Analog Devices Inc. AD574ALD/+

Overview

AD574ALD/+ from Analog Devices is a complete 12-bit monolithic analog-to-digital converter with on-chip reference, successive-approximation architecture, and parallel digital output. It delivers ±1/2 LSB linearity error over 0°C to +70°C, supports unipolar (0 V to +10 V or 0 V to +20 V) and bipolar (±5 V or ±10 V) input ranges, and operates from ±12 V or ±15 V analog supplies plus +5 V logic supply - used in precision data acquisition systems for industrial process control and test instrumentation.

For engineers reviewing the AD574ALD/+ datasheet, AD574ALD/+ pinout, AD574ALD/+ application, or AD574ALD/+ equivalent, this page provides verified technical context, exact pin functions, real-world use cases, and validated alternative parts - all grounded in the official AD574A Rev. B specification and Analog Devices' ordering guide.

Technical Context

The AD574ALD/+ implements a fully self-contained successive-approximation ADC with internal 10 V buried Zener reference (±0.2% initial accuracy, 10 ppm/°C full-scale T.C.), thin-film trimmed scaling resistors, and current-output DAC. Its SAR core sequences MSB-to-LSB in ≤35 µs (12-bit), with status flag (STS) signaling conversion progress and three-state parallel outputs (DB11–DB0).

It supports dual data modes: 12-bit parallel (12/8 = VLOGIC) or byte-accessed 8-bit + 4-bit nibble reads (12/8 = DIGITAL COMMON), controlled by CE/CS/R/C/A0 logic. Input impedance is 5 kΩ (10 V span) or 10 kΩ (20 V span); reference output supplies 1.5 mA but requires buffering under ±12 V operation or variable external loads.

Key Specifications

Pinout & Package

Ceramic DIP-28 (D-28) package with hermetic seal, rated for 0°C to +70°C operation. Pin numbering follows standard DIP layout with notch orientation as per AD574A block diagram (Rev. B, p.4).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 12-bit ADC applications.

Compared with AD7874KNZ and ADS7800KP, the AD574ALD/+ uniquely combines ceramic DIP ruggedness, self-contained parallel interface, and factory-trimmed 10 V reference - making it optimal for legacy industrial controllers where drop-in replacement and minimal redesign are critical.

Availability

AD574ALD/+ is available at Aetrix Electronics and suitable for industrial process monitoring, automated test equipment, avionics sensor interfaces, and medical diagnostic instrumentation requiring stable component supply across long product lifecycles.

Supply support for AD574ALD/+ 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 leader specializing in high-performance analog, mixed-signal, and digital signal processing technologies for precision measurement and control.

The AD574A family was engineered for high-accuracy, self-contained data acquisition in harsh environments - targeting industrial automation, aerospace, and test instrumentation where reliability, long-term stability, and minimal external components are mandatory.

FAQ

What is the maximum conversion rate supported by the AD574ALD/+?

The AD574ALD/+ has a maximum conversion time of 35 µs for a full 12-bit cycle, yielding a theoretical maximum throughput of ~28.6 kSPS. However, due to control signal setup/hold timing (e.g., tHEC ≥300 ns, tSSC ≥300 ns) and STS handshake overhead, sustained practical rates in microprocessor systems are typically ≤10 kSPS. The device does not support continuous conversion mode - each conversion must be explicitly initiated via CE/CS/R/C.

Does the AD574ALD/+ require an external clock source?

No, the AD574ALD/+ does not require an external clock source. It integrates an internal oscillator and successive-approximation register (SAR) control logic that executes the full 12-bit conversion autonomously once triggered. The only timing constraints are those governing the CE, CS, and R/C control signals - specified in the AD574A Rev. B timing tables (e.g., tC = 15–35 µs, tHEC ≥300 ns). This self-timed operation simplifies system design and eliminates clock distribution noise.

Can the AD574ALD/+ operate from ±12 V supplies instead of ±15 V?

Yes, the AD574ALD/+ is fully specified for operation from ±12 V analog supplies (VCC = +12 V ±0.6 V, VEE = –12 V ±0.6 V) as confirmed in the "POWER SUPPLIES" section of the AD574A Rev. B datasheet. However, the internal 10 V reference output current drops to 1.5 mA, and external loading must remain constant during conversion. For ±12 V operation with >1 mA external reference load, Analog Devices recommends buffering REF OUT with an op amp (e.g., AD707) to maintain accuracy and prevent code flicker.

How is the 12-bit result read from the AD574ALD/+ in parallel mode?

In 12-bit parallel mode (12/8 pin tied to VLOGIC), the AD574ALD/+ places the full 12-bit result on DB11–DB0 simultaneously after conversion completes. To read it, assert CE = low, CS = low, and R/C = high; the outputs become active within 200 ns (tDD1). The STS pin must be low before reading - indicating conversion completion. Data remains valid for ≥25 ns after CE goes high (tHD), and outputs enter high-impedance state within 100 ns (tHL2) after CE deassertion. No byte-splitting or latching is required.

What is the purpose of the 12/8 pin on the AD574ALD/+ and how should it be connected?

The 12/8 pin configures the AD574ALD/+ data output format: tying it to VLOGIC enables 12-bit parallel output on DB11–DB0; tying it to DIGITAL COMMON enables 8-bit bus interface mode, where AO selects either the 8 MSBs (AO = 0) or 4 LSBs + 4 trailing zeroes (AO = 1). Per AD574A Rev. B Note 2, 12/8 is not TTL-compatible and must be hard-wired directly to VLOGIC or DIGITAL COMMON - never driven by logic gates or microprocessor pins.