Analog Devices Inc. AD976CNZ

Overview

AD976CNZ from Analog Devices is a 16-bit, 100 kSPS BiCMOS successive-approximation analog-to-digital converter with ±10 V input range, internal 2.5 V reference, and parallel 16-bit twos-complement output interface. It operates from a single +5 V supply, dissipates ≤100 mW, and targets precision data acquisition in industrial instrumentation and test equipment.

For engineers reviewing the AD976CNZ datasheet, AD976CNZ pinout, AD976CNZ application, or AD976CNZ equivalent, key selection criteria include its 100 kSPS throughput, ±10 V bipolar input compliance, factory-calibrated INL (±3 LSB), on-chip clock, and 28-lead PDIP package compatibility with legacy systems requiring high-resolution DC/AC performance.

Technical Context

The AD976CNZ implements a switched-capacitor SAR architecture with laser-trimmed scaling resistors and on-chip capacitor array charge redistribution-eliminating external sample-and-hold circuitry and minimizing temperature-induced linearity drift. Calibration coefficients are stored in thin-film resistor ROM and applied dynamically during conversion to correct capacitor mismatches and offset errors.

It features dual analog grounds (AGND1 for REF/VIN reference, AGND2 for CAP), separate digital ground (DGND), and supports both internal 2.5 V reference (±0.5% accuracy) and external reference (2.3–2.7 V). The parallel interface uses BYTE-selectable 16-bit or dual-byte output mode with BUSY-driven timing control and R/C-initiated conversion sequencing.

Key Specifications

Pinout & Package

AD976CNZ is packaged in a 28-lead plastic DIP (N-28B) with 0.3-inch body width and through-hole mounting. Pin layout is identical across DIP, SOIC, and SSOP variants per Analog Devices' pin-compatible family design.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ADS8860IDRCT and MAX1190ECM+, the AD976CNZ uniquely combines ±10 V input range, internal 2.5 V reference, BYTE-configurable parallel output, and proven 28-pin DIP compatibility-making it irreplaceable in legacy industrial DAQ systems requiring full-scale bipolar fidelity and drop-in mechanical fit.

Availability

AD976CNZ is available at Aetrix Electronics and suitable for industrial data acquisition, automated test equipment, and medical instrumentation requiring stable component supply and long-term obsolescence support.

Supply support for AD976CNZ 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, headquartered in Wilmington, MA.

The AD976 product line was designed for high-accuracy, medium-speed data acquisition in industrial, medical, and test equipment-emphasizing factory-calibrated DC precision, robust AC performance, and single-supply simplicity.

FAQ

What is the maximum sampling rate supported by the AD976CNZ?

The AD976CNZ supports a maximum throughput rate of 100 kSPS, corresponding to a complete conversion cycle time of 10 µs. This is specified for all grades (A/B/C) across the –40°C to +85°C operating range with internal reference and 5 V supplies. The AD976CNZ does not support the 200 kSPS rate-that is exclusive to the AD976A variant. Timing parameters such as t7 (conversion time) and t8 (acquisition time) are validated to guarantee this rate under worst-case conditions.

Does the AD976CNZ require an external reference, or can it operate with its internal reference?

The AD976CNZ can operate with either its internal 2.5 V reference (2.48 V to 2.52 V, ±0.5%) or an external reference (2.3 V to 2.7 V). When using the internal reference, the REF pin outputs 2.5 V and must be decoupled to AGND1 with a 2.2 µF tantalum capacitor; CAP must be similarly decoupled to AGND2. No external reference is required unless tighter initial accuracy or different reference voltage is needed-making the AD976CNZ a self-contained solution for most precision applications.

How is the analog input range of ±10 V achieved in the AD976CNZ?

The AD976CNZ achieves its ±10 V analog input range using laser-trimmed scaling resistors and a switched-capacitor SAR architecture referenced to the internal or external 2.5 V reference. The full-scale range is defined as ±4 × VREF, so with VREF = 2.5 V, the range becomes ±10 V. A 200 Ω series resistor is required between the signal source and VIN to match input impedance and protect against overvoltage-this value is specified in the datasheet for optimal linearity and transient response.

What are the grounding requirements for optimal performance of the AD976CNZ?

The AD976CNZ requires three distinct ground connections: AGND1 (reference and VIN ground), AGND2 (CAP ground), and DGND (digital ground). AGND1 must serve as the reference point for the analog input and REF pin; AGND2 must be used exclusively for the CAP decoupling capacitor; DGND carries digital switching currents. These grounds should be tied together at a single point near the device, preferably at the AGND1 pad, to prevent ground loops and minimize offset drift caused by current-induced voltage drops across shared traces.

Can the AD976CNZ interface directly with an 8-bit microcontroller?

Yes-the AD976CNZ supports byte-mode operation via the BYTE pin. When BYTE is HIGH, the upper 8 bits (D15–D8) appear on pins 15–22 and the lower 8 bits (D7–D0) appear on pins 6–13, enabling sequential 8-bit reads from standard microcontrollers without data alignment logic. This mode preserves full 16-bit resolution and is fully compatible with the timing specifications in the datasheet-including BUSY-synchronized latching and CS-controlled read enable-making the AD976CNZ suitable for resource-constrained embedded systems.