Tel: 886-2-66296288

Fax: 886-2-29174598

URL: http://www.princeton.com.tw

PT6955 V1.5

- 5 -

June, 2005

LED Driver IC

PT6955

FUNCTION DESCRIPTION

COMMANDS

A command is the first byte (b0 to b7) inputted to PT6955 via the DIN Pin after STB Pin has changed

from “HIGH” to “LOW” State. If for some reason the STB Pin is set to “HIGH” while data or commands

are being transmitted, the serial communication is initialized, and the data/commands being

transmitted are considered invalid.

COMMAND 1: DISPLAY MODE SETTING COMMANDS

PT6955 provides 4 display mode settings as shown in the diagram below: As stated earlier a command

is the first one byte (b0 to b7) transmitted to PT6955 via the DIN Pin when STB is “LOW”. However, for

these commands, Bit No. 3 to Bit No.6 (b2 to b5) are ignored, Bit No.7 & Bit No.8 (b6 to b7) are given

a value of “0”.

The Display Mode Setting Commands determine the number of segments and grids to be used (1/4 to

1/7 duty, 12 to 9 segments). When these commands are executed, the display is forcibly turned off.

A display command “ON” must be executed in order to resume display. If the same mode setting is

selected, no command execution is take place, therefore, nothing happens.

When Power is turned “ON”, the 7-Grid, 9-Segment Mode is selected.

MSB

LSB

0

0

-

-

-

-

b1 b0

Not Relevant

Display Mode Settings:

00: 4 digits, 12 segments

01: 5 digits, 11 segments

10: 6 digits, 10 segments

11: 7 digits, 9 segments