Analog Devices Inc. AD977ACNZ

Overview

AD977ACNZ from Analog Devices is a 16-bit, 100 kSPS successive-approximation analog-to-digital converter (ADC) operating from a single 5 V supply, featuring ±10 V/0 V–5 V input ranges, on-chip 2.5 V reference, and high-speed serial interface in a 20-lead SOIC package. It delivers 83 dB SNR, ±3 LSB INL (A-grade), and 100 mW max power dissipation for precision data acquisition in industrial instrumentation.

For engineers reviewing the AD977ACNZ datasheet, AD977ACNZ pinout, AD977ACNZ application, or AD977ACNZ equivalent, this page provides verified technical context, real-world timing behavior, package-specific layout guidance, and validated alternative options for system-level ADC selection and replacement planning.

Technical Context

The AD977ACNZ implements a factory-calibrated switched-capacitor SAR architecture with internal clock generation and dual-mode serial interface (internal or external DATACLK). Its conversion control relies on R/C and CS signals, with BUSY indicating active conversion and pipeline delay enforcing post-conversion data availability.

It supports both binary two's complement and straight binary output formats via SB/BTC, accepts external references from 2.3 V to 2.7 V, and includes power-down mode reducing consumption to 50 µW while retaining the last conversion result in the shift register.

Key Specifications

Pinout & Package

AD977ACNZ is packaged in a 20-lead skinny SOIC (SOIC_N) with 0.3" body width and 0.050" lead pitch. Thermal resistance θ_JA = 75°C/W enables operation up to +85°C ambient with minimal heatsinking.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD977ACNZ, AD7606BCPZ offers higher channel count and throughput but requires PCB redesign and firmware adaptation, while ADS8860IDRCT trades bipolar capability and integrated reference for speed and size-neither is pin-compatible, but both serve distinct system-level trade-offs in resolution, integration, and scalability.

Availability

AD977ACNZ is available at Aetrix Electronics and suitable for industrial process monitoring, automated test equipment, and medical instrumentation requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.

Supply support for AD977ACNZ 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, founded in 1965 and headquartered in Wilmington, MA.

The AD977 series belongs to Analog Devices' precision data acquisition product line, designed specifically for medium-speed, high-resolution industrial and instrumentation applications where factory-calibrated linearity and single-supply operation are critical.

FAQ

What is the maximum input frequency the AD977ACNZ can accurately digitize?

The AD977ACNZ has a full-power bandwidth of 700 kHz and a –3 dB input bandwidth of 1.5 MHz. For accurate digitization without SNR degradation, input signals should remain below 700 kHz when operating at full scale. This specification is measured with a ±10 V input and reflects the frequency at which Signal-to-(Noise+Distortion) drops to 60 dB (10-bit accuracy). The AD977ACNZ maintains 83 dB SNR up to 20 kHz, making it optimal for DC-coupled sensor and process monitoring applications.

Does the AD977ACNZ support bipolar input ranges, and how are they configured?

Yes, the AD977ACNZ supports bipolar input ranges of ±10 V, ±5 V, and ±3.3 V using external resistor networks connected to R1IN, R2IN, and R3IN pins as specified in Table 8 of the datasheet. Configuration requires precision resistors to set gain and offset; for example, ±10 V operation uses R1IN = 10 kΩ, R2IN = 10 kΩ, and R3IN = 20 kΩ tied to AGND2. Bipolar zero error is guaranteed ≤±15 mV (C grade), enabling accurate midscale (0 V) detection in closed-loop control systems.

Can the AD977ACNZ operate with an external reference, and what are the voltage limits?

Yes, the AD977ACNZ accepts an external reference voltage applied to the REF pin within 2.3 V to 2.7 V for specified linearity performance. When using an external 2.5 V reference, the device draws 100 µA from that source. The internal 2.5 V reference remains available as a buffered output on the CAP pin, requiring a 2.2 µF tantalum capacitor to AGND1. External reference use improves system-level accuracy when a higher-stability or temperature-compensated reference is already present on the board.

How does the power-down mode affect data retention and wake-up time in the AD977ACNZ?

In power-down mode (PWRD = HIGH), the AD977ACNZ reduces supply current to 10 µA and halts conversions, but retains the most recent conversion result in its internal shift register. Recovery to full accuracy takes 1 ms when a 2.2 µF capacitor is connected to CAP, as specified in Table 1. During wake-up, the device resumes tracking the analog input immediately upon PWRD going LOW, and the next conversion completes in 10 µs - enabling rapid, deterministic reactivation in duty-cycled measurement systems.

What are the timing constraints for reading conversion results using the internal DATACLK mode?

In internal DATACLK mode (EXT/INT = LOW), the AD977ACNZ generates 16 clock pulses on DATACLK after conversion initiation, with DATA valid on both rising and falling edges. The first bit (MSB) appears on the first DATACLK edge, and the LSB on the 16th edge. After the LSB, DATA holds the logic level of the TAG input at conversion start. Minimum DATACLK period is 450 ns (2.22 MHz), and R/C must remain stable for ≥10 ns before CS goes LOW to avoid metastability in the control logic.