AD7984BCPZ-RL

Overview

The AD7984BCPZ-RL is an 18-bit, 1.33 MSPS PulSAR analog-to-digital converter (ADC) manufactured by Analog Devices Inc. It features a true differential analog input range of ±VREF and operates from a single 2.5 V supply with logic interfaces supporting 1.8 V, 2.5 V, 3 V, or 5 V via the VIO pin. The device delivers a signal-to-noise ratio (SNR) of 98.5 dB at a full-scale reference voltage of 5 V. Total power dissipation is 10.5 mW at maximum throughput. It utilizes a proprietary serial interface compatible with SPI, QSPI, Microwire, and DSP standards, allowing for daisy-chaining multiple ADCs on a single bus.

Feature Summary

• Zero latency architecture providing immediate data availability after conversion completion without pipeline delay.
• Versatile serial interface port supporting multiple communication protocols including SPI, QSPI, Microwire, and DSP modes.
• Daisy-chain capability enabling multiple converters to share a single SDO line through the SDI input.

Applications

• Automated test equipment
• Data acquisition systems
• Medical instruments
• Machine automation

Procurement Notes

Verify the specific package variant against the datasheet ordering guide, as the BC suffix indicates the LFCSP package while other suffixes may denote MSOP. Confirm that the RL suffix corresponds to reel packaging requirements for your assembly process. Ensure the external reference voltage falls within the specified 2.9 V to 5.1 V range for optimal performance.

Selection Notes

Select this component when high resolution and low power consumption are critical for battery-operated or space-constrained designs. The device is suitable for applications requiring true differential inputs and flexible digital logic levels. Consider the thermal resistance characteristics if operating in enclosed environments, as heat dissipation depends heavily on PCB layout.

Part Context

The AD7984 belongs to the PulSAR family of successive approximation register (SAR) ADCs from Analog Devices. It shares architectural similarities with the AD7982 but offers higher resolution. The part is designed to bridge the gap between medium-speed data acquisition and high-precision measurement, utilizing charge redistribution DAC technology for accurate sampling.

Replacement Considerations

The AD7982 is a pin-for-pin compatible alternative within the same product family. Verify that the required resolution and throughput specifications of the replacement part meet the system design constraints before substitution.

FAQ

How does the AD7984 handle interface mode selection?

The interface mode is determined by the state of the SDI input during the rising edge of the CNV signal. A low SDI selects chain mode, while a high SDI selects chip select (CS) mode.

What is the maximum allowable analog input voltage relative to the reference?

The absolute input voltage on IN+ and IN− must not exceed VREF + 0.1 V or go below −0.1 V to prevent forward-biasing the internal ESD protection diodes.

Does the AD7984 require an external clock for conversion?

No, the AD7984 contains an on-board conversion clock. The external Serial Clock (SCK) is only required for shifting out the digital data results.