register sets low-voltage detection and the operation mode.
This register can be set by a 1-bit or 8-bit memory manipulation instruction.
Reset signal generation sets LVIM to 00H.
Figure 24-2. Format of Low-Voltage Detection Register (LVIM)
Address: FFBEH After reset: 00H
<7>
Symbol
LVION
LVIM
Notes 2, 3
LVION
0 Disables operation
1 Enables operation
Note 2
LVISEL
0 Detects level of supply voltage (V
1 Detects level of input voltage from external input pin (EXLVI)
Note 2
LVIMD
• LVISEL = 0: Generates interrupt signal when supply voltage (V
0
• LVISEL = 1: Generates interrupt signal when input voltage from external input pin
• LVISEL = 0: Generates internal reset signal when supply voltage (V
1
• LVISEL = 1: Generates internal reset signal when input voltage from external input pin
Note 4
LVIF
• LVISEL = 0: Supply voltage (V
0
• LVISEL = 1: Input voltage from external input pin (EXLVI) ≥ detection voltage (V
• LVISEL = 0: Supply voltage (V
1
• LVISEL = 1: Input voltage from external input pin (EXLVI) < detection voltage (V
Notes 1. Bit 0 is read-only.
2. LVION, LVIMD, and LVISEL are cleared to 0 in the case of a reset other than an LVI reset.
These are not cleared to 0 in the case of an LVI reset.
3. When LVION is set to 1, operation of the comparator in the LVI circuit is started. Use
software to wait for an operation stabilization time (10
the voltage is confirmed at LVIF.
4. The value of LVIF is output as the interrupt request signal INTLVI when LVION = 1 and
LVIMD = 0.
Cautions 1. To stop LVI, follow either of the procedures below.
• When using 8-bit memory manipulation instruction: Write 00H to LVIM.
• When using 1-bit memory manipulation instruction: Clear LVION to 0.
2. Input voltage from external input pin (EXLVI) must be EXLVI < V
538
CHAPTER 24 LOW-VOLTAGE DETECTOR
Note 1
R/W
6 5 4
0 0 0
Enables low-voltage detection operation
Voltage detection selection
DD
Low-voltage detection operation mode selection
(V )
LVI
(EXLVI) < detection voltage (V
voltage (V )
LVI
(EXLVI) < detection voltage (V
Low-voltage detection flag
DD
disabled
or when operation is disabled
DD
Preliminary User's Manual U17260EJ3V1UD
3 <2>
0 LVISEL
)
)
EXLVI
)
EXLVI
) ≥ detection voltage (V
), or when operation is
LVI
) < detection voltage (V )
LVI
µ
s (MAX.)) when LVION is set to 1 until
<1> <0>
LVIMD LVIF
) < detection voltage
DD
) < detection
DD
),
EXLVI
)
EXLVI
.
DD