Analog Devices Inc. AD977ACN

Overview

AD977ACN from Analog Devices is a 16-bit, 100 kSPS successive-approximation analog-to-digital converter (ADC) operating from a single 5 V supply. It features factory-calibrated linearity, on-chip 2.5 V reference, high-speed serial interface, and supports unipolar (0 V–10 V, 0 V–5 V) and bipolar (±10 V, ±5 V) input ranges - used in precision industrial data acquisition systems requiring stable dc accuracy and low power.

For engineers reviewing the AD977ACN datasheet, AD977ACN pinout, AD977ACN application, or AD977ACN equivalent, this page delivers verified technical context, real-world timing behavior, confirmed package mapping to 20-lead SOIC, and validated alternative options for 16-bit, sub-200 kSPS ADC selection in embedded instrumentation and process control.

Technical Context

The AD977ACN implements a switched-capacitor SAR architecture with internal clock generation and serial data output synchronized to either internal or external DATACLK. Its conversion control relies on R/C and CS signals, with BUSY indicating active conversion and pipeline delay ensuring results are only available after completion.

It supports two data formats (Binary Two's Complement or Straight Binary) via SB/BTC, dual reference modes (internal 2.48–2.52 V or external 2.3–2.7 V), and power-down mode reducing dissipation to 50 µW. Aperture delay is fixed at 40 ns, and transient response to full-scale step is 2 µs across all grades.

Key Specifications

Pinout & Package

AD977ACN is packaged in a 20-lead narrow-body SOIC (SOIC_N) with standard 0.3-inch body width and 0.050-inch lead pitch. Thermal resistance θ_JA = 75°C/W enables reliable operation up to +85°C ambient under typical PCB layout conditions.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD977ACN, AD7606BSTZ offers higher channel density and built-in signal conditioning but demands more board area and dual supplies; LTC2311-16 trades bipolar flexibility and internal reference for lower power and simpler interface - making it viable only where input range and reference autonomy are secondary concerns.

Availability

AD977ACN is available at Aetrix Electronics and suitable for industrial process monitoring, automated test equipment, medical instrumentation, and energy metering reference designs requiring stable component supply and long-term obsolescence management.

Supply support for AD977ACN 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 AD977 family was designed for precision, low-power, medium-speed data acquisition in space- and power-constrained embedded systems - emphasizing factory-trimmed linearity, single-supply simplicity, and robust serial interfacing.

FAQ

What is the maximum sampling rate supported by the AD977ACN?

The AD977ACN supports a maximum throughput rate of 100 kSPS, corresponding to a complete conversion cycle time of 10 µs. This is specified across all A/B/C grades at –40°C to +85°C with 5 V supplies. The AD977ACN does not support the 200 kSPS rate - that applies only to the AD977A variant. Timing parameters such as t6 (conversion time) and t7 (acquisition time) are tightly bounded to ensure consistent 100 kSPS operation under worst-case conditions.

Does the AD977ACN include an internal voltage reference?

Yes, the AD977ACN integrates a 2.5 V internal reference with initial accuracy of ±20 mV (2.48 V to 2.52 V) and drift of ±2 ppm/°C. This reference is accessible at the REF pin and can be overridden by an external 2.3–2.7 V source. The CAP pin provides the buffered output of this reference and must be decoupled with a 2.2 µF tantalum capacitor to AGND2 to ensure stability and low-noise performance.

Which package type is used for the AD977ACN?

The AD977ACN is supplied in a 20-lead narrow-body SOIC (SOIC_N) package, also referred to as "Skinny SOIC" in the datasheet. It has a 0.3-inch body width and 0.050-inch lead pitch. This package is distinct from the 28-lead SSOP option offered for the AD977/AD977A family and is explicitly assigned to the AD977ACN ordering code per the official Analog Devices ordering guide.

Can the AD977ACN operate with bipolar input ranges?

Yes, the AD977ACN supports bipolar input ranges of ±10 V, ±5 V, and ±3.3 V, as well as unipolar ranges of 0–10 V, 0–5 V, and 0–4 V. Configuration is achieved using external resistor networks connected to R1IN, R2IN, and R3IN pins per Table 8 in the datasheet. Bipolar zero error is specified at ±15 mV max (C grade), and full-scale error includes offset contribution per Analog Devices' definition in the Terminology section.

How does the power-down mode function on the AD977ACN?

The AD977ACN enters power-down mode when the PWRD pin is driven HIGH, reducing supply current to ≤10 µA and total power dissipation to 50 µW. During power-down, conversions are inhibited, but the last conversion result remains latched in the internal shift register and is available on the DATA line. Recovery to full accuracy takes ≤1 ms after PWRD is returned LOW and the 2.2 µF capacitor on CAP is fully charged.