Analog Devices Inc. AD774BJN

Overview

AD774BJN from Analog Devices is a complete monolithic 12-bit successive-approximation analog-to-digital converter (ADC) with on-chip 10 V reference, clock generator, and three-state digital output buffers. It supports 0 V–10 V, 0 V–20 V, ±5 V, and ±10 V input ranges; operates from +5 V logic, ±12 V/±15 V analog supplies; and delivers 8 µs maximum conversion time in J-grade commercial temperature range (0°C to +70°C). It is used in industrial data acquisition systems requiring high-accuracy, self-contained ADC functionality without external timing or reference components.

For engineers reviewing the AD774BJN datasheet, AD774BJN pinout, AD774BJN application, or AD774BJN equivalent, this page provides verified technical context, exact pin functions, calibrated input range behavior, timing-critical interface guidance for 8-/16-bit microprocessors, and validated alternative options for legacy AD574A upgrade paths.

Technical Context

The AD774BJN implements a SAR architecture with internal 12-bit current-output DAC, laser-trimmed thin-film resistors for scaling and bipolar offset, and comparator-based bit decision logic synchronized to an on-chip clock. Its analog front-end includes dedicated 10 VIN and 20 VIN inputs with programmable span selection via external resistor configuration.

Digital control uses CE (active-high chip enable), CS (active-low chip select), R/C (read/convert), A0 (byte address/short cycle), and 12/8 (data format select) signals to manage 12-bit word or dual 8-bit byte reads. Status output (STS) provides real-time conversion progress indication, and all digital outputs feature three-state buffering compatible with TTL/CMOS busses.

Key Specifications

Pinout & Package

AD774BJN is housed in a 28-pin plastic DIP (N-28) package with 0.6-inch width and through-hole mounting. Pin layout follows industry-standard AD574A footprint for drop-in replacement in legacy designs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD774BJN, AD781JRZ trades integrated reference and pin compatibility for sample-and-hold capability and lower power, while AD1674KN retains identical packaging and adds S/H at the cost of higher dissipation and tighter linearity tolerance - enabling direct upgrade paths based on signal dynamics and system integration constraints.

Availability

AD774BJN is available at Aetrix Electronics and suitable for industrial data acquisition, test equipment manufacturing, and legacy system upgrades requiring stable component supply, long-term obsolescence management, and traceable sourcing for commercial-grade analog converters.

Supply support for AD774BJN 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, founded in 1965 and headquartered in Wilmington, MA.

The AD774BJN belongs to Analog Devices' legacy precision ADC product line, designed specifically for industrial and instrumentation applications demanding self-contained, high-accuracy digitization with minimal external components.

FAQ

What is the maximum conversion rate supported by the AD774BJN?

The AD774BJN achieves a maximum conversion time of 8 µs, enabling a theoretical maximum throughput of 125 kSPS in continuous mode. However, practical sustained rate depends on interface timing margins, bus access latency, and STS-driven read synchronization. For reliable operation with standard 8-bit microprocessors, achievable rates are typically 50–80 kSPS due to CS/CE setup/hold and data access timing constraints specified in the AD774BJN timing diagrams.

Does the AD774BJN require external calibration components?

The AD774BJN includes factory-laser-trimmed resistors for offset and full-scale calibration, so external trims are optional. For J-grade operation, unipolar offset is guaranteed ≤±2 LSB and full-scale error ≤0.25% FS without trimming. If higher accuracy is needed, a 50 Ω resistor between REF OUT and REF IN enables full-scale calibration, and a trimmer on BIP OFF (Pin 12) adjusts bipolar offset - but these are not required for basic compliance with AD774BJN specifications.

Can the AD774BJN operate with only +5 V and ground supplies?

No. The AD774BJN requires three independent supplies: +5 V (VLOGIC, Pin 1), +12 V or +15 V (VCC, Pin 7), and –12 V or –15 V (VEE, Pin 11). The analog section cannot function without dual-rail analog supplies to support bipolar input ranges and internal DAC operation. Operating with only +5 V and ground will prevent conversion, damage internal circuitry, or produce invalid output codes.

How does the AD774BJN handle input signals exceeding its specified voltage ranges?

The AD774BJN specifies absolute maximum ratings of ±24 V on 20 VIN (Pin 14) relative to AGND, allowing safe operation with overvoltage transients up to that level. However, accurate digitization is only guaranteed within the calibrated ranges (e.g., 0 V–20 V or ±10 V). Inputs beyond those ranges will saturate the internal comparator and produce clipped output codes (all 0s or all 1s), but will not damage the AD774BJN if current-limited per datasheet guidelines.

Is the AD774BJN pin-compatible with the AD574A, and what are the key functional improvements?

Yes, the AD774BJN uses the identical 28-pin DIP footprint and signal mapping as the AD574A, enabling direct PCB replacement. Key improvements include 8 µs max conversion time (vs. 25 µs for AD574A), lower power consumption (220 mW vs. ~350 mW), integrated 10 V reference with 10 ppm/°C drift (vs. external reference required for AD574A), and enhanced linearity (±1 LSB vs. ±0.5 LSB typical for AD574A, with guaranteed monotonicity).