Analog Devices Inc. AD9843AJST

Overview

AD9843AJST from Analog Devices is a complete 10-bit, 20 MSPS CCD signal processor IC designed for analog front-end conditioning of interlaced and progressive-scan area CCD outputs. It integrates correlated double sampling (CDS) with programmable gain (–2 dB to +10 dB), a 10-bit VGA (2 dB to 36 dB), input clamping, optical black clamping, and a 10-bit ADC - all operating from a single 3.0 V supply and dissipating 78 mW typical in CCD mode. It is deployed in digital still cameras and camcorders for high-fidelity pixel-level signal extraction.

For engineers reviewing the AD9843AJST datasheet, AD9843AJST pinout, AD9843AJST application, or AD9843AJST equivalent, this page delivers verified functional identity, confirmed LQFP-48 package mapping, validated 48-pin terminal roles, real-world timing constraints (e.g., 20 MHz DATACLK, 3 ns internal SHP/SHD delay), and two rigorously cross-checked alternative AFEs for CCD signal chain design.

Technical Context

The AD9843AJST implements a single-channel CCD signal chain with three distinct operational modes: CCD-mode (default), AUX1-mode (AC-coupled waveform sampling), and AUX2-mode (video clamping). Its CDS stage uses dual rising-edge sampling on SHP and SHD clocks with 3 ns internal aperture delay and supports 64-step programmable gain via two's complement coding in the CDS Gain Register.

The VGA provides monotonic 10-bit gain control (1024 steps) across 2 dB–36 dB, split into two mathematical regions (0–511 and 512–1023 codes) with ±0.5 dB gain accuracy. The optical black clamp loop operates per horizontal line using CLPOB timing and adjusts ADC input via an 8-bit DAC based on user-programmed clamp level (0–63.75 LSB).

Key Specifications

Pinout & Package

AD9843AJST is housed in a 48-lead Thin Plastic Quad Flatpack (LQFP), ST-48 package (θ_JA = 92°C/W), with exposed pad not electrically connected. Pin 1 identifier located at top-left corner; pins numbered counterclockwise.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar CCD signal processor applications.

Compared with AD9843AJST, AD9844ASTZ extends functionality with an auxiliary DAC while maintaining pin and code compatibility, whereas TDA8785HN/C1 offers higher sample rate but sacrifices programmable CDS gain and optical black loop configurability - trade-offs center on calibration flexibility versus raw speed.

Availability

AD9843AJST is available at Aetrix Electronics and suitable for digital still cameras, video camcorders, and PC camera modules requiring stable component supply, long-term lifecycle support, and traceable sourcing for production ramp.

Supply support for AD9843AJST includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Analog Devices, Inc. is a global semiconductor leader specializing in high-performance analog, mixed-signal, and digital signal processing technologies for precision measurement and signal conditioning.

The AD9843A product line was engineered specifically as a fully integrated CCD analog front end for portable imaging systems - emphasizing low power, single-supply operation, and robust noise rejection in space-constrained camera modules.

FAQ

What is the operating temperature range for AD9843AJST?

The AD9843AJST is rated for operation from –20°C to +85°C, matching its ordering designation "–20°C to +85°C" in the Analog Devices ordering guide. This industrial-grade temperature range ensures reliable performance in consumer and professional imaging equipment exposed to ambient thermal variations, including handheld cameras and automotive dashcams. All electrical specifications in the datasheet are guaranteed across this full range.

Does AD9843AJST support multiple input signal types?

Yes, AD9843AJST supports three distinct input configurations: CCD-mode (via CCDIN pin with CDS), AUX1-mode (via AUX1IN for AC-coupled waveforms), and AUX2-mode (via AUX2IN with integrated video clamping for NTSC/PAL). Each mode uses shared VGA and ADC resources but differs in clocking, clamping behavior, and gain register interpretation - enabling reuse of the same IC across diverse imaging and video acquisition platforms.

How is the CDS gain programmed on AD9843AJST?

The CDS gain on AD9843AJST is programmed via the 6-bit CDS Gain Register (address 0x06), which controls gain from –2 dB to +10 dB in 64 steps using two's complement coding. To activate programmable gain, bit D3 of the Control Register must be set high; otherwise, the default fixed gain is 4 dB. The gain curve is documented in Figure 12 of the datasheet, and register writes occur through the 3-wire serial interface (SCK/SL/SDATA).

What is the purpose of the CLPOB and CLPDM pins on AD9843AJST?

CLPOB (Pin 20) triggers the optical black clamp loop, which corrects residual DC offsets by comparing ADC output against a user-defined clamp level during optical black pixel intervals. CLPDM (Pin 23) enables the input clamp circuit that removes CCD black pixel offset prior to CDS - preventing gain-dependent black level shifts. Both are essential for stable black level control but operate at different stages: CLPDM acts early in the signal chain, CLPOB acts late for fine correction.

Can AD9843AJST be powered down to reduce system power consumption?

Yes, AD9843AJST provides three power-down modes accessible via the Operation Register: Fast Recovery (45 mW, 0.1 ms wake-up), Standby (5 mW, 1 ms wake-up), and Total Power-Down (1 mW, 3 ms wake-up). These modes disable internal blocks selectively while preserving register contents, allowing rapid resumption of imaging operations - critical for battery-powered devices implementing duty-cycled capture sequences.