Analog Devices Inc. AD977AARS

Overview

AD977AARS from Analog Devices is a 16-bit, 200 kSPS successive-approximation ADC operating from a single 5 V supply, featuring internal 2.5 V reference, high-speed serial interface, and power-down mode consuming only 50 µW. It supports ±10 V, ±5 V, ±3.3 V bipolar and 0 V–10 V/0 V–5 V/0 V–4 V unipolar input ranges, and is housed in a 20-lead skinny SOIC package. It targets precision data acquisition in industrial process control and automated test equipment.

For engineers reviewing the AD977AARS datasheet, AD977AARS pinout, AD977AARS application, or AD977AARS equivalent, key selection considerations include its 200 kSPS throughput, 16-bit resolution with ±3 LSB INL (A grade), 83 dB SNR at 20 kHz, 1 MHz full-power bandwidth, and dual-clock operation (internal or external DATACLK) for flexible microprocessor interfacing.

Technical Context

The AD977AARS implements a factory-calibrated switched-capacitor SAR architecture with on-chip clock generation and configurable serial output timing. Its conversion control relies on R/C and CS signals, supporting both internal clocked reads (16 DATACLK pulses per result) and externally clocked modes with SYNC framing or daisy-chain TAG capability.

It integrates a 2.5 V internal reference (±2 mV accuracy, 2 ppm/°C drift) and accepts external references from 2.3 V to 2.7 V. Input sampling capacitance is fixed at 40 pF, and aperture delay is tightly specified at 40 ns - enabling accurate time-domain signal capture in systems requiring sub-microsecond transient response (1 µs full-scale step recovery).

Key Specifications

Pinout & Package

AD977AARS is supplied in a 20-lead skinny SOIC (SOIC_N) package with standard 0.3-inch body width and 0.050-inch lead pitch. Pin 1 is marked by a beveled corner; leads are gull-wing shaped and RoHS-compliant.

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 AD977AARS uniquely combines 200 kSPS throughput, ±10 V bipolar input support, integrated 2.5 V reference, and guaranteed ±3 LSB INL in a 5 V single-supply SOIC package - making it the optimal choice for retrofitting legacy industrial DAQ systems and cost-sensitive metrology designs.

Availability

AD977AARS is available at Aetrix Electronics and suitable for industrial process control, automated test equipment, and scientific instrumentation requiring stable component supply, long-term obsolescence management, and traceable lot-level documentation.

Supply support for AD977AARS 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 Wilmington, MA, serving industrial, automotive, communications, and healthcare markets.

The AD977AARS belongs to Analog Devices' precision data acquisition product line, designed specifically for high-accuracy, medium-speed digitization in harsh industrial environments where reliability, temperature stability, and minimal calibration overhead are critical.

FAQ

What is the maximum sampling rate supported by the AD977AARS?

The AD977AARS 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" and applies across all grade versions (A/B/C) at –40°C to +85°C with 5 V supplies. The AD977AARS achieves this using a factory-calibrated switched-capacitor SAR architecture with on-chip clock generation.

Does the AD977AARS include an internal voltage reference?

Yes, the AD977AARS integrates a precision 2.5 V internal reference with ±2 mV initial accuracy (±0.08%) and ±2 ppm/°C drift over temperature. As stated in Table 2 and Figure 1, this reference is accessible at the REF pin and can be overridden by an external 2.3–2.7 V source. A 2.2 µF capacitor must be placed between REF and AGND2 to ensure stability and specified linearity performance.

Which package type is used for the AD977AARS variant?

The AD977AARS uses a 20-lead skinny SOIC (SOIC_N) package, as explicitly indicated by the "ARS" suffix in the part number and confirmed in the "Ordering Guide" (page 32) and Figure 3 of the Rev. E datasheet. This package has a 0.3-inch body width, gull-wing leads, and is distinct from the 28-lead SSOP option (AD977AARU). Pin functions are identical between packages per Table 6.

Can the AD977AARS operate with bipolar input ranges like ±10 V?

Yes, the AD977AARS fully supports bipolar input ranges including ±10 V, ±5 V, and ±3.3 V, as specified in the "ANALOG INPUT" section of Table 2 and the General Description. Configuration is achieved via external resistor networks connected to R1IN, R2IN, and R3IN pins per Table 8. Bipolar zero error is guaranteed to ±15 mV (C grade) with ±2 ppm/°C drift, ensuring stable midscale accuracy.

How does the power-down mode function on the AD977AARS?

The AD977AARS enters power-down mode when the PWRD pin is driven HIGH, reducing total power dissipation to 50 µW while retaining the last conversion result in its internal shift register. As detailed in the "Power-Down Feature" section (page 29), recovery to full accuracy requires 1 ms after PWRD is returned LOW and a 2.2 µF capacitor is connected to CAP - enabling rapid wake-up in duty-cycled measurement systems.