AD7856KR

Overview

The AD7856KR is a high-speed, low-power 14-bit analog-to-digital converter manufactured by Analog Devices Inc. It operates from a single 5 V supply and supports an input throughput rate of 285 kSPS for the A version, while the K version is rated for a maximum master clock frequency of 4 MHz with a sample rate up to 102 kSPS. The device features eight single-ended or four pseudo-differential inputs and utilizes a successive approximation register (SAR) architecture. It includes self-calibration and system calibration options to maintain accuracy over temperature variations. The part is housed in a 24-lead SOIC package and operates within a commercial temperature range of 0°C to +105°C.

Feature Summary

• Supports flexible serial interface modes compatible with SPI, QSPI, 8051, and microprocessor systems.
• Includes on-chip self-calibration and system calibration capabilities to ensure long-term accuracy.
• Features automatic power-down after conversion to minimize energy consumption in battery-powered applications.

Applications

• Battery-powered personal digital assistants and mobile communication devices
• Pen computers and portable instrumentation systems
• Industrial control systems requiring multi-channel data acquisition

Procurement Notes

Verify the specific suffix 'KR' indicates the K grade variant with a 0°C to +105°C operating range and 4 MHz max clock speed, distinct from the A grade. Confirm the package type corresponds to the R-24 designation (SOIC). Check current availability status as older components may have limited stock or end-of-life notifications.

Selection Notes

Select the AD7856KR when a commercial temperature range (0°C to +105°C) is sufficient and a lower maximum sampling rate of 102 kSPS meets application requirements. This variant offers cost advantages over the A grade if the higher 285 kSPS throughput is not necessary. Ensure the system design accommodates the 4 MHz master clock limit for proper timing compliance.

Part Context

The AD7856KR belongs to the AD7856 family of 14-bit, 8-channel ADCs from Analog Devices. It shares the same functional block diagram and pinout with other variants like the AD7856AN and AD7856AR but differs in performance grades and temperature specifications. The K grade specifically targets commercial applications where extreme cold tolerance is not required.

Replacement Considerations

Direct substitutes include other AD7856 variants such as AD7856AR or AD7856AN, provided the temperature range and clock speed differences are acceptable. Cross-vendor replacements require matching 14-bit resolution, SAR architecture, and 5V single-supply operation.