AD9807/AD9805

–20–

REV. 0

NO

BRING STRTLN HIGH

THE FIRST PIXEL IS GREEN

THE SECOND PIXEL IS RED, ALTERNATING GRGR...

BRING STRTLN LOW AT THE END OF THE LINE

NEXT LINE

GRGR AGAIN

(NEW FRAME)

?

YES

APPLY AT LEAST ONE ADCCLK CYCLE

WRITE A "1" TO THE LSB OF THE BAYER REGISTER

BRING STRTLN LOW

SET PGA AND INPUT OFFSET FOR RED

PIXELS USING THE BLUE REGISTERS

SET PGA AND INPUT OFFSET FOR GREEN

PIXELS USING THE GREEN REGISTERS

CHANGE THE PGA AND INPUT OFFSET OF BLUE

REGISTERS FOR BLUE PIXELS

BRING STRTLN HIGH

THE FIRST PIXEL IS BLUE

THE SECOND PIXEL IS GREEN, ALTERNATING BGBG...

BRING STRTLN LOW AT THE END OF THE LINE

CHANGE GAIN

AND OFFSET

FOR RED PIXELS

WITH BLUE

REGISTERS

Figure 21. Bayer Mode Operation

Grounding and Decoupling

Figure 22 shows the recommended decoupling capacitors and

ground connections for the AD9807/AD9805. Notice that all of

the power and ground connections are common for the analog

and digital portions of the chip. This would be the best way to

connect the device on a board containing a large number of

digital components. By treating the AD9807/AD9805 as an

analog component, the on-board digital circuitry is considered

“quiet digital” and the digital supply pins are connected to the

clean analog supply and analog ground plane. For this tech-

nique to work well, it is important that the digital supply pins be

well decoupled to the analog ground plane and that the digital

outputs of the AD9807/AD9805 are buffered to minimize the

digital drive current. The buffers would be referred to the digital

supply and ground. This scheme is preferable to tying the digital

portion of the AD9807/AD9805 to a noisy digital ground and

power plane, capacitively coupling noise to the analog circuitry

within the device. The AD9807/AD9805 evaluation boards use

this grounding method, shown in Figures 26 and 27. If a

minimum amount of digital circuitry exists on the board, it is

possible that the power and ground connections of the AD9807

can be separated; be sure to maintain a single point connection

between the two ground planes at the AD9807/AD9805.

+5

0.1µF

0.1µF

0.1µF

10µF

+

0.1µF

+

10µF

0.1µF

0.1µF

0.1µF

+5

52

+5

0.1µF

0.1µF

+5

28

+5

0.1µF

DVSS

DVDD

29

41

40

51

1

AD9807/AD9805

(PINS OMITTED FOR CLARITY)

AVDD

AVSS

CAPT

CAPT

CAPB

CAPB

REF

CML

AVSS

AVSS

AVSS

AVDD

DVSS

DRVDD

DRVSS

2

3

4

5

6

7

8

10

12

14

15

DVSS

DVDD

Figure 22.