HD49335F/HF

Rev.1.0, Feb.25.2004, page 13 of 29

Dummy Clamp

It adjusts the mis-clamp which occurs when taking the photo under the highlight conditions. (Like a sun) Normally it

woks with the OB clamp, however when black level is out of the range caused by hightlight enter to OB part, it changes

to clamp processing by dummy bit level. Resister settings are follows.

D12, D11, D10 of address H'F7 (Dummy CP)

0, 0, 0 ; OFF

0, 0, 1 ; +32

0, 1, 0 ; +64

0, 1, 1 ; +96

:

:

1, 1, 1 ; +224

The amount of offset are changes automatically

depends on PGA gain in the LSI.

D8, D8 of address H'F7 (DMCG)

The amount of feed back current can be

reduced with only dummy clamp.

Data = 0:1/4

1:1/8

2:1/16

3:1/32

D10 to D12 of address H'F7

Note: OB/Dummy switching part has 1/8 hysteresis of threshold value.

D8 to D9 of address H'F7

Digital output

CDS

AGC

CDS_in

BLKFB

BLKSH

SH

AMP

VRT

SP1

SP2

SP1

on/off

Clamp level

+

−

−

+

+

(+)

(

−)

ADC

OB

DET

Current

cell

Dummy

DET

Detect 4clk

from OPDM edge

Detect 8clk

from OBP edge

Figure 7 Internal Bias Circuitry