Analog Devices Inc. AD7851ARSZ

Overview

AD7851ARSZ from Analog Devices is a 14-bit, 333 kSPS serial analog-to-digital converter (ADC) with pseudo-differential input, on-chip 4.096 V reference, self- and system-calibration capability, and flexible SPI/QSPI/8051-compatible serial interface. It operates from a single 5 V supply, delivers ±2 LSB integral nonlinearity (A grade), and supports dual input ranges (0 V to VREF and ±VREF/2) for precision signal acquisition in high-speed data acquisition systems.

For engineers reviewing the AD7851ARSZ datasheet, AD7851ARSZ pinout, AD7851ARSZ application, or AD7851ARSZ equivalent, this page provides verified technical context, real-world design meaning of key specs, validated pin functions, application-specific implementation guidance, and two confirmed alternative parts with documented functional and application-level differences.

Technical Context

The AD7851ARSZ employs a successive approximation register (SAR) architecture with integrated track-and-hold, charge redistribution DAC, and comparator-based conversion core. Its calibration engine supports both automatic power-up self-calibration and user-initiated system calibration, enabling stable performance over temperature (–40°C to +125°C) and time without external recalibration hardware.

It features five configurable serial interface modes-including master-clock-driven (CLKIN) and self-clocked (SCLK output) variants-with programmable polarity and phase control via the POLARITY pin. The analog front-end supports pseudo-differential sampling with acquisition time of 0.33 µs and full-power bandwidth of 20 MHz, allowing accurate digitization of fast transient signals.

Key Specifications

Pinout & Package

The AD7851ARSZ is housed in a 24-lead SSOP (Shrink Small Outline Package) with 0.635 mm pitch, JEDEC MO-153 compliant, footprint compatible with AD7851AR (SOIC) and AD7851AN (PDIP) variants.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-speed SAR ADC applications.

Compared with AD7851ARSZ, AD7852ARSZ sacrifices resolution and integration for cost reduction, while ADS8325IPW trades speed and embedded features for enhanced DC precision-making AD7851ARSZ optimal for balanced high-speed, high-accuracy, and self-contained operation.

Availability

AD7851ARSZ is available at Aetrix Electronics and suitable for motor control feedback, DSP-based spectrum analysis, automotive battery monitoring, and industrial process instrumentation requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for AD7851ARSZ 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, founded in 1965 and headquartered in Wilmington, MA.

The AD7851 belongs to Analog Devices' precision SAR ADC product line, designed specifically for high-speed, high-accuracy data acquisition in demanding industrial, automotive, and instrumentation environments where calibration stability and single-supply operation are critical.

FAQ

What is the maximum sample rate of the AD7851ARSZ and under what conditions is it guaranteed?

The AD7851ARSZ achieves a maximum throughput rate of 333 kSPS in A-grade operation (–40°C to +85°C) with 7 MHz CLKIN and 5 V supply. At 125°C, the guaranteed rate drops to 238 kSPS using 5 MHz CLKIN. This specification assumes proper decoupling, correct AMODE and POLARITY settings, and use of the internal 4.096 V reference. The AD7851ARSZ maintains ±2 LSB INL across this full range.

Does the AD7851ARSZ require external reference components, and if so, which ones?

Yes-the AD7851ARSZ requires two external capacitors on its reference pins: a 0.1 µF ceramic disc capacitor (CREF1) and a 470 nF tantalum capacitor (CREF1) connected between CREF1 and AGND, plus a 0.01 µF ceramic disc capacitor (CREF2) between CREF2 and AGND. These stabilize the internal reference and DAC charge redistribution network. The REFIN/REFOUT pin can be overdriven by an external reference, but the default 4.096 V internal reference remains active unless explicitly disabled.

How does the AD7851ARSZ handle calibration, and can calibration data be stored externally?

The AD7851ARSZ supports both automatic power-up self-calibration and user-initiated system calibration, storing results in on-chip nonvolatile memory. Calibration registers (offset and gain) are readable and writable via the serial interface, allowing field updates without hardware modification. While calibration data resides internally, users may log values externally for traceability-but the AD7851ARSZ itself does not support external EEPROM storage of calibration coefficients.

Is the AD7851ARSZ pin-compatible with other members of the AD785x family, such as the AD7852 or AD7853?

No-the AD7851ARSZ is not pin-compatible with AD7852 or AD7853. Although all share the same 24-pin SSOP package outline, pin functions differ significantly: AD7852 lacks REFIN/REFOUT, CAL, and SM1/SM2 pins; AD7853 adds parallel interface pins not present on AD7851ARSZ. The AD7851ARSZ pinout is identical only to AD7851AR (SOIC) and AD7851AN (PDIP) variants within the same generation.

What serial interface modes does the AD7851ARSZ support, and how is mode selection configured?

The AD7851ARSZ supports five serial interface modes selected via the SM1 and SM2 pins: Mode 1 (2-wire 8051), Mode 2 (3-wire SPI/QSPI), Mode 3 (QSPI with SYNC as output), and Modes 4/5 (self-clocked with SCLK generated internally). POLARITY pin sets clock edge sensitivity. Configuration is hardwired at power-up; no register writes are needed to set the mode, making interface initialization deterministic and robust in safety-critical systems.