WM8152

Production Data

w

PD, Rev 4.3, August 2008

14

MCLK

VSMP

VS

R

R

R

R

Figure 9 Reset Sample and Clamp Timing

For CIS type sensor signals, non-CDS processing is used. In this case, the video level is processed

with respect to the voltage on pin VRLC/VBIAS, generated internally or externally as described

mode; non-CDS processing is achieved by setting switch 2 in the lower position, CDS = 0.

OFFSET ADJUST AND PROGRAMMABLE GAIN

The output from the CDS block is a differential signal, which is added to the output of an 8-bit Offset

DAC to compensate for offsets and then amplified by an 8-bit PGA. The gain and offset can be set

for each of three colours by writing to control bits DACx[7:0] and PGAx[7:0] (where x can be R, G or

B).

In colour line-by-line mode the gain and offset coefficients that are applied to the PGA and offset

DAC can be multiplexed by control of the INTM[1:0] bits as shown in Table 2.

INTM[1:0]

DESCRIPTION

00

Red offset and gain registers are applied to offset DAC and PGA

(DACR[7:0] and PGAR[7:0])

01

Green offset and gain registers applied to offset DAC and PGA

(DACG[7:0] and PGAG[7:0])

10

Blue offset and gain registers applied to offset DAC and PGA

(DACB[7:0] and PGAB[7:0])

11

Reserved.

Table 2 Offset DAC and PGA Register Control

The gain characteristic of the WM8152 PGA is shown in Figure 10. Figure 11 shows the maximum

input voltage (at VINP) that can be gained up to match the ADC full-scale input range (2.5V).

0

1

2

3

4

5

6

7

8

9

0

64

128

192

256

GAIN REGISTER VALUE, PGA[7:0]

0

0.5

1

1.5

2

2.5

3

3.5

0

64

128

192

256

GAIN REGISTER VALUE, PGA[7:0]

Figure 10 PGA Gain Characteristic

Figure 11 Peak Input Voltage to Match ADC Full-scale