Analog Devices Inc. AD977AAR

Overview

AD977AAR from Analog Devices is a 16-bit, 200 kSPS successive-approximation analog-to-digital converter (ADC) operating from a single 5 V supply. It features on-chip 2.5 V reference, high-speed serial interface, power-down mode (50 µW), and supports ±10 V, ±5 V, ±3.3 V bipolar and 0 V–10 V/5 V/4 V unipolar input ranges - used in precision industrial data acquisition systems requiring high linearity and low power.

For engineers reviewing the AD977AAR datasheet, AD977AAR pinout, AD977AAR application, or AD977AAR equivalent, this page delivers verified specifications, package mapping, real-world timing behavior, functional alternatives, and design-critical interface guidance for embedded measurement and control systems.

Technical Context

The AD977AAR implements a factory-calibrated switched-capacitor SAR architecture with internal clock generation and dual-mode serial data output (internal or external DATACLK). Its conversion control relies on R/C and CS signals, with BUSY indicating active conversion and SYNC supporting frame-synchronized reads under external clocking.

It supports two data formats (Binary Two's Complement or Straight Binary via SB/BTC), daisy-chain capability via TAG input, and configurable reference sourcing (internal 2.48–2.52 V or external 2.3–2.7 V). Power-down mode preserves the last conversion result in the shift register while reducing dissipation to 50 µW.

Key Specifications

Pinout & Package

AD977AAR is available in a 20-lead Skinny SOIC (SOIC_N) package with exposed pad not present; thermal resistance θ_JA = 75°C/W. Pin functions are electrically and mechanically defined per Analog Devices Rev. E datasheet Figures 3 and Table 6.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 16-bit SAR ADC applications.

Compared with ADS8860IDRCT and MAX11902ETX+, the AD977AAR uniquely combines 200 kSPS throughput, factory-calibrated ±3 LSB INL, integrated 2.5 V reference, and native ±10 V bipolar input support - making it optimal for retrofitting legacy industrial systems without redesigning signal conditioning.

Availability

AD977AAR is available at Aetrix Electronics and suitable for industrial process monitoring, automated test equipment, medical instrumentation, and energy metering applications requiring stable component supply and long-lifecycle support.

Supply support for AD977AAR 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 since 1965.

The AD977AAR belongs to Analog Devices' precision data acquisition product line, engineered for high-accuracy, low-drift, single-supply ADC applications in harsh industrial environments where calibration stability and long-term reliability are critical.

FAQ

What is the maximum sampling rate supported by the AD977AAR?

The AD977AAR supports a maximum throughput rate of 200 kSPS, corresponding to a complete conversion cycle time of 5 µs. This is confirmed in Table 2 of the Rev. E datasheet under AD977A–SPECIFICATIONS. The AD977AAR achieves this speed using a factory-calibrated switched-capacitor SAR architecture with on-chip clock generation. At 200 kSPS, the device maintains full 16-bit linearity and 83 dB S/(N+D) performance with a 20 kHz input tone.

Does the AD977AAR include an internal voltage reference?

Yes, the AD977AAR integrates a precision 2.5 V internal reference with ±1% tolerance (2.48 V to 2.52 V) and ±2 ppm/°C drift when using external reference, or ±7 ppm/°C with internal reference. This is specified in Table 2 and Figure 1. The REF pin serves as both output (for internal reference) and input (to override with external 2.3–2.7 V source), and requires a 2.2 µF tantalum capacitor to AGND2 on the CAP pin for stability.

Can the AD977AAR operate with bipolar input ranges such as ±10 V?

Yes, the AD977AAR natively supports bipolar input ranges including ±10 V, ±5 V, and ±3.3 V, as explicitly stated in the General Description and Table 2. Bipolar operation requires proper external resistor network configuration per Table 8 and Figure 14. Bipolar zero error is specified at ±10 mV (max), and full-scale error remains within ±0.5% across temperature - enabling direct connection to industrial transmitters without external level-shifting.

How does the power-down mode function on the AD977AAR?

The AD977AAR enters power-down mode when the PWRD pin is driven HIGH, reducing supply current to 50 µW while retaining the last conversion result in its internal shift register. Recovery to full accuracy takes 1 ms (per Table 2), and the device resumes normal operation upon PWRD LOW. This feature is ideal for intermittent sampling in battery-powered instruments - the AD977AAR consumes only 100 mW during active conversion, minimizing thermal drift in precision measurement chains.

What package options are available for the AD977AAR?

The AD977AAR is offered exclusively in a 20-lead Skinny SOIC (SOIC_N) package, as documented in the Ordering Guide and Figure 3 of the Rev. E datasheet. This package has standard JEDEC MO-153 dimensions (7.5 mm × 5.3 mm), 1.27 mm pitch, and no exposed thermal pad. The 28-lead SSOP variant applies to the broader AD977/AD977A family but is not assigned to the AD977AAR part number - only the SOIC version carries the "AR" suffix per Analog Devices' ordering nomenclature.