點晶科技股份有限公司

SILICON TOUCH TECHNOLOGY INC.

DM164

8x3-CHANNEL CONSTANT CURRENT LED DRIVERS

Version:A.002

Page 21

c) Less Than 16-bit PWM Grayscale Application

c.1 IWAVE=”H” and less than 16-bit PWM application

When the DM164 operates at n-bit PWM grayscale application and IWAVE is set to ”H”

(where n is less than 16). Users must add k-bit dummy data into the 16-bit GD mode data

of each channel (where k = 16-n). The 16-bit GD mode data format of each channel is

showed below:

Data

[n-1]

PWM

MSB

‧‧‧

0

0

‧‧‧

Data

[1]

Data

[0]

Data

[n-2]

PWM

MSB-1

PWM

LSB

PWM

LSB+1

n-bit

k-bit

16-bit

n-bit PWM Data

k-bit Dummy Data

The k-bit MSB of 16-bit GD mode data of each channel must be filled with all “0” ( k=16-n ).

For example:

When the DM164 operates at 14-bit PWM grayscale application and IWAVE=”H”, the 2-bit

MSB of the 16-bit GD mode data must be filled with “0”. The 16-bit data format is showed

below:

Data

[13]

PWM

MSB

0

0

‧‧‧

Data

[1]

Data

[0]

Data

[12]

PWM

MSB-1

PWM

LSB

PWM

LSB+1

14-bit

2-bit

16-bit

14-bit PWM Data

2-bit

Dummy Data

Figure 14 shows the timing diagram when the DM164 operates at n-bit PWM grayscale

application. The frame cycle of n-bit PWM grayscale application can be controlled by GCK

and LTH signals.