Datasheet

AD9822
Rev. B | Page 14 of 20
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 15 for the PGA gain vs. the PGA
register code. The coding for the PGA registers is straight binary, with an all 0s word corresponding to the minimum gain setting (1×)
and an all 1s word corresponding to the maximum gain setting (5.7×).
Table 9. PGA Gain Register Settings
D8 D7 D6 D5 D4 D3 D2 D1 D0
Set to 0 Set to 0 Set to 0 MSB LSB Gain (V/V) Gain (dB)
0 0 0 0 0 0 0 0 0
1
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
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 10 shows the offset range as a function of the Bits D8 through D0.
Table 10. Offset Register Settings
D8 (MSB) D7 D6 D5 D4 D3 D2 D1 D0 (LSB) Offset (mV)
0 0 0 0 0 0 0 0 0
1
0
0 0 0 0 0 0 0 0 1 +1.2
• •
• •
• •
0 1 1 1 1 1 1 1 1 +350
1 0 0 0 0 0 0 0 0 0
1 0 0 0 0 0 0 0 1 −1.2
• •
• •
• •
1 1 1 1 1 1 1 1 1 −350
1
Power-on default value.