Analog Devices Inc. AD7865ASZ-3

Overview

AD7865ASZ-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 integrated 2.5 V reference - used in precision motor control and power monitoring systems requiring phase-coherent multichannel sampling.

For engineers reviewing the AD7865ASZ-3 datasheet, AD7865ASZ-3 pinout, AD7865ASZ-3 application, or AD7865ASZ-3 equivalent, key selection criteria include simultaneous sampling capability, aperture delay matching ≤4 ns, bipolar ±2.5 V input range, 77 dB SNR at full temperature range, and PQFP-44 package compatibility with industrial embedded signal acquisition designs.

Technical Context

The AD7865ASZ-3 implements four independent track/hold amplifiers feeding a single 14-bit successive approximation ADC core, enabling true simultaneous sampling across all channels while preserving inter-channel phase relationships. Its internal laser-trimmed clock oscillator eliminates external timing components and ensures 2.4 µs deterministic conversion time.

Channel selection is configurable via hardware (SL1–SL4 pins) or software (DB0–DB3 register write), and conversion sequencing supports any subset of the four inputs to maximize throughput. The device uses two's complement output coding and features overvoltage protection up to –4 V / +18 V on analog inputs without affecting other channels.

Key Specifications

Pinout & Package

AD7865ASZ-3 is housed in a 44-lead Plastic Quad Flatpack (PQFP) measuring 10 mm × 10 mm with 0.8 mm lead pitch. The package features separate analog (AGND) and digital (DGND) ground planes, dual supply rails (AVDD/DVDD), and dedicated VDRIVE for 3 V/5 V I/O flexibility.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7865ASZ-3, AD7656ASTZ offers higher resolution and more channels but requires external reference and lacks ±2.5 V support; ADS8588HIPM provides greater channel count and modern SPI interface but abandons the parallel bus and exact input range - making AD7865ASZ-3 uniquely suited for cost-sensitive, phase-critical, ±2.5 V signal acquisition with minimal system redesign.

Availability

AD7865ASZ-3 is available at Aetrix Electronics and suitable for AC motor control, uninterruptible power supplies, industrial power meters/monitors, and data acquisition systems requiring stable component supply throughout product lifecycles.

Supply support for AD7865ASZ-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 industrial and instrumentation applications demanding simultaneous multichannel sampling, tight inter-channel timing matching, and robust operation in electrically noisy environments.

FAQ

What input voltage range does the AD7865ASZ-3 support?

The AD7865ASZ-3 supports a bipolar ±2.5 V analog input range, optimized for signal processing applications where symmetric dynamic range around ground is required. This differs from the AD7865ASZ-1 (±5 V/±10 V) and AD7865ASZ-2 (0 V to 2.5 V / 0 V to 5 V) variants. Input overvoltage tolerance extends to –4 V to +18 V without damage or cross-channel interference, as specified in the Absolute Maximum Ratings table.

How does the AD7865ASZ-3 achieve simultaneous sampling across four channels?

The AD7865ASZ-3 achieves true simultaneous sampling using four independent on-chip track/hold amplifiers, each connected to one analog input pair (VIN1A/B through VIN4A/B). A single CONVST rising edge places all four amplifiers into hold mode at the exact same instant, freezing their respective input voltages before conversion begins. This architecture preserves relative phase information between channels, with aperture delay matching guaranteed ≤4 ns.

What is the role of the VDRIVE pin on the AD7865ASZ-3?

The VDRIVE pin on the AD7865ASZ-3 supplies power to the digital output drivers (DB0–DB13, BUSY, EOC, FRSTDATA), enabling independent voltage control of the parallel interface. It can be tied to DVDD for 5 V operation or driven with a 3 V ±10% supply to directly interface with 3 V microprocessors and DSPs without level-shifting circuitry - a key feature for mixed-voltage system designs involving the AD7865ASZ-3.

Does the AD7865ASZ-3 require an external clock source?

No, the AD7865ASZ-3 includes an internal laser-trimmed clock oscillator that generates the master conversion clock, eliminating the need for external timing components. An external clock may be applied via CLK IN/SL1 only when INT/EXT CLK/SL2 is set high, but the internal clock delivers optimal 2.4 µs conversion time and simplifies PCB layout - a design advantage confirmed in the AD7865ASZ-3 functional description and timing characteristics.

What packaging and thermal specifications apply to the AD7865ASZ-3?

The AD7865ASZ-3 is packaged in a 44-lead Plastic Quad Flatpack (PQFP) with 10 mm × 10 mm body size and 0.8 mm lead pitch. Its thermal impedance is θJA = 95°C/W, and maximum power dissipation is rated at 450 mW. The device operates across –40°C to +85°C (Commercial A-grade), with junction temperature limited to 150°C - consistent with the ordering guide entry for AD7865ASZ-3 and verified in the Absolute Maximum Ratings section.