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AS1122

Datasheet - D e t a i l e d D e s c r i p t i o n

For n devices in a chain only one identifier needs to be send to set all n devices to the same register setting.

Figure 30. Command Data for n-devices

Setting Dot Correction

The AS1122 can perform independent fine-adjustments to the output current of each channel. Dot correction is used to adjust brightness devia-

tions of LEDs connected to the output channels (OUT0:OUT11).

The device powers up with the following default settings: DC = 0 and GS = 0.

The 12 channels can be individually programmed with a 6-bit word for Dot Correction. The channel output can be adjusted in 64 steps from 0 to

Where:

DCn is the programmed dot correction value for output (DCn = 0 to 63);

n = 0 to 11

Dot correction data are simultaneously entered for all channels. The complete dot correction data format consists of 12 x 6-bit words, which

forms a 72-bit serial data packet (see Figure 31) and 8-bit for the identifier. Channel data is put on one by one, and the data is clocked in with the

MSB first.

Figure 31. Dot Correction Data Packet Format

The Dot Correction data is only valid if the exact identifier byte was send. Otherwise the data will be ignored.

Setting Greyscale Brightness (PWM)

The brightness of each channel output can be adjusted using a 12 bits-per-channel PWM control scheme which results in 4096 brightness steps,

from 0% to 100% brightness. The brightness level for each output is calculated as:

Where:

GSn is the programmed greyscale value for OUTn (GSn = 0 to 4095);

n = 0 to 11 greyscale data for all outputs.

The device powers up with the following default settings: GS = 0 and DC = 0.

DCn

63

(EQ 1)

%Brightness =

GSn

4095

(EQ 2)

x 100