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AD9826

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REV. A

MUX Configuration Register

The MUX Configuration Register controls the sampling chan-

nel order and the 2-Channel Mode configuration in the AD9826.

Bits D8 and D3–D0 should always be set low. Bit D7 is used

when operating in 3-Channel or 2-Channel Mode. Setting Bit

D7 high will sequence the MUX to sample the Red channel

first, then the Green channel, and then the Blue channel. When

in 3-channel mode, the CDSCLK2 pulse always resets the MUX

to sample the Red channel first (see Figure 11). When Bit D7 is

set low, the channel order is reversed to Blue first, Green sec-

ond, and Red third. The CDSCLK2 pulse will always reset the

MUX to sample the Blue channel first. Bits D6, D5, and D4 are

used when operating in 1 or 2-Channel Mode. Bit D6 is set high

to sample the Red channel. Bit D5 is set high to sample the

Green channel. Bit D4 is set high to sample the Blue channel.

The MUX will remain stationary during 1-channel mode. Two-

Channel Mode is selected by setting two of the channel select

Bits (D4–D6) high. The MUX samples the channels in the

order selected by Bit D7.

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 from 1

× to 6× in 64 increments. See

Figure 17 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

×) and an all “ones” word corresponding to the maximum

gain setting (6

×).

Offset Registers

There are three Offset Registers for individually programming

the offset in the Red, Green, and Blue channels. Bits D8 through

D0 control the offset range from –300 mV to +300 mV in 512

increments. The coding for the Offset Registers is Sign Mag-

nitude, with D8 as the sign bit. Table V shows the offset range

as a function of the Bits D8 through D0.

Table III. MUX Configuration Register Settings

Set

MUX Order

Channel Select

Set

1 = R-G-B

1 = RED

1 = GREEN

1 = BLUE

0 = B-G-R

0 = Off

*Power-on default value.

Table IV. PGA Gain Register Settings

Gain (V/V)

Gain (dB)

Set to 0

MSB

LSB

000000000

1.0

0.0

000000001

1.013

0.12

•

000111111

5.56

14.9

000111111

6.0

15.56

*Power-on default value.

Table V. Offset Register Settings

Offset (mV)

MSB

LSB

000000000

000000001

+1.2

•

011111111

+300

100000000

100000001

–1.2

•

111111111

–300

*Power-on default value.

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