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Engineer-to-Engineer and Application Notes

These engineer-to-engineer and application notes, published within the past 12 months, are listed in chronological order.

September 2015

AN1377: Gain and Offset Temperature Drift Compensation for the AD7403/AD7405

The AD7403/AD7405 are high performance, second-order, Σ-Δ modulators that convert an analog input signal into a high speed, single-bit data stream, with on-chip digital isolation based on Analog Devices. Inc., iCoupler® technology. This application note describes a method of using a collocated, system integrated, temperature sensor with the AD7403/AD7405 devices to calibrate out a large degree of offset and gain error drift over temperature.

AN1371: Variable Dynamic Range

Variable dynamic range (VDR) provides an efficient, non- obstructive technique to provide wideband, high resolution, and fast sample rate to digital predistortion (DPD) observation receivers. In this application, nonlinearities are measured and digitally corrected such that overall intermodulation performance is significantly better than that of the core signal chain while at the same time boosting amplifier efficiency.

AN-1367: I2C Interface Between the ADE7953 and the ADuCM360

This application note demonstrates the implementation of an I2C interface between the ADE7953 (the slave) and the ADuCM360 (the master), using C programming language. The ADE7953 is a single-phase energy metering IC, and the ADuCM360 is an ARM® Cortex®-M3-based microcontroller.

AN-1374: ADE7912/ADE7913 Front-End DSP Specifications

This application note explains several aspects of the digital filtering associated with the Σ-Δ modulators used in the ADE7912/ADE7913. The role of the filters is to decimate the outputs of the modulators to various rates, while eliminating high frequency noise. These rates start from a high of 8 kHz and go as low as 1 kHz, allowing the user to update the rates to the microcontroller processing bandwidth.

AN-1365: AD1933/AD1934/AD1938/AD1939/AD1974 Boot Up Application

The AD1933/AD1934/AD1938/AD1939/AD1974 family of codecs, ADCs, and DACs have a standalone mode of operation that allows them to be used without a microcontroller. This application note details a low cost solution for booting up these parts in any desired mode of operation. For this example, a Microchip® PIC12(L)F1571/PIC12(L)F1572 is used to boot up the AD1938 and also provides for a mute function. This part is very low cost and is available through normal distribution channels. It is offered in a variety of packages to meet the cost/size needs of most applications.

AN-1250: Interfacing an ADT7310/ADT7410 to a Cortex-M3 Based Precision Analog Microcontroller (ADuCM360)

This application note describes how to connect evaluation boards and how to easily start collecting high accuracy, digital temperature readings from the ADT7310 and ADT7410 sensors using the Cortex-M3® based precision Analog Devices Inc., microcontrollers, such as the ADuCM360.

August 2015

AN1366: Using the ADP5070/ADP5071 to Create Positive and Negative Voltage Rails when VOUT < VIN

This application note provides appropriate design formulas and considerations for designing the ADP5070/ADP5071 in one of the least understood, yet most commonly used, dc-to-dc converter topologies, the SEPIC configuration.

AN1368: Ferrite Bead Demystified< VIN

This application note discusses the important considerations that system designers need to be aware of when using ferrite beads in power supply systems, including response characteristics of the ferrite bead, a simplified ferrite bead model and simulation, dc current considerations, LC resonance effects, and damping methods.

July 2015

AN-1349: PCB Implementation Guidelines to Minimize Radiated Emissions on the ADM2582E/ADM2587E RS-485/RS-422 Transceivers

This application note examines specific layout options and component selection to achieve radiated emissions standards EN55022/CISPR22 Class A (FCC Class A) emissions standards commonly used in industrial environments, and EN55022/CISPR22 Class B (FCC Class B) standards in an unshielded environment, for the ADM2582E/ADM2587E RS-485/RS-422 transceivers.

AN-1364 Differential Filter Design for a Receive Chain in Communication Systems

This application note looks at some basic filter key specifications concepts, a few types of frequently used filter responses, a Chebyshev Type 1 filter application, and step-by-step instructions on how to transfer a single-ended filter design to a differential filter design. A differential filter design example is in this application note as well as a few points on how to optimize differential circuit PCB design.

June 2015

AN1352: Calibration Procedures for the ADA4571

The ADA4571 is an analog anisotropic magnetoresistive (AMR) angle sensor consisting of a sensing element and a conditioning analog instrumentation amplifier. This application note discusses various simple calibration procedures to reduce the angle linearity error from the device.

April 2015

AN-1340: ADF7023-J IEEE 802.15.4g/UBUSAir/FAN Firmware Module

This application note describes the IEEE 802.15.4g (15d4g) firmware download module for the ADF7023-J transceiver IC. The firmware module adds the following features: IEEE 802.15.4g physical layer header formatting and data whitening, transmitter/receiver rolling data buffer, 4‑byte to 1000-byte preamble, and ARIB STD T108 compliant clear channel assessment. The ADF7023-J low power, 902 MHz to 958 MHz transceiver contains a custom microcontroller core with mask ROM that implements packet handling functions and translates radio commands into internal control sequences. An additional 2 kB of program RAM is available and serves as program code memory, which enables the radio controller commands that provide modified or extended functionality. The IEEE 802.15.4g firmware download module described in this application note is based on program code downloaded into the program RAM.

March 2015

AN-1339: ADF7023-J AD_15d4g Firmware Download Module

This application note describes the AD_15d4g firmware download module for the ADF7023-J transceiver IC. This firmware download module adds the following features to the ADF7023-J: IEEE 802.15.4g physical layer (PHY) header formatting, IEEE 802.15.4g data whitening, Tx/Rx rolling data buffer, 1 byte to 1000 byte Tx preamble, ARIB STD T108 clear channel assessment (CCA), and Rx antenna diversity.

AN-1318: Differential Overvoltage Protection Circuits for Current Sense Amplifiers

Most current sense amplifiers are capable of handling high common-mode voltages (CMVs) but not high differential input voltages. In certain applications, there are fault conditions wherein the differential input voltage at the shunt exceeds the specified maximum voltage of the amplifier. These conditions can cause damage to the amplifier. This application note introduces two basic overvoltage protection circuits for current sense amplifiers and discusses the effects of the circuits on device performance for two types of current sense architectures—a current sense amplifier (using the AD8210 as an example) and a difference amplifier (using the AD8418 as an example).

January 2015

AN-1347: Operating the ADF4360-7 at High PFD Frequencies

The ADF4360-7 is a very flexible synthesizer (phase-locked loop (PLL) with an integrated voltage controlled oscillator (VCO)) that enables the generation of frequencies from 350 MHz to 1800 MHz. An on-chip calibration engine fine tunes the output frequency after power-on. Under most operating conditions, the calibration process works well; however, timing uncertainty errors can occur, which result in tuning errors that degrade the phase noise and/or spurious performance. This application note describes how to maintain optimum performance when operating the device at a relatively high phase frequency detector (PFD) frequency.AN-1337

AN-1343: Energy Metering on Hot Swap and Power Monitor Devices

A variety of hot swap and power monitor devices, including the ADM1075, ADM1276, ADM1278, ADM1293, and ADM1294 include energy metering functionality. Each device can measure input voltage as well as output current. The 12-bit input voltage and 12-bit output current measurement values are multiplied to give the input power value. This multiplication uses fixed point arithmetic and produces a 24-bit value. The PMBus™ Application Profile for Hot Swap Controllers specifies that users can read individual power samples or use on-chip energy metering functionality. The advantage of on-chip functionality is that the host processor does not have to poll the power monitor continuously to read power samples. Individual power samples are accumulated on chip, so the user can read from the power monitor via PMBus intermittently, freeing up the I2C bus for other transactions.

AN-1342: AD9142 to AD9142A Migration

The AD9142 and AD9142A dual 16-bit high-speed digital-to-analog converters (DACs) use low-voltage differential signaling (LVDS). The AD9142A, recommended for new designs, serves wider bandwidth applications due to its higher maximum interface speed. This application note describes the differences between the two products and provides a guide for upgrading from the AD9142 to the AD9142A.

AN-1341: Using the AD8436 True RMS to DC Converter

The AD8436 complete true rms measurement system-on-a-chip comprises three independent circuit blocks. Its rail-to-rail field effect transistor (FET) input amplifier, high dynamic range, true zero rms computing core, and precision rail-to-rail output amplifier facilitate measurement systems that operate from high-impedance voltage sources in the megohm range to deliver high-accuracy dc output voltages equivalent to the rms value of applied input voltages. This 16-page Application Note explores configuration options for the AD8436.

AN-1335: Temperature Measurements on the ADE7932/ADE7933 and ADE7978 Chipset

The ADE7932/ADE7933 and the ADE7978 form a chipset for measuring 3-phase electrical energy measurement using shunts as current sensors. The ADE7932 and ADE7933 contain a temperature sensor that is measured by the ADE7978. The temperature is used to compensate the gain variation in the current channel datapath. This application note presents the factors that influence the meter performance over temperature, and how temperature measurements are used to compensate these factors and make the meter more stable with temperature.

December 2014

AN-1338: ADM1278 Design Guide

This 4-page Application Note provides a guide to the ADM1278 Hot Swap Designer Excel-based design tool, which allows a designer to enter system specifications and then compute the undervoltage threshold, overvoltage threshold, current limit, and other settings.

AN-1322: ADuCM320 Code Execution Speed

The ADuCM320 contains an ARM® Cortex®-M3 processor with integrated flash and RAM for code and data. To increase the execution speed of the central processing unit, it also includes a cache with various modes of operation. This application note presents the modes that are of interest for user applications, without covering the specific features of the ARM Cortex-M3.

AN-1319: Compensator Design for a Battery Charge/Discharge Unit Using the AD8450 or the AD8451

Most battery formation and test systems implement the CC-CV algorithm using high-accuracy feedback loops that control the battery current and voltage. To ensure high battery quality, the feedback loops need to be stable and robust. This 20-page Application Note describes how to design and implement the compensation network for the constant current and constant voltage feedback loops in a battery test or formation system using the AD8450 or AD8451 analog front-end and controller.

November 2014

AN-1336: Adaptive Dead Time in Full Bridge Phase Shifted Topology Using ADP1055

The growing demand for compact size in the power supply industry is forcing the size of power supply units to decrease. In addition to the power level, the size of the power supply is determined by the switching frequency and efficiency. The switching frequency determines the size of the transformer and the inductor, while the efficiency determines the size of the switches and board, which can be bulky. This 6-page Application Note details the setup of the PWMs in the full-bridge phase-shifted topology and explores the adaptive dead time feature of the ADP1055 digital controller that enables zero-voltage switching at light loads.

AN-1333: Architecting a Direct, 3-Phase Energy Meter with Shunts Using the ADE7932/ADE7933/ADE7978

The ADE7932/ADE7933/ADE7978 isolated metering chipset targets polyphase energy metering applications that use shunt current sensors. This 13-page Application Note expands on the information found in the ADE7932/ADE7933/ADE7978 data sheet, providing in-depth explanations of how to use the chipset when developing a direct, 3-phase meter with shunts.

AN-1317: Rolling Data Buffer on the ADF7024

When the ADF7024 integrated transceiver receives a packet, it stores the data in a linear sequence in the packet RAM. Prior to transmission, the data to be transmitted is written to the packet RAM in a linear sequence. This functionality is described in the ADF7024 Reference Manual, UG-698. The packet RAM is 240 bytes long. If the packet length is greater than 240 bytes, additional measures are required. This 3-page Application Note describes a method for handling longer packet lengths, up to a maximum length of 65,535 bytes, via a rolling buffer.

October 2014

AN-1334: Impact of Adding a Neutral Attenuation Network in a 3P4W Wye System

A 3-phase 4-wire (3P4W) wye configuration includes three phase wires and one neutral wire. Each phase voltage is measured with respect to the neutral. The phase voltages are typically 220 V rms or 110 V rms, with each phase voltage phase-shifted 120° with respect to the others. Attenuation networks are commonly used on each of the 3-phase wires to step down the 220 V/110 V signals into signals small enough to enter the ADExxxx metering IC. The neutral wire is typically used as the ground reference. In certain cases, however, the neutral cannot be treated as the ground reference. In such situations, an attenuation network is added to the neutral, thus forming a large resistance between neutral and ground. This 11-page Application Note analyzes the performance impact of adding a neutral attenuation network in a 3P4W wye system.

AN-1332: Architecting a Direct, 3-Phase Energy Meter with Shunts Using the ADE7912/ADE7913

The ADE7912/ADE7913 3-channel, isolated, Σ-Δ analog-to-digital converters (ADCs) target polyphase energy metering applications using shunt current sensors. This 11-page Application Note provides in depth explanations on how to use the ADE7912/ADE7913 when developing a direct, 3-phase meter with shunts.

AN-1329: Noise Reduction Network for Adjustable Low Dropout Regulators

Noise is extremely important to designers of high-performance analog circuits. This is especially true for high-speed clocks, analog-to-digital converters (ADCs), digital-to-analog converters (DACs), voltage-controlled oscillators (VCOs), and phase-locked loops (PLLs). The key to reducing the output voltage noise is keeping the ac closed-loop gain close to unity without compromising the ac performance and dc closed-loop gain. This 8-page Application Note describes how to use a simple RC network to reduce the output noise of an adjustable low dropout regulator (LDO). Experimental data for several LDOs is presented to demonstrate the efficacy of this simple circuit technique. Although noise reduction (NR) is the primary focus, test data also shows the effect on power supply rejection ratio (PSRR) and transient load response.

AN-1321: Common-Mode Transients in Current Sense Applications

Current sense amplifiers are used in a variety of applications, such as motor or solenoid control, load current monitoring, and fault detection. In such applications, it is typical for the input common-mode voltage to swing from ground to a certain high-side supply. While a user may assume that the input common-mode swings are limited to this high-side supply, transient voltages must be considered. The result of these transients is that a supposed low-voltage application tends to appear as a high-voltage application, and the current sense amplifier must be robust enough to handle these occurrences. This 2-page Application Note explains how to choose a suitable amplifier.

AN-1320: ADuCM360/ADuCM361 Self Diagnostic Features

The ADuCM360/ADuCM361 32-bit, Cortex™-M3-based microcontrollers integrate 24-bit Σ-Δ analog-to-digital converters (ADC), each with a fully programmable instrumentation amplifier front-end. These microcontrollers target a wide range of applications including industrial control and instrumentation. In many of the target applications, self-diagnostic features are important in safety critical environments for smart recovery from failure modes. This 6-page Application Note describes some of the features that diagnose issues with the ADuCM360/ADuCM361 and surrounding circuitry.

AN-1315: Autonomous IR Calibration on the ADF7024

Heterodyne radios, such as the ADF7024 transceiver, use a mixer to downconvert received radio frequency (RF) signals to an intermediate frequency (IF). Interfering signals, called interferers, that lay on the image frequency are also mixed down to the wanted frequency. The interfering signals desensitize the receiver, resulting in blocking on the wanted channel. In theory, an ideal transceiver that employs an IQ receive architecture can be configured to prevent the image frequency from mixing onto the wanted channel. This assumes that the gain balance and the phase orthogonality of the mixer quadrature paths are perfectly aligned. In practice, some imbalance exists due to imperfections in the mixer. This 6-page Application Note describes the fully autonomous image rejection (IR) calibration firmware download module for the ADF7024 transceiver IC.

AN-1314: AMR Angle Sensors

This 10-page Application Note describes anisotropic magnetoresistive (AMR) thin film materials, which are becoming increasingly important for position sensing. Magnetoresistive (MR) position measurement has many advantages over traditional technologies, including reliability, accuracy, and overall robustness. Low cost, small relative size, contactless operation, wide temperature range, insensitivity to dust and light, and operation over a wide magnetic field range all lead to a robust sensor design.


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