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Design Tips

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Interpreting loop gain measurements

Dr. Ray Ridley, President, Ridley Engineering

There have been many dramatic changes in power supply development over the last 20 years, but loop gain measurements remain the key to rugged and aggressive system performance. Understanding how to read a loop gain is important. Loop gain measurements in modern systems Quite
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Date:
04/30/2014
Power Supply Failure Survey â€

Dr. Ray Ridley, Ridley Engineering

In this third article about power supply failures, the magnetics are examined for their contribution to the failure rate. These are usually the least understood of all components, and poor magnetics design can lead to many different failure mechanisms in power supplies. Power
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Date:
04/06/2014
Power supply failure survey â€

Dr. Ray Ridley, President, Ridley Engineering

In this second article about power supply failures, the capacitors are examined for their contribution to the failure rate. The causes of failure for different types of capacitors are discussed. In the last part of this article, the question was asked of group members “Why do power supplies fail?” and the
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Date:
03/03/2014

Results of a power supply failure survey

Dr. Ray Ridley, President, Ridley Engineering

We here at Ridley Engineering recently conducted a survey with a group of almost 3,000 active power supply design engineers to discover the various reasons and circumstances they have encountered power supplies that failed. The experiences the engineers shared with us were very enlightening, and this article
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Date:
02/15/2014
Point-Of-Load Converter Design â€

Dr. Ray Ridley, Ridley Engineering

Point-of-load converters commonly use multilayer ceramic capacitors instead of electrolytic capacitors. The effect of this change is strongly felt in the bulk storage capacitor value, and can lead to unexpected variations in control measurements. Instability can result if input filter capacitors become too small.  Input
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Date:
01/12/2014
Point-Of-Load Converter Design

Dr. Ray Ridley, Ridley Engineering

There has always been a debate about how essential it is to measure the loop of a switching power supply. Some power designers have always resisted this part of development and design validation, claiming they are able to tune a loop properly through step-load testing [1]. While this may have worked with low
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Date:
12/07/2013
Designing snubbers for nonisolated converters

Click image to enlarge

Figure 1: Buck Switching Cell and Circuit Placement

All power electronics circuits with devices which rapidly turn on and turn off will exhibit voltage ringing when currents are interrupted or initiated. For transformer-isolated designs, the leakage
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Date:
10/16/2013
Tapped Boost Converter Modeling

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Figure 1: PWM switches and the three equivalent circuits used for different types of analysis

As mentioned in the last article of this series [1], Dr. Vatché Vorpérian developed the PWM switch model in 1986, which replaced the need for state-space averaging and greatly simplified the
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Date:
10/10/2013
PWM Switch Modeling

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Figure 1: PWM switches needed to create a switching power supply. The diode can also be a synchronous rectifier if desired.

Soon after switching power supplies were implemented in industry in the 60s and 70s, it became apparent that they had unique issues with control that defied normal circuit analysis. This gave rise
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Date:
08/18/2013
Flyback Power Supply Development Part V

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Figure 1: Schematic of the flyback converter with AP300 connections for measuring the control-to-output transfer functions.

This article is the fifth of a series in which Dr. Ridley shows the steps involved in designing and building an offline flyback converter. With full input voltage and full load applied, the control-to-output
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Date:
08/06/2013
In this video, Ray Ridley of Ridley Engineering describes his company's services
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Date:
07/10/2013
In this introductory video on switching power supply design, Dr. Ridley
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Date:
06/14/2013
In this third part of a series of videos on frequency response analysis,
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Date:
05/21/2013
Flyback Power Supply Development Part IV

Dr. Ray Ridley, President, Ridley Engineering

This article is the fourth of a series in which Dr. Ridley shows the steps involved in designing and building an offline flyback converter. The power transformer is added to the circuit, and the current sensing and snubbers are designed to operate at full power without excessive stress on the components. Power
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Date:
05/16/2013
Alix Paultre, Editorial Director of Power Systems Design, and Dr. Ray Ridley
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Date:
05/16/2013
Flyback Power Supply Development - Part III

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Figure 1: Input line voltage POWER 4-5-6 simulation, showing rectified voltage on a 10 ï½F input capacitor.

This article is the third of a series in which Dr. Ridley shows the steps involved in designing and building an offline flyback converter. The input filter rectifier is simulated to find the design
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Date:
05/14/2013
In this video, Dr. Ridley presents the agenda for this unique power supply
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Date:
05/08/2013
In this second part of a series of videos on frequency response analysis,
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Date:
05/03/2013
In this video, the first part of a series of videos on frequency response
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Date:
05/01/2013
Flyback Power Supply Development Part II

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Figure 1: Full schematic of a flyback converter.

This article is the second of a series in which Dr. Ridley shows the steps involved in designing and building an offline flyback converter. The second part of the series begins testing on the bias
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Date:
03/09/2013
Flyback power supply development - part II

Figure 1: Full schematic of a flyback converter

This article is the second of a series in which Dr. Ridley shows the steps involved in designing and building an offline flyback converter. The second part of the series begins testing on the
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Date:
02/28/2013
This article is the first of a series in which Dr. Ridley shows the steps involved in designing and building an offline flyback converter. The first part of the series presents the power supply architecture and schematic, including the control and bias circuits. Flyback power converter The
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Date:
01/15/2013
Input Impedance Measurements and Filter Interactions Part III

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Fig. 1: Power supply with input filter module. A damping network is used to control the output impedance peaking.

In this article, Dr. Ridley continues the discussion of power supplies with input filters. He shows how the presence of a poorly-designed filter has a drastic effect on the loop gain of a voltage-mode
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Date:
01/09/2013
Input Impedance Measurements and Filter Interactions Part II
In this article, Dr. Ridley continues the discussion of power supplies with input filters. He shows how the output impedance of the input filter is measured, and demonstrates the importance of
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Date:
12/22/2012
Input Impedance Measurements and Filter Interactions Part I

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Fig. 1: Power supply with input filter module

In this article, Dr. Ridley continues the discussion of input impedance measurements, and shows the effect of properly locating all of the input filter components. Middlebrook's input filter stability
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Date:
11/10/2012
Input Impedance Measurements
In this third part of this series of articles, Dr. Ridley discusses the fourth important frequency-response measurement made during full characterization of a switching power supply. The closed-loop
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Date:
09/07/2012
Manual Frequency Response Measurements for Magnetics - Part II
In this article, Dr. Ridley provides further insight into frequency response measurements of transformers and inductors using equipment that you probably already have in your laboratory. An improved
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Date:
05/18/2012
Manual Frequency Response Measurements for Magnetics
In this article, Dr. Ridley describes how you can make frequency response measurements of transformers and inductors using equipment that you probably already have in your laboratory. This is
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Date:
04/14/2012
Hardware Testing and Computer Simulation
In over 30 years of designing power supplies, I have written multiple computer programs to help design, simulate, and understand power supply operation. This has culminated in Release 9 of POWER
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Date:
03/06/2012
Flyback Transformer Primary Winding Structures
Dr. Ridley shows how the intricate details of magnetics construction can have a major impact on the operation of a flyback converter. Flyback Transformer Primaries If you are designing
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Date:
03/02/2012
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