[Design View / Design Solution] Reap The Benefits Of Integrated Power-Limiting Controller ICs
Many cost and engineering improvements are realized by integrating the current pass element and currentsense function into a hot-plug controller integrated circuit (IC). Controlling the passelement power is the safest and fastest way to charge the load capacitance. Pass-element protection is maintained while boosting efficiency and reliability. A circuit controlling current to a load usually consists of three components—an IC...
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Bob Kando
[Ideas For Design] Use Hybrid PMOS-NMOS Active Loads To Cut Substrate Noise In Differential Amplifiers
BY MAKING A RELATIVELY simple change in a differential amplifier stage, designers can significantly reduce the sensitivity to digital switching noise. In mixed-signal ICs, digital switching noise couples through the common substrate into analog circuits, degrading their performance. In CMOS circuits, most substrate noise couples into NMOS transistors through backgate modulation. That is, the substrate acts as a second gate with a transconductance gain...
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Cosmin Iorga
[Ideas For Design] Create A Mixed-Mode Precision Rectifier With Second-Generation Current Conveyors
RECTIFIERS PERFORM AN IMPORTANT signal-processing function in many analog circuits. But conventional half-wave, full-wave, or bridge rectifiers employing diodes can’t be used with low-amplitude signals. The circuit described below is a mixed-mode precision rectifier that can handle both low-amplitude voltage and current signals. Many previously described precision rectifiers use voltage op amps, but conventional voltage op amps suffer from a...
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Abhirup Lahiri
[Ideas For Design] High Power-Factor LED Driver Converts AC Input To Power Halogen Replacement
HIGH-BRIGHTNESS LEDS ARE AN inexpensive, robust, and green replacement for halogen light bulbs. LEDs offer a much longer lifetime and eliminate the safety hazards of the inert gas, the expense of the UV filter encasement, and the handling sensitivity of halogens. Since halogen bulbs typically are driven with 12 or 24 V due to their excellent efficacy at those voltages, buildings have been wired with 12- and 24-V ac transformers for halogen...
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Keith Szolusha
[Ideas For Design] Interface Circuit Allows Users To Control DC Motor's Speed
THE CIRCUIT IN THE figure provides three levels of speed control for a dc motor, using a PC’s parallel port (LPT1). A C++ program performs the control functions by allowing the signals from the PC port to deliver three different voltages to the motor. The system is an interface circuit that connects the motor to the PC using a 4-bit binary counter (a 74LS193), three current- limiting...
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Firas M. Ali Al-Raie
[Ideas For Design] Control Current And Voltage Precisely For Regulators, Oscillators, And Amps
THE CURRENT REGULATOR IN Figure 1 boasts a very high current stability of around 1.7% within a temperature range that spans -40°C to 125°C. It can be used in precise current and voltage regulators, oscillators, and amplifiers. For its operation, the device utilizes a unique composition of thermal coefficients of bipolar transistors and Schottky diodes, which efficiently compensate for each ...
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Gregory Mirsky
[Ideas For Design] Backstory: Implement A Spark-Gap-Based Design For Low-Cost Energy Harvesting
The idea of using a spark-gap (SG) as the active element of a converter did not come as a sudden illumination. For a long time, I had been looking for an “acceptable” way of using high-voltage, low-current power-supply sources. For me, “acceptable” simply meant technically feasible without exotic technology and sufficiently efficient to be usable. As it was a selfimposed challenge, I had no definite specifications or deadline. When I had first reviewed the...
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Louis Vlemincq
[Ideas For Design] Backstory: Full-Wave Active Rectifier Requires No Diodes
When Electronic Design asked me to write about my Idea for Design, first seen in this year’s August 13 issue, it seemed a simple enough task. We’re all familiar with design. Most of us do it in some form or another almost every day. But, ideas? We all have them, but where do they come from? And what is the essence of a good idea? Simplicity? Elegance? Performance, novelty, creativity? Thomas Edison once said that genius is 1% inspiration and 99% perspiration....
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Anthony H. Smith
[Ideas For Design] Two Wires Carry Power And Data
At times, designers face a limited amount of wire and/or a limited cost to communicate with a remote device such as a sensor. Many devices allow communication over an ac or dc power line employing an AM or FM modulation scheme. However, they tend to be costly. This design is a simple, low-cost method for sending data across the same wire used to supply power. It’s based on modulating current from a remote device back to a host. A later example...
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Robert M. Hanrahan
[Ideas For Design] Two Wires Carry Power And Data: Backstory
This application is as useful today as it was when I described it in the Oct. 1, 1996 issue. The deployment of sensors has increased significantly, resulting in an increased demand for efficient interconnect techniques between sensors and a host system. The use of only two wires often is attractive from both a cost and reliability standpoint. Sensing applications are no different than others—power and size are being driven smaller while faster operation is desirable...
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Robert M. Hanrahan
[Editorial] Engineering Students Take Home A Prize For Their Design Idea
WELCOME TO THE SECOND annual Ideas for Design issue, celebrating one of our most popular departments. This issue includes additional IFDs, written by readers like you, and feature stories by staff and industry contributors alike. All of these authors got their start as engineering students, learning how to put together their first designs. Today, students still have to complete senior projects as part of their initiation into the real world of...
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Joseph Desposito
[Pease Porridge] What's All This Noise-Rejection Stuff, Anyhow?
IT’S WELL KNOWN THAT audio power amplifiers like to get a good set of grounds, or noise around the inputs may not be rejected properly, causing hum and buzz. So when a guy called me asking how to clean up his interface from his clean audio signals to his LM3886 power amplifier, whose ground system was pretty noisy and lumpy, I thought for a second and replied that the solution was easy (Fig....
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Bob Pease
[Engineering Essentials] Regenerative Current Transformation Delivers Sub-Volt Regulated Output
Regenerative topologies and systems have been explored extensively in regards to providing regenerative loads for burn-in systems,1 enabling efficient burn-in of power supplies. Regenerative burnin systems are desirable, as the power supply ideally functions as both source and load. This means a substantial energy savings (up to 90%) when attempting to provide a burn-in function. For example, in a non-regenerative burn-in...
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Paul Yeaman
[Engineering Essentials] Phase-Change Technology Enters The Memory Market
Phase-change memory (PCM) is a new class of nonvolatile memory technology. Like most new technologies, it offers benefits to those who know where and when to apply it. To understand where PCM fits today and to appreciate its potential value, we need to evaluate its relative cost, reliability, and performance compared to incumbent technologies such as single-level cell (SLC) and multilevel cell (MLC) NAND flash, as well as system solutions...
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Ed Doller
[Engineering Essentials] Prototype Your Way To Success
An infinite number of inventions is waiting to happen. It’s often hard to figure out why one idea succeeds and another falls by the wayside. Many factors can impact success, ranging from the quality of the product, to the way it’s marketed, to the timing of its release. Sometimes, it’s just pure luck. Often, great ideas fail because the inventor spends too much time trying to develop the perfect 1.0 version instead of simply producing...
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Mike Santori
[Engineering Essentials] Stubble Trouble—Beating Back Those Tin Whiskers
What is a tenth of the diameter of a human hair and only 1.5 mm long, but can shut down nuclear plants, misguide Patriot missiles, and cause the recall of thousands of quartz watches? The answer is tin whiskers, those tiny singlecrystal filaments that grow from the surface of tin and subsequently occur in electronic circuitry—often with devastating effect. Tin whiskers cause short circuits in the position they grow in or as ...
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Paul Whytock
[Engineering Essentials] Boost Instrumentation Accuracy With Direct Digital Synthesis
Direct digital synthesis (DDS) generates arbitrary frequency sinewaves with amazing accuracy and spectral purity. The ability to generate spectrally pure sinewaves at programmable arbitrary frequencies has application in instrumentation and communications products, among other uses. Today’s DDS components provide extremely accurate, spectrally pure sinewave generation with reasonable power requirements. Modern DDS components have...
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Paul Nickelsberg
[Engineering Essentials] Save Power By Managing Unused CMOS I/O Pins
It’s easy to overlook unused digital inputs when designing with a CMOS device, but doing so invites problems. When unused digital inputs are left unconnected they will float, which can cause both unexpected logic behavior and excessive current draw. Several simple approaches for managing these unused inputs can save significant debugging grief. Essentially, a CMOS digital input circuit uses MOSFET transistors in pairs (...
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Jonathan Dillon
[Engineering Essentials] Verify Control Systems Before Committing To Hardware
Embedded-control system designers feel more pressure than ever to provide better performance and more features, all while meeting tight deadlines and keeping costs down. As these demands intensify, traditional design and verification methodologies tend to fall short. In traditional design flows, designers can’t determine if their controller works until late in the effort, when hardware is available. This was often sufficient for ...
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Brian McKay
[Lab Bench] Take Advantage Of Multicore Platforms
Multicore is everything these days, from laptops to servers. Getting started programming a multicore PC is as easy as downloading Intel’s Thread Building Blocks (see “Threads Make The Move To Open Source”). It’s just one of the many frameworks designed to take advantage of the multicore hardware that is readily available. Even C++ is making it easier ...
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William Wong
[Analog/Mixed-Signal Design] Synchronous Detection Plays A Role In Better Analog Design
Synchronous detection is a measurement method where a stimulus is modulated with some frequency and the response is demodulated to bring the signal back down to base band. Performed when a dc stimulus is not acceptable, it’s widely used in medical and scientific signal conditioning and in capacitive, inductive, or complex impedance measurements. It also allows for the collection of signals in a high-noise environment. Densitydomain signal...
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Dave Van Ess
[Power Design] Fixed DC-DC Regulator Output Uses A Digitally Controlled Potentiometer
Digitally controlled potentiometers (DCPs) have become very popular in a wide variety of applications, including control, parameter adjustment, and signal processing. The digital pots replace mechanical potentiometers and provide advantages such as remote operation and programmability, higher resolution, a much smaller form factor, increased reliability, the ability to store multiple wiper positions, and lower total system cost. A...
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Yuriy Kurtsevoy
, et al.
