Analog Devices Inc. AD7865BS-3

Overview

AD7865BS-3 from Analog Devices is a four-channel, simultaneous-sampling, 14-bit analog-to-digital converter (ADC) with ±2.5 V input range, 2.4 µs conversion time per channel, 0.35 µs track/hold acquisition time, and ±1.5 LSB relative accuracy (INL). It operates from a single 5 V supply and delivers up to 100 kSPS aggregate throughput across all four channels for phase-critical applications such as motor current sensing and power quality monitoring.

For engineers reviewing the AD7865BS-3 datasheet, AD7865BS-3 pinout, AD7865BS-3 application, or AD7865BS-3 equivalent, key selection considerations include simultaneous sampling integrity, aperture delay matching (≤4 ns), bipolar ±2.5 V signal compatibility, parallel 14-bit interface timing, and standby power consumption (20 µA).

Technical Context

The AD7865BS-3 integrates four matched track/hold amplifiers and a successive approximation ADC core, enabling true simultaneous sampling across all four analog inputs to preserve inter-channel phase relationships. Its internal 2.5 V reference, laser-trimmed oscillator, and hardware/software channel selection logic support deterministic conversion sequencing without external clocking.

It supports two read modes - reading between conversions (using EOC strobes) or after full sequence completion (using BUSY deassertion) - and features overvoltage protection up to –4 V / +18 V on analog inputs. The 14-bit parallel interface operates with 5 V or 3 V VDRIVE, enabling direct interfacing to both legacy and low-voltage microcontrollers.

Key Specifications

Pinout & Package

The AD7865BS-3 is housed in a 44-lead Plastic Lead Quad Flatpack (PQFP), 10 mm × 10 mm body, 0.8 mm lead pitch, with exposed thermal pad (not electrically connected). Pin 1 is marked by a corner notch or dot.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar simultaneous-sampling ADC applications.

Compared with AD7865BS-3, AD7656ASTZ trades parallel interface simplicity for higher resolution and channel count, while ADS8588HIPM extends channel density and voltage flexibility at the cost of increased supply complexity and absence of ±2.5 V native range optimization.

Availability

AD7865BS-3 is available at Aetrix Electronics and suitable for industrial motor control, power quality monitoring, PLC analog input modules, and digital power supply controllers requiring stable component supply and long-term obsolescence management.

Supply support for AD7865BS-3 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.

The AD7865 product line was designed specifically for high-fidelity, phase-coherent multichannel data acquisition in industrial automation and energy systems - emphasizing simultaneous sampling integrity, robust input protection, and single-supply operation.

FAQ

What is the maximum sampling rate achievable with AD7865BS-3 when all four channels are active?

The AD7865BS-3 achieves a maximum aggregate throughput of 100 kSPS when converting all four channels in sequence. This is derived from its 2.4 µs per-channel conversion time multiplied by four channels, resulting in a full-sequence duration of 9.6 µs - equivalent to 104.2 kSPS theoretical, with 100 kSPS guaranteed under datasheet conditions including timing margins and temperature range.

Does AD7865BS-3 require an external reference, or does it include an internal one?

The AD7865BS-3 includes an internal 2.5 V ±20 mV reference accessible at the VREF pin. It can be overdriven by an external 2.5 V ±5% reference for improved stability and temperature drift performance. No external reference is required for basic operation, but using a precision external reference improves gain accuracy and long-term drift specifications.

How does the AD7865BS-3 handle channel selection - is it configurable in hardware or software?

The AD7865BS-3 supports both hardware and software channel selection. When H/S SEL (Pin 11) is low, SL1–SL4 pins directly configure which channels (1–4) are included in the conversion sequence. When H/S SEL is high, the channel select register is programmed via DB0–DB3 during a write cycle, allowing dynamic reconfiguration under processor control without changing pin states.

What is the significance of the ±2.5 V input range specified for AD7865BS-3?

Unlike the ±10 V or 0 V–5 V ranges of other AD7865 variants, the ±2.5 V range of AD7865BS-3 is optimized for signal processing applications where sensor outputs or isolation amplifier stages deliver centered bipolar signals. This range maximizes utilization of the 14-bit code space for signals like audio, vibration, or differential sensor outputs without attenuation or gain scaling.

Can AD7865BS-3 interface directly with a 3 V microcontroller without level-shifting circuitry?

Yes - the AD7865BS-3 supports 3 V logic interfacing via the VDRIVE pin (Pin 36), which powers the DB0–DB13, BUSY, EOC, and FRSTDATA outputs independently. When VDRIVE is supplied with 3 V ±10%, the outputs meet 3 V TTL thresholds, enabling direct connection to 3 V microcontrollers, DSPs, or FPGAs without external level shifters.