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CHAPTER 16 RESET FUNCTION
User’s Manual U15104EJ2V0UD
7
0
6
0
5
0
4
0
3
0
2
0
1
VM45
0
POCM
Symbol
POCS
After reset
Retained
Note
R/W
R&Reset
Address
FF1BH
16.3 4.5 V Voltage Detection Function
This function is used to detect a voltage drop on the V
DD
pin below 4.5 V (4.5 V
±
0.3 V). If the voltage on the V
DD
pin drops below 4.5 V (4.5 V
±
0.3 V), bit 1 (VM45) of the POC status register (POCS) is set.
Note, however, that this 4.5 V voltage detection function does not cause internal reset.
Figure 16-6. Format of POC Status Register (POCS)
VM45
Detection of voltage level of V
DD
pin
0
Does not detect if V
DD
pin is less than 4.5 V (4.3 V
±
0.3 V)
1
Detects if V
DD
pin is less than 4.5 V (4.3 V
±
0.3 V)
Note
The value of this register is set to 03H only at power-on clear reset, and is not reset by the RESET
pin and watchdog timer.
Remark
The values of the special function registers, other than POCS and PLLUL, at power-on clear are
the same as the values following a reset by the RESET pin or watchdog timer (see Table 16-1).