Analog Devices Inc. AD677KNZ

Overview

AD677KNZ from Analog Devices is a 16-bit, 100 kSPS autocalibrating successive-approximation ADC with on-chip sample-hold, serial output, ±5 V to ±10 V input range, and 1 MHz full-power bandwidth-designed for precision data acquisition in instrumentation and signal processing systems.

For engineers reviewing the AD677KNZ datasheet, AD677KNZ pinout, AD677KNZ application, or AD677KNZ equivalent, key selection criteria include its post-calibration ±1.5 LSB INL (K-grade), –99 dB THD, 92 dB S/(N+D), TTL-compatible digital interface, and dual-chip BiMOS II + DSP CMOS architecture enabling stable dc and dynamic performance without external trimming.

Technical Context

The AD677KNZ implements a switched-capacitor charge-redistribution SAR architecture with integrated microcoded controller and on-chip 16-bit DAC for autocalibration. It segments analog and digital functions across two monolithic dies-an analog ADC chip (BiMOS II) and a digital control chip (DSP CMOS)-housed in one package.

It uses a 17-clock-cycle conversion sequence with precise timing control via SAMPLE and CLK inputs, delivers twos-complement serial output synchronized to SCLK, and supports remote analog ground sensing (AGND SENSE) to mitigate source-ground offset errors in distributed signal paths.

Key Specifications

Pinout & Package

AD677KNZ is packaged in a 16-pin 0.3" narrow-body plastic DIP (N-16). Pin assignments are validated per Analog Devices AD677 datasheet Rev. A, with pins 6, 7, 13, 14, 18–20, 24, 25 designated NC (no connection).

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7606BSTZ and ADS8860IDRCT, the AD677KNZ uniquely combines factory-trimmed autocalibration, 1 MHz bandwidth, and –99 dB THD in a single-channel 16-bit SAR architecture-making it optimal for applications where long-term dc accuracy and dynamic fidelity outweigh channel count or raw speed requirements.

Availability

AD677KNZ is available at Aetrix Electronics and suitable for high-accuracy data logging, industrial process monitoring, and communications signal analysis requiring stable component supply and long-term calibration integrity.

Supply support for AD677KNZ 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 AD677KNZ belongs to Analog Devices' precision data acquisition product line, engineered specifically for applications demanding uncompromised dc accuracy, low distortion, and self-maintained linearity-such as metrology, automated test equipment, and scientific instrumentation.

FAQ

What is the maximum recommended conversion rate for the AD677KNZ?

The AD677KNZ is specified for a maximum conversion rate of 100 kSPS, corresponding to a 10 µs total conversion time. Exceeding this rate may degrade INL, THD, or S/(N+D) performance due to insufficient settling time in the internal sample-hold and capacitor array. The device supports continuous conversion mode with proper timing alignment, but all AC and DC specifications assume operation at or below 100 kSPS as tested in the AD677KNZ datasheet.

Does the AD677KNZ require an external voltage reference?

Yes, the AD677KNZ requires an external precision voltage reference applied to the VREF pin. It accepts 5 V to 10 V inputs, and the selected reference directly sets the full-scale input range (±VREF). While the AD677KNZ includes on-chip autocalibration for linearity and offset, it does not integrate a reference-so a stable, low-noise external reference such as the REF02 or ADR435 is necessary to achieve specified accuracy.

How does the autocalibration function work in the AD677KNZ?

The AD677KNZ autocalibration sequence measures and compensates for capacitor mismatch errors in its charge-redistribution array. When CAL is pulsed, the device nulls sample/hold offset using AGND SENSE, then sequentially tests each of the nine most significant capacitors against a calibration DAC. Correction values are stored in on-chip RAM and applied during subsequent conversions-ensuring ±1.5 LSB INL without user intervention. Calibration takes 85,532 clock cycles and is typically performed once at power-up.

Can the AD677KNZ operate with a single +5 V supply?

No, the AD677KNZ requires three independent supplies: +12 V (VCC), –12 V (VEE), and +5 V (VDD). These are not interchangeable or combinable-the analog section needs symmetric ±12 V rails to support ±10 V input ranges and maintain linearity, while the digital logic operates from +5 V. Attempting to run from a single +5 V supply will prevent proper operation and may damage the device, as confirmed by Absolute Maximum Ratings and functional description in the AD677KNZ datasheet.

What is the purpose of the AGND SENSE pin on the AD677KNZ?

The AGND SENSE pin on the AD677KNZ enables remote sensing of the analog ground potential at the signal source-critical when VIN originates from a distant sensor or front-end amplifier. By connecting AGND SENSE to the source's local ground, the AD677KNZ cancels voltage drops across ground return paths, eliminating common-mode offset errors that would otherwise degrade 16-bit accuracy. This feature is especially valuable in strain gauge bridges or thermocouple circuits with long interconnects.