Analog Devices Inc. AD7865ASZ-1

Overview

AD7865ASZ-1 from Analog Devices is a four-channel, simultaneous-sampling, 14-bit analog-to-digital converter (ADC) with 2.4 µs conversion time per channel, ±10 V/±5 V input ranges, and integrated track/hold amplifiers. It operates from a single 5 V supply, consumes 115 mW typical power, and delivers 77 dB SNR at full temperature range - used in industrial motor control and power metering systems requiring phase-coherent multichannel acquisition.

For engineers reviewing the AD7865ASZ-1 datasheet, AD7865ASZ-1 pinout, AD7865ASZ-1 application, or AD7865ASZ-1 equivalent, key selection criteria include simultaneous sampling integrity, aperture delay matching (≤4 ns), bipolar input support, parallel 14-bit interface timing, and compatibility with 3 V/5 V digital logic via VDRIVE.

Technical Context

The AD7865ASZ-1 implements four independent track/hold amplifiers feeding a shared successive-approximation ADC core, enabling true simultaneous sampling across all channels to preserve inter-channel phase relationships. Its internal 2.5 V reference, laser-trimmed oscillator, and configurable channel sequence (hardware or software-selectable) support deterministic timing in real-time control loops.

Conversion is initiated by a rising edge on CONVST, which latches channel selection and places all track/holds into hold mode; BUSY remains high until all selected channels complete conversion, while EOC pulses low after each individual channel's result is ready. The device supports both reading between conversions and post-sequence read modes with strict timing windows (e.g., t6 = 35 ns data access time at VDRIVE = 5 V).

Key Specifications

Pinout & Package

AD7865ASZ-1 is housed in a 44-lead Plastic Quad Flatpack (PQFP), 10 mm × 10 mm body, 0.8 mm lead pitch, with exposed thermal pad (not electrically connected). Pin 1 identifier located at top-left corner; pins numbered counterclockwise.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7865ASZ-1, AD7656ASTZ trades parallel interface simplicity for higher resolution and two extra channels, while ADS8588SIPM adds channel count and resolution but removes 5 V logic compatibility - making AD7865ASZ-1 optimal for cost-sensitive, 5 V-based industrial controllers needing exact four-channel simultaneity.

Availability

AD7865ASZ-1 is available at Aetrix Electronics and suitable for AC motor control, uninterruptible power supplies, and industrial power meters requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for AD7865ASZ-1 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 U.S.-based semiconductor company specializing in high-performance analog, mixed-signal, and digital signal processing technologies for precision measurement and control.

The AD7865 product line delivers simultaneous-sampling ADCs optimized for industrial automation, power electronics, and real-time data acquisition - designed to replace multiple single-channel converters while guaranteeing inter-channel timing integrity.

FAQ

What input voltage ranges does the AD7865ASZ-1 support?

The AD7865ASZ-1 supports ±10 V and ±5 V bipolar input ranges, as specified in its ordering guide and electrical characteristics table. These ranges are factory-configured for the -1 variant and cannot be changed in-circuit. Input overvoltage protection extends to ±18 V (for ±10 V range) and ±9 V (for ±5 V range), safeguarding against transient surges without affecting adjacent channel accuracy. The AD7865ASZ-1 does not support unipolar or ±2.5 V ranges - those are assigned to AD7865ASZ-2 and AD7865ASZ-3 variants respectively.

How does the AD7865ASZ-1 achieve simultaneous sampling across four channels?

The AD7865ASZ-1 achieves true simultaneous sampling using four independent, matched track/hold amplifiers - one per analog input pair (VIN1A/B through VIN4A/B). On the rising edge of the CONVST signal, all four amplifiers switch from track to hold mode at the same instant, freezing their respective input voltages. This preserves relative phase information between channels, with aperture delay matching guaranteed ≤4 ns. The subsequent ADC conversion proceeds sequentially across selected channels, but sampling itself occurs concurrently - a key distinction from multiplexed architectures.

Can the AD7865ASZ-1 interface directly with a 3 V microcontroller?

Yes, the AD7865ASZ-1 can interface directly with a 3 V microcontroller using its VDRIVE pin (Pin 36). When VDRIVE is supplied with 3.0 V ± 10%, the parallel data outputs (DB0–DB13), BUSY, EOC, and FRSTDATA signals operate at 3 V logic levels while remaining compatible with 5 V-tolerant inputs. This eliminates external level shifters. Note that AVDD and DVDD must still be 5 V ± 5% for analog and digital core operation - only the output driver supply is decoupled via VDRIVE.

What is the purpose of the H/S SEL pin on the AD7865ASZ-1?

The H/S SEL pin (Pin 11) selects between hardware- and software-controlled channel sequencing. When pulled low, channel selection is determined by the logic states of SL1–SL4 pins (Pins 7, 8, 9, 10); when pulled high, the channel select register is programmed via DB0–DB3 during a write cycle with CS low and WR high. This dual-mode flexibility allows the AD7865ASZ-1 to serve both fixed-function systems (e.g., dedicated motor drive ASICs) and programmable platforms (e.g., FPGA-based DAQ), without requiring firmware changes to alter channel configuration.

Does the AD7865ASZ-1 include an internal voltage reference?

Yes, the AD7865ASZ-1 includes an internal 2.5 V reference with ±20 mV error over –40°C to +85°C, accessible at the VREF pin (Pin 24). This reference is used by default for ADC conversion and can be overdriven by an external 2.5 V ± 5% source if higher precision or temperature stability is required. A 0.1 µF decoupling capacitor is mandatory between VREF and AGND. The internal reference eliminates the need for external components in most industrial applications, reducing BOM cost and PCB area - a key advantage over reference-less ADCs requiring external REF02 or ADR431 circuits.