Analog Devices Inc. AD9040AJN

Overview

AD9840AJN from Analog Devices is a complete 10-bit, 40 MSPS CCD signal processor IC integrating correlated double sampling (CDS), 2 dB to 36 dB VGA, black level clamp, and analog-to-digital conversion in a single 48-lead LQFP package. It processes interlaced/progressive scan CCD outputs with 64-step CDS gain control, 1024-step VGA resolution, and 256-step optical black clamp adjustment - deployed in digital still cameras for high-fidelity pixel-level analog conditioning prior to image processing ASICs.

For engineers reviewing the AD9840AJN datasheet, AD9840AJN pinout, AD9840AJN application, or AD9840AJN equivalent, this page delivers verified functional identity, confirmed 48-lead LQFP package mapping, validated 10-bit ADC + CDS + VGA signal chain architecture, real-world timing constraints (e.g., 40 MHz DATACLK, 3 ns internal SHP/SHD delay), and two rigorously cross-checked alternative AFEs for CCD imaging systems.

Technical Context

The AD9840AJN implements a single-channel CCD analog front end with three distinct operating modes: CCD-mode (default, with CDS), AUX1-mode (ac-coupled waveform sampling), and AUX2-mode (video clamping). Its CDS stage uses dual rising-edge sampling (SHP/SHD) with programmable –2 dB to +10 dB gain in 64 steps, while the VGA provides monotonic 2–36 dB gain across 1024 codes using piecewise-linear-in-dB transfer functions.

Internal timing is synchronized to DATACLK (max 40 MHz), with pipeline latency of 9 clock cycles and strict setup/hold requirements (e.g., tDS = 10 ns, tH = 7.0 ns). The 3-wire serial interface (SCK/SL/SDATA) supports register readback and write operations at up to 10 MHz, enabling dynamic gain, clamp level, and power-down mode configuration during operation.

Key Specifications

Pinout & Package

AD9840AJN is housed in a 48-lead LQFP (Lead Pitch: 0.5 mm, Body Size: 7 mm × 7 mm), with separate analog (AVSS/AVDD), digital (DVSS/DVDD), and driver (DRVSS/DRVDD) supply domains to minimize noise coupling.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar CCD analog front end applications.

Compared with AD9840AJN, AD9841AJN offers higher resolution and speed at the cost of power and voltage compliance, while TDA8785HN/N1 reduces integration but sacrifices noise performance and design simplicity - AD9840AJN remains optimal for balanced 10-bit CCD imaging where CDS, VGA, and clamp are co-integrated.

Availability

AD9840AJN is available at Aetrix Electronics and suitable for digital still cameras, industrial imaging systems, and machine vision inspection requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for AD9840AJN 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 leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, headquartered in Norwood, MA.

The AD9840AJN belongs to Analog Devices' CCD signal processor product line, designed specifically to replace multi-chip analog front ends in digital imaging systems with a single, low-power, highly integrated solution.

FAQ

What is the maximum DATACLK frequency supported by the AD9840AJN?

The AD9840AJN supports a maximum DATACLK frequency of 40 MHz in CCD-mode and AUX1/AUX2-modes. This timing constraint is strictly enforced by internal logic and must be met to guarantee correct 10-bit sampling, pipeline latency (9 cycles), and serial interface synchronization. Exceeding 40 MHz may cause metastability or data corruption in the D0–D9 output bus. The AD9840AJN datasheet specifies tCP = 25 ns minimum clock period, confirming the 40 MHz limit.

Does the AD9840AJN include an integrated correlated double sampler?

Yes, the AD9840AJN integrates a fully programmable correlated double sampler (CDS) as a core function within its signal chain. It uses SHP and SHD inputs to sample CCD reference and data levels respectively, with default 4 dB gain that can be adjusted from –2 dB to +10 dB in 64 steps via the CDS Gain Register. The CDS block operates before the VGA stage to reject low-frequency noise and reset transients, and is active only in CCD-mode - confirmed in the Functional Block Diagram and CCD-Mode Specifications sections of the AD9840AJN datasheet.

What are the power supply requirements for the AD9840AJN?

The AD9840AJN requires three independent supply domains: analog (AVDD1/AVDD2 = 2.7–3.6 V), digital (DVDD1/DVDD2 = 2.7–3.6 V), and digital driver (DRVDD = 2.7–3.6 V), all referenced to their respective ground planes (AVSS, DVSS, DRVSS). Each domain must be decoupled with 0.1 µF ceramic capacitors placed near the pins. The device consumes 155 mW in normal operation at 3.0 V, dropping to 1 mW in total power-down mode. Supply sequencing is not specified, but simultaneous ramp-up is recommended.

How does the optical black clamp function in the AD9840AJN?

The AD9840AJN implements an optical black clamp loop that operates during the CCD's shielded black pixel interval, using the CLPOB input to trigger correction. It compares the ADC output against a user-programmed clamp level (0–63.75 LSB, 256 steps) and applies feedback via an internal 8-bit DAC to adjust the ADC input baseline. This loop corrects residual offsets and tracks low-frequency black level drift line-by-line. The clamp level is stored in the Clamp Level Register and updated on each CLPOB pulse - detailed in Figure 6 and Table IV of the AD9840AJN datasheet.

Is the AD9840AJN pin-compatible with other members of the AD984x family?

No, the AD9840AJN is not pin-compatible with AD9841AJN or AD9842AJN. While all share the same 48-lead LQFP package outline, pin functions differ significantly - for example, AD9841AJN reassigns Pins 25–26 for additional analog inputs and modifies serial interface timing. The AD9840AJN Pin Function Descriptions table (page 7) confirms unique assignments for CCDIN, AUX1IN, AUX2IN, and control signals. Substitution requires PCB redesign and firmware adaptation; no drop-in replacement exists within the family.