Analog Devices Inc. AD677JRZ

Overview

AD677JRZ 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. It operates from +5 V (VDD) and ±12 V (VCC/VEE) supplies, delivers 92 dB S/(N+D), and targets precision data acquisition in industrial instrumentation and signal processing systems.

For engineers reviewing the AD677JRZ datasheet, AD677JRZ pinout, AD677JRZ application, or AD677JRZ equivalent, key selection criteria include its autocalibration architecture, bipolar input support, TTL-compatible serial interface timing, and dual-ground (AGND/DGND) isolation for noise-sensitive measurement designs.

Technical Context

The AD677JRZ implements a switched-capacitor charge-redistribution SAR architecture segmented across two monolithic chips-an analog BiMOS II ADC die and a digital CMOS controller die-co-packaged in a single SOIC. Its autocalibration uses an on-chip microcontroller and calibration DAC to measure and correct capacitor mismatch errors for the top nine bits, storing correction values in RAM for real-time compensation during conversion.

Conversion is initiated by a HIGH-to-LOW transition on SAMPLE after a minimum 2 µs acquisition window, followed by exactly 17 CLK pulses; output is twos-complement serial data synchronized to SCLK, with BUSY indicating active conversion or calibration. The device supports remote AGND sensing via AGND SENSE and separates analog/digital grounds to minimize crosstalk.

Key Specifications

Pinout & Package

AD677JRZ is packaged in a 28-lead small-outline IC (SOIC) with gull-wing leads, 0.020" lead pitch, and RoHS-compliant matte tin finish. Pin 1 is marked by a beveled corner or dot; package outline conforms to JEDEC MS-012AA.

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 AD677JRZ uniquely combines single-channel 100 kSPS performance with factory-trimmed autocalibration, eliminating post-manufacture calibration labor while sustaining 92 dB S/(N+D) and ±1.5 LSB INL-making it optimal for fixed-installation industrial and test systems where long-term dc stability is non-negotiable.

Availability

AD677JRZ is available at Aetrix Electronics and suitable for industrial process monitoring, audio signal digitization, automated test equipment, scientific data acquisition, and precision instrumentation requiring stable component supply across extended product lifecycles.

Supply support for AD677JRZ 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 AD677JRZ belongs to Analog Devices' legacy precision SAR ADC product line, engineered specifically for applications demanding guaranteed dc accuracy, low distortion, and autonomous calibration in harsh industrial environments.

FAQ

What is the maximum recommended clock frequency for reliable operation of the AD677JRZ?

The AD677JRZ specifies a minimum CLK period of 480 ns (2.08 MHz maximum), but 580 ns (1.72 MHz) is recommended for optimal accuracy over temperature. Operation above this frequency may degrade INL and THD due to reduced internal settling time; the device requires exactly 17 CLK pulses per conversion regardless of rate, and timing parameters like tFCD and tCB scale accordingly. Always verify timing margins against worst-case process/voltage/temperature corners when designing with AD677JRZ.

Does the AD677JRZ require an external voltage reference, and what are the acceptable ranges?

Yes, the AD677JRZ requires an external voltage reference applied to the VREF pin. It accepts 5 V to 10 V, with ±VREF defining the full-scale input range (e.g., ±5 V or ±10 V). Reference accuracy directly impacts gain error-typical specs assume 0.01% initial tolerance and <10 ppm/°C drift. The AD677JRZ does not include an internal reference; recommended companions include the REF02 (5.0 V) or ADR435 (5.0 V/10.0 V) for low-drift, low-noise performance.

How does the autocalibration sequence of the AD677JRZ affect system startup and runtime behavior?

The AD677JRZ autocalibration sequence takes 85,532 CLK cycles (~40 ms at 2 MHz) and is triggered by taking CAL HIGH then LOW. It must be performed at least once after power-up-failure to calibrate may result in only 10-bit effective resolution. Calibration can be repeated anytime during operation, but interrupts ongoing conversions. The AD677JRZ stores correction coefficients in on-chip RAM, so recalibration is only needed if temperature shifts exceed ±5°C or after significant supply variation; no external memory or host intervention is required for AD677JRZ calibration execution.

Can the AD677JRZ operate with a single +5 V supply, or are the ±12 V rails mandatory?

No, the AD677JRZ cannot operate with only a +5 V supply. It requires three independent supplies: +5 V (VDD) for digital logic, +12 V (VCC) for positive analog circuitry, and –12 V (VEE) for negative analog circuitry. These rails power the internal comparator, DAC, and input buffers; omitting either VCC or VEE will prevent proper bipolar input operation and cause functional failure. Decoupling each rail with 0.1 µF ceramic capacitors placed within 2 mm of their respective pins is mandatory for AD677JRZ stability.

What is the purpose of the AGND SENSE pin on the AD677JRZ, and how should it be connected?

The AGND SENSE pin on the AD677JRZ provides remote sensing of the analog ground potential at the signal source to compensate for voltage drops in PCB traces or cables. It should be connected directly to the ground reference point of the analog input source (e.g., sensor ground or front-end amplifier ground), not to the ADC's AGND pin. This creates a Kelvin connection that allows the AD677JRZ to adjust its internal bias points, reducing offset errors caused by ground differentials-critical when VIN originates meters away or shares noisy return paths.