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SSD1811_

Application of SSD181X/SSD1815A/SSD1815B to Existing LCD Modules

Solomon Systech  

APPLICATION NOTE 6: CASCADE OPERATION

FOR SSD181X/SSD1815A/SSD1815B

Two SSD181X/SSD1815A/SSD1815B ICs can be cascaded to form a “master amd slave”system which enlarge the

maximum display size to 264 segment x 64 common. The master device generates all the necessary analog and digital

control signals for the slave device. The following section summarizes some important note of the system.

Analog control part:

It is obvious that both master and slave devices should have the same LCD driving capability under various operating

conditions. The LCD driving voltage of the whole cascade system is generated by the analog circuitry of the master de-

vice. The analog circuitry consists of DC-DC voltage booster, voltage reguator with contrast control, temperature com-

pensation circuitry and voltage divider. The divider levels of the master device, which includes VL2 to VL6, are used to

generate the divider levels of the slave device. The implementations are carried out by:

1. Connect all the divider output pins (VL2 to VL6) of master device to the slave device.

2. Disable all the analog circuitry in the slave device by software command (28H).

Digital control part:

The communication between master and slave device is carried out by three signals. These three signals are Frame

signal (M), display blanking signal (DOFF) and the system clock signal (CL). The master device provides the frame,

display blanking and the system clock signals to the slave device. As a result, the slave device is synchronized with the

master device. The data interface of the master and slave devices should be the same, either parallel or serial interface.

The clock selection pins of the master and slave devices should be the same, either external or internal clock mode.

The following digram shows an example of the cascade application. The product features are listed below.

- Maximum display size: 264 segment x 64 common

- Driving scheme: 4-lines serial interface

- Supply Vdd: 2.4 to 3.5V

- VLCD driving voltage: - 9.3V

- Regulator, clock, contrast control: All internal mode

- Boosting configuration: 4X boosting mode

SOLOMON

Application of SSD181X/SSD1815A/SSD1815B to Existing LCD Modules

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