Analog Devices Inc. AD7734BRU

Overview

AD7734BRU from Analog Devices is a 24-bit sigma-delta analog-to-digital converter optimized for high-precision, high-throughput multiplexed industrial measurement. It features four single-ended analog inputs with ±10 V input range, 18-bit peak-to-peak resolution at 500 Hz, on-chip per-channel system calibration, and 3-wire SPI-compatible serial interface - deployed in PLC analog input modules requiring fast channel switching and robust overvoltage tolerance.

For engineers reviewing the AD7734BRU datasheet, AD7734BRU pinout, AD7734BRU application, or AD7734BRU equivalent, key selection criteria include channel isolation (110 dB), chopping-enabled noise performance (9.6 µV rms at 372 Hz), ±16.5 V overvoltage tolerance without adjacent channel crosstalk, and support for single +5 V analog supply with flexible 3 V/5 V digital supply.

Technical Context

The AD7734BRU integrates a 24-bit Σ-Δ modulator with programmable filter word (FW) and configurable chopping mode to trade off resolution versus throughput - enabling 18-bit p-p resolution at 500 Hz or 14-bit p-p resolution at 15 kHz. Its analog front end uses internal bias networks (BIAS0–BIAS3, BIASHI, BIASLO) to support unipolar/bipolar ranges up to ±10 V while maintaining channel-to-channel isolation of 110 dB at DC.

It implements per-channel zero-scale and full-scale system calibration with ±1.05 × FS limits, "No-Reference" detect on REFIN(±), and Schmitt-triggered logic inputs compatible with 3 V or 5 V microcontrollers. The device operates across –40°C to +105°C and supports continuous conversion, dump mode, and single-conversion read sequences via its 3-wire serial interface.

Key Specifications

Pinout & Package

Package: 28-lead TSSOP (4.4 mm × 9.7 mm, 0.65 mm pitch), RoHS-compliant, surface-mount.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-precision, multi-channel sigma-delta ADC applications.

Compared with AD7734BRU, AD7732BRU offers superior differential noise rejection but lacks channel count for dense I/O modules, while AD7738BRU provides greater flexibility in input configuration and signal conditioning but requires additional external components to achieve ±10 V range compatibility.

Availability

AD7734BRU is available at Aetrix Electronics and suitable for industrial process control, PLC analog input modules, and precision weigh scale systems requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.

Supply support for AD7734BRU 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 Wilmington, MA, with design centers worldwide and ISO 9001-certified manufacturing.

The AD7734BRU belongs to Analog Devices' precision sigma-delta ADC product line, engineered specifically for industrial automation and process instrumentation where resolution, channel density, and robustness under harsh electrical conditions are critical.

FAQ

What is the maximum sample rate of the AD7734BRU with 16-bit peak-to-peak resolution?

The AD7734BRU achieves 16-bit peak-to-peak resolution at 2 kHz when chopping is enabled (FW = 0x96, conversion time = 499 µs). At this rate, it delivers 16-bit p-p resolution across ±10 V input range with 19.7 bits effective resolution - suitable for high-speed multiplexed sensor acquisition in distributed control systems. This performance is confirmed in Table 6 of the AD7734 Rev. B datasheet.

Does the AD7734BRU require an external reference voltage?

Yes, the AD7734BRU requires an external differential reference voltage applied to REFIN(+) and REFIN(–) pins. The specified range is 2.475 V to 2.525 V for full accuracy, though it remains functional down to 0.5 V with "No-Reference" detection activated. The AD7734BRU does not include an internal reference; using a precision 2.5 V reference (e.g., ADR441) ensures ±0.0025% INL performance across temperature.

How does the AD7734BRU handle overvoltage on analog inputs without affecting adjacent channels?

The AD7734BRU guarantees ±16.5 V overvoltage tolerance on any AIN pin without degrading performance of adjacent channels, verified by 110 dB channel-to-channel isolation at DC. This is achieved through proprietary input stage design and internal bias network separation. Absolute maximum rating is ±50 V, but operation beyond ±16.5 V may trigger OVR bit and affect data validity - confirmed in Absolute Maximum Ratings Table 3 and General Description.

Can the AD7734BRU operate with a 3 V digital supply while using a 5 V analog supply?

Yes, the AD7734BRU supports independent 5 V analog supply (AVDD) and 3 V digital supply (DVDD), as specified in the Power Requirements table (Page 5). DVDD current is 1.0–1.5 mA at 3 V, and all digital inputs (CS, SCLK, DIN) feature Schmitt triggers with valid thresholds at 3 V logic levels. This dual-supply capability enables direct interfacing with 3 V microcontrollers while maintaining full analog performance.

What calibration capabilities does the AD7734BRU provide for field deployment?

The AD7734BRU supports both ADC-wide zero-scale self-calibration and per-channel system calibration for zero-scale and full-scale errors. System calibration uses external known inputs (e.g., 0 V and ±10 V references) and stores correction coefficients in dedicated registers. Full-scale calibration limit is +1.05 × FS and zero-scale limit is –1.05 × FS - enabling field recalibration to maintain accuracy after thermal aging or mechanical stress, as detailed in Register Description section (Page 17).