Datasheet

CHAPTER 22 LOW-VOLTAGE DETECTOR
User’s Manual U18698EJ1V0UD
490
22.4.1 When used as reset
(1) When detecting level of supply voltage (V
DD)
• 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
DD)) (default value).
<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
μ s (MAX.)).
<6> Wait until it is checked that (supply voltage (VDD) ≥ detection voltage (VLVI)) by bit 0 (LVIF) of LVIM.
<7> Set bit 1 (LVIMD) of LVIM to 1 (generates reset when the level is detected).
Figure 22-5 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
DD) ≥ detection voltage (VLVI) when LVIMD is set to 1, an internal reset
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.