UPD78F1502AGK-GAK-AX Datasheet, PDF (839/1031 Pages) Renesas Technology Corp – 16-Bit Single-Chip Microcontrollers

78K0R/Lx3
CHAPTER 24 LOW-VOLTAGE DETECTOR
24.5 Cautions for Low-Voltage Detector
(1) Measures method when supply voltage (VDD) frequently fluctuates in the vicinity of the LVI detection voltage
(VLVI)
In a system where the supply voltage (VDD) fluctuates for a certain period in the vicinity of the LVI detection voltage
(VLVI), the operation is as follows depending on how the low-voltage detector is used.
Operation example 1: When used as reset
The system may be repeatedly reset and released from the reset status.
The time from reset release through microcontroller operation start can be set arbitrarily by the following
action.
<Action>
After releasing the reset signal, wait for the supply voltage fluctuation period of each system by means of a
software counter that uses a timer, and then initialize the ports (see Figure 24-11).
Remark
If bit 2 (LVISEL) of the low voltage detection register (LVIM) is set to “1”, the meanings of the above words
change as follows.
• Supply voltage (VDD) → Input voltage from external input pin (EXLVI)
• Detection voltage (VLVI) → Detection voltage (VEXLVI = 1.21 V)
R01UH0004EJ0501 Rev.5.01
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Jun 20, 2011