GENERAL DESCRIPTION

The AD9822 is a complete analog signal processor for CCD imaging applications. It features a 3-channel architecture designed to sample and condition the outputs of trilinear color CCD arrays. Each channel consists of an input clamp, correlated double sampler (CDS), offset DAC, and programmable gain amplifier (PGA) multiplexed to a high performance 14-bit ADC.

The CDS amplifiers may be disabled for use with sensors such as contact image sensors (CIS) and CMOS active pixel sensors, which do not require CDS.

The 14-bit digital output is multiplexed into an 8-bit output word that is accessed using two read cycles. The internal registers are programmed through a 3-wire serial interface and provide adjustment of the gain, offset, and operating mode.

The AD9822 operates from a single 5 V power supply, consumes 385 mW of power typically, and is packaged in a 28-lead SOIC or SSOP.

FEATURES

14-bit 15 MSPS ADC

No missing codes guaranteed

3-channel operation up to 15 MSPS

1-channel operation up to 12.5 MSPS

Correlated double sampling

1–6× programmable gain

±350 mV programmable offset

Input clamp circuitry

Internal voltage reference

Multiplexed byte-wide output (8 + 6 format)

3-wire serial digital interface

3 V/5 V digital I/O compatibility

28-Lead SOIC or SSOP

Low power CMOS: 385 mW (typ)

Power-down mode: <1 mW

APPLICATIONS

Flatbed document scanners

Film scanners

Digital color copiers

Multifunction peripherals