Analog Devices Inc. AD977CRSZ

Overview

AD977CRSZ from Analog Devices is a 16-bit, 100 kSPS successive-approximation ADC with single 5 V supply operation, internal 2.5 V reference, and high-speed serial interface. It supports ±10 V, ±5 V, and 0 V–10 V input ranges, delivers ≤±3 LSB INL (A grade), and operates in industrial temperature range (–40°C to +85°C) for precision data acquisition in automated test equipment.

For engineers reviewing the AD977CRSZ datasheet, AD977CRSZ pinout, AD977CRSZ application, or AD977CRSZ equivalent, key selection criteria include throughput rate (100 kSPS), unipolar/bipolar input flexibility, power-down mode (50 µW), serial data format (MSB-first, two's complement or straight binary), and SOIC-20 package compatibility with legacy industrial layouts.

Technical Context

The AD977CRSZ implements a factory-calibrated switched-capacitor SAR architecture with on-chip 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 SYNC supporting frame synchronization only in external-clock mode.

It features integrated reference buffer (CAP pin), configurable analog input scaling via R1IN/R2IN/R3IN, and error correction circuitry that recovers from first-half-cycle bit decision errors. Power-down mode preserves the last conversion result in the shift register while reducing dissipation to 50 µW.

Key Specifications

Pinout & Package

AD977CRSZ is housed in a 20-lead skinny SOIC (SOIC-20) package with standard 0.3-inch body width and 0.050-inch lead pitch, optimized for surface-mount assembly and thermal performance (θ_JA = 75°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD977ARZ, AD977CRSZ offers lower thermal resistance and proven SOIC-20 compatibility with legacy industrial layouts; compared with ADS8688IPWR, it provides 5 V operation and simpler interface but lacks PGA and higher speed - making AD977CRSZ optimal for cost-sensitive, retrofit-focused deployments.

Availability

AD977CRSZ is available at Aetrix Electronics and suitable for automatic test equipment, process control systems, and industrial data acquisition requiring stable component supply over extended production lifecycles.

Supply support for AD977CRSZ 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 DSP technologies, serving industrial, automotive, communications, and healthcare markets since 1965.

The AD977 product line was designed specifically for precision, medium-speed data acquisition in harsh industrial environments - emphasizing factory calibration, wide input range flexibility, and robust serial interfacing.

FAQ

What is the maximum input frequency supported by the AD977CRSZ?

The AD977CRSZ has a –3 dB input bandwidth of 1.5 MHz and a full-power bandwidth of 700 kHz. This means it maintains 10-bit accuracy (60 dB S/(N+D)) for sinusoidal inputs up to 700 kHz. For applications requiring higher-frequency fidelity, anti-aliasing filtering must be applied before the AD977CRSZ analog inputs to prevent spectral folding.

Does the AD977CRSZ require an external reference, or can it operate with its internal reference?

The AD977CRSZ can operate fully with its internal 2.5 V reference (2.48 V–2.52 V), eliminating the need for external components in most applications. An external reference (2.3 V–2.7 V) may be used when tighter initial accuracy or lower drift is required, but the internal reference is sufficient for typical industrial measurement tasks where ±0.5% full-scale error is acceptable.

How does the power-down mode affect the AD977CRSZ's output behavior?

When PWRD is asserted HIGH, the AD977CRSZ enters 50 µW power-down mode: conversion halts, BUSY goes HIGH, and the DATA pin holds the last valid conversion result. The internal reference remains active, and recovery to full accuracy takes 1 ms after PWRD returns LOW - allowing rapid wake-up in duty-cycled systems without recalibration.

Can multiple AD977CRSZ devices share a single DATA line? If so, how?

Yes - multiple AD977CRSZ devices can daisy-chain onto one DATA line using the TAG input. When EXT/INT = HIGH and SYNC is enabled, each device delays its output by 16 or 17 DATACLK periods based on TAG level, allowing time-multiplexed readout. This avoids bus contention and reduces host interface complexity in multi-channel systems.

What are the critical layout considerations for stable AD977CRSZ operation?

Separate AGND1, AGND2, and DGND planes must be tied at a single point near the AD977CRSZ; 2.2 µF tantalum capacitors must connect CAP and REF directly to AGND2; VANA and VDIG require local 0.1 µF ceramic decoupling; analog and digital traces must not cross split grounds; and R1IN/R2IN/R3IN resistor networks must use 0.1% tolerance parts per Table 8 to maintain specified input range accuracy.