AD7851KRZ

Overview

The AD7851KRZ is a 14-bit, serial sampling Analog-to-Digital Converter (ADC) manufactured by Analog Devices Inc. It operates from a single 5 V supply and supports throughput rates of 285 kSPS at standard conditions and 238 kSPS when operating up to 125°C. The device features a pseudo-differential input with two selectable voltage ranges: 0 V to VREF and ±VREF/2. Key performance metrics include a Signal-to-Noise Ratio (SNR) of 78 dB minimum, Integral Nonlinearity (INL) of ±1 LSB maximum, and Differential Nonlinearity (DNL) of ±1 LSB maximum. Power consumption is typically 60 mW in normal mode and drops to 5 µW in power-down mode.

Feature Summary

• Integrated self-calibration and system calibration capabilities with autocalibration on power-up to maintain accuracy over time and temperature.
• Flexible serial interface compatible with 8051, SPI, QSPI, and microprocessor standards for versatile digital connectivity.
• Low power architecture featuring a dedicated sleep mode with minimal power consumption while retaining calibration data.

Applications

• Digital Signal Processing
• Speech Recognition and Synthesis
• Spectrum Analysis
• DSP Servo Control
• Instrumentation and Control Systems

Procurement Notes

Verify the specific grade suffix 'K' corresponds to the required commercial temperature range (0°C to 85°C) and throughput specifications (285 kSPS). Confirm that the 'Z' suffix indicates lead-free packaging compliance if environmental regulations apply to your assembly process. Ensure the package type matches your PCB footprint requirements.

Selection Notes

Select the AD7851KRZ when a 14-bit resolution and high-speed serial interface are required within a commercial temperature range. Consider this component for applications needing pseudo-differential inputs and internal calibration to reduce external component count. Evaluate the 285 kSPS throughput against system timing constraints, noting the reduction to 238 kSPS at elevated temperatures up to 125°C.

Part Context

The AD7851KRZ belongs to the AD7851 family of high-speed, 14-bit serial ADCs from Analog Devices. It shares architectural similarities with the A-grade version but is optimized for the commercial temperature range. The KRZ designation specifically denotes the K-grade performance variant housed in a Pb-free SSOP-24 package, distinguishing it from PDIP or SOIC options available in the same series.

Replacement Considerations

The AD7851ARZ serves as a direct functional replacement offering identical electrical characteristics but rated for an extended industrial temperature range (-40°C to +85°C). Both parts share the same pinout and software compatibility, allowing for drop-in substitution where wider thermal operation is beneficial.

FAQ

What is the difference between the A and K grades of the AD7851?

The primary difference lies in the guaranteed throughput rate at standard temperatures and the operating temperature range. The K grade guarantees 285 kSPS from 0°C to 85°C, while the A grade guarantees 333 kSPS from -40°C to +85°C. Both grades support 238 kSPS up to 125°C.

How does the AD7851 handle calibration?

The device includes both self-calibration and system calibration options. It can perform autocalibration automatically upon power-up to ensure accurate operation. Users also have read/write capability to adjust calibration data stored in on-chip registers for offset and gain errors.

What input voltage ranges are supported?

The AD7851 supports two pseudo-differential input ranges selectable via the AMODE pin. Range 1 is 0 V to VREF, and Range 2 is ±VREF/2 centered about VREF/2. The analog input signal range extends from 0 V to VDD.