AD7985BCPZ-RL7

Overview

The AD7985BCPZ-RL7 is a 16-bit successive approximation analog-to-digital converter (ADC) from Analog Devices. It operates with a throughput of up to 2.5 MSPS in turbo mode and 2.0 MSPS in normal mode. The device features a pseudo-differential analog input range from 0 V to VREF, supporting reference voltages up to 5.0 V. Power dissipation is 15.5 mW at 2.5 MSPS with an external reference and 28 mW with the internal 4.096 V reference. Key accuracy specifications include an INL of ±0.7 LSB typical and ±1.5 LSB maximum, and an SNR of 88.5 dB with the internal reference or 90 dB with an external reference. It utilizes a versatile serial interface compatible with SPI, QSPI, MICROWIRE, and DSP protocols.

Feature Summary

• Features a low-power SAR architecture with no pipeline delay for immediate data availability.
• Includes an on-chip 4.096 V bandgap reference with a buffer and error correction circuits.
• Supports daisy-chaining multiple ADCs on a single bus using the SDI input for chain mode operation.
• Offers flexible logic interface compatibility with 1.8 V, 2.5 V, and 2.7 V digital supplies via a separate VIO pin.

Applications

• Battery-powered equipment
• Communications systems
• Automated test equipment (ATE)
• Data acquisition systems
• Medical instruments

Procurement Notes

Verify the specific ordering suffix RL7 corresponds to the reel packaging configuration required for your assembly line. Confirm that the BCZ variant meets the specified commercial temperature range of −40°C to +85°C. Ensure the LFCSP package dimensions align with your PCB footprint design rules. Check for any RoHS compliance documentation updates prior to final procurement authorization.

Selection Notes

Select this component when a 16-bit resolution with high sampling rates is required alongside low power consumption. Consider the internal reference if board space is limited, but use an external reference for optimal SNR performance above 90 dB. Evaluate the need for turbo mode versus normal mode based on whether power scaling during idle conversion phases is necessary for the application.

Part Context

This part belongs to the PulSAR family of ADCs from Analog Devices, designed for precision data conversion tasks. It shares pin-for-pin compatibility with the 18-bit AD7986, allowing for potential upgrade paths within the same footprint. The series is characterized by its charge redistribution DAC architecture and proprietary serial interface capabilities.

Replacement Considerations

The AD7986 is a pin-for-pin compatible alternative offering 18-bit resolution. For lower speed requirements, the AD7980 provides 16-bit resolution at 1 MSPS. Verify that any substitute maintains the 20-lead LFCSP package and compatible voltage supply ranges.

FAQ

How does the TURBO pin affect power consumption and throughput?

When the TURBO pin is high, the device achieves maximum throughput of 2.5 MSPS without powering down between conversions. When low, it enters normal mode with a maximum rate of 2.0 MSPS, powering down between conversions to reduce power dissipation.

What is the function of the PDREF pin?

The PDREF pin controls the internal reference. When low, the internal 4.096 V reference and buffer are enabled. When high, the internal reference is powered down, requiring an external reference voltage connected to the REF pin.

Can multiple AD7985 devices be connected to a single microcontroller?

Yes, by setting the SDI pin low during the CNV rising edge, the device enters chain mode. This allows multiple ADCs to be daisy-chained onto a single SDO line, with the SDI input shifting in data from previous devices in the chain.