When Used As Reset - NEC 78K0 Series User Manual

24.4.1 When used as reset

(1) When detecting level of supply voltage (V
• When starting operation
<1> Mask the LVI interrupt (LVIMK = 1).
<2> Clear bit 2 (LVISEL) of the low-voltage detection register (LVIM) to 0 (detects level of supply voltage
(V )) (default value).
DD
<3> Set the detection voltage using bits 3 to 0 (LVIS3 to LVIS0) of the low-voltage detection level selection
register (LVIS).
<4> Set bit 7 (LVION) of LVIM to 1 (enables LVI operation).
<5> Use software to wait for an operation stabilization time (10
<6> Wait until it is checked that (supply voltage (V
<7> Set bit 1 (LVIMD) of LVIM to 1 (generates internal reset signal when supply voltage (V
voltage (V )).
LVI
Figure 24-5 shows the timing of the internal reset signal generated by the low-voltage detector. The numbers
in this timing chart correspond to <1> to <7> above.
Cautions 1. <1> must always be executed. When LVIMK = 0, an interrupt may occur immediately
after the processing in <4>.
2. If supply voltage (V
signal is not generated.
• When stopping operation
Either of the following procedures must be executed.
When using 8-bit memory manipulation instruction:
•
Write 00H to LVIM.
When using 1-bit memory manipulation instruction:
•
Clear LVIMD to 0 and then LVION to 0.
CHAPTER 24 LOW-VOLTAGE DETECTOR
)
DD
) ≥ detection voltage (V
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) ≥ detection voltage (V
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Preliminary User's Manual U17260EJ3V1UD
µ
s (MAX.)).
)) by bit 0 (LVIF) of LVIM.
LVI
) when LVIMD is set to 1, an internal reset
LVI
) < detection
DD
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