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AD9945

Complete 12-Bit 40 MHz

CCD Signal Processor

FEATURES

40 MSPS Correlated Double Sampler (CDS)

6 dB to 40 dB 10-Bit Variable Gain Amplifier (VGA)

Low Noise Optical Black Clamp Circuit

Preblanking Function

12-Bit 40 MSPS A/D Converter

No Missing Codes Guaranteed

3-Wire Serial Digital Interface

3 V Single-Supply Operation

Low Power: 140 mW @ 3 V Supply

Space-Saving 32-Lead 5 mm

5 mm LFCSP

APPLICATIONS

Digital Still Cameras

Digital Video Camcorders

PC Cameras

Portable CCD Imaging Devices

CCTV Cameras

FUNCTIONAL BLOCK DIAGRAM

DATACLK

SHD

SHP

BAND GAP

REFERENCE

DOUT

CCDIN

PBLK

REFT REFB

INTERNAL

TIMING

6dB TO 40dB

AVDD

DVDD

DVSS

AVSS

DRVDD

DRVSS

10

DIGITAL

INTERFACE

SDATA

SCK

SL

CLPOB

12

AD9945

CONTROL

REGISTERS

12-BIT

ADC

CLP

VGA

CDS

GENERAL DESCRIPTION

The AD9945 is a complete analog signal processor for CCD

applications. It features a 40 MHz single-channel architecture

designed to sample and condition the outputs of interlaced and

progressive scan area CCD arrays. The AD9945’s signal chain

consists of a correlated double sampler (CDS), a digitally con-

trolled variable gain amplifier (VGA), a black level clamp, and a

12-bit A/D converter.

The internal registers are programmed through a 3-wire serial digital

interface. Programmable features include gain adjustment, black

level adjustment, input clock polarity, and power-down modes.

The AD9945 operates from a single 3 V power supply, typi-

cally dissipates 140 mW, and is packaged in a space-saving

32-lead LFCSP.