SM5M2 datasheet(24/28 Pages) SHARP

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SM5M2

- 24 -

VDD

RF1

SM5M2

R1 = R2

VOA

VDD

• Blank display

There are two way to blank the entire display to

match the purpose.

(a) Blanking the display for a short time.

Set bit 0 of the RF register to "1" : Display

Set bit 0 of the RF register to "0" : Blank state

(b) Blanking the display for a long period mainy to

reduce supply current.

Set bit 0 and 1 of the RF register to "1" :

Display

Set bit 0 and 1 of the RF register to "0" :

Blank state

When bit 1 of the RF register is set "0", the voltage

(VDD) applied to the bleeder resistors is turned off

and common outputs and segment outputs are

dropped to GND level so that the display blanks.

By cutting off the bleeder supply, the current

consumption can be greatly reduced. However,

when the display is blanked using method (b), the

response speed of the LCD returning to the display

state drops slightly. The RF register is in the blank

state after initialization (reset state) from hardware

reset.

Fig. 17

Booster Circuit

SM5M2

VDD

VOA

Fig. 18

Externally Connected Capacitor Circuit

• VOA pin

Bleeder resistors are built-in to drive the LCD at 1/2

bias. The bieeder resistors have the configuration

shown in Fig. 17. When bit 1 of the RF registor is

set and VDD is 3 V, VOA output 1.5 V.

Normally, the VOA pin is used in its open state. To

drive an LCD with a large display area, the leading

edge of the LCD drive waveform can be improved

by connecting capacitor across the VOA pin and

VDD. The same effect can be obtained by

connecting capacitor across the VOA pin and GND.

When bit 1 of the RF register is set "0", VOA drop

to GND level to reduce power consumption. At the

same time, the H0-H3 and S0-S33 pin are GND

level.

• Booster circuit

It is necessary to apply external capacitors

between VDD pin and VOA pin. (see Fig. 18)

SM5M2 Datasheet(PDF) 24 Page - Sharp Corporation

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