Analog Devices Inc. AD7667AST

Overview

AD7667AST from Analog Devices is a 16-bit, 1 MSPS charge redistribution SAR analog-to-digital converter with integrated 2.5 V reference, unipolar 0 V to 2.5 V input range, and dual parallel/serial (SPI/QSPI/MICROWIRE/DSP-compatible) interface. It operates from a single 5 V supply and delivers ±2.0 LSB INL, 88 dB S/(N+D), and no missing codes for high-accuracy data acquisition in medical instruments and process control systems.

For engineers reviewing the AD7667AST datasheet, AD7667AST pinout, AD7667AST application, or AD7667AST equivalent, this page provides verified technical context, mode-specific throughput timing (Warp/Normal/Impulse), real-world power dissipation values (133 mW @ 1 MSPS with REF), and confirmed pin-to-pin compatibility with AD7671 and AD7677 - critical for legacy system upgrades and mixed-signal board layout planning.

Technical Context

The AD7667AST implements a factory-calibrated charge redistribution SAR architecture with internal error correction circuitry, eliminating pipeline delay and enabling immediate data availability post-conversion. Its three selectable operating modes-Warp (1 µs cycle, 1 MSPS), Normal (1.25 µs, 800 kSPS), and Impulse (1.5 µs, 666 kSPS)-dynamically scale power consumption with throughput, achieving 130 µW at 1 kSPS without reference buffer activation.

It integrates a 2.5 V internal reference with ±3 ppm/°C typical drift and supports external reference via REFBUFIN, while its dual-voltage I/O interface (OVDD = 2.7–5.25 V) ensures interoperability with both 3 V and 5 V logic families. The device uses a dedicated CNVST-controlled sampling architecture with 2 ns aperture delay and 5 ps rms jitter for low-noise signal capture.

Key Specifications

Pinout & Package

AD7667AST is packaged in a 48-lead LQFP (ST-48) with exposed pad, pin-compatible with AD7671 and AD7677. Thermal resistance θ_JA = 91°C/W enables operation up to +85°C ambient without forced airflow.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7671ASTZ and AD7666ASTZ, the AD7667AST uniquely combines 1 MSPS unipolar sampling, integrated 2.5 V reference, and pin compatibility with legacy AD767x designs - making it the only option that preserves both performance and layout continuity in high-throughput medical and industrial DAQ upgrades.

Availability

AD7667AST is available at Aetrix Electronics and suitable for medical instrumentation, process control, and digital signal processing applications requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for AD7667AST 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, serving industrial, automotive, communications, and healthcare markets since 1965.

The AD7667AST belongs to Analog Devices' PulSAR® family of precision SAR ADCs, engineered specifically for high-speed, high-accuracy data acquisition in space- and power-constrained environments where dc accuracy and ac performance must coexist.

FAQ

What are the key differences between AD7667AST Warp, Normal, and Impulse modes?

The AD7667AST offers three hardware-selectable operating modes via WARP and IMPULSE pins. Warp mode achieves 1 MSPS throughput with 1 µs conversion cycle but requires minimum conversion rate for full accuracy. Normal mode delivers 800 kSPS with asynchronous timing flexibility. Impulse mode scales power linearly with throughput - consuming just 130 µW at 1 kSPS - ideal for battery-powered sensing. All modes retain the same 16-bit resolution and ±2.0 LSB INL specification. The AD7667AST datasheet defines precise timing relationships for each mode in Tables 3 and 4.

Does AD7667AST require external reference components for basic operation?

No, the AD7667AST includes a fully integrated 2.5 V internal reference with ±3 ppm/°C typical temperature drift and 5 ms turn-on settling time, enabling standalone operation with no external reference components. The PDREF and PDBUF pins allow disabling the internal reference and enabling an external source if higher precision or different voltage levels are needed. For standard 0 V to 2.5 V unipolar applications, the AD7667AST functions autonomously - a key advantage over alternatives like AD7671ASTZ which lack internal reference.

How does AD7667AST handle digital interface voltage translation between 3 V and 5 V systems?

The AD7667AST uses a dedicated OVDD supply pin (2.7–5.25 V) for its digital I/O interface, decoupled from AVDD and DVDD. This allows direct connection to either 3 V or 5 V logic families without level shifters. When OVDD = 3.3 V, outputs swing from 0 V to 3.3 V with VIH ≥ 2.0 V and VIL ≤ 0.8 V; when OVDD = 5 V, outputs comply with standard TTL thresholds. The AD7667AST serial interface remains SPI/QSPI/MICROWIRE compatible across both voltage domains, preserving timing margins per Table 3.

Is AD7667AST pin-compatible with other PulSAR® devices beyond AD7671 and AD7677?

The AD7667AST is explicitly specified as pin-to-pin compatible only with AD7671 and AD7677 in the official datasheet (Rev. 0, Page 1). While it shares the same 48-lead LQFP package footprint with other PulSAR® converters like AD7666ASTZ, pin functions differ significantly - for example, AD7666ASTZ lacks WARP/IMPULSE mode control pins and has different serial interface mapping. Therefore, AD7667AST cannot be substituted for AD7664 or AD7660 without PCB redesign. Always verify pin function alignment using the AD7667AST Pin Configuration table (Page 8) before migration.

What thermal considerations apply to AD7667AST in continuous 1 MSPS operation?

In Warp mode at 1 MSPS with internal reference enabled, the AD7667AST dissipates 133 mW typical, resulting in a junction temperature rise of approximately 12°C above ambient (θ_JA = 91°C/W for LQFP). To maintain operation within the –40°C to +85°C specified range, keep ambient temperature below +73°C with standard PCB copper pour. For sealed enclosures, add ≥2 cm² of 2-oz copper under the exposed pad. The AD7667AST thermal characteristics are validated per Absolute Maximum Ratings (Table 5), and junction temperature must not exceed 150°C under any condition.