wm8152scds-v Wolfson Microelectronics plc, wm8152scds-v Datasheet - Page 14

• Manufacturer Part Number: wm8152scds-v
• Description: Single Channel 16-bit Cis/ccd Afe With 4-bit Wide Output
• Manufacturer: Wolfson Microelectronics plc

WM8152
OFFSET ADJUST AND PROGRAMMABLE GAIN
w
Figure 10 PGA Gain Characteristic
9
8
7
6
5
4
3
2
1
0
0
GAIN REGISTER VALUE, PGA[7:0]
64
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
above. The VRLC/VBIAS pin is sampled by R
mode; non-CDS processing is achieved by setting switch 2 in the lower position, CDS = 0.
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.
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).
INTM[1:0]
128
R
R
R
R
S
S
S
S
00
01
10
11
/CL (CDSREF = 00)
/CL (CDSREF = 01)
/CL (CDSREF = 10)
/CL (CDSREF = 11)
192
Red offset and gain registers are applied to offset DAC and PGA
(DACR[7:0] and PGAR[7:0])
Green offset and gain registers applied to offset DAC and PGA
(DACG[7:0] and PGAG[7:0])
Blue offset and gain registers applied to offset DAC and PGA
(DACB[7:0] and PGAB[7:0])
Reserved.
MCLK
VSMP
VS
256
DESCRIPTION
Figure 11 Peak Input Voltage to Match ADC Full-scale
s
at the same time as V
3.5
2.5
1.5
0.5
3
2
1
0
0
GAIN REGISTER VALUE, PGA[7:0]
64
s
samples the video level in this
128
PD, Rev 4.3, August 2008
192
Production Data
256
14