Analog Devices Inc. AD7939BSUZ

Overview

AD7939BSUZ from Analog Devices is a 10-bit, 8-channel, 1.5 MSPS successive approximation register (SAR) analog-to-digital converter with integrated channel sequencer, on-chip 2.5 V reference (±0.2% max @ 25°C), and parallel word/byte interface. It operates from a single 2.7 V to 5.25 V supply, consumes 6 mW at 3 V, and supports single-ended, pseudo-differential, and fully differential input configurations for industrial data acquisition systems.

For engineers reviewing the AD7939BSUZ datasheet, AD7939BSUZ pinout, AD7939BSUZ application, or AD7939BSUZ equivalent, key selection criteria include its 10-bit resolution with ±0.5 LSB INL, 61 dB SINAD at 50 kHz, 125 ns track-and-hold acquisition time, and software-configurable analog input modes - all critical for high-channel-count, medium-speed sensor interfacing in programmable logic controllers and motor control feedback loops.

Technical Context

The AD7939BSUZ implements a SAR architecture with no pipeline delay, enabling deterministic conversion timing controlled by a falling-edge-triggered CONVST signal and synchronized to a 25.5 MHz master clock (CLKIN). Its internal sequencer supports preprogrammed 8-channel scanning without host intervention.

It features dual-supply flexibility via independent VDD (analog/digital core) and VDRIVE (interface logic level), allowing direct connection to 3 V or 5 V microprocessors regardless of VDD voltage. The on-chip 2.5 V reference has 25 ppm/°C tempco and can be overdriven by an external reference between 0.1 V and VDD.

Key Specifications

Pinout & Package

AD7939BSUZ is housed in a 32-lead LFCSP (Lead Frame Chip Scale Package) with exposed pad, optimized for thermal performance (θJA = 108.2°C/W) and PCB area efficiency. Pin 1 identification is marked on top-side silkscreen; exposed pad must be soldered to ground plane via multiple vias.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7938BSUZ, AD7939BSUZ trades 2 bits of resolution and 8 dB SINAD for 45% lower power at 3 V and reduced cost, while retaining identical pinout, sequencer functionality, and package - making it the preferred choice for cost-sensitive, power-constrained 10-bit industrial data acquisition.

Availability

AD7939BSUZ is available at Aetrix Electronics and suitable for industrial PLC analog input modules, motor control current feedback systems, programmable power supply monitoring, and multi-sensor environmental data loggers requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for AD7939BSUZ 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 leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, headquartered in Norwood, MA, serving industrial, automotive, communications, and healthcare markets.

The AD793x family was designed specifically for high-channel-count, medium-speed data acquisition in space- and power-constrained industrial environments - emphasizing integrated functionality, flexible interfacing, and robust operation across −40°C to +85°C.

FAQ

What is the maximum sampling rate supported by the AD7939BSUZ?

The AD7939BSUZ supports a maximum throughput rate of 1.5 MSPS, achieved with a 25.5 MHz master clock (CLKIN) and 13-clock-cycle conversion time. This rate applies to single-channel operation; in 8-channel sequenced mode, effective per-channel rate is ~187.5 kSPS assuming uniform distribution. The device maintains specified AC performance (61 dB SINAD) up to 50 kHz input frequency at this rate.

Does the AD7939BSUZ require an external reference, or does it have an internal one?

The AD7939BSUZ includes an accurate on-chip 2.5 V reference with ±0.2% maximum initial error at 25°C and 25 ppm/°C temperature coefficient. This internal reference is available at the VREFIN/VREFOUT pin and may be used directly for analog-to-digital conversion. Alternatively, the pin accepts an external reference from 0.1 V to VDD, overriding the internal source.

How does the AD7939BSUZ handle analog input configuration for different sensor types?

The AD7939BSUZ supports three analog input modes - single-ended, pseudo-differential, and fully differential - selected via the RANGE and CODING bits in its control register. For example, setting RANGE = 0 configures 0–2.5 V single-ended range, while RANGE = 1 enables 0–5 V range. Pseudo-differential mode accepts VIN− from −0.3 V to +1.8 V (at 5 V VDD), accommodating biased sensors like RTDs or bridge amplifiers.

What power-saving modes are available on the AD7939BSUZ, and how much current do they consume?

The AD7939BSUZ offers three power management states: Normal Mode (2.0 mA max at 3 V), Autostandby Mode (160 µA typ at 100 kSPS), and Full/Autoshutdown Mode (2 µA max). In Autostandby, the device automatically enters low-power state between conversions; in Full Shutdown, all circuitry except wake-up logic is disabled. These modes are controlled via the POWER bits in the control register.

Is the AD7939BSUZ pin-compatible with other devices in the AD793x family?

Yes, the AD7939BSUZ shares identical pinout, package (32-lead LFCSP), and parallel interface timing with AD7938BSUZ, AD7934, and AD7933. All support the same control register map, sequencer operation, and VDRIVE/VDD separation. This enables drop-in replacement between 10-bit and 12-bit variants without PCB redesign - though firmware must accommodate differing resolution and output coding behavior.