Analog Devices Inc. AD977AAN

Overview

AD977AAN from Analog Devices is a 16-bit, 200 kSPS successive-approximation ADC operating from a single 5 V supply. It features internal 2.5 V reference, high-speed serial interface, on-chip clock, and 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 - used in precision industrial data acquisition systems requiring high linearity and low power.

For engineers reviewing the AD977AAN datasheet, AD977AAN pinout, AD977AAN application, or AD977AAN equivalent, key selection considerations include throughput rate (200 kSPS), integral linearity error (±3 LSB), power-down mode (50 µW), serial data format (binary two's complement or straight binary), and compatibility with external or internal clocking modes.

Technical Context

The AD977AAN implements a factory-calibrated switched-capacitor SAR architecture with integrated reference buffer and serial output register. Its conversion control relies on dual digital inputs (R/C and CS), supporting both internal clock generation and external clock synchronization via EXT/INT pin configuration.

It provides two distinct serial read modes: internal clock mode (DATACLK output, MSB-first, valid on both edges) and external clock mode (with optional SYNC framing and TAG-enabled daisy-chaining). Aperture delay is fixed at 40 ns, and transient response to full-scale step is 1 µs - enabling accurate sampling of fast-changing analog signals in closed-loop control systems.

Key Specifications

Pinout & Package

AD977AAN is available in a 20-lead skinny SOIC (SOIC_N) package with 0.3" body width and standard 0.050" lead pitch. 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 AD7606C-16 and ADS8860, the AD977AAN uniquely balances single-channel 200 kSPS performance, integrated 2.5 V reference, bipolar/unipolar flexibility, and daisy-chain capability in a compact 20-lead SOIC - making it optimal for upgrade paths from legacy 12–14 bit ADCs in space- and cost-sensitive industrial nodes.

Availability

AD977AAN is available at Aetrix Electronics and suitable for industrial automation, process control, and automated test equipment requiring stable component supply, long-lifecycle support, and guaranteed traceability.

Supply support for AD977AAN 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.

The AD977AAN belongs to Analog Devices' precision SAR ADC product line, designed specifically for high-accuracy, medium-speed data acquisition in industrial, instrumentation, and test equipment where linearity, low power, and flexible interfacing are critical.

FAQ

What is the maximum sampling rate supported by the AD977AAN?

The AD977AAN 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 AD977AAN achieves this rate using its factory-calibrated switched-capacitor SAR architecture and on-chip clock generator. At 200 kSPS, the device maintains full 16-bit linearity and specified AC performance including 85 dB SNR and 96 dB SFDR at 20 kHz input.

Does the AD977AAN include an internal voltage reference?

Yes, the AD977AAN integrates a precision 2.5 V internal reference with ±0.02 V tolerance (2.48 V to 2.52 V) and 1 µA source current, as specified in Table 2 and Figure 1. The REF pin serves as both output and input: it delivers the internal reference or accepts an external 2.3 V–2.7 V source. When using the internal reference, a 2.2 µF tantalum capacitor must be connected between REF and AGND2, and CAP must be similarly decoupled to AGND2 for stability and noise rejection.

Can the AD977AAN operate with bipolar input signals?

Yes, the AD977AAN supports bipolar input ranges of ±10 V, ±5 V, and ±3.3 V, as explicitly stated in the General Description and Table 2. Bipolar operation requires appropriate external resistor network configuration per Table 8 and Figure 14–16 in the datasheet. Bipolar zero error is specified at ±10 mV (max), ensuring accurate midscale (0 V) detection. The device outputs data in two's complement format when SB/BTC is LOW, preserving sign information for direct digital processing.

How does the power-down mode function on the AD977AAN?

The AD977AAN enters power-down mode when the PWRD pin is driven HIGH, reducing supply current to 50 µW while retaining the last conversion result in the internal shift register. As stated in the FEATURES section and Table 3, power dissipation drops from 100 mW (active) to 50 µW (power-down). Recovery to full accuracy takes 1 ms when a 2.2 µF capacitor is connected to CAP, per Table 2 footnote 5. During power-down, conversions are inhibited but serial readout remains possible - enabling ultra-low-power wake-on-read architectures.

What package options are available for the AD977AAN?

AD977AAN is offered exclusively in a 20-lead skinny SOIC (SOIC_N) package with 0.3" body width, as confirmed in the FEATURES section and Figure 3 of the Rev. E datasheet. While the AD977/AD977A family also includes a 28-lead SSOP variant (e.g., AD977ARS), the "AAN" suffix specifically denotes the 20-lead SOIC option. This package supports standard surface-mount reflow profiles and provides adequate thermal performance (θJA = 75°C/W) for typical industrial ambient conditions.