AD7865AS-3REEL

Overview

The AD7865AS-3REEL is a four-channel, simultaneous sampling, 14-bit analog-to-digital converter (ADC) from Analog Devices. It operates on a single +5 V supply and features a 2.4 µs successive approximation ADC with four track/hold amplifiers. The device accepts an analog input range of ±2.5 V and includes overvoltage protection allowing inputs up to ±18 V without damage. It offers a high-speed parallel interface compatible with 3 V processors, internal clock oscillator, and a 2.5 V reference. Maximum throughput is 350 kSPS per channel or 100 kSPS for all four channels.

Feature Summary

• Four simultaneously sampled inputs preserve relative phase information across channels.
• Hardware or software selectable channel conversion sequences optimize throughput rates.
• High-speed parallel interface facilitates direct connection to microprocessors and DSPs.
• Low power consumption with a dedicated standby mode for energy efficiency.

Applications

• AC motor control systems
• Uninterruptible power supplies
• Industrial power meters and monitors
• Data acquisition systems

Procurement Notes

Verify the specific suffix 'REEL' indicates tape-and-reel packaging when sourcing components. Confirm that the '-3' designation corresponds to the ±2.5 V input range variant. Ensure compatibility with the required operating temperature range of -40°C to +85°C for the AS grade. Cross-reference the datasheet revision to confirm pinout and electrical specifications match the design requirements.

Selection Notes

Select this component when simultaneous multi-channel sampling is critical for phase accuracy. The ±2.5 V input range suits signal processing applications requiring bipolar signals within this amplitude. Consider the 14-bit resolution and 350 kSPS speed for high-performance data acquisition needs. Evaluate the parallel interface requirements against the target processor's capabilities.

Part Context

The AD7865 series comprises three variants differentiated by input voltage ranges: ±10 V/±5 V, 0 V to 5 V/2.5 V, and ±2.5 V. The AS-3 variant specifically targets the common ±2.5 V industrial standard. It belongs to the fast, low-power SAR ADC family designed for portable and battery-operated instrumentation where power efficiency and channel synchronization are paramount.

Replacement Considerations

Direct replacements include other AD7865 variants such as AD7865AS-1 or AD7865AS-2 if input voltage ranges differ. For higher channel counts, consider the AD7866 or AD7867 families. Verify pin compatibility and software register mapping when substituting with newer generations of simultaneous sampling ADCs.

FAQ

How is the channel conversion sequence selected?

The sequence can be selected via hardware using the SL1-SL4 pins or via software by programming the channel select register using DB0-DB3 and the WR signal.

What is the maximum input voltage allowed without damage?

For the AD7865-3 variant, the analog inputs can withstand voltages up to ±18 V without damaging the device or affecting ongoing conversions.

Can the device interface with 3 V logic processors?

Yes, the VDRIVE pin allows the output drivers to be powered by a 3 V supply, enabling direct interfacing with 3 V processors and DSPs.