Analog Devices Inc. AD677JR

Overview

AD677JR from Analog Devices is a 16-bit, 100 kSPS autocalibrating successive-approximation ADC with on-chip sample-hold, serial output, and ±VREF input range (±5 V to ±10 V). It uses charge-redistribution capacitor DAC architecture, operates from +5 V / ±12 V supplies, and delivers 92 dB S/(N+D), –99 dB THD, and ±1 LSB INL (typ) at 100 kSPS for precision measurement and signal processing applications.

For engineers reviewing the AD677JR datasheet, AD677JR pinout, AD677JR application, or AD677JR equivalent, this page provides verified technical context, real-world timing constraints (e.g., 10 µs conversion time, 85,532-clock calibration cycle), package-specific pin mapping (28-lead SOIC), and validated alternatives for industrial data acquisition, instrumentation, and DSP interface designs.

Technical Context

The AD677JR implements a two-chip architecture: an analog BiMOS II ADC chip and a digital CMOS controller chip, both housed in a single 28-lead SOIC package. Its charge-redistribution SAR core eliminates resistor-ladder mismatches and enables inherent sample-hold functionality without external components.

Autocalibration is performed via on-chip microcontroller and calibration DAC, measuring and storing capacitor mismatch corrections in RAM for use during subsequent conversions. Calibration requires 85,532 CLK cycles and is triggered asynchronously by the CAL pin, with BUSY signaling active-high status during execution.

Key Specifications

Pinout & Package

AD677JR is packaged in a 28-lead small-outline integrated circuit (SOIC) with 0.3-inch body width and standard JEDEC MS-012AC footprint. Pin 1 is located at the top-left corner adjacent to the index mark; pins are numbered counterclockwise.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7606-6 and ADS8588S, the AD677JR offers unique autocalibration and true bipolar input architecture without PGA or multiplexing-making it optimal for single-channel, high-stability DC-critical applications where long-term drift must be minimized without firmware intervention.

Availability

AD677JR is available at Aetrix Electronics and suitable for industrial process monitoring, high-accuracy data loggers, and test & measurement equipment requiring stable component supply across commercial temperature range (0°C to +70°C).

Supply support for AD677JR 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 AD677JR belongs to Analog Devices' precision data converter product line, engineered specifically for applications demanding uncompromised DC accuracy, low distortion, and autonomous calibration in industrial and instrumentation environments.

FAQ

What is the maximum recommended clock frequency for reliable operation of the AD677JR?

The AD677JR requires a minimum CLK period of 480 ns (2.08 MHz max), but 580 ns (1.72 MHz) is recommended for optimal accuracy over temperature. Exceeding this limit risks violating setup/hold timing for internal logic and degrading INL or THD performance. The device uses 17 CLK pulses per conversion, so 100 kSPS operation corresponds to a 1.7 MHz clock - consistent with the recommended value.

Does the AD677JR require external calibration components or trimming resistors?

No, the AD677JR does not require external calibration components or trimming resistors. Its on-chip autocalibration circuitry measures and corrects capacitor mismatch errors using an internal calibration DAC and stores correction values in RAM. This enables the AD677JR to achieve ±1 LSB INL (typ) without user intervention after initial power-up calibration.

Can the AD677JR operate with a 5 V reference instead of 10 V, and how does that affect performance?

Yes, the AD677JR supports VREF from 5 V to 10 V. With 5 V reference, full-scale input range becomes ±5 V, and power consumption drops to 360 mW (vs. 450 mW at 10 V). Dynamic performance remains unchanged - S/(N+D) stays at 92 dB and THD at –99 dB - because noise and distortion are ratio-based metrics referenced to full-scale signal level.

How is the AGND SENSE pin used in practical PCB layout for the AD677JR?

The AGND SENSE pin on the AD677JR should be connected directly to the analog ground plane near the signal source (e.g., sensor or transducer), not to the ADC's local AGND pad. This creates a Kelvin sense path that cancels voltage drop across PCB traces between source and converter, improving DC accuracy. Layout best practice requires routing AGND SENSE as a dedicated low-impedance trace, shielded from digital noise sources.

What happens if the AD677JR is powered up without performing calibration?

If the AD677JR is powered up without calibration, it may initialize in an unknown state with degraded performance - potentially as low as 10-bit effective resolution due to uncorrected capacitor mismatches. The device will still function, but INL could exceed ±4 LSB and offset errors may drift unpredictably. Calibration is mandatory for guaranteed 16-bit accuracy; it is typically performed once at power-up after supplies and VREF have stabilized.

Is the AD677JR pin-compatible with other members of the AD67x family, such as the AD676?

No, the AD677JR is not pin-compatible with the AD676. The AD676 is a parallel-output version offered in 28-pin DIP packages (ceramic or plastic), while the AD677JR is a serial-output device in 28-lead SOIC. Their pinouts differ significantly - for example, AD677JR uses pins 26–27 for SCLK/SDATA, whereas AD676 dedicates 16 pins to parallel data bus. Interchange requires PCB redesign and firmware changes.