UPD78F0138 NEC, UPD78F0138 Datasheet - Page 408

• Manufacturer Part Number: UPD78F0138
• Description: (UPD78xxxx) 8-Bit Single-Chip Microcontrollers
• Manufacturer: NEC

408
22.1 Functions of Power-on-Clear Circuit
The power-on-clear circuit (POC) has the following functions.
• Generates internal reset signal at power on.
• Compares supply voltage (V
• The following can be selected by a mask option.
Note This option cannot be selected in (A1) and (A2) grade products because the supply voltage V
Caution If an internal reset signal is generated in the POC circuit, the reset control flag register (RESF) is
Remark This product incorporates multiple hardware functions that generate an internal reset signal. A flag that
V
•
•
•
POC
POC disabled
POC used (detection voltage: V
POC used (detection voltage: V
5.5 V.
.
cleared to 00H.
indicates the reset cause is located in the reset control flag register (RESF) for when an internal reset
signal is generated by the watchdog timer (WDT), low-voltage-detection (LVI) circuit, or clock monitor.
RESF is not cleared to 00H and the flag is set to 1 when an internal reset signal is generated by WDT,
LVI, or the clock monitor.
For details of the RESF, refer to CHAPTER 20 RESET FUNCTION.
CHAPTER 22 POWER-ON-CLEAR CIRCUIT
DD
) and detection voltage (V
POC
POC
= 2.85 V ±0.15 V)
= 3.5 V ±0.2 V)
User’s Manual U16228EJ2V0UD
Note
POC
), and generates internal reset signal when V
DD
is 3.3 to
DD
<