AD7864ASZ-2

Overview

The AD7864ASZ-2 is a high-speed, low-power, 4-channel simultaneous sampling 12-bit analog-to-digital converter (ADC) from Analog Devices. It operates from a single 5 V supply and features four track-and-hold amplifiers with an acquisition time of 0.35 μs and a conversion time of 1.65 μs per channel. The device supports unipolar input ranges of 0 V to +2.5 V or 0 V to +5 V. It includes an internal 2.5 V reference, on-chip clock oscillator, and signal conditioning circuitry. The part utilizes a high-speed parallel interface compatible with 3 V processors and offers power-saving standby mode.

Feature Summary

• Four simultaneously sampled inputs preserve relative phase information across channels.
• Hardware or software selectable channel sequence allows conversion of any subset of the four channels.
• Integrated overvoltage protection on analog inputs prevents damage from excessive voltage levels.
• Low power consumption with typical normal mode dissipation of 90 mW and standby mode of 20 μW.

Applications

• AC motor control
• Uninterrupted power supplies
• Data acquisition systems
• Communications

Procurement Notes

Verify the specific suffix -2 indicates the 0 V to +2.5 V or 0 V to +5 V unipolar input range configuration. Confirm package type is MQFP-44 and temperature range is industrial (-40°C to +85°C). Check for RoHS compliance status in current manufacturer documentation before ordering.

Selection Notes

Select this component when simultaneous sampling of four channels is required to maintain phase coherence. Ensure the application requires unipolar input signals within the 0 V to 5 V range. Consider the 12-bit resolution and 500 kSPS maximum throughput per channel against system accuracy needs.

Part Context

The AD7864 series includes variants with different input ranges: AD7864-1 for ±10 V/±5 V bipolar, AD7864-3 for ±2.5 V bipolar, and AD7864-2 for unipolar applications. All share the same core architecture, pinout, and digital interface specifications.

Replacement Considerations

No direct public substitute part numbers are confirmed in the provided documentation. Cross-reference with other 4-channel simultaneous sampling ADCs if availability is an issue, ensuring similar resolution and sampling rates.

FAQ

What is the input coding format for the AD7864ASZ-2?

The AD7864-2 uses straight (natural) binary output coding, unlike the two's complement format used by the bipolar versions.

How is the conversion sequence selected?

The conversion sequence can be selected via hardware pins (SL1-SL4) when H/S SEL is Logic 0, or via software programming of the channel select register when H/S SEL is Logic 1.

Can the AD7864 interface with 3 V processors?

Yes, the high-speed parallel interface allows interfacing to 3 V processors by powering the VDRIVE pin with a 3 V supply instead of the standard 5 V.