Analog Devices Inc. AD7899AR-3REEL

Overview

AD7899AR-3REEL from Analog Devices is a 14-bit, 400 kSPS successive-approximation ADC with ±2.5 V analog input range, internal 2.5 V reference, and high-speed parallel interface. It operates from a single 5 V supply, consumes 80 mW typical power, and features 2.2 µs conversion time and 0.3 µs track/hold acquisition time. It is used in precision data acquisition systems requiring fast sampling of bipolar sensor signals such as strain gauges or instrumentation amplifiers.

For engineers reviewing the AD7899AR-3REEL datasheet, AD7899AR-3REEL pinout, AD7899AR-3REEL application, or AD7899AR-3REEL equivalent, key selection criteria include its ±2.5 V input range compatibility, two's complement output coding, STBY-controlled power-down mode, and support for both internal and external clocking - critical for synchronized multi-channel sampling in industrial control and test equipment.

Technical Context

The AD7899AR-3REEL integrates a laser-trimmed internal oscillator (enabling 400 kSPS throughput without external clock), a track/hold amplifier with 0.3 µs acquisition time, and on-chip 2.5 V reference buffered to 6 kΩ output impedance. Its analog front-end supports ±2.5 V full-scale input with overvoltage tolerance up to –4 V to +18 V.

Conversion is initiated by CONVST rising edge, which places the track/hold into hold mode and triggers BUSY/EOC assertion. Data is latched onto a 14-bit parallel bus (DB0–DB13) using CS and RD controls, with timing compatible with both 3 V and 5 V logic via dedicated VDRIVE pin.

Key Specifications

Pinout & Package

AD7899AR-3REEL is housed in a 28-lead SOIC (R-28) package with standard JEDEC MS-013AC footprint and 1.27 mm pitch.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 14-bit SAR ADC applications.

Compared with AD7899BR-3, the AD7899AR-3 trades 0.5 LSB INL tolerance for cost efficiency while retaining identical timing, power, and interface behavior; versus ADS8505IPW, it offers faster throughput and simpler hardware integration at the expense of resolution and reference flexibility.

Availability

AD7899AR-3REEL is available at Aetrix Electronics and suitable for industrial process monitoring, test & measurement equipment, and medical instrumentation requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for AD7899AR-3REEL 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 AD7899 product line delivers high-speed, low-power 14-bit SAR ADCs optimized for precision data acquisition in industrial, instrumentation, and medical systems where accuracy, speed, and single-supply simplicity are essential.

FAQ

What is the analog input voltage range supported by the AD7899AR-3REEL?

The AD7899AR-3REEL supports a bipolar ±2.5 V analog input range, as defined for the AD7899-3 variant. This range is fixed and not software-configurable; it is implemented using an internal resistor network optimized for ±2.5 V full-scale operation. The part tolerates overvoltage up to –4 V to +18 V on the input pins without damage, enabling robust operation in noisy industrial environments. The AD7899AR-3REEL does not support ±10 V, ±5 V, or unipolar ranges - those require AD7899AR-1 or AD7899AR-2 variants.

Does the AD7899AR-3REEL require an external clock to achieve its maximum 400 kSPS throughput?

No, the AD7899AR-3REEL does not require an external clock to achieve 400 kSPS throughput. It includes an internal laser-trimmed oscillator that provides the necessary 6.5 MHz clock for full-speed operation. An external clock is optional and selected by asserting CLKIN high at the rising edge of CONVST; otherwise, the internal oscillator is automatically used. This eliminates clock-generation circuitry in designs where timing synchronization across multiple ADCs is not required.

How is the reference configured on the AD7899AR-3REEL, and can it be overdriven?

The AD7899AR-3REEL uses an internal 2.5 V reference accessible at the VREF pin. By default, a 0.1 µF capacitor to AGND enables the internal reference. The VREF pin also accepts an external 2.5 V ±5% reference, which overdrives and replaces the internal source. The internal reference has ±20 mV max error over temperature and 25 ppm/°C tempco; external references like AD780 or REF43 improve stability for high-accuracy applications. The AD7899AR-3REEL does not support reference voltages other than 2.5 V.

What logic voltage levels are supported by the AD7899AR-3REEL's parallel interface?

The AD7899AR-3REEL supports both 3 V and 5 V logic levels via the dedicated VDRIVE pin. When VDRIVE is tied to 3 V ±10%, all digital inputs (CONVST, CS, RD, CLKIN, STBY) and outputs (DB0–DB13, BUSY/EOC) operate at 3 V logic thresholds, enabling direct interfacing with 3 V microcontrollers or FPGAs. When VDRIVE = 5 V, it operates at standard 5 V TTL/CMOS levels. This dual-voltage capability eliminates level-shifting components in mixed-voltage systems.

What is the purpose of the OPGND pin on the AD7899AR-3REEL, and how should it be connected?

The OPGND pin on the AD7899AR-3REEL is the dedicated ground return for the digital output drivers (DB0–DB13 and BUSY/EOC). It must be connected to the system's analog ground plane - not digital ground - to prevent switching noise from the parallel bus from coupling into sensitive analog sections. Separating OPGND from AGND (pins 2 and 6) minimizes crosstalk and preserves the 77 dB SNR specification. Improper OPGND routing is a common cause of degraded AC performance in prototype layouts.