Analog Devices Inc. AD7899AR-3

Overview

AD7899AR-3 from Analog Devices is a 14-bit, 400 kSPS successive-approximation ADC with ±2.5 V analog input range, single 5 V supply operation, internal 2.5 V reference, and high-speed parallel interface - used in precision industrial data acquisition systems requiring fast, low-power digitization of bipolar sensor signals.

For engineers reviewing the AD7899AR-3 datasheet, AD7899AR-3 pinout, AD7899AR-3 application, or AD7899AR-3 equivalent, key selection criteria include its ±2.5 V input range, 2.2 µs conversion time, 0.3 µs track/hold acquisition, two's complement output coding, and SOIC-28 package compatibility with 3 V/5 V digital interfaces.

Technical Context

The AD7899AR-3 integrates a laser-trimmed internal clock oscillator (enabling 400 kSPS throughput without external timing components) and a track/hold amplifier with 500 kHz –0.1 dB full-power bandwidth and 25 ps aperture jitter. Its analog front-end supports ±2.5 V differential input via VINA/VINB pins with overvoltage tolerance up to –4 V to +18 V.

Conversion control uses CONVST-triggered hold mode and BUSY/EOC status signaling; data is latched via CS/RD-controlled 14-bit parallel bus (DB0–DB13), with VDRIVE pin enabling 3 V or 5 V logic level compatibility. Output coding is two's complement, matching bipolar signal polarity directly.

Key Specifications

Pinout & Package

AD7899AR-3 is housed in a 28-lead Small Outline Integrated Circuit (SOIC) package (package option R-28), with standard 0.3-inch body width and gull-wing leads. Pin 1 is marked by a beveled corner or dot; device orientation follows JEDEC MS-012AC.

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 broader commercial temperature qualification (–40°C to +85°C); versus ADS8860IDRCT, it offers parallel interface simplicity and integrated reference at the cost of 2-bit resolution and lower speed.

Availability

AD7899AR-3 is available at Aetrix Electronics and suitable for industrial process monitoring, test & measurement equipment, motor drive current sensing, and medical instrumentation requiring stable component supply across extended production lifecycles.

Supply support for AD7899AR-3 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 industrial data acquisition where precision, robustness, and single-supply simplicity are critical - targeting applications from programmable logic controllers to portable instrumentation.

FAQ

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

The AD7899AR-3 supports a fixed bipolar analog input range of ±2.5 V on the VINA pin, with VINB referenced to AGND. This range is factory-configured and not software-selectable. Input overvoltage protection extends to –4 V to +18 V, safeguarding against transient faults without external clamping circuitry. The ±2.5 V range yields a 610.4 µV LSB step size, matching common industrial sensor outputs directly.

Does the AD7899AR-3 require an external clock to operate?

No, the AD7899AR-3 does not require an external clock. It features an internal laser-trimmed oscillator that enables full 400 kSPS throughput without any external timing components. An external clock may be applied via CLKIN only if precise synchronization or non-standard sampling rates are needed; otherwise, tying CLKIN to GND selects internal clock operation. The internal clock eliminates timing component count and layout sensitivity.

How is the reference voltage configured on the AD7899AR-3?

The AD7899AR-3 uses its internal 2.5 V reference by default. To enable it, connect a 0.1 µF decoupling capacitor between the VREF pin and AGND. The VREF pin also accepts an external 2.5 V ±5% reference, which overdrives the internal source. Internal reference accuracy is ±10 mV at 25°C and ±20 mV over –40°C to +85°C, with 25 ppm/°C temperature coefficient - sufficient for most industrial DAQ applications without calibration.

What logic voltage levels are supported by the AD7899AR-3 digital interface?

AD7899AR-3 supports both 3 V and 5 V logic levels via the VDRIVE pin. When VDRIVE = 5 V, digital inputs accept 0.8 V/2.0 V thresholds and outputs drive to 4.6 V/0.4 V. When VDRIVE = 3 V, thresholds shift to 1.9 V/1.1 V and outputs swing to 2.6 V/0.4 V. This flexibility allows direct interfacing with 3 V microcontrollers or FPGAs without level shifters, reducing signal integrity risk and board complexity.

Can the AD7899AR-3 be powered down to reduce system power consumption?

Yes, the AD7899AR-3 includes a dedicated STBY pin for hardware-controlled power-down. Driving STBY low reduces supply current to 20 µA typical (5 µA typ), cutting dynamic power from 80 mW to 100 µW. This mode retains register state and reference bias, enabling wake-up in <5 µs. It is ideal for battery-powered instruments or systems with intermittent sampling requirements, where average power must be minimized without sacrificing conversion readiness.