Analog Devices Inc. AD7864ASZ-2

Overview

AD7864ASZ-2 from Analog Devices is a 4-channel, simultaneous-sampling, 12-bit analog-to-digital converter (ADC) with 1.65 μs conversion time, 0.35 μs track-and-hold acquisition time, ±2.5 V input range compatibility, and straight binary output coding. It operates from a single 5 V supply, consumes 90 mW typical power, and is used in AC motor control systems requiring phase-coherent multichannel voltage monitoring.

For engineers reviewing the AD7864ASZ-2 datasheet, AD7864ASZ-2 pinout, AD7864ASZ-2 application, or AD7864ASZ-2 equivalent, key selection criteria include simultaneous sampling capability, unipolar input support (0 V to 2.5 V / 0 V to 5 V), hardware/software channel sequencing, high-speed parallel interface timing, and aperture delay matching ≤4 ns across all four channels.

Technical Context

The AD7864ASZ-2 integrates four independent track-and-hold amplifiers with matched aperture delay (≤4 ns), a 12-bit successive approximation ADC core, on-chip 2.5 V reference, internal clock oscillator, and signal scaling circuitry. Its simultaneous sampling preserves inter-channel phase relationships critical for vector control algorithms.

Conversion is initiated by a rising edge on CONVST, which latches channel selection via SL1–SL4 pins or software-programmed register, then triggers concurrent hold and conversion across selected channels. EOC pulses indicate per-channel completion; BUSY remains high until the full sequence ends.

Key Specifications

Pinout & Package

The AD7864ASZ-2 is housed in a 44-lead MQFP (Metric Quad Flat Package) with 0.3 inch² footprint and standard 0.8 mm lead pitch.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 4-channel simultaneous-sampling ADC applications.

Compared with AD7864ASZ-2, AD7865ASZ-2 offers 2 extra bits at identical timing and packaging but increases power and cost; ADS8588SIPM provides double the channels and resolution but eliminates parallel interface support and adds design complexity with external reference/clock requirements.

Availability

AD7864ASZ-2 is available at Aetrix Electronics and suitable for AC motor control, uninterruptible power supplies, and industrial data acquisition systems requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.

Supply support for AD7864ASZ-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, serving industrial, automotive, communications, and healthcare markets.

The AD7864 product line delivers high-speed, multichannel simultaneous-sampling ADCs optimized for real-time control systems where phase coherence, low latency, and robust analog input handling are essential.

FAQ

What input voltage ranges does the AD7864ASZ-2 support?

The AD7864ASZ-2 supports two unipolar input ranges: 0 V to 2.5 V and 0 V to 5 V. These are selectable via external configuration and are distinct from the bipolar ranges of other AD7864 variants. The device includes overvoltage protection allowing analog inputs to tolerate −1 V to +20 V without damage, making it suitable for noisy industrial environments. This specification is confirmed in the Rev. D datasheet Table 1 under ANALOG INPUTS.

How does the AD7864ASZ-2 achieve simultaneous sampling across four channels?

The AD7864ASZ-2 achieves true simultaneous sampling using four independent track-and-hold amplifiers, each associated with one analog input pair (VIN1A/B through VIN4A/B). A single rising edge on the CONVST pin places all four amplifiers into hold mode at the exact same instant, freezing their input voltages coherently. This architecture preserves phase relationships between channels-critical for vector control-and is validated by aperture delay matching ≤4 ns across all channels per the datasheet.

What is the function of the VDRIVE pin on the AD7864ASZ-2?

The VDRIVE pin on the AD7864ASZ-2 supplies power to the parallel data bus drivers (DB0–DB11), BUSY, EOC, and FRSTDATA outputs. It can be tied to DVDD (5 V) or driven with a 3 V ±10% supply, enabling direct interfacing with 3 V microcontrollers and DSPs without level shifters. Decoupling VDRIVE with a 0.1 μF capacitor improves noise immunity during read-during-conversion operations, as specified in the Functional Block Diagram and Pin Descriptions sections of the AD7864ASZ-2 datasheet.

Does the AD7864ASZ-2 include an internal voltage reference?

Yes, the AD7864ASZ-2 includes an on-chip 2.5 V reference with ±20 mV error over temperature (±25 ppm/°C typical drift). The VREF pin serves as both output (2.5 V ±5%) and input, allowing the internal reference to be overdriven by an external precision source if higher accuracy is required. This integrated reference eliminates the need for external components in most industrial applications and is explicitly documented in the REFERENCE INPUT/OUTPUT section of the AD7864ASZ-2 datasheet Rev. D.

What is the maximum throughput rate of the AD7864ASZ-2 when converting all four channels?

The AD7864ASZ-2 achieves a maximum throughput rate of 130 kSPS when converting all four channels in read-during-conversion sequence mode. This is enabled by overlapping conversion and data read cycles, leveraging the high-speed parallel interface and EOC signaling. In read-after-conversion mode, throughput depends on the host processor's read cycle time. Both modes and timing constraints are detailed in the Timing and Control section of the AD7864ASZ-2 datasheet Rev. D.