Analog Devices Inc. AD571SD

Overview

AD571SD from Analog Devices is a military-grade 10-bit monolithic successive-approximation analog-to-digital converter (ADC) with integrated DAC, comparator, SAR register, and temperature-compensated buried Zener reference. It operates from +5 V and –15 V supplies, delivers ±1/2 LSB relative accuracy over –55°C to +125°C, supports unipolar (0 V to +10 V) and bipolar (–5 V to +5 V) input ranges, and achieves 15 μs minimum conversion time - used in precision data acquisition for aerospace telemetry and hardened instrumentation systems.

For engineers reviewing the AD571SD datasheet, AD571SD pinout, AD571SD application, or AD571SD equivalent, key selection considerations include its MIL-STD-883B qualified SBDIP-18 package, guaranteed ±1/2 LSB linearity across full military temperature range, bipolar offset control via open-circuit pin, and compatibility with TTL/CMOS logic interfaces without external components.

Technical Context

The AD571SD implements a fully self-contained successive-approximation architecture using I²L logic, where the internal 10-bit current-output DAC is sequenced by the SAR register from MSB to LSB to balance input current through a laser-trimmed 5 kΩ thin-film resistor. Conversion completion is signaled by an open-collector DATA READY output with nominal 6 kΩ internal pull-up.

It features separate analog and digital common terminals with ±200 mV allowable common-mode voltage, bipolar operation enabled by leaving the BIPOLAR OFFSET pin open (injecting MSB–½ LSB current into the comparator summing node), and zero-offset adjustment via series resistance on the analog common terminal - all without requiring external timing or calibration components.

Key Specifications

Pinout & Package

AD571SD is housed in an 18-lead Side-Brazed Ceramic Dual In-Line Package (SBDIP), designated D-18 per Analog Devices' ordering guide, with hermetic sealing and lead finish suitable for high-reliability military and space applications.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 10-bit SAR ADC applications.

Compared with AD571KD and MAX160BCWI+, the AD571SD uniquely combines MIL-STD-883B qualification, monolithic Zener reference, and guaranteed ±1/2 LSB linearity over –55°C to +125°C - making it irreplaceable for flight-critical analog digitization where calibration stability and environmental survivability are non-negotiable.

Availability

AD571SD is available at Aetrix Electronics and suitable for flight control sensor interface, missile guidance telemetry, and hardened power monitoring requiring stable component supply across extended temperature extremes and long production lifecycles.

Supply support for AD571SD 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 semiconductor company specializing in high-performance analog, mixed-signal, and digital signal processing technologies for precision measurement and control.

The AD571 product line was designed specifically for high-reliability data acquisition in military, aerospace, and industrial systems demanding guaranteed 10-bit accuracy without external support components.

FAQ

What is the guaranteed relative accuracy specification for AD571SD over its full operating temperature range?

The AD571SD guarantees ±1/2 LSB relative accuracy from –55°C to +125°C, as confirmed in the "RELATIVE ACCURACY, TMIN to TMAX" row of the official Analog Devices datasheet revision B. This specification ensures monotonic operation and absence of missing codes across the entire military temperature range, critical for safety-critical feedback control loops where non-monotonic behavior could cause instability. The AD571SD achieves this with on-chip laser-trimmed thin-film resistors and a temperature-compensated buried Zener reference.

Does AD571SD require external components to operate as a complete A/D converter?

No, the AD571SD requires no external components to perform full 10-bit successive-approximation conversion. Its monolithic design integrates the DAC, SAR register, comparator, and temperature-compensated buried Zener reference. Only power supplies (+5 V and –15 V), analog input signal, and BLANK AND CONV control line are needed for basic operation. External resistors (e.g., 15 Ω fixed or 50 Ω trimmer) are optional for fine full-scale calibration but not mandatory for functional operation.

How is bipolar input range (–5 V to +5 V) enabled on AD571SD?

Bipolar operation on the AD571SD is enabled by leaving Pin 18 (BIPOLAR OFF) unconnected (open circuit), which injects a precise offset current equal to MSB–½ LSB into the comparator's summing node. This shifts the transfer function so that –5.00 V maps to 0000000000, 0.00 V maps to 1000000000, and +4.99 V maps to 1111111111 using positive true offset binary coding. Shorting Pin 18 to DIGITAL COM restores unipolar 0 V to +10 V operation. No external logic or level-shifting circuitry is required.

What package type and qualification standard applies to AD571SD?

The AD571SD uses an 18-lead Side-Brazed Ceramic Dual In-Line Package (SBDIP), designated D-18, and is qualified per MIL-STD-883B, including tests for thermal cycling, mechanical shock, vibration, and long-term reliability. This qualification is explicitly confirmed in Note 2 of the datasheet and the Ordering Guide, distinguishing it from commercial variants like AD571JD or AD571KD. The hermetic ceramic package ensures moisture resistance and stability in harsh environmental conditions.

Can AD571SD interface directly with TTL or CMOS logic without level shifters?

Yes, the AD571SD supports direct interface with both TTL and CMOS logic families. Its logic inputs meet TTL thresholds (Logic "1" ≥2.0 V, Logic "0" ≤0.8 V) at V+ = +5 V, and its digital outputs provide 3.2 mA sink and 0.5 mA source capability - sufficient to drive standard TTL loads. For CMOS interfaces, the device operates with V+ up to +7.0 V, enabling compatibility with higher-voltage CMOS families. No level-shifting circuitry is required for either logic family when operated within specified supply and loading conditions.