Analog Devices Inc. AD7863ARS-2

Overview

AD7863ARS-2 from Analog Devices is a dual-channel, simultaneous-sampling 14-bit analog-to-digital converter (ADC) operating from a single 5 V supply. It delivers 175 kSPS throughput per channel with 5.2 μs conversion time, ±2.5 V input range (unipolar 0 V to 2.5 V), and integrated 2.5 V reference - designed for precision motor control feedback and real-time power quality monitoring.

For engineers reviewing the AD7863ARS-2 datasheet, AD7863ARS-2 pinout, AD7863ARS-2 application, or AD7863ARS-2 equivalent, key selection criteria include simultaneous dual-channel sampling integrity, aperture delay matching (<350 ps), straight-binary output coding, 0.5 μs track/hold acquisition time, and SOIC_W package compatibility with industrial PCB layouts.

Technical Context

The AD7863ARS-2 integrates two independent successive approximation ADCs, each paired with a track-and-hold amplifier and sharing a single internal 2.5 V reference. Its A0-controlled multiplexer selects between Channel A (VA1/VA2) or Channel B (VB1/VB2), enabling synchronized sampling of two analog inputs while preserving phase coherence.

Conversion is triggered by a falling edge on CONVST, initiating simultaneous hold and conversion across both channels. The BUSY signal asserts high until completion, after which results are read via a 14-bit parallel bus (DB0–DB13) using CS and RD strobes - supporting direct interfacing with 80C196, MC68000, and ADSP-21xx processors.

Key Specifications

Pinout & Package

AD7863ARS-2 is housed in a 28-lead SOIC_W (Wide-body Small Outline Integrated Circuit) package, 10.3 mm × 7.6 mm body size, 1.27 mm pitch, RoHS-compliant, with exposed pad not electrically connected.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-channel simultaneous-sampling ADC applications.

Compared with AD7863ARS-2, AD7656ASTZ trades parallel interface simplicity and on-chip reference for higher resolution and lower noise floor, while ADS8556IPMR sacrifices SOIC_W compactness and 5 V compatibility to deliver triple the channel count and faster aggregate throughput - neither offers drop-in replacement capability.

Availability

AD7863ARS-2 is available at Aetrix Electronics and suitable for motor control systems, power quality analyzers, and industrial PLC analog input modules requiring stable component supply, long-term lifecycle support, and guaranteed SOIC_W packaging consistency.

Supply support for AD7863ARS-2 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 AD7863 family was engineered specifically for industrial real-time control applications demanding deterministic sampling, tight inter-channel timing, and robust operation in electrically noisy environments - with AD7863ARS-2 optimized for unipolar 0 V to 2.5 V sensor interfaces.

FAQ

What is the maximum analog input voltage rating for AD7863ARS-2?

The AD7863ARS-2 has an absolute maximum analog input voltage rating of +7 V relative to AGND, as specified in the Absolute Maximum Ratings table. This overvoltage tolerance applies only during fault conditions - normal operation must remain within the 0 V to 2.5 V unipolar input range to ensure 14-bit accuracy and avoid clipping. Exceeding +7 V risks permanent damage to the input ESD protection structures.

Does AD7863ARS-2 require an external reference, or does it use the internal 2.5 V reference by default?

The AD7863ARS-2 uses its internal 2.5 V reference by default when the VREF pin is decoupled with two 0.1 μF ceramic capacitors to AGND. No external reference is required for standard operation. However, an external 2.5 V reference can be connected to VREF if tighter initial accuracy or lower temperature drift is needed - the internal reference exhibits ±10 mV error at 25°C and ±20 mV over temperature.

How does the A0 pin determine which channel pair is converted in AD7863ARS-2?

In AD7863ARS-2, the A0 pin is sampled at the falling edge of the CONVST signal to select the active channel pair: A0 = low selects VA1 and VA2; A0 = high selects VB1 and VB2. Both inputs within the selected pair are sampled and converted simultaneously, and their 14-bit results are read sequentially - first read returns VA1/VB1, second read returns VA2/VB2 - with no additional control required.

What is the significance of straight-binary output coding in AD7863ARS-2 compared to two's complement?

Straight-binary output coding in AD7863ARS-2 maps 0x0000 to 0 V and 0x3FFF (16383 decimal) to 2.5 V full scale, simplifying firmware math for unipolar sensor signals. Unlike two's complement (used in AD7863-10/-3), it avoids sign-extension handling and negative-value interpretation - reducing CPU cycles in real-time control loops where all inputs are positive and scaling is linear.

Can AD7863ARS-2 operate reliably in industrial environments with high EMI, and what layout practices are recommended?

Yes, AD7863ARS-2 is designed for industrial EMI resilience, featuring separate AGND and DGND pins, on-chip track/hold amplifiers with 7 MHz small-signal bandwidth, and differential input structure. To maintain 77 dB SNR, follow strict layout rules: use continuous AGND plane under analog section, isolate DGND plane with narrow bridge near VDD pin, place 0.1 μF + 10 μF decoupling on VDD, and route analog inputs away from digital traces - as validated in Analog Devices' AN-682 application note.