Analog Devices Inc. AD7939BCP

Overview

AD7939BCP 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% @ 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/1.5 MSPS, and supports single-ended, pseudo-differential, and fully differential input configurations for industrial data acquisition systems.

For engineers reviewing the AD7939BCP datasheet, AD7939BCP pinout, AD7939BCP application, or AD7939BCP equivalent, key selection considerations include its 10-bit resolution with ±0.5 LSB INL, software-configurable input modes, VDRIVE-independent 3 V/5 V interface compatibility, and LFCSP-32 package suitability for space-constrained high-density PCBs.

Technical Context

The AD7939BCP implements a SAR architecture with no pipeline delay, enabling deterministic conversion timing of t₂ + 13×t_CLKIN. Its track-and-hold amplifier supports full-power bandwidth up to 50 MHz and handles 50 kHz sinusoidal inputs with 61 dB SINAD in differential mode.

It integrates an on-chip sequencer that enables preprogrammed channel scanning across eight analog inputs (VIN0–VIN7), configurable via control register bits for single-ended, pseudo-differential (7-channel or 4-channel), or fully differential (4-channel) operation - all selectable in real time via software.

Key Specifications

Pinout & Package

AD7939BCP is housed in a 32-lead LFCSP (CP-32-7) package with exposed pad, requiring connection to PCB ground plane via multiple vias per Analog Devices' layout guidelines.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7939BCP, AD7938BCP offers higher resolution and dynamic performance at identical speed and footprint, while ADS8688IPWR trades speed and parallel interface for enhanced resolution and integration - making AD7939BCP optimal for cost-sensitive, space-constrained 10-bit multichannel DAQ where deterministic timing is critical.

Availability

AD7939BCP is available at Aetrix Electronics and suitable for industrial motor control, programmable logic controller (PLC) input modules, and portable test equipment requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for AD7939BCP 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, with R&D and manufacturing operations worldwide.

The AD7938/AD7939 product line was designed specifically for high-speed, low-power, multichannel data acquisition in space- and power-constrained industrial and instrumentation systems - emphasizing integrated sequencers, flexible input structures, and robust parallel interfacing.

FAQ

What is the maximum sampling rate supported by the AD7939BCP?

The AD7939BCP supports a maximum throughput rate of 1.5 MSPS, achieved with a 25.5 MHz master clock input (CLKIN) and 13-clock-cycle conversion time. This rate is maintained across its full operating temperature range (−40°C to +85°C) and supply voltage range (2.7 V to 5.25 V), making AD7939BCP suitable for real-time control loop sampling in demanding industrial environments.

Does the AD7939BCP require an external reference voltage?

No, the AD7939BCP includes an accurate on-chip 2.5 V reference with ±0.2% initial accuracy at 25°C and 25 ppm/°C temperature coefficient, sufficient for most industrial applications. However, the VREFIN/VREFOUT pin can be overdriven with an external reference (0.1 V to VDD) when higher precision or custom voltage scaling is required - the AD7939BCP automatically disables its internal reference when external voltage exceeds 2.5 V.

How does the AD7939BCP handle different analog input configurations?

The AD7939BCP supports three analog input modes - single-ended (8 channels), pseudo-differential (4- or 7-channel), and fully differential (4-channel) - selected via configuration bits in its control register. Input ranges scale automatically: 0–VREF or 0–2×VREF for single-ended/pseudo-diff, and VCM ± VREF/2 for fully differential. This flexibility allows one AD7939BCP design to interface with diverse sensors without hardware changes.

What package type is used for the AD7939BCP, and what are its layout requirements?

The AD7939BCP uses a 32-lead LFCSP (CP-32-7) package with an exposed thermal pad on the underside. Per Analog Devices' guidelines, this pad must be soldered to the PCB ground plane using ≥4 thermal vias (0.3 mm diameter) to ensure proper heat dissipation and noise immunity. Separation of AGND and DGND planes with ≤0.3 V potential difference is mandatory to achieve specified 61 dB SINAD performance.

Can the AD7939BCP interface directly with a 3 V microcontroller while operating from a 5 V supply?

Yes, the AD7939BCP's VDRIVE pin enables independent logic-level setting: connecting VDRIVE to 3 V allows the parallel data bus (DB0–DB11, RD, WR, CS, etc.) to operate at 3 V logic levels, even when VDD is 5 V. This eliminates external level shifters and simplifies interfacing with mixed-voltage systems - a key advantage confirmed in AD7939BCP's functional block diagram and pin description table.