LH155BA datasheet(22/51 Pages) SHARP

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LH155BA

2.18. Booster Circuit

Setting BS register, booster circuit multiple can be

selected. Placing capacitor C1 across CAP+ and

CAP–, across VEE2 and VSS, across VEE3 and VSS

and across VOUT and VSS boosts four times.

Placing capacitor C1 across CAP+ and CAP–,

across VEE2 and VSS, across VOUT and VSS, and

setting VEE3 to NC when boosting three times.

Placing C1 across CAP+ and CAP–, across VOUT

and VSS, and setting VEE2 and VEE3 to NC when

boosting two times.

The boosted voltage is output to VOUT pin.

Since the booster circuit uses the clock derived

from the internal oscillation circuit or external clock

as the boosting clock, the internal oscillation circuit

must be enabled, or if external clock is selected, it

must be fed to CK pin.

The output level at the VOUT pin does not exceed

the recommended maximum operating voltage

(14.0 V) when the voltage is boosted. If this value

is exceeded, the operation of the LH155BA is not

covered by warranty.

When boosting four times and three times,

placement of capacitor is as shown below.

VEE = 1.8 V

VSS = 0 V

VOUT = 5.4 V

When Boosted Three Times

VEE = 1.8 V

VSS = 0 V

VOUT = 7.2 V

When Boosted Four Times

CAP+

CAP–

VEE2

VEE3

VOUT

When Boosted Four Times

CAP+

CAP–

VEE2

VEE3

VOUT

When Boosted Three Times

If charge up of LCD drive voltage is not successful,

check

capacity,

voltage

dependency

and

temperature characteristics of external capacitor,

and select appropriate device. When charge up is

unsuccessful, it is advisable to charge up LCD drive

voltage step by step (x 2, x 3, x 4) by inputting

software from external microcontroller.

LH155BA Datasheet(PDF) 22 Page - Sharp Corporation

LH155BA Datasheet(HTML) 22 Page - Sharp Corporation

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