Analog Devices Inc. AD7865BSZ-2

Overview

AD7865BSZ-2 from Analog Devices is a four-channel, simultaneous-sampling, 14-bit analog-to-digital converter (ADC) with 2.4 µs conversion time per channel, 0 V to 5 V or 0 V to 2.5 V unipolar input ranges, and integrated track/hold amplifiers. It operates from a single 5 V supply, consumes 100 mW typical power in normal mode, and delivers 77 dB SNR at 100 kHz input - used in industrial power meters and motor control systems requiring phase-coherent multichannel acquisition.

For engineers reviewing the AD7865BSZ-2 datasheet, AD7865BSZ-2 pinout, AD7865BSZ-2 application, or AD7865BSZ-2 equivalent, key selection considerations include its straight-binary output coding, ±1.5 LSB INL accuracy, hardware/software channel selection flexibility, and compatibility with 3 V digital interfaces via VDRIVE pin.

Technical Context

The AD7865BSZ-2 implements a successive approximation ADC architecture with four independent track/hold amplifiers enabling true simultaneous sampling across all channels. Its aperture delay matching is ≤4 ns, preserving inter-channel phase integrity for synchronized waveform capture.

Conversion sequencing is configurable via hardware (SL1–SL4 pins) or software (channel select register via DB0–DB3), with internal clock generation (2.4 µs conversion) or external 5 MHz clock support. The device uses straight binary coding and features overvoltage protection up to –1 V to +18 V on analog inputs.

Key Specifications

Pinout & Package

AD7865BSZ-2 is housed in a 44-lead Plastic Quad Flatpack (PQFP) measuring 10 mm × 10 mm with 0.8 mm lead pitch. The package provides separate analog/digital ground planes and dedicated reference decoupling capability.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7865BSZ-2, AD7656ASTZ offers greater resolution and channel count but lacks unipolar input flexibility, while ADS8588HIPM provides more channels and faster conversion but requires SPI protocol handling instead of simple parallel reads - making AD7865BSZ-2 optimal for cost-sensitive, 4-channel, 0–5 V industrial control designs needing minimal firmware overhead.

Availability

AD7865BSZ-2 is available at Aetrix Electronics and suitable for industrial power meters, AC motor control systems, and uninterruptible power supplies requiring stable component supply and long-term production continuity.

Supply support for AD7865BSZ-2 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 Norwood, MA.

The AD7865 product line was designed specifically for industrial automation and power electronics applications demanding precise, phase-coherent multichannel data acquisition - with emphasis on robustness, low power, and ease of microprocessor interfacing.

FAQ

What input voltage ranges does the AD7865BSZ-2 support?

The AD7865BSZ-2 supports two unipolar analog input ranges: 0 V to 2.5 V and 0 V to 5 V. It does not support bipolar ranges like ±10 V or ±2.5 V - those are handled by the AD7865-1 and AD7865-3 variants. Input current is limited to 10 µA max for the 0–2.5 V range and 1 mA max for the 0–5 V range, ensuring minimal loading on sensor sources. This makes the AD7865BSZ-2 especially suitable for interfacing with resistive sensors, current-output transducers, and DAC feedback paths.

How does the AD7865BSZ-2 achieve simultaneous sampling across four channels?

The AD7865BSZ-2 achieves true simultaneous sampling using four independent track/hold amplifiers - one per analog input pair (VIN1A/B through VIN4A/B). On the rising edge of the CONVST signal, all four track/holds switch from track to hold mode at the same instant, freezing the input voltages with ≤4 ns aperture delay matching. This preserves relative phase information between channels, which is essential for vector control, power quality analysis, and coherent signal reconstruction. The subsequent ADC conversion proceeds sequentially across the selected channels, but sampling is strictly simultaneous.

What is the output coding format of the AD7865BSZ-2 and why does it matter?

The AD7865BSZ-2 uses straight (natural) binary output coding - unlike the two's complement format used by AD7865-1 and AD7865-3. This means full-scale 0–5 V maps to 0x0000 (0 V) to 0x3FFF (16383 decimal), eliminating sign-extension logic in firmware. For applications reading sensor outputs or DAC feedback where unipolar signals dominate, straight binary simplifies scaling, avoids signed-integer arithmetic, and reduces CPU cycles in real-time control loops - directly benefiting implementations using the AD7865BSZ-2 in motor drives and power converters.

Can the AD7865BSZ-2 interface with 3 V microcontrollers?

Yes, the AD7865BSZ-2 can directly interface with 3 V microcontrollers using its VDRIVE pin (Pin 36). By supplying 3 V ±10% to VDRIVE while maintaining 5 V on AVDD/DVDD, the DB0–DB13 data lines, BUSY, EOC, and FRSTDATA outputs become 3 V–tolerant - meeting TTL logic thresholds for 3 V systems. This eliminates external level shifters and reduces board area and BOM cost. The AD7865BSZ-2 datasheet confirms VOL ≤0.4 V and VOH ≥2.4 V under 3 V VDRIVE conditions, ensuring reliable communication with ARM Cortex-M or RISC-V MCUs operating at 3.3 V I/O.

What is the purpose of the STBY pin on the AD7865BSZ-2?

The STBY pin (Pin 22) controls the AD7865BSZ-2's power-saving standby mode. When pulled low, the device enters standby mode, reducing supply current to 20 µA maximum while retaining configuration state. A rising edge on STBY wakes the part within 1 µs - fast enough to support burst-mode acquisition in battery-powered condition monitoring systems. During standby, the internal clock oscillator and ADC core are disabled, but the channel select register and I/O buffers remain functional, allowing immediate resumption of conversions after wake-up - a key efficiency feature for the AD7865BSZ-2 in energy-conscious industrial IoT deployments.