ST7585 datasheet(49/51 Pages) SITRONIX

49 / 51 page

ST7585

Ver 1.0c

49/51

2009/04/14

Selection of Application Voltage

Referential LCD Module Setting

VDD1=2.8V, VDD2 =2.8V, Panel Size=1.4

”, Ta=25°C

Duty

Booster

Vop

Bias

Adjustment

Temperature

Effect (-30

°C)

Max. Vop

8.8V

1/9

+/- 0.3V

+ 0.24V

9.34V

1/66

8.6V

1/7

+/- 0.2V

+ 0.23V

8.93V

The Bias can be used to select suitable Liquid Crystal.

It is usually reserved some range for user adjustment (the reserved range depends on customer

’s system).

Be sure that: there is a suitable V0 level can be programmed into the V0 control register (V0[4:0]).

The internal Regulator has Temperature Gradient (-0.05%/

°C).

Be sure that: the

“Max. Vop” is still available by internal Booster (watch out the Booster Efficiency).

Besides, the VG limitation should be followed.

The display performance should be checked with customer

’s LCD modules.

Note:

Positive Booster: (VDD2 x 5 x BE)

≥ V0 or (VDD2 x5 x BE) ≥ Vop;

Negative Booster: [

–VDD2 x4 x BE] ≤ XV0 or [VDD2 x4 x BE] ≥ (Vop - VG),

where VG = Vop x 2 / N;

Vop requirement: [VDD2 x4 x BE]

≥ [Vop x (N - 2) / N] or [Vop ≤ VDD2 x4 x BE x N / (N - 2)].

BE is the booster efficiency. Referential values are listed below:

(assume VDD2 =2.8V)

Module Size

≤ 1.4”: BE=80% (Typical);

Module Size = 1.5

”~1.8”: BE=76% (Typical).

Actual BE should be determined by module loading and ITO resistance value.

1.6V

≤ VG < VDD2. Recommend VG is: VDD2-VG around 0.5~0.8V.

VM=VG/2 and 0.8V

≤ VM < VDD2.

The worse condition should be considered:

Low temperature effect and display on with snow pattern on panel (max: 1.8

”).

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