Analog Devices Inc. AD7864ASZ-1

Overview

AD7864ASZ-1 from Analog Devices is a 4-channel, simultaneous-sampling, 12-bit analog-to-digital converter (ADC) with 1.65 μs conversion time, ±10 V/±5 V input ranges, and integrated track-and-hold amplifiers. It operates from a single 5 V supply, delivers 130 kSPS full-channel throughput, and preserves phase coherence across channels-ideal for real-time motor current sensing in vector-controlled AC drives.

For engineers reviewing the AD7864ASZ-1 datasheet, AD7864ASZ-1 pinout, AD7864ASZ-1 application, or AD7864ASZ-1 equivalent, key selection considerations include simultaneous sampling integrity, bipolar input range support, hardware/software channel sequencing, and low-power standby mode (20 μW typical) for energy-sensitive industrial data acquisition systems.

Technical Context

The AD7864ASZ-1 implements four independent track-and-hold amplifiers with ≤4 ns aperture delay matching and a 1.65 μs successive approximation ADC core. Its internal 2.5 V reference (±20 mV error over temperature) and on-chip clock oscillator enable self-contained operation without external timing components.

Conversion control supports both hardware (SL1–SL4 pins) and software (DB0–DB3 register write) channel selection, with CONVST initiating simultaneous hold and sequence start. BUSY and EOC signals provide precise timing coordination: BUSY asserts at CONVST rising edge and deasserts after all selected channels complete; EOC pulses low per-channel during the sequence.

Key Specifications

Pinout & Package

AD7864ASZ-1 is housed in a 44-lead MQFP (0.3 inch square) package with exposed thermal pad. Pin functions are validated per Analog Devices Rev. D datasheet Figure 3 and Table 4.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7864ASZ-1, AD7656ASTZ offers higher resolution and channel count but demands more board space and external support components, while ADS8588HIPM trades simultaneity for speed and channel density-making AD7864ASZ-1 the optimal balance of phase fidelity, integration, and industrial ruggedness for 4-channel real-time control.

Availability

AD7864ASZ-1 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 support, and guaranteed traceable sourcing.

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

The AD7864 product line was engineered specifically for industrial real-time control applications demanding simultaneous multi-channel sampling, robust input protection, and single-supply simplicity-targeting motor drives, power quality analyzers, and automated test equipment.

FAQ

What input voltage ranges does the AD7864ASZ-1 support?

The AD7864ASZ-1 supports ±10 V and ±5 V bipolar input ranges, as specified in its model suffix "-1". These ranges are factory-configured and do not require external resistor networks or range-select jumpers. The device maintains ±1 LSB relative accuracy across the full temperature range (−40°C to +85°C) for both ranges, enabling direct connection to industrial current shunt amplifiers and voltage dividers without recalibration.

How does the AD7864ASZ-1 achieve simultaneous sampling across four channels?

The AD7864ASZ-1 achieves true simultaneous sampling using four independent, tightly matched track-and-hold amplifiers. A single CONVST rising edge freezes all four inputs at precisely the same instant, with aperture delay matching ≤4 ns. This hardware-synchronized hold operation-followed by sequential ADC conversion-preserves phase relationships between channels, unlike multiplexed ADCs that introduce inter-channel timing skew.

Can the AD7864ASZ-1 interface with 3 V microcontrollers?

Yes, the AD7864ASZ-1 supports 3 V logic interfacing via its dedicated VDRIVE pin (Pin 36). When VDRIVE is supplied with 3 V ±10%, the parallel data bus (DB0–DB11), BUSY, EOC, and FRSTDATA outputs operate at 3 V logic levels while maintaining full timing compliance. This eliminates level-shifters in mixed-voltage systems and is validated in the datasheet's timing characteristics for VDRIVE = 3 V.

What is the purpose of the STBY pin on the AD7864ASZ-1?

STBY (Pin 22) controls the AD7864ASZ-1's power-saving mode. Driving STBY low reduces supply current to 20 μW typical, ideal for idle periods in battery-powered or thermally constrained systems. Wake-up time is 6 ms maximum when using the internal reference (with 0.1 μF VREF decoupling), allowing rapid resumption of sampling without external reference stabilization delays.

Does the AD7864ASZ-1 require an external clock source?

No, the AD7864ASZ-1 includes an on-chip clock oscillator and operates autonomously with only a 5 V supply. The INT/EXT CLK pin (Pin 27) allows optional use of an external clock (e.g., for synchronization to system master clock), but it is not required. Internal clock operation simplifies design, reduces component count, and ensures consistent 1.65 μs conversion time without external frequency tolerance dependencies.