Analog Devices Inc. AD7899ARZ-2

Overview

AD7899ARZ-2 from Analog Devices is a 14-bit, 400 kSPS successive-approximation ADC with single 5 V supply operation, unipolar input ranges of 0 V to 2.5 V or 0 V to 5 V, and integrated 2.5 V reference. It features 2.2 µs conversion time, 0.3 µs track/hold acquisition, and high-speed parallel interface compatible with both 3 V and 5 V processors - used in precision data acquisition systems for industrial process monitoring.

For engineers reviewing the AD7899ARZ-2 datasheet, AD7899ARZ-2 pinout, AD7899ARZ-2 application, or AD7899ARZ-2 equivalent, key selection criteria include unipolar input range support, internal reference accuracy (±20 mV over temperature), standby power consumption (20 µA typ), and parallel bus timing compatibility with microcontroller read cycles.

Technical Context

The AD7899ARZ-2 implements a laser-trimmed internal clock oscillator or accepts external CLKIN up to 6.5 MHz, requiring 16 clock cycles per conversion. Its track/hold amplifier achieves full-scale settling within 0.3 µs and supports ±18 V analog input overvoltage tolerance on VINA/VINB.

Conversion control uses edge-triggered CONVST to initiate hold mode and BUSY/EOC to signal completion; data is latched via CS/RD-controlled 14-bit parallel bus (DB0–DB13) with straight binary coding and 3-state outputs. VDRIVE decoupling enables mixed-voltage interfacing without level shifters.

Key Specifications

Pinout & Package

AD7899ARZ-2 is housed in a 28-lead SOIC package (R-28) with standard 0.3-inch body width and gull-wing leads. Pin 1 is marked by a beveled corner; pins are numbered counterclockwise from top-left when viewed from top.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7899BRZ-2, AD7899ARZ-2 trades 0.5 LSB INL for lower cost in volume production; versus ADS8684IPWR, it offers simpler parallel timing and lower system-level BOM count but lacks on-chip PGA and higher resolution.

Availability

AD7899ARZ-2 is available at Aetrix Electronics and suitable for industrial process monitoring, automated test equipment, and portable medical instrumentation requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for AD7899ARZ-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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets.

The AD7899 product line delivers high-speed, low-power 14-bit SAR ADCs with integrated references and flexible input configurations for precision data acquisition in space- and power-constrained systems.

FAQ

What input voltage ranges does the AD7899ARZ-2 support?

The AD7899ARZ-2 supports two unipolar input ranges: 0 V to 2.5 V and 0 V to 5 V. Configuration is achieved by connecting VINB to GND for 0 V–5 V operation or tying VINA and VINB together for 0 V–2.5 V operation. The AD7899ARZ-2 does not support bipolar ranges - those are handled by AD7899ARZ-1 and AD7899ARZ-3 variants. Input overvoltage tolerance extends to –1 V to +18 V, protecting against transient faults.

Does the AD7899ARZ-2 require an external reference voltage?

No, the AD7899ARZ-2 includes an internal 2.5 V reference with ±10 mV accuracy at 25°C and ±20 mV max error over –40°C to +85°C. A 0.1 µF capacitor between VREF and AGND is required for stability. An external 2.5 V ±5% reference may be applied to the VREF pin to override the internal source, useful when system-level reference sharing or tighter tolerance is needed. The AD7899ARZ-2 reference output impedance is 6 kΩ.

How does the AD7899ARZ-2 interface with a 3 V microcontroller?

The AD7899ARZ-2 interfaces directly with 3 V microcontrollers using the VDRIVE pin: tie VDRIVE to a clean 3 V supply (±10%) instead of VDD, and connect DB0–DB13, BUSY/EOC, RD, CS, CONVST, and STBY to the MCU's 3 V I/O. The part's logic thresholds scale with VDRIVE, eliminating level shifters. Ensure OPGND and AGND are properly partitioned to avoid digital noise coupling into the analog section.

What is the purpose of the OPGND pin on the AD7899ARZ-2?

The OPGND pin (Pin 14) provides a dedicated ground return path for the digital output drivers (DB0–DB13 and BUSY/EOC), isolating switching noise from the analog ground plane. It must be connected to the system's analog ground - not digital ground - to prevent digital current transients from modulating the reference or analog input paths. This separation maintains SNR and THD performance, especially critical at 14-bit resolution.

Can the AD7899ARZ-2 operate with an external clock source?

Yes, the AD7899ARZ-2 supports external clocking via the CLKIN pin. When CLKIN is high at the rising edge of CONVST, the device uses the external clock (up to 6.5 MHz, 60/40 duty cycle) for conversion timing; when low, it uses the internal laser-trimmed oscillator. External clocking allows synchronization to system clocks or precise timing control, but the internal oscillator delivers optimal 400 kSPS throughput without additional components.