AD7938BCP

Overview

The AD7938BCP is a 12-bit, high-speed successive approximation register (SAR) analog-to-digital converter manufactured by Analog Devices Inc. It features eight multiplexed analog input channels with an integrated sequencer and operates from a single 2.7 V to 5.25 V supply. The device achieves throughput rates up to 1.5 MSPS with low power consumption of 6 mW at 3 V and 13.5 mW at 5 V. It includes an accurate on-chip 2.5 V reference and supports single-ended, fully differential, or pseudo-differential inputs. The parallel interface allows direct connection to 3 V or 5 V processors via the VDRIVE function.

Feature Summary

• Eight software-configurable analog input channels with a channel sequencer for automated conversion sequences.
• Integrated precise 2.5 V internal voltage reference with low temperature coefficient.
• Flexible power management including full shutdown mode with minimal current draw.
• VDRIVE function enabling parallel interface compatibility with independent 3 V or 5 V processor systems.

Applications

• Industrial process control systems requiring multi-channel data acquisition.
• Portable instrumentation utilizing single-supply operation.
• Motor control applications needing fast sampling rates.
• Data acquisition modules in automated test equipment.

Procurement Notes

Verify the specific suffix 'BCP' against the manufacturer's official ordering guide to confirm package type and temperature grade. Ensure the component matches the required LFCSP or TQFP footprint and that the revision level aligns with your design specifications. Cross-reference the datasheet version to confirm pinout and electrical characteristics.

Selection Notes

Select this component when a 12-bit resolution and 1.5 MSPS throughput are required for multi-channel applications. Consider the AD7938 over the AD7939 if higher dynamic performance and DC accuracy are necessary. Evaluate the power consumption requirements against the available supply voltage range of 2.7 V to 5.25 V.

Part Context

The AD7938 belongs to the AD793x family of high-speed, low-power SAR ADCs from Analog Devices. It shares architectural similarities with the AD7939 but offers superior 12-bit performance metrics. The family is designed for applications demanding efficient multi-channel sampling with minimal power dissipation.

Replacement Considerations

The AD7939 serves as a lower-cost alternative within the same family, offering 10-bit resolution. For 4-channel variants, consider the AD7933 or AD7934. Verify pin compatibility and register settings when substituting these parts.

FAQ

How does the VDRIVE function benefit system integration?

The VDRIVE pin allows the digital interface logic levels to be set independently of the analog supply voltage (VDD), enabling direct connection to 3 V or 5 V microprocessors without level shifting.

What is the maximum input frequency the track-and-hold amplifier can handle?

The differential track-and-hold amplifier can handle input frequencies up to 50 MHz, ensuring accurate sampling of high-frequency signals.

Can the internal reference be bypassed for external use?

Yes, the VREFIN/VREFOUT pin can be overdriven by an external reference voltage ranging from 0.1 V to VDD to provide an alternative reference source.