SSD1854U Ver la hoja de datos (PDF) - Solomon Systech

Número de pieza

componentes Descripción

Fabricante

SSD1854U

LCD Segment / Common Driver with Controller CMOS

Solomon Systech  

7.10 Level selector

Level Selector is a control of the display synchronization. Display voltage can be separated into

two sets and used with different cycles. Synchronization is important since it selects the

required LCD voltage level to the HV Buffer Cell, which in turn outputs the COM or SEG LCD

waveform.

7.11 HV Buffer Cell (Level Shifter)

HV Buffer Cell works as a level shifter which translated the low voltage output signal to the

required driving voltage. The output is shifted out with an internal FRM clock, which comes

from the Display Timing Generator. The voltage levels are given by the level selector, which is

synchronized with the internal M signal.

For a panel with N rows and M columns, the optimal LCD driving voltage are given as:

( ) VL7 −VL4 = VL4 −VSS =

N

4

×

2

N

N −1

×Vth

( ) VL6

− VL4

= VL4

− VL 2

=

4×

VL7 −VL4

N

And

VL5

− VL 4

= VL4

− VL 3

=

VL6

− VL 4

2

where:

Vth is the threshold voltage of the LCD panel

VL7 is the maximum (Row) driving level with reference to VSS

(The peak-to-peak Row driving voltage is given by VL7-VSS)

VL4 is the middle of all driving levels

VL6, VL5, VL3 and VL2 are the other Column driving levels

(The peak-to-peak Column driving voltage is given by VL6-VSS)

Relationship between the levels:

VL7 > VL6 > VL5 > VL4 > VL3 > VL2 > VSS

and

VCC > VL4 + 2V

SSD1854

Series

Rev 1.0

08/2002

14

SOLOMON

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