UPD7228 datasheet(30/39 Pages) NEC

30 / 39 page

Data Sheet S10299EJ4V0DS00

µµµµ PD16434

R1 =

× R2 (16-time-divisions)

5.2 Reduction in Current Consumption by RESET Signal

If a resistor network is used to supply the LCD drive reference voltage, some current is drained by the resistor

network connected across VDD and VSS when no display operation is performed, such as when the

µ PD16434 is in

the STOP mode or when it is being reset. Therefore, for a system to which reducing the current draw is extremely

important, the current path thorough the resistor network must be cut off by an external circuit, when no displaying is

performed, to eliminate unnecessary current flow.

Figure 5–5 shows a circuit which cuts off the current to the resistor network during reset state (RESET = high)

using the the RESET signal level instead of the VSS level.

Figure 5–5. Example of Controlling Current Path Using RESET Signal

VDD(VLC0)

VDD

VLC1

VLC2

VLC3

VLC4

VLC5

RESET

Output port

µPD16434

CPU

VDD

Remark The power to the CPU and the

µ PD16434 must be from the same source.

)

5(V

LCD

−

UPD7228 Datasheet(PDF) 30 Page - NEC