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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.

February 2014

AN-1295: Mechanical Design Tips for ADIS16375, ADIS16480, ADIS16485, and ADIS16488

Packages for the ADIS16375, ADIS16480, ADIS16485, and ADIS16488 include four 2.4-mm mounting holes, an aluminum housing, and a 2-row, 24-pin, 1-mm pitch electrical interface connector. This 4-page Application Note provides tips for system-level installation.

AN-1292: Reed-Solomon Forward Error Correction and the ADF7023

This 7-page Application Note describes the Reed-Solomon firmware module, which contains both forward error correction and advanced encryption standard (AES) encryption, for the ADF7023 transceiver. Reed-Solomon encoding appends check symbols to the transmitted data. When received, these symbols detect the presence of errors and correct them in the received data. The firmware module is flexible, allowing the user to select values that enable correction of up to five error bytes within a packet. Encoded packets are resilient to burst and random errors; their coding gain improves link margin.

AN-1285: ADF7021-N Radio Performance for Wireless Meter-Bus (WM-Bus), Mode N

This 11-page Application Note describes the radio performance of the ADF7021-N transceiver when configured for operation according to the wireless meter-bus (WM-Bus) standard, focusing on key receiver parameters applicable to the 2.4 kbps and 4.8 kbps modes of operation. These parameters are packet error rate (PER) over power, sensitivity over carrier frequency error, blocking, and adjacent channel selectivity.

AN-1277: Utilizing the Cyclic Redundancy Check Block of the ADV7850

The ADV7850, the first complete audio/video front-end device developed by Analog Devices, targets the professional and consumer video markets. The device incorporates a frame checker block that employs cyclic redundancy checking (CRC). This 3-page Application Note outlines the background of the frame checker function and details how it is utilized.

AN-1176: Component Footprints and Symbols in the Binary .Bxl File Format

ADI provides symbols and footprints for components in binary Xlator (.bxl) files that were created using the Ultra Librarian tool offered by Accelerated Designs, Inc. A free version of this tool is available on the Accelerated Designs website. Once the .bxl file is opened, the Ultra Librarian Reader allows the footprint and symbol to be exported to one of many CAD toolsets, including Cadence® Allegro® Allegro®OrCAD®, Accel15/PCAD 2xxx/Altium6, Mentor PADS®, PowerPCB, and Zuken, Inc., CADSTAR®. These toolsets cover 97% of CAD users.

January 2014

AN-1283: Receiving the 4:2:0 Stream with the ADV7619

This 2-page Application Note outlines the usage of the ADV7619 HDMI® video receiver for the 4:2:0 HDMI stream 4k × 2k at 60 Hz. The ADV7619 can receive 4:2:0 video streams in the same way it receives 4:4:4 data in 4k × 2k modes. To enable this, set OP_FORMAT_SEL to the value of 0x54 and set all other I2C writes in the same way as for 4k × 2k 4:4:4 video mode. Because the ADV7619 works only as a bypass for 4k × 2k modes, it outputs samples as they are received without providing color space conversion (CSC). The receiver bypasses CP core and thus neither CSC nor up-conversion/down-conversion of video standard is available.

AN-1279: How to Oversample 5 MSPS, 18-Bit/16-Bit Precision SAR Converters to Increase Dynamic Range

High-performance data acquisition signal chains used for spectroscopy, magnetic resonance imaging (MRI), and gas chromatography—and vibration, oil/gas, and seismic systems demand a state-of-the-art, high dynamic range (DR) while addressing difficult thermal design, space, and cost challenges. One way to achieve a higher dynamic range is to oversample the converter to accurately monitor and measure both small and large input signals from the sensors. Other ways include using programmable-gain amplifiers or operating multiple ADCs in parallel, using digital postprocessing to average the result. These methods may be cumbersome or impractical to implement in some systems, mainly due to power, space, and cost constraints. This 4-page Application Note focuses on the oversampling of high-throughput, 5‑MSPS, 18-bit/16-bit precision successive approximation register (SAR) converters by implementing a straightforward averaging of ADC output samples to increase the dynamic range.

AN-1278: Autonomous IR Calibration on the ADF7023

Heterodyne radios, such as the ADF7023 family of transceivers, 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. This desensitizes the receiver, resulting in blocking on the wanted channel. In theory, an ideal transceiver, which employs an IQ receive architecture, can be configured to eliminate the image frequency mixing onto the wanted channel. This theory 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. The image calibration process adjusts the gain and phase of the mixer via a firmware download module, until the quadrature signals are optimally balanced, providing maximum image rejection. This 6-page Application Note describes the fully autonomous image rejection (IR) calibration firmware download module for the ADF7023 transceiver IC. With minimum user input, this firmware optimizes the image rejection with a default configuration completely autonomously.

December 2013

AN-1276: Embedded Packet Error Rate Testing on the ADF7023 and ADF7023-J

This 4-page Application Note provides information on the built-in packet error rate (PER) test mode on the ADF7023 and ADF7023-J. This mode helps the user to set up a communication link and test its quality. Up to 65,535 packets can be transmitted with a programmable delay between packets. The packet stored in packet RAM is transmitted each time. If the cyclic redundancy check (CRC) is correct, the receiver determines it has correctly received a packet.

AN-1275: Rolling Data Buffer on the ADF7023

When the ADF7023 receives a packet in packet mode, 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, as described in the ADF7023 data sheet. The ADF7023 packet RAM is 240 bytes long. If the packet length is greater than 240 bytes, additional measures are required. This 4-page Application Note describes a method for handling longer packet lengths on the ADF7023, up to a maximum length of 65,535 bytes, via a rolling buffer mechanism. This method reuses and renames several registers of the ADF7023.

AN-1264: Precision Signal Conditioning for High Resolution Industrial Applications

Industrial measurement and control systems often need to interface to sensors while operating in noisy environments. Because sensors typically generate very small electrical signals, extracting their output from the noise can be challenging. Applying signal conditioning techniques such as amplification and filtering increases the system sensitivity and simplifies signal extraction. The signal can be scaled and shifted to take full advantage of high-performance ADCs. This 7-page Application Note introduces a general-purpose precision signal conditioning front-end that can close the gap between sensors and high-resolution ADCs. The circuit is analyzed to find its noise contribution, ambient noise rejection, and ability to perform highly sensitive measurements.

AN-1254: Synchronizing Multiple AD9915 DDS-Based Synthesizers

Various applications require the generation of two or more sinusoidal or square wave signals with a known phase relationship between them. The AD9915 DDS IC is capable of providing such signals. This 6-page Application Note offers detailed instructions on how to synchronize two or more of these devices and considers possible sources of phase error.

November 2013

AN-1270: ADV7511/ADV7511W/ADV7513 Based Video Generators

This 8-page Application Note shows a basic configuration in which a field-programmable gate array (FPGA) is used as a signal source, producing sync timing and a video pattern, and the ADV7511/ADV7511W/ADV7513 are configured to output a valid High-Definition Multimedia Interface (HDMI®) or digital visual interface (DVI) stream—focusing on the most basic example to illustrate ways of generating a valid video stream.

AN-1259: Calibrating the ADE7978 and ADE7932/ADE7933 Isolated Metering Chipset

This 16-page application note explains the process of calibrating a 3-phase energy meter built around the ADE7978 and ADE7932/ADE7933 isolated metering chipset. A single 3.3-V supply powers the chipset. Three isolated ADCs sense phase currents using shunts and phase-to-neutral voltages using resistor dividers. A microcontroller manages the ADCs via I2C or SPI.

AN-1258: Image Rejection Calibration on the ADF7021, ADF7021-N, and ADF7021-V

Heterodyne radios, such as the ADF7021 family of transceivers, use a mixer to down convert received RF signals to an intermediate frequency (IF). The output of the mixer contains the wanted frequency component along with an unwanted component at the image frequency. Unwanted signals present at the image frequency can degrade receiver sensitivity, resulting in loss of signal on the wanted channel. In theory, transceivers employing an I/Q receive architecture can be configured to infinitely reject the image frequency, assuming 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. The image calibration process adjusts the gain and phase of the mixer via a digital control register until the quadrature signals are optimally balanced, providing maximum image rejection. This 11-page Application Note provides information on the mechanism that generates the image frequency and describes how image calibration can be implemented on the ADF7021, ADF7021-N, and ADF7021-V.

AN-1252: How to Configure the AD5933/AD5934

The AD5933 and AD5934 high precision impedance converter network analyzers are finite systems with some limitations. This 11-page Application Note explains the optimum measurement setup.

October 2013

AN-1268: Reference Design Using the ADF7241/ADF7242 and Skyworks SE2431L

This 11-page Application Note describes a reference design using the ADF7241/ADF7242 highly integrated, low power, high performance transceiver and the SE2431L fully integrated RF front-end. The ADF7241 and ADF7242, which operate in the global 2.4-GHz ISM band, provides flexibility, robustness, ease of use, and low current consumption. They support the IEEE 802.15.4-2006 2.4‑GHz PHY requirements. The ADF7242 also supports proprietary GFSK/FSK/GMSK/MSK modulation schemes in both packet and data streaming modes. The Skyworks SE2431L, designed for 2.4 GHz applications, provides ease of use and maximum flexibility, with fully matched 50 Ω input and output, integrated interstage matching, harmonic filter, and digital controls that are compatible with 1.6 V to 3.6 V CMOS levels.

September 2013

AN-1267: Motor Control Feedback Sample Timing Using the ADSP-CM408F ADC Controller

This 17-page Application Note introduces the main features of the ADSP-CM408F’s analog-to-digital converter controller (ADCC), focusing on current feedback systems in high performance motor control applications. It highlights key capabilities of the analog-to-digital converter (ADC) module, guides configuration for motor control applications, and provides code samples for the ADCC drivers.

AN-1266: Autonomous Shock Event Monitoring with the ADXL375

This 6-page Application Note describes a technique for autonomously detecting and capturing shock events using a low power, high-g, 3-axis digital MEMS accelerometer with minimal intervention from the host processor. The accelerometer can be programmed to monitor single or double (primary and secondary) shocks along any combination of X, Y, and/or Z axes. In addition, the entire shock profile can be captured for further analysis using an integrated 32 sample memory.

AN-1265: Isolated Motor Control Feedback Using the ADSP-CM402F/ADSP-CM403F/ADSP-CM407F/ADSP-CM408F SINC Filters and the AD7401A

This 16-page Application Note introduces the main features of the ADSP-CM40xF’s SINC filters, focusing on high performance motor control applications. It highlights the key capabilities of the SINC filter and shows usage of the SINC filter drivers. Each SINC filter is part of a complete motor current feedback subsystem that includes a current shunt, a modulator to digitize and isolate the signal, and the SINC filter to decode the bit stream and present it to the controller.

AN-1260: Crystal Design Considerations for Video Decoders, HDMI Receivers, and Transceivers

This 3-page Application Note helps designers to achieve frequency stability and accuracy for the external oscillators used with video decoders, which typically require a 28.63636-MHz crystal with 50-ppm frequency stability in fundamental mode.

AN-1256: Manual Scaling in the ADV7186

This 4-page Application Note describes the automatic and manual scaling algorithms used in the ADV7186 video decoder. Upscaling changes a low resolution video input to a higher resolution video output; downscaling changes a high resolution video input to a lower resolution video output to satisfy the back end device without the need for external memory.

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

This 6-page Application Note describes how to connect evaluation boards to collect high accuracy digital temperature readings from the ADT7310/ADT7410 sensors using Cortex-M3® based precision analog microcontrollers, such as the ADuCM360. Example code shows how the microcontroller and temperature sensor can communicate using I2C and SPI interfaces.

August 2013

AN-1253: Layout Considerations for Digital Power Management (ADP1046A)

The ADP1046A secondary side digital power controller features analog-to-digital converters, integrated I2C communication, analog comparators, and digital compensation. Layout is crucial for complex mixed signal devices with closely spaced input and output functions, so proper care must be taken to avoid hazards. This 7-page Application Note provides guidelines to avoid noise coupling and techniques for proper grounding.

July 2013

AN-1248: SPI Interface

The SPI bus interface, widely used for synchronous data transmission, allows relatively high transmission rates with versatile configurations. Although it has become a de facto standard, SPI is not officially specified. This can be an advantage, as designers can get the most from a part, but it complicates the interconnection between different parts. This 7-page Application Note explains conventions, compatibility, and other considerations.

June 2013

AN-1249: Converting 3D Images to 2D Images Using the ADV8003 Evaluation Boards

The ADV8003 video signal processor with TTL logic and serial video inputs can de-interlace and scale input video. It generates and blends a bitmap-based on-screen display and provides the blended video to one or more output. Other available outputs include two HDMI transmitters, a six-DAC encoder with SD and HD support, and a TTL output. This application note describes how to pass 3D video through the ADV8003 and convert the 3D image to a 2D image.

AN-1238: High Accuracy, Bipolar Voltage Output Digital-to-Analog Conversion Using the AD5765 DAC

This circuit provides high accuracy, bipolar data conversion using the AD5765 quad 16‑bit, serial input, bipolar voltage output, digital-to-analog converter (DAC). This circuit uses the ADR420 precision reference to achieve optimal DAC performance over a full operating temperature range. The only external components needed for this precision DAC are a reference voltage, decoupling capacitors on the supply pins and reference inputs, and an optional short-circuit current-setting resistor. This implementation, therefore, leads to savings in cost and reduced board space. The circuit is well suited for both closed-loop servo control and open-loop control applications.

AN-1230: 8 to 16 Channels of Programmable Voltage with Excellent Temperature Drift Performance Using the AD5390/AD5391/AD5392 DACs

This multichannel DAC configuration has excellent temperature drift. It uses the AD5390/AD5391/AD5392 to provide 8 to 16 DAC channels with 12-bit to 14-bit resolution. The ADR421/ADR431 precision voltage reference ensures that the temperature stability of the circuit is typically less than 3 ppm/°C.

AN-1213: Powering the AD9788 800 MSPS TxDAC Digital-to-Analog Converter Using the ADP2105 Synchronous Step-Down DC-to-DC Regulator for Increased Efficiency

This 3-page Application Note describes a circuit that uses a pair of ADP2105 synchronous step-down dc-to-dc regulators to provide the individual power supply rails required for the AD9788 dual channel, 16-bit, high dynamic range TxDAC® digital-to-analog converter at greater than 85% efficiency.

AN-1211: Powering the AD9268 Dual Channel 16-Bit, 125 MSPS Analog-to-Digital Converter with the ADP2114 Synchronous Step-Down DC-to-DC Regulator for Increased Efficiency

This 3-page Application Note describes a circuit that uses the ADP2114 dual channel synchronous step-down dc-to-dc regulator to provide the individual power supply rails required for the AD9268 dual 16-bit, 125 MSPS, 1.8 V ADC at 85% efficiency.

AN-1210: Powering the AD9272 Octal Ultrasound ADC/LNA/VGA/AAF with the ADP5020 Switching Regulator PMU for Increased Efficiency

This 4-page Application Note describes a circuit that uses the ADP5020 power management unit to provide the individual power supply rails required for the AD9272 octal LNA/VGA/AAF/ADC and crosspoint switch.

AN-1197: Software Configurable 14-Bit Dual-Channel Unipolar/Bipolar Voltage Output Using the AD5732R DAC

This circuit provides unipolar and bipolar data conversion using the AD5732R dual, 14-bit, serial input, unipolar/bipolar voltage-output DAC. The only other components needed are decoupling capacitors, leading to savings in cost and board space. This circuit is well suited for closed-loop servo control applications.

May 2013

AN-1247: Software Configurable 14-Bit Quad Channel Unipolar/Bipolar Voltage Output Using the AD5734 DAC

This circuit provides unipolar and bipolar data conversion using the AD5734BREZ quad 14-bit, serial input, unipolar/bipolar voltage output DAC and the REF192ESZ precision 2.5 V voltage reference. The only additional external components needed are decoupling capacitors on the supply pins and reference input, leading to savings in cost and board space. This circuit is well suited for closed-loop servo control applications.

AN-1237: Precise Control of I/Q Modulator Output Power Using the ADL5386 Quadrature Modulator and the AD5621 12-Bit DAC

This circuit provides upconversion of I/Q modulated data and automatic power control of the RF/IF carrier level. The output power is set by a 12-bit digital-to-analog converter (DAC) and can be precisely set over a linear-in-dB range of up to 30 dB. Stability over temperature is typically ±0.2 dB from −40°C to +85°C. The circuit operates from 50 MHz to 2.2 GHz.

AN-1236: Interfacing the ADL5382 Quadrature I/Q Demodulator to the AD9262 16-Bit Continuous Time Sigma-Delta ADC as an RF-to-Bits Solution

This circuit combines the ADL5382 and AD9262 to provide an RF-to-bits solution with optimized performance, low cost, and minimal board space. This two-chip combination uses a single frequency translation step to convert the RF channel directly to the baseband without intermediate frequency translations. The frequency translation is accomplished by the ADL5382 broadband quadrature I/Q demodulator, which covers the RF input frequency range from 700 MHz to 2.7 GHz. The ADL5382 is followed by the AD9262 16-bit dual continuous time sigma-delta (Σ-Δ) analog-to-digital converter.

AN-1235: AC Signal Processing Using the AD5450/AD5451/AD5452/AD5453 Current Output DACs

This circuit provides two-quadrant signal multiplication using an AD5450, AD5451, AD5452, or AD5453 current output digital-to-analog converter (DAC) and an AD8038 operational amplifier. It provides a multiplying bandwidth of up to 12 MHz, allowing the user to accurately condition ac signals with bandwidths up to this frequency. The circuit is well suited for ac signal conditioning applications in the communications, industrial, and medical market segments.

AN-1233: Using the AD8599 Op Amp as an Ultralow Distortion Driver for the AD7999 4-Channel, 8-Bit ADC

This circuit provides an ultralow distortion driver circuit for the AD7999 8-bit, 4-channel ADC that is designed to achieve optimum ac and dc performance. It uses the ultralow distortion, ultralow noise AD8599 dual-supply op amp and ultrahigh precision AD780 band gap voltage reference to ensure that the maximum AD7999 performance is achieved by providing a low impedance driver with adequate settling time and a highly accurate reference voltage.

AN-1232: Using the AD8599 Op Amp as an Ultralow Distortion Driver for the AD7991 4-Channel, 12-Bit ADC

This circuit provides an ultralow distortion driver circuit for the AD7991 12-bit, 4-channel, analog-to-digital converter (ADC) that is designed to achieve optimum ac and dc performance. It uses the ultralow distortion, ultralow noise AD8599 dual-supply op amp and ultrahigh precision AD780 band gap voltage reference to ensure that the maximum AD7991 performance is achieved by providing a low impedance driver with adequate settling time and a highly accurate reference voltage.

AN-1231: AC Signal Processing Using the AD5426/AD5432/AD5443 Current Output DACs

This circuit provides two-quadrant signal multiplication using the AD5426/AD5432/AD5443 current output digital-to-analog converters (DACs) and an operational amplifier. It provides multiplying bandwidth up to 10 MHz, allowing accurate conditioning of ac signals with bandwidths up to this frequency. The circuit is well suited for ac signal conditioning in communications, industrial, and medical applications.

AN-1229: AD5383 Channel Monitor Function

In a multichannel digital-to-analog converter (DAC) system, the ability to monitor all outputs at a single point is a significant advantage for troubleshooting and diagnostic analysis. This circuit provides multichannel DAC output channel monitoring using a single-channel successive-approximation analog-to-digital converter (ADC). The combination of the AD5383 and the AD7476 provides a complete 32-channel analog output control solution with a space-efficient monitor function for system debug, fault, and diagnostic analysis.

AN-1228: 32 Channels of Programmable Voltage with Excellent Temperature Drift Performance Using the AD5383 DAC

This multichannel DAC configuration has excellent temperature drift. It provides 32 individual output voltage channels with 12-bit resolution and less than 3-ppm/°C typical temperature stability.

AN-1227: AD5381 Channel Monitor Function

In a multichannel digital-to-analog converter (DAC) system, the ability to monitor all outputs at a single point is a significant advantage for troubleshooting and diagnostic analysis. This circuit provides multichannel DAC output channel monitoring using a single-channel successive-aproximation analog-to-digital converter (ADC).

AN-1226: AD5382 Channel Monitor Function

In a multichannel digital-to-analog converter (DAC) system, the ability to monitor all outputs at a single point is a significant advantage for troubleshooting and diagnostic analysis. This circuit provides multichannel DAC output channel monitoring using a single-channel successive-approximation analog-to-digital converter (ADC). The combination of the AD5382 and the AD7476 provides a complete 32-channel analog output control solution with a space-efficient monitor function for system debug, fault, and diagnostic analysis.

AN-1225: 32 Channels of Programmable Voltage with Excellent Temperature Drift Performance Using the AD5382 DAC

This multichannel DAC configuration has excellent temperature drift. It provides 40 individual output voltage channels with 14-bit resolution and less than 3-ppm/°C typical temperature stability.

AN-1224: 40 Channels of Programmable Voltage with Excellent Temperature Drift Performance Using the AD5381 DAC

This multichannel DAC configuration has excellent temperature drift. It provides 40 individual output voltage channels with 12-bit resolution and less than 3-ppm/°C typical temperature stability.

AN-1223: Output Channel Monitoring Using the AD5380 Multichannel DAC

In a multichannel digital-to-analog converter (DAC) system, the ability to monitor all outputs at a single point is a significant advantage for troubleshooting and diagnostic analysis. This circuit provides multichannel DAC output channel monitoring using a single-channel successive-approximation analog-to-digital converter (ADC).

AN-1220: Compact, Low Cost, 5 V, Variable Gain, Inverting Amplifier Using the AD5270/AD5272 Digital Rheostat and AD8615 Op Amp

This circuit provides a compact, low-cost, low-voltage, inverting variable-gain amplifier using the AD5270/AD5272 digital rheostat in conjunction with the AD8615 operational amplifier. The small size and low cost of the AD5270/AD5272 and AD8615 present an industry leading solution to a common analog signal processing circuit. The circuit offers 1024 different gains, controllable through an SPI (AD5270) or I2C-compatible (AD5272) serial digital interface. The ±1% resistor tolerance of the AD5270/AD5272 provides low gain error over the full resistor range. The circuit supports rail-to-rail inputs and outputs for both single-supply operation at +5 V and dual-supply operation at ±2.5 V and is capable of delivering up to ±150 mA output current. In addition, the AD5270 and AD5272 have an internal 50-times programmable memory that allows a customized gain setting at power-up. Well suited for signal conditioning, the circuit provides high accuracy, low noise, and low THD.

AN-1201: Software Configurable 12-Bit Dual-Channel Unipolar/Bipolar Voltage Output Using the AD5722 DAC

This circuit provides unipolar and bipolar data conversion using the AD5732BREZ dual, 14-bit, serial input, unipolar/bipolar voltage-output DAC and the REF192ESZ precision 2.5-V reference. The only other components needed are decoupling capacitors, leading to savings in cost and board space. This circuit is well suited for closed-loop servo control applications.

April 2013

AN-1246: Software Configurable 16-Bit Quad Channel Unipolar/Bipolar Voltage Output Using the AD5754 DAC

This circuit provides unipolar and bipolar data conversion using the AD5754BREZ quad 16-bit, serial input, unipolar/bipolar voltage output DAC and the REF192ESZ precision 2.5 V voltage reference. The only additional external components needed are decoupling capacitors on the supply pins and reference input, leading to savings in cost and board space. This circuit is well suited for closed-loop servo control applications.

AN-1245: Software Configurable 12-Bit Quad Channel Unipolar/Bipolar Voltage Output Using the AD5724R DAC

This circuit provides unipolar and bipolar digital-to-analog conversion using the AD5724R quad 12-bit, serial input, unipolar/bipolar voltage output DAC. The only external components needed are decoupling capacitors on the supply pins and reference input, leading to savings in cost and board space. This circuit is well suited for closed-loop servo control applications.

AN-1244: Software Configurable 14-Bit Quad-Channel Unipolar/Bipolar Voltage Output Using the AD5734R DAC

This circuit provides unipolar and bipolar digital-to-analog conversion using the AD5734R quad 14-bit, serial input, unipolar/bipolar voltage output DAC. The only external components needed are decoupling capacitors on the supply pins and reference input, leading to savings in cost and board space. This circuit is well suited for closed-loop servo control applications.

AN-1243: Software Configurable 16-Bit Quad-Channel Unipolar/Bipolar Voltage Output Using the AD5754R DAC

This circuit provides unipolar and bipolar digital-to-analog conversion using the AD5754R quad 16-bit, serial input, unipolar/bipolar voltage output DAC. The only external components needed are decoupling capacitors on the supply pins and reference input, leading to savings in cost and board space. This circuit is well suited for closed-loop servo control applications.

AN-1242: Simplified 12-Bit, 4 mA-to-20 mA Output Solution Using the AD5410 Current Source DAC

This circuit provides a 4 mA-to-20 mA output using the AD5410 single channel, 12-bit, serial input, 4 mA-to-20 mA current source DAC. The only external components needed are decoupling capacitors on the supply pins and reference input and a pull-up resistor for the open-drain FAULT output, which alerts to a loss of compliance voltage on the output or an overtemperature condition. This implementation offers a level of integration that leads to savings in both cost and board space, making it well suited for both programmable logic controllers and distributed control systems in industrial control applications.

AN-1241: Simplified 16-Bit Voltage Output and 4 mA-to-20 mA Output Solution Using the AD5422

This circuit provides unipolar/bipolar voltage and 4 mA-to-20 mA outputs using the AD5422 single channel, 16-bit, serial input, unipolar/bipolar voltage and 4 mA-to-20 mA current source DAC. The only external components needed are decoupling capacitors on the supply pins and reference input and a pull-up resistor for the open-drain FAULT output, which alerts to a loss of compliance voltage on the current output or an overtemperature condition. This solution offers a level of integration that leads to savings in both cost and board space, making it well suited for programmable logic controllers and distributed control systems in industrial control applications.

AN-1240: Low Cost Video Multiplexer for Video Switching Using the ADA4853-2 Op Amp with Disable Function

This circuit provides a low cost, low power video multiplexer using the ADA4853-2 dual high speed amplifier, allowing a fourth video input to an ADV7180 3-channel video decoder, saving cost and board space.

AN-1239: High Accuracy, Bipolar Voltage Output Digital-to-Analog Conversion

This circuit provides high accuracy, bipolar data conversion using the AD5763 dual 16‑bit, serial input, bipolar voltage output DAC. The circuit uses an ADR420 precision reference to achieve optimal DAC performance over the full operating temperature range. The only external components needed for this precision 16-bit DAC are a reference voltage source, decoupling capacitors on the supply pins and reference inputs, and an optional short-circuit current setting resistor. This implementation, therefore, leads to savings in cost and reduced board space. This circuit is well suited for both closed-loop servo control and open-loop control applications.

AN-1234: Interfacing the ADL5534 Dual IF Gain Block to the AD9640 High Speed ADC

This circuit uses the ADL5534 IF amplifier to provide a dual IF gain block for the AD9640 14-bit, 150 MSPS dual ADC. The ADL5534 high linearity, dual amplifier with fixed 20 dB gain can be adapted for use as a driver for a high performance IF sampling ADC. The ADL5534 provides a simple approach to interfacing the RFIN signal level of 200 mV p-p to the 2 V p-p full scale of the high speed ADC. The low noise (2.5 dB NF at 70 MHz) and low distortion (IP3 of 40 dBm at 70 MHz) of the ADL5534 ensure that the ADC performance is not compromised.

AN-1222: 40 Channels of Programmable Voltage with Excellent Temperature Drift Performance Using the AD5380 DAC

This multichannel DAC configuration has excellent temperature drift. It provides 40 individual output voltage channels with 14-bit resolution and less than 3‑ppm/°C typical temperature stability.

AN-1221: Very Low Jitter Encode (Sampling) Clocks for High Speed Analog-to-Digital Converters Using the ADF4002 PLL

This circuit uses the ADF4002 frequency synthesizer to generate a very low jitter encode clock to control sampling on the AD9215 analog-to-digital converter. Jitter on the encode clock degrades the overall signal-to-noise ratio (SNR). SNR = 20 log(1/2πftj), where f is the full-scale analog input frequency and tj is the rms jitter. This SNR is solely due to clock jitter and does not depend on the resolution of the ADC.

AN-1219: Power-Off Protected Data Acquisition Signal Chain Using Fault-Protected CMOS Switches

Signals that come from remote sources cause an increased likelihood of damaging faults, such as overvoltage conditions, which may occur in systems with poorly designed power supply sequencing or where hot-plug insertion is used. Transient voltages due to poor connections or inductive coupling may damage components if not protected. Faults can also occur due to power supply failures or in cases where there is a loss of the power connection while switch inputs remain connected to analog signals. Significant damage may result from these fault conditions, which can mean expensive repairs. This circuit provides protection to a data-acquisition signal chain using a low on-resistance ADG4612 quad SPST with power-off protection. The data-acquisition system is composed of the ADA4000-1 low-cost, precision JFET input op amp followed by an AD7476 low power, 12-bit, 1-MSPS SAR ADC. The ADG4612 provides low-cost protection against loss of power while input signals are still present, as well as overvoltage fault protection up to 16 V. The extra board area required for the ADG4612 is minimal. The ADG4612 provides protection for four separate data acquisition channels without requiring any additional discrete components.

AN-1218: Compact, Low Cost, 5 V, Variable Gain, Noninverting Amplifier Using the AD5270/AD5272 Digital Rheostat and AD8615 Op Amp

This circuit provides a compact, low-cost, low-voltage, noninverting variable-gain amplifier using the AD5270/AD5272 digital rheostat in conjunction with the AD8615 operational amplifier. The small size and low cost of the AD5270/AD5272 and AD8615 present an industry leading solution to a common analog signal processing circuit. The circuit offers 1024 different gains, controllable through an SPI (AD5270) or I2C-compatible (AD5272) serial digital interface. The ±1% resistor tolerance of the AD5270/AD5272 provides low gain error over the full resistor range. The circuit supports rail-to-rail inputs and outputs for both single-supply operation at +5 V and dual-supply operation at ±2.5 V and is capable of delivering up to ±150 mA output current. In addition, the AD5270 and AD5272 have an internal 50-times programmable memory that allows a customized gain setting at power-up. Well suited for signal conditioning, the circuit provides high accuracy, low noise, and low THD.

AN-1217: Clock Distribution Circuit with Pin-Programmable Output Frequency, Output Logic Levels, and Fanout

This circuit combines the AD9552 oscillator frequency upconverter and ADCLK854 LVDS/CMOS clock fanout buffer to create a flexible pin-programmable clock distribution solution. The AD9552 is equipped with an SPI port to program the device. The 900-MHz output frequency range is pin-programmable, with up to 64 standard output frequencies, allowing the AD9552 to function as a frequency programmable VCXO. The AD9552 is also equipped to use a crystal resonator at the input for additional flexibility.

AN-1215: 40 Channels of Programmable Industrial Level Output Span Using the AD5370 16-Bit Voltage Output DAC

This multichannel DAC provides independent output spans on groups of channels. It utilizes the AD5370 to provide 40 DAC channels with 16-bit resolution. The AD5370 is configured to have eight channels with an output span of ±10 V and 24 channels with an output span of −4 V to +8 V.

AN-1214: High CMRR Circuit for Converting Wideband Complementary DAC Output to Single-Ended Without Precision Resistors

Traditional methods for converting wideband DAC complementary current outputs to a single-ended signal are to either use a center-tapped transformer or a single op amp in a differential-to-single-ended configuration. However, the transformer low frequency nonlinearities may limit its use near dc; and the operational amplifier approach requires closely matched resistors to provide dc common-mode rejection, load impedance, and gain matching between the complementary DAC outputs. Errors in the matching will produce errors at the final output. This circuit uses the AD8130 differential receiver amplifier to generate a simple differential-to-single-ended translation without the use of expensive precision resistors, thereby providing higher accuracy with fewer components. An added benefit of the AD8130 is its industry-leading ac common-mode rejection (70 dB at 10 MHz). This feature can be used to reject noise between the DAC digital ground plane and the receiver analog ground plane—a common problem in this type of mixed-signal application.

AN-1212: Single Supply Low Noise LED Current Source Driver Using a Current Output DAC in the Reverse Mode

This circuit provides a low-noise, single-supply current drive for an LED. Each component is selected to operate from a single 3.0-V supply while maintaining very low peak-to-peak noise. The signal chain is optimized for low-power, low-noise optical communications and medical applications. In a typical pulse oximetry application, an LED is pulsed from a high level of current (e.g., 3/4 scale) to a lower level of current (e.g., 1/4 scale). The on time of these pulses is typically on the order of several hundred microseconds. Peak-to-peak 1/f noise superimposed on the LED brightness levels during the on time affects the accuracy of the overall measurement. The R-2R core of a current-output DAC has inherently low 0.1 Hz to 10 Hz noise because only the resistive noise of the ladder causes the noise. The AD5452 current-output DAC is used in the reverse mode so it can support single-supply applications. By applying 1.25 V to the IOUT pin, a full-scale code will result in 1.25 V − 1 LSB appearing on the VREF pin, while a zero-scale code will result in 0 V on the VREF pin. Key to maintaining low noise in the signal chain is the ADR127 reference, which has 9 μV p-p noise from 0.1 Hz to 10 Hz. In addition, with 1.23 μV p-p noise, the AD8655 is the industry's lowest noise precision CMOS amplifier. The combined circuit has a typical 0.1 Hz to 10 Hz noise of only 14.7 μV p-p.

AN-1209: Logarithmic Audio Volume Control with Glitch Reduction Using the AD5292 Digital Potentiometer

This circuit provides a logarithmic audio volume control with glitch reduction using the AD5292 digital potentiometer in conjunction with the dual AD8676 and single AD8541 op amps, ADCMP371 comparator, and 7408 AND gates. This circuit provides low total harmonic distortion (THD), 46-dB maximum signal attenuation, and a shutdown function that attenuates up to 130 dB. The AD5292 can be placed in shutdown mode by executing a software shutdown command. This feature places the RDAC in a special state in which terminal A is open-circuited and wiper W is connected to terminal B. This circuit offers a logarithmic gain control function over a ±14 V (10 V rms) output voltage range and is capable of delivering up to ±20 mA output current. The AD5292 is programmable over an SPI-compatible serial interface. In addition, the AD5292 has an internal 20-times programmable memory that allows a customized volume setting at power-up. Well suited for many audio applications, this circuit provides low noise, low THD, high signal attenuation, low drift, and high voltage capability.

AN-1208: Programmable Bidirectional Current Source Using the AD5292 Digital Potentiometer and the ADA4091-4 Op Amp

This circuit provides a programmable bidirectional Howland current source using the AD5292 digital potentiometer in conjunction with the quad ADA4091-4 op amp and the ADR512 voltage reference. This circuit offers 10-bit resolution over a ±18.4-mA output current range. The AD5292 is programmable over an SPI-compatible serial interface. The ±1% resistor tolerance of the AD5292 allows it to be placed in series with external divider resistors to reduce the maximum output current without the need to match the resistors in the circuit. Reducing the IOUT range serves to increase the sensitivity of the output current. The AD5292 has an internal 20-times programmable memory that allows a customized IOUT at power-up. Well suited for digital calibration applications, the circuit provides an accurate, low-noise, low-drift output voltage.

AN-1207: Programmable High Voltage Source with Boosted Output Current Using the AD5292 Digital Potentiometer, OP184 Op Amp, and MOSFETs

This circuit provides a low-cost, programmable, high-voltage source with boosted output current using the AD5292 digital potentiometer in conjunction with the OP184 operational amplifier. The BSS138 PMOS transistor and Si2307CDS NMOS transistor provide current drive capability up to 2.5 A. The circuit offers 1024 different voltage settings, controllable through an SPI-compatible digital interface. This circuit offers 10-bit resolution over a 0-V to 30-V output voltage range and is capable of delivering up to 2.5 A output current. The ±1% resistor tolerance of the AD5292, in conjunction with an external resistor, increases the accuracy of the circuit by providing 10-bit resolution over a reduced output voltage range. This, in effect, creates a vernier DAC, which offers higher resolution over the reduced range. In addition, the AD5292 has an internal 20-times programmable memory that allows a customized VOUT at power-up. Well suited for power applications, the circuit provides an accurate, low-noise, low-drift output voltage and high current capability.

AN-1206: Variable Gain Inverting Amplifier Using the AD5292 Digital Potentiometer and the OP184 Op Amp

This circuit provides a low-cost, high-voltage, variable-gain inverting amplifier using the AD5292 digital potentiometer in conjunction with the OP184 operational amplifier. The circuit offers 1024 different gains, controllable through an SPI-compatible serial digital interface. The ±1% resistor tolerance performance of the AD5292 provides low gain error over the full resistor range. The circuit supports rail-to-rail inputs and output for 30-V single-supply operation and ±15-V dual supply operation; and is capable of delivering up to ±6.5 mA output current. In addition, the AD5292 has an internal 20-times programmable memory that allows a customized gain setting at power-up. Well suited for signal conditioning applications, the circuit provides high accuracy, low noise, and low THD.

AN-1205: 30 V Low Cost DAC Using the AD5292 Digital Potentiometer

This circuit provides a low-cost, high-voltage unipolar DAC using the AD5292 digital potentiometer in conjunction with the dual ADA4091-2 op amp and ADR512 voltage reference. The circuit offers 10-bit resolution over a 0-V to 30-V output voltage range and can deliver up to ±20 mA output current. The AD5292 is programmable over an SPI-compatible serial interface. The ±1% resistor tolerance of the AD5292 allows it to be placed in series with an external resistive divider to create a vernier DAC with 10-bit resolution over a reduced VOUT range, increasing the sensitivity of the DAC. In addition, the AD5292 has an internal 20-times programmable memory that allows a customized VOUT at power-up. Well suited for digital calibration applications, the circuit provides an accurate, low-noise, low-drift output voltage.

AN-1204: Using the ADL5562 Differential Amplifier to Drive Wide Bandwidth ADCs

This circuit provides high-frequency sampling using the ADL5562 high-performance, low-noise, ultralow-distortion, high-linearity differential amplifier with pin-programmable gain, plus a high-speed ADC. Optimized for driving high-frequency IF-sampling ADCs, such as the AD9445, AD9246, or AD6655, the ADL5562 provides exceptional SFDR beyond 100 MSPS at its maximum gain.

AN-1203: Simplified 16-Bit, 4 mA-to-20 mA Output Solution Using the AD5420

This circuit provides 4-mA to 20-mA outputs using the AD5420 single-channel, 16-bit, serial input, current source DAC. The only other components needed are decoupling capacitors and a pull-up resistor, leading to savings in cost and board space. This circuit is well suited for programmable logic controllers and distributed control systems in industrial control applications.

AN-1202: Simplified 12-Bit Voltage and 4 mA-to-20 mA Output Solution Using the AD5412

This circuit provides unipolar/bipolar voltage and 4-mA to 20-mA outputs using the AD5412 single-channel, 12-bit, serial input, unipolar/bipolar voltage and current source DAC. The only other components needed are decoupling capacitors and a pull-up resistor, leading to savings in cost and board space. This circuit is well suited for programmable logic controllers and distributed control systems in industrial control applications.

AN-1200: Software Configurable, 14-Bit Dual-Channel, Unipolar/Bipolar Voltage Output Using the AD5732 DAC

This circuit provides unipolar and bipolar data conversion using the AD5732BREZ dual, 14-bit, serial input, unipolar/bipolar voltage-output DAC and the REF192ESZ precision 2.5-V reference. The only other components needed are decoupling capacitors, leading to savings in cost and board space. This circuit is well suited for closed-loop servo control applications.

AN-1199: Software Configurable, 16-Bit Dual-Channel, Unipolar/Bipolar Voltage Output Using the AD5752 DAC

This 2-page Application Note offers a circuit that provides unipolar and bipolar data conversion using the AD5752BREZ dual, 16-bit, serial input, unipolar/bipolar voltage-output DAC and the REF192ESZ precision 2.5-V reference. The only other components needed are decoupling capacitors, leading to savings in cost and board space. This circuit is well suited for closed-loop servo control applications.

AN-1198: Software Configurable, 12-Bit Dual-Channel, Unipolar/Bipolar Voltage Output Using the AD5722R DAC

This 2-page Application Note offers a circuit that provides unipolar and bipolar data conversion using the AD5722R dual, 12-bit, serial input, unipolar/bipolar voltage-output DAC. The only other components needed are decoupling capacitors, leading to savings in cost and board space. This circuit is well suited for closed-loop servo control applications.

AN-1196: Software Configurable 16-Bit Dual-Channel Unipolar/Bipolar Voltage Output Using the AD5752R DAC

This 2-page Application Note offers a circuit that provides unipolar and bipolar data conversion using the AD5752R dual, 16-bit, serial input, unipolar/bipolar voltage-output DAC. The only other components needed are decoupling capacitors, leading to savings in cost and board space. This circuit is well suited for closed-loop servo control applications.

AN-1195: Software Configurable 12-Bit Quad-Channel Unipolar/Bipolar Voltage Output Using the AD5724 DAC

This 2-page Application Note offers a circuit that provides unipolar and bipolar data conversion using the AD5724BREZ dual, 12-bit, serial input, unipolar/bipolar voltage-output DAC and the REF192ESZ precision 2.5-V reference. The only other components needed are decoupling capacitors, leading to savings in cost and board space. This circuit is well suited for closed-loop servo control applications.

AN-1181: Using a MEMS Microphone in a 2-Wire Microphone Circuit

MEMS microphones are being used to replace electret condenser microphones (ECMs) in audio circuits. These two types of microphones perform the same function, but the connection between the microphone and the rest of the system is different for ECMs and MEMS microphones. This 2-page Application Note explains those differences and provides design details for a simple MEMS microphone based replacement circuit.

March 2013

AN-1187: Radiated Immunity Performance of the AD7780 in Weigh Scale Applications

The AD7780 low-noise, low-power, 24-bit sigma-delta analog-to-digital converter with integrated PGA is used in low- to mid-end weigh scale systems. The radiated immunity of the system is tested as part of the release process. This 12-page Application Note describes how to achieve the best radiated immunity performance from the AD7780, taking into account the effects of layout and component placement when designing a printed circuit board (PCB). The radiated immunity testing is performed on the complete system (ADC, PCB, and load cell) as per standard IEC 61000-4-3.

AN-1182: Understanding and Optimizing the AFC Loop on the ADF7021 for Minimum Preamble

Remote transceivers within radio communication networks use their own independent clock sources, and are thus susceptible to frequency errors. When a transmitter initiates a communication link, the associated receiver must correct these errors during the preamble phase of the data packet to ensure correct demodulation. An effective design block that performs this correction is an automatic frequency control (AFC) loop. This 7‑page Application Note provides information on how AFC is implemented and optimized on the ADF7021, ADF7021-N, and ADF7021-V.

AN-1180: Optimizing Video Platforms for Automated Post-Production Self-Tests

This 10-page Application Note describes techniques to use for post-production testing and debugging of video platforms using advanced video (ADV) series devices. Advanced video systems are becoming more complex and the video chains contain more and more links. Employing built-in self-tests on video evaluation systems allows a significant increase in productivity by automated tests. The ADV parts include features that allow finding a short, an open, or a problem in video processing, audio processing, or data/control circuitry. Many of ADV parts contain internal pattern generators, synchronization detection circuitry (for video), and built-in external memory tests that can be used to test a platform and facilitate the process of debugging a potentially faulty platform. To test the system, the final video processing circuitry must contain a microprocessor that includes a connection to tested video parts and a postproduction program that can be enabled and run at least once after production.

 

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