AD7858LARZ

Overview

The AD7858LARZ is a low-power, 12-bit successive approximation analog-to-digital converter (ADC) manufactured by Analog Devices Inc. It operates from a single 3 V to 5.5 V supply and features eight single-ended or four pseudo-differential analog input channels. The device supports a maximum sampling rate of 100 kSPS with a typical power dissipation of 6.85 mW at 3 V. It includes an internal 2.5 V reference, system calibration capabilities, and a flexible serial interface compatible with SPI, QSPI, and 8051 microprocessors. The component is housed in a 24-lead SSOP package.

Feature Summary

• Integrated self-calibration and system calibration functions ensure accurate operation over time and temperature variations.
• Flexible serial interface supports multiple communication protocols including SPI, QSPI, and 8051 compatibility.
• Automatic power-down mode reduces power consumption significantly after each conversion cycle.
• Pseudo-differential sampling scheme minimizes common-mode noise effects on analog inputs.

Applications

• Battery-powered personal digital assistants and mobile communications devices
• Medical instrumentation requiring low power and high accuracy
• Pen computers and portable data acquisition systems
• Industrial control systems and high-speed modems

Procurement Notes

Verify the specific suffix 'R' indicates the SOIC package variant when cross-referencing with other AD7858 family members. Confirm that the 'L' designation corresponds to the low-power 100 kSPS version rather than the standard 200 kSPS model. Ensure the ordering information matches the required thermal and electrical specifications for the target application environment.

Selection Notes

Select the AD7858LARZ when low power consumption is critical alongside 12-bit resolution. Compare against the standard AD7858AR if higher throughput speeds are required, noting the difference in sampling rates. Consider the SSOP package constraints for PCB layout and thermal management compared to DIP or SOIC alternatives.

Part Context

This component belongs to the AD7858/AD7858L family of high-speed, low-power ADCs. The 'L' suffix denotes the low-power optimized version with a 100 kSPS throughput rate, while the base AD7858 offers 200 kSPS. The 'R' suffix typically identifies the SOIC package, whereas 'RS' identifies the SSOP package used in this part number.

Replacement Considerations

The AD7858LBRZ is a documented equivalent within the same family offering similar low-power characteristics. Verify pinout compatibility and software register configurations when substituting between different package types or speed grades within the AD7858 series.