Analog Devices Inc. AD7854AQ

Overview

AD7854AQ from Analog Devices is a 12-bit, 200 kSPS sampling analog-to-digital converter (ADC) with pseudo-differential input, on-chip 2.5 V reference, self- and system-calibration capability, and flexible parallel interface. It operates from a single 3 V to 5.5 V supply, consumes 15 mW at 3 V, and targets high-accuracy data acquisition in portable instrumentation and battery-powered control systems.

For engineers reviewing the AD7854AQ datasheet, AD7854AQ pinout, AD7854AQ application, or AD7854AQ equivalent, this page delivers verified technical context, real-world timing constraints, calibrated DC accuracy specs (±1 LSB INL), power-down behavior at 10 kSPS, and validated alternative options for unipolar/bipolar signal chain design.

Technical Context

The AD7854AQ employs a charge redistribution SAR architecture with integrated track-and-hold (500 ns acquisition), internal 2.5 V reference (20 ppm/°C tempco), and programmable analog input range (0 V to VREF or ±VREF/2). Its control register enables software-triggered conversion, selectable calibration modes (self/system), and three power management states via PMGT1/PMGT0 bits.

It supports 12-bit parallel readout (DB0–DB11) with HBEN-controlled byte alignment, requires external CREF1 (0.1 µF) and CREF2 (0.01 µF) capacitors, and uses CONVST edge-triggered sampling synchronized to CLKIN (up to 4 MHz). Calibration spans are defined as ±0.05 × VREF (offset) and ±0.025 × VREF (gain), enabling correction of system-level errors.

Key Specifications

Pinout & Package

AD7854AQ is housed in a 28-lead Cerdip (Q-28) package with 0.6-inch width, rated for –40°C to +85°C operation and 450 mW power dissipation. Pin layout matches DIP/SOIC/SSOP footprints for drop-in compatibility across package variants.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 12-bit, parallel-interface ADC applications.

Compared with AD7854LAR3 and ADS7822U, the AD7854AQ uniquely balances 200 kSPS speed, internal reference, parallel interface simplicity, and industrial temperature rating in a hermetic Cerdip package - making it optimal for legacy-compatible, high-reliability data acquisition where layout reuse and calibration robustness are critical.

Availability

AD7854AQ is available at Aetrix Electronics and suitable for portable medical instrumentation, battery-powered data loggers, and industrial control loop monitoring requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for AD7854AQ 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, serving precision instrumentation, industrial automation, and communications markets since 1965.

The AD7854AQ belongs to Analog Devices' precision SAR ADC product line, designed specifically for high-accuracy, low-power, single-supply data acquisition in portable and harsh-environment applications where calibration integrity and supply flexibility are essential.

FAQ

What is the maximum sampling rate supported by the AD7854AQ?

The AD7854AQ supports a maximum sampling rate of 200 kSPS, achieved with a 4 MHz master clock (CLKIN) and 4.5 µs conversion time (18 × t_CLKIN). This rate is specified across the full –40°C to +85°C operating range and enables accurate digitization of signals up to ~90 kHz. The AD7854AQ datasheet confirms this performance under AVDD = DVDD = 3.0 V to 5.5 V and f_CLKIN = 4 MHz conditions.

Does the AD7854AQ include an internal voltage reference?

Yes, the AD7854AQ integrates a 2.5 V internal reference with ±2.5% initial accuracy and 20 ppm/°C temperature coefficient, accessible at the REFIN/REFOUT pin. It can serve as the ADC's reference source or be overdriven by an external reference from 1.2 V to AVDD. External 0.1 µF (CREF1) and 0.01 µF (CREF2) capacitors are required for stability, as specified in the AD7854AQ functional description and pinout documentation.

How does the AD7854AQ handle power management for battery-operated systems?

The AD7854AQ implements three power-down modes controlled by PMGT1/PMGT0 bits in its control register: full power-down (5 µA with clock off), partial power-down (200 µA), and sleep mode (10 µA with clock on). After each conversion, it automatically enters low-power state unless disabled. At 10 kSPS, typical power drops to 1.3 mW - a key advantage for battery longevity in portable AD7854AQ-based systems.

Can the AD7854AQ perform system-level calibration, and how is it initiated?

Yes, the AD7854AQ supports both self-calibration and system calibration via its control register. System calibration is selected by setting CALMD = 1 and initiating with STCAL = 1 and appropriate CALSLT1/CALSLT0 bits (e.g., 00 for full system cal). It corrects system-level gain/offset errors using external reference and sensor path - with allowable spans of ±0.05 × VREF (offset) and ±0.025 × VREF (gain) - as defined in the AD7854AQ calibration section.

What package type and temperature range does the AD7854AQ use?

The AD7854AQ is supplied in a 28-lead Cerdip (Q-28) package with 0.6-inch width and is rated for operation from –40°C to +85°C. This hermetic ceramic package provides superior moisture resistance and thermal stability versus plastic alternatives, supporting long-term reliability in industrial and medical AD7854AQ deployments. The ordering guide explicitly lists "Q-28" and "–40°C to +85°C" for the AD7854AQ model.