Analog Devices Inc. AD9821KSTRL

Overview

AD9821KSTRL from Analog Devices is a complete 12-bit, 40 MSPS imaging signal processor optimized for CMOS and CCD imagers with on-chip correlated double sampling (CDS). It integrates a differential sample-and-hold amplifier (SHA), 0 dB to 36 dB 10-bit VGA, optical black clamp, and 12-bit ADC in a single 48-lead LQFP package, operating from a 3 V supply with 150 mW typical power consumption.

For engineers reviewing the AD9821KSTRL datasheet, AD9821KSTRL pinout, AD9821KSTRL application, or AD9821KSTRL equivalent, this device serves as a full analog front-end (AFE) for digital still cameras and industrial imaging systems requiring precise gain control, black-level correction, and high-speed digitization without external CDS circuitry.

Technical Context

The AD9821KSTRL implements a single-channel, imager-optimized signal chain: differential SHA samples VIN+ and VIN– simultaneously on DATACLK rising edges (3 ns aperture delay); VGA provides monotonic 10-bit programmable gain (0–36 dB, linear-in-dB); and optical black clamp corrects offset using CLPOB-synchronized feedback with 256-step resolution and ±30 mV correction range at max gain.

Digital interface uses a 3-wire serial protocol (SCK, SDATA, SL) supporting register read/write at up to 10 MHz; internal registers configure VGA gain, clamp level, power-down modes (standby/total power-down), and DATACLK/CLPOB polarity. Output data is straight-binary 12-bit D0–D11 with 9-cycle pipeline latency and 13–16 ns output delay referenced to DATACLK.

Key Specifications

Pinout & Package

AD9821KSTRL is housed in a 48-lead LQFP (ST-48) package, 9.0 mm × 9.0 mm × 1.4 mm, JEDEC MS-026BBC compliant, with exposed pad not connected internally. Pin 1 identifier located at top-left corner; pins 18, 24, 37, 42, 47, 48 are NC (internally not connected).

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD9822KSTRL and TDA9886HN/C1, the AD9821KSTRL delivers optimal integration for single-sensor digital imaging-combining VGA, clamp, and 12-bit ADC in one package with 40 MSPS throughput and 3 V operation-whereas alternatives trade off channel count, resolution, or feature completeness.

Availability

AD9821KSTRL is available at Aetrix Electronics and suitable for digital still cameras, industrial machine vision systems, scientific imaging equipment, and medical endoscopy devices requiring stable component supply and long-term manufacturability.

Supply support for AD9821KSTRL 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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, headquartered in Norwood, MA, with design centers worldwide and ISO 9001-certified manufacturing.

The AD9821KSTRL belongs to Analog Devices' Imaging Signal Processor product line, engineered specifically for high-fidelity digitization of CMOS and CCD sensor outputs in applications where on-chip CDS eliminates the need for external correlated double sampling circuitry.

FAQ

What is the maximum sampling rate supported by the AD9821KSTRL?

The AD9821KSTRL supports a maximum sampling rate of 40 MSPS, as confirmed by its DATACLK specification (25 ns period, 40 MHz). This rate is validated across the full operating temperature range (–20°C to +85°C) and enables real-time digitization of high-resolution image sensors. The AD9821KSTRL maintains specified DNL (±0.5 LSB) and noise performance (0.5 LSB_rms) at this rate, making it suitable for demanding imaging applications requiring both speed and fidelity.

Does the AD9821KSTRL include an integrated correlated double sampling (CDS) circuit?

No, the AD9821KSTRL does not include an integrated CDS circuit. Its datasheet explicitly states it is designed for imaging applications that *do not require* CDS - targeting CMOS imagers and CCD arrays that already implement on-chip CDS. Instead, the AD9821KSTRL provides complementary functions: differential sample-and-hold, variable gain amplification, optical black clamping, and 12-bit ADC conversion. Using it with a sensor lacking on-chip CDS would result in uncorrected reset noise.

What is the function of the CLPOB and PBLK pins on the AD9821KSTRL?

CLPOB (Pin 20) is the optical black clamp clock input, which triggers the internal black-level correction loop during the shielded (optical black) pixel interval of each scan line. PBLK (Pin 19) is the preblanking clock input, forcing digital outputs D0–D11 to zero during horizontal blanking periods. CLPOB takes precedence - if both signals overlap, CLPOB overrides PBLK. Both are essential for synchronized timing with imager output, and their pulse widths must align with sensor timing specifications to ensure accurate black-level tracking and clean blanking.

Can the AD9821KSTRL operate from a single 3 V supply?

Yes, the AD9821KSTRL operates from a single 3 V supply across its specified voltage range (2.7 V to 3.6 V) for AVDD, DVDD, and DRVDD rails. It achieves 150 mW typical power consumption at 3.0 V and 40 MSPS, with standby and total power-down modes reducing consumption to 5 mW and 1 mW respectively. The device's internal voltage references (VRT = 2.0 V, VRB = 1.0 V) and bias generation are fully self-contained, eliminating need for external regulators or reference ICs in most implementations.

How is gain controlled on the AD9821KSTRL, and what is its resolution?

Gain on the AD9821KSTRL is controlled digitally via a 10-bit VGA gain register accessible through its 3-wire serial interface (SCK/SDATA/SL). The register accepts values from 0 to 1023, corresponding to a linear-in-dB gain range of 0 dB to 36 dB (0.0351 dB per LSB). Gain monotonicity is guaranteed across the full range, and the exact gain in dB is calculated as Gain(dB) = Code × 0.0351. This 1024-step resolution enables precise exposure control in automated imaging systems without interpolation or lookup tables.