UPD78F0838 Renesas Electronics Corporation., UPD78F0838 Datasheet - Page 799

• Manufacturer Part Number: UPD78F0838
• Description: 8-bit Single-chip Microcontrollers
• Manufacturer: Renesas Electronics Corporation.

24.5 Cautions for Low-Voltage Detector
(V
(1) When used as reset
(2) When used as interrupt
<Action>
(1) When used as reset
(2) When used as interrupt
LVI
In a system where the supply voltage (V
), the operation is as follows depending on how the low-voltage detector is used.
The system may be repeatedly reset and released from the reset status.
In this case, the time from release of reset to the start of the operation of the microcontroller can be arbitrarily set
by taking action (1) below.
Interrupt requests may be frequently generated. Take (b) of action (2) below.
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 24-9).
(a) Confirm that “supply voltage (V
(b) In a system where the supply voltage fluctuation period is long in the vicinity of the LVI detection voltage, wait
Remark
“supply voltage (V
of the LVI interrupt by using bit 0 (LVIF) of the low-voltage detection register (LVIM). Clear bit 0 (LVIIF) of
interrupt request flag register 0L (IF0L) to 0.
for the supply voltage fluctuation period, confirm that “supply voltage (V
detecting the falling edge of V
edge of V
If bit 2 (LVISEL) of the low voltage detection register (LVIM) is set to “1”, the meanings of the above
words change as follows.
DD
Supply voltage (V
Detection voltage (V
, using the LVIF flag, and clear the LVIIF flag to 0.
DD
) < detection voltage (V
DD
CHAPTER 24 LOW-VOLTAGE DETECTOR
)
DD
LVI
, or “supply voltage (V
)
Preliminary User’s Manual U19748EJ1V0UD
DD
DD
)
) fluctuates for a certain period in the vicinity of the LVI detection voltage
detection voltage (V
Input voltage from external input pin (EXLVI)
Detection voltage (V
LVI
)” when detecting the rising edge of V
DD
) < detection voltage (V
EXLVI
LVI
)” when detecting the falling edge of V
= 1.21 V)
DD
)
detection voltage (V
LVI
)” when detecting the rising
DD
, in the servicing routine
LVI
)” when
DD
797
, or