Analog Devices Inc. AD7482AST

Overview

AD7482AST from Analog Devices is a 12-bit, 3 MSPS successive approximation register (SAR) analog-to-digital converter with parallel interface, 40 MHz input bandwidth, internal 2.5 V reference, and dual power-saving modes (nap/standby). It operates from a single 5 V supply and supports ±200 mV input offset for single-supply op amp interfacing in high-speed data acquisition systems.

For engineers reviewing the AD7482AST datasheet, AD7482AST pinout, AD7482AST application, or AD7482AST equivalent, key selection considerations include its no-pipeline-delay SAR architecture, 300 ns conversion time, 14-pin-compatible upgrade path to AD7484, VDRIVE-configurable I/O voltage (2.7–5.25 V), and full-scale overrange detection via D12 bit.

Technical Context

The AD7482AST uses an algorithmic capacitive DAC-based SAR core with track-and-hold acquisition time of 70 ns and no pipeline latency. Its conversion is initiated on the falling edge of CONVST and completed in 300 ns, with BUSY signaling active-low duration matching conversion time.

It features two parallel interface modes (Mode 1 and Mode 2), configurable via MODE1/MODE2 pins, differing in BUSY deassertion timing relative to result latching. The device supports both internal 2.5 V reference (REFOUT/REFIN/REFSEL) and external reference operation, with REFOUT output impedance of 1 Ω and ±100 mV error over −40°C to +85°C.

Key Specifications

Pinout & Package

The AD7482AST is housed in a 48-lead LQFP package (7 mm × 7 mm, 0.5 mm pitch) with exposed thermal pad, rated for −40°C to +85°C operation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-speed SAR ADC applications.

Compared with AD7484AST, the AD7482AST trades 2 bits of resolution for 30% lower power and identical pin compatibility-ideal for cost- and power-sensitive 12-bit applications. Against ADS8325IPFBT, it provides deterministic parallel timing, flexible I/O voltage, and dual low-power modes, at the expense of resolution and serial-only architecture.

Availability

AD7482AST is available at Aetrix Electronics and suitable for high-speed data acquisition, industrial process monitoring, communications baseband processing, and portable test & measurement equipment requiring stable component supply across extended temperature ranges.

Supply support for AD7482AST 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 Norwood, MA.

The AD7482AST belongs to Analog Devices' high-speed SAR ADC product line, engineered for applications demanding low latency, excellent dc accuracy, and flexible power management in instrumentation and industrial control systems.

FAQ

What is the maximum throughput rate supported by the AD7482AST?

The AD7482AST supports a maximum throughput rate of 3 MSPS in Parallel Mode 2. This is achieved with a fixed 300 ns conversion time and optimized timing for RD/CS handshaking. In Parallel Mode 1, the throughput is limited to 2.5 MSPS due to BUSY deassertion timing constraints tied to output register latching. Both modes maintain identical conversion latency and accuracy specifications.

Does the AD7482AST require an external reference, or does it include an internal one?

The AD7482AST includes an internal 2.5 V reference buffer accessible via REFOUT, and supports external reference operation via REFIN. When using the internal reference, a 1 nF capacitor must be placed from REFSEL to AGND; for external reference, REFSEL is grounded and a 470 nF capacitor is required from REFIN to AGND. The internal reference exhibits ±100 mV error over −40°C to +85°C, while external reference performance depends on source stability and noise.

How does the overrange feature work on the AD7482AST, and what is its design impact?

The AD7482AST provides full-scale overrange detection via the D12 output bit, indicating when the analog input exceeds ±8% of the nominal 0 V to 2.5 V range. This 13th bit is not part of the 12-bit conversion result but serves as a status flag-allowing firmware to detect clipping without data corruption. It enables robust signal monitoring in unpredictable environments (e.g., surge-prone industrial sensors) while preserving the integrity of valid 12-bit samples.

Can the AD7482AST interface directly with a 3.3 V microcontroller, and how is this configured?

Yes, the AD7482AST can interface directly with a 3.3 V microcontroller using the VDRIVE pin. By connecting VDRIVE to 3.3 V, all digital I/O pins (D0–D12, CS, RD, WRITE, BUSY, etc.) operate at 3.3 V logic levels-ensuring compatible voltage thresholds without external level shifters. The analog core remains powered from AVDD/DVDD = 5 V, maintaining full dynamic performance while simplifying system-level voltage domain management.

What are the key differences between nap mode and standby mode on the AD7482AST?

Nap mode reduces power to 2.5 mW while keeping the reference circuitry active, enabling wake-up and conversion initiation within 300 ns-ideal for burst-mode acquisition. Standby mode cuts power to 10 µW by powering down all internal circuitry, but requires 500 ms wake-up time with internal reference (or 80 µs with external reference kept active). Nap mode preserves timing determinism; standby mode maximizes energy savings in infrequent-sampling applications.