UPD6P8 NEC [NEC], UPD6P8 Datasheet - Page 24

• Manufacturer Part Number: UPD6P8
• Description: MOS INTEGRATED CIRCUIT 4-BIT SINGLE-CHIP MICROCONTROLLER FOR INFRARED REMOTE CONTROL TRANSMISSION
• Manufacturer: NEC [NEC]

24
(1) If the supply voltage rises after the battery has been set, and exceeds V
(2) The supply voltage has now risen to the level at which the device can operate. Write the necessary data
(3) The device is reset if the supply voltage drops below V
(4) If the RAM retention flag is checked by software after reset has been cleared, it is 1. This means that
(5) The device is reset if the supply voltage drops below V
(6) If the RAM retention flag is checked by software after reset has been cleared, it is 0. This means that
reset is cleared. Because the supply voltage rises from 0 V, which is lower than V
detection voltage), the RAM retention flag remains in the initial status 0.
to the RAM and set the RAM retention flag to 1.
retention flag remains 1 because the supply voltage is higher than V
the contents of the RAM have not been lost. It is therefore not necessary to initialize the RAM by
software.
than V
the contents of the RAM may have been lost. If this case, initialize the RAM by software.
RAM retention flag
ID
Figure 4-3. Supply Voltage Transition and Detection Voltage ( PD6P8A, 6P8B)
. Consequently, the RAM retention flag is cleared to 0.
V
0 V
POC
V
ID
V
DD
(1)
Set to 1
(2)
Data Sheet U17848EJ3V0DS
(A)
(3)
Flag contents
are read
(4)
(B)
POC
(5)
POC
. At point (B) in the figure, the voltage is lower
. At point (A) in the above figure, the RAM
Flag contents
are read
(6)
t
POC detection voltage
(Refer to 8. POC CIRCUIT)
V
RAM retention detection voltage
V
ID
POC
ID
= 1.6 V (TYP.)
at this point.
POC
= 1.8 V (TYP.)
PD6P8, 6P8A, 6P8B
(POC detection voltage),
ID
(RAM retention