Analog Devices Inc. AD7864ASZ-3

Overview

AD7864ASZ-3 from Analog Devices is a 4-channel, simultaneous-sampling, 12-bit analog-to-digital converter (ADC) with ±2.5 V input range, 1.65 μs conversion time, and integrated 2.5 V reference - designed for phase-critical motor control and power quality monitoring where channel-to-channel timing alignment is essential.

For engineers reviewing the AD7864ASZ-3 datasheet, AD7864ASZ-3 pinout, AD7864ASZ-3 application, or AD7864ASZ-3 equivalent, key selection criteria include simultaneous sampling capability, aperture delay matching ≤4 ns, bipolar twos-complement output coding, 130 kSPS four-channel throughput, and MQFP-44 package compatibility with industrial signal conditioning layouts.

Technical Context

The AD7864ASZ-3 implements four independent track-and-hold amplifiers feeding a single 12-bit successive approximation register (SAR) ADC core, enabling true simultaneous sampling across all channels while preserving inter-channel phase relationships. Its internal 2.5 V reference (±20 mV error over temperature) and ±2.5 V input range are factory-trimmed for the AD7864-3 variant.

Conversion sequencing is configurable via hardware (SL1–SL4 pins) or software (DB0–DB3 latched into channel select register), with CONVST initiating simultaneous hold and conversion start. BUSY and EOC signals provide precise timing control for real-time systems, supporting both read-during-conversion (130 kSPS) and read-after-conversion modes.

Key Specifications

Pinout & Package

AD7864ASZ-3 is housed in a 44-lead MQFP (Metric Quad Flat Package) with 0.8 mm lead pitch and 10 mm × 10 mm body size, suitable for automated SMT assembly and industrial PCB layouts requiring thermal and EMI robustness.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7864ASZ-3, AD7656ASTZ offers higher resolution but demands external reference and consumes more power, while ADS8588HIPM provides greater channel count and integration at the cost of parallel interface compatibility and increased firmware complexity.

Availability

AD7864ASZ-3 is available at Aetrix Electronics and suitable for AC motor control, uninterruptible power supplies, and power quality data acquisition systems requiring stable component supply, long-term industrial lifecycle support, and MQFP-44 package compatibility.

Supply support for AD7864ASZ-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, Inc. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, headquartered in Norwood, MA.

The AD7864 product line delivers simultaneous-sampling ADCs optimized for real-time industrial control and power electronics, emphasizing timing precision, low power, and system-level integration for closed-loop feedback systems.

FAQ

What is the maximum sample rate for all four channels on the AD7864ASZ-3?

The AD7864ASZ-3 achieves a maximum throughput of 130 kSPS when converting all four channels in sequence using the read-during-conversion mode. This rate is determined by the 1.65 μs conversion time per channel plus EOC pulse width, and is validated across the full −40°C to +85°C operating range. The AD7864ASZ-3 maintains this performance without external clocking or timing adjustments.

Does the AD7864ASZ-3 require an external reference voltage?

No, the AD7864ASZ-3 includes an integrated 2.5 V reference with ±20 mV error over temperature, eliminating the need for an external reference in most applications. Pin 24 (VREF) provides access to this internal reference and also accepts an external 2.5 V source if higher accuracy is required. The AD7864ASZ-3 datasheet specifies that the internal reference is trimmed and tested for the AD7864-3 variant.

How does the AD7864ASZ-3 handle channel selection - hardware or software?

The AD7864ASZ-3 supports dual-mode channel selection: hardware via SL1–SL4 pins (when H/S SEL = Logic 0) or software via DB0–DB3 programmed into the channel select register (when H/S SEL = Logic 1). The selection is latched on the rising edge of CONVST, allowing flexible configuration for fixed-function or programmable systems. Both methods are fully supported in the AD7864ASZ-3 datasheet.

What is the significance of aperture delay matching in the AD7864ASZ-3?

The AD7864ASZ-3 guarantees aperture delay matching of ≤4 ns max between its four track-and-hold amplifiers. This specification ensures phase alignment better than 0.02° at 100 kHz, which is critical for accurate vector transformations in motor control and coherent FFT analysis in power quality monitoring. It is measured and specified separately for the AD7864-3 variant in the Rev. D datasheet.

Can the AD7864ASZ-3 interface directly with 3 V microcontrollers?

Yes, the AD7864ASZ-3 supports 3 V logic interfacing via the VDRIVE pin (Pin 36), which powers the DB0–DB11 outputs, BUSY, EOC, and FRSTDATA signals. When VDRIVE is supplied with 3 V ±10%, the outputs meet TTL-compatible levels (VOH ≥ 2.4 V, VOL ≤ 0.4 V) and timing parameters remain valid. This capability is explicitly documented in the AD7864ASZ-3 timing characteristics table.