REV. A

AD9822

–11–

PGA Gain Registers

There are three PGA registers for individually programming the gain in the red, green, and blue channels. Bits D8, D7, and D6 in

each register must be set low, and bits D5 through D0 control the gain range in 64 increments. See Figure 13 for a graph of the PGA

Gain versus PGA register code. The coding for the PGA registers is straight binary, with an all “zeros” word corresponding to the

minimum gain setting (1x) and an all “ones” word corresponding to the maximum gain setting (5.7x).

Table IV. PGA Gain Register Settings

D8

D7

D6

D5

D4

D3

D2

D1

D0

Gain (V/V)

Gain (dB)

Set to 0

Set to 0

Set to 0

MSB

LSB

00

00

0

0

0

0

0

*

1.0

0.0

0

0

0

0

0

0

0

0

1

1.013

0.12

•

•

•

•

•

•

•

•

•

0

0

0

1

1

1

1

1

0

5.4

14.6

0

0

0

1

1

1

1

1

1

5.7

15.1

*Power-on default value.

Offset Registers

There are three PGA registers for individually programming the offset in the red, green, and blue channels. Bits D8 through D0

control the offset range from –350 mV to +350 mV in 512 increments. The coding for the offset registers is sign magnitude, with D8

as the sign bit. Table V shows the offset range as a function of the Bits D8 through D0.

Table V. Offset Register Settings

D8

D7

D6

D5

D4

D3

D2

D1

D0

Offset (mV)

MSB

LSB

000000000

*

0

000000001+1.2

•

•

•

•

•

•

011111111

+350

1000000000

100000001

–1.2

•

•

•

•

•

•

111111111

–350

*Power-on default value.