Analog Devices Inc. AD9845BJSTZ

Overview

AD9845BJSTZ from Analog Devices is a complete 12-bit, 30 MSPS CCD signal processor IC designed for high-fidelity analog front-end conditioning of interlaced and progressive-scan area CCD outputs. It integrates a correlated double sampler (CDS), 6-bit PxGA (±2.5 dB to +9.5 dB), 10-bit VGA (2 dB to 36 dB), black-level clamp, and 12-bit ADC - all operating from a single 3 V supply with 153 mW typical power consumption.

For engineers reviewing the AD9845BJSTZ datasheet, AD9845BJSTZ pinout, AD9845BJSTZ application, or AD9845BJSTZ equivalent, this page delivers verified functional architecture, validated timing-critical pin roles (e.g., SHP/SHD sampling clocks, CLPOB clamp control), confirmed CCD-mode gain accuracy (±0.5 dB at 6 dB, ±0.7 dB at 40 dB), and real-world design constraints including 3 ns internal SHP/SHD aperture delay and 48-lead LQFP thermal resistance (θ_JA = 56°C/W).

Technical Context

The AD9845BJSTZ implements a single-channel CCD signal chain with CDS sampling synchronized to SHP (reference level) and SHD (data level) rising edges, featuring 3 ns internal aperture delay and strict placement requirements between SHD rising edge and next SHP falling edge. Its pixel gain amplifier supports seven programmable color steering modes-including Mosaic Separate (Bayer), Interlace, and VD-Selected-driven by HD/VD sync inputs and controlled via six PxGA gain registers (Gain0–Gain3, each 6-bit, monotonic, 64-step).

Signal path includes DC restore via external 0.1 µF coupling capacitor, input clamping during optical black pixels (CLPDM), and optical black clamping (CLPOB) with 256-step adjustable reference (0–255 LSB). The 3-wire serial interface (SCK ≤ 10 MHz, SL-active-high load pulse) programs all registers-including VGA gain (10-bit, linear-in-dB), clamp level, and operation mode-with simultaneous update on SL rising edge.

Key Specifications

Pinout & Package

AD9845BJSTZ is housed in a 48-lead LQFP package (ST-48) with exposed pad, θ_JA = 56°C/W on 4-layer PCB. Pin 1 identifier located top-left; pins 31, 37, 42, 43, 45 are NC (internally not connected).

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD9845BJSTZ, AD9846BJSTZ adds dual-channel parallel processing but increases layout complexity and power (210 mW), while TDC1308IPWPR trades color-aware gain flexibility for higher resolution and lower noise at reduced speed - making AD9845BJSTZ optimal for cost-sensitive, single-channel, color-accurate 30 MSPS imaging.

Availability

AD9845BJSTZ is available at Aetrix Electronics and suitable for high-performance digital still cameras, industrial machine vision systems, and scientific low-light imaging requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for AD9845BJSTZ 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.

The AD9845B product line delivers integrated CCD analog front-ends optimized for image fidelity, low power, and programmable color processing - targeting digital photography, industrial inspection, and scientific instrumentation markets.

FAQ

What is the maximum guaranteed sampling rate for AD9845BJSTZ in CCD mode?

The AD9845BJSTZ is specified for a maximum clock rate of 30 MHz in CCD mode, with full performance (including DNL ±1.0 LSB, SNR, and gain accuracy) maintained at this rate. Timing parameters such as tCP = 33 ns, tSHP ≥5 ns, and tSHD ≥5 ns are validated under these conditions, and the device achieves 12-bit no-missing-codes operation up to 30 MSPS with AVDD = DVDD = 3.0 V and T_A = –20°C to +85°C.

Does AD9845BJSTZ support external clamping, or is optical black clamping mandatory?

AD9845BJSTZ supports both internal and external clamping. The optical black clamp (CLPOB) can be disabled via Bit D5 in the Operation Register, allowing external digital clamping during postprocessing. When disabled, the clamp level register remains functional for programmable DC offset adjustment, and the input clamp (CLPDM) may still be used independently for line-rate correction.

How does the PxGA gain resolution translate to actual voltage gain steps in AD9845BJSTZ?

The PxGA provides 64 monotonic gain steps across –2.5 dB to +9.5 dB, corresponding to a voltage gain range of ≈0.75× to 2.97×. Each step represents approximately 0.1875 dB, enabling precise per-pixel color balancing - for example, adjusting green pixel gain relative to red/blue in Bayer-filtered CCDs without introducing gain discontinuities or missing codes.

Can AD9845BJSTZ operate with a 2.7 V supply, and what performance trade-offs occur?

Yes, AD9845BJSTZ operates across AVDD/DVDD = 2.7 V to 3.6 V. At 2.7 V, power consumption drops to ~130 mW (TPC 1), but full-scale input voltage reduces to 1.8 V, and PSR degrades from 40 dB to ~34 dB. All timing specs remain valid, and 12-bit no-missing-codes operation is guaranteed - however, system-level SNR may decrease by ~1.5 dB due to reduced headroom.

What is the function of the STBY pin on AD9845BJSTZ, and how does it differ from software power-down?

The STBY pin (Pin 44) is an active-high hardware control that places AD9845BJSTZ into total power-down mode (0.5 mW), identical to writing "11" to bits D1:D0 in the Operation Register. Unlike software-initiated standby (5 mW), STBY bypasses serial interface logic and immediately disables analog blocks, achieving 3 ms wake-up recovery - critical for battery-powered imaging systems requiring rapid duty cycling.