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The DC/DC Book Of Knowledge

RECOM´s DC/DC Book of Knowledge is a detailed introduction to the various DC/DC converter topologies, feedback loops (analogue and digital), test and measurement, protection, filtering, safety, reliability, constant current drivers and DC/DC applications. The level is necessarily technical, but readable for engineers, designers and students.

The function of any AC/DC or DC/DC converter module is to meet one or more of the following requirements:

  • To match the secondary load to the primary power supply
  • To provide isolation between primary and secondary circuits
  • To provide protection against the effects of faults, short circuit or over heating
  • To simplify compliance with safety, performance or EMC legislation.

 

Enjoy reading.

The DC/DC Book Of Knowledge

Chapters

Chapter 1: Power Regulation

This chapter is a comprehensive overview of DC/DC power supply topologies: linear and switching regulators, buck, boost and buck-boost converters and flyback, forward and push-pull topologies.

If you want to know your SEPIC from your ZETA, you need to read this chapter!

Chapter 2: Feedback Loops

Feedback is the essence of every stable system. How can I design my analogue or digital power supply to react quickly to sudden changes in load or input voltage, but stay smooth when the load is constant?

And why do I have to worry about my right half plane stability?

Chapter 3: Understanding Datasheet Parameters

If in doubt, read the datasheet! This chapter explains what all the parameters mean so your DC/DC design behaves the way you expect it to. What is the worst case performance I can expect?

Chapter 4: DC/DC Converter Protection

Prevention is better than cure. How to protect my DC/DC converter and how my DC/DC converter can protect my application. Read this or be sorry!

Chapter 5: Input and Output Filtering

Input and output filtering is one of the most important and most poorly understood aspects of any DC/DC converter design. Sort out your common mode from your differentials, and you don’t have to worry about your back ripple any more.

Chapter 6: Safety

Safety first. This chapter explains the hazards, risks and countermeasures that you need to know to make a safe design that meets the regulatory requirements. Get  creepages and your clearances right and your design can pass the safety certification first time.

Chapter 7: Reliability

All manufacturers say that their product is reliable, but how do you design for high reliability? Find out which factors do the most harm to the lifetime of DC/DC converters.

Chapter 8: LED Characteristics

Power LEDs for lighting run best from a constant current supply, not a constant voltage. How do you protect your LEDs from being overdriven or over-heating? And which is better: Analogue or PWM dimming?

Chapter 9: DC/DC Application Ideas

This chapter is a collection of DC/DC tips and tricks that every designer might find useful: How can I double the output power? Can I connect DC/DC converters in series? How can I increase the isolation?

Chapter 10: Magnetics

The heart of a DC/DC converter is the magnetic component. This chapter takes you through the entire design process from choosing the right magnetic core and topology, to coping with the losses and handling the leakage inductances and capacitances.

The AC/DC Book Of Knowledge

Chapters

Chapter 1. A Historical Introduction

Have you ever wondered why we have 115VAC or 230VAC mains voltages, or 50Hz or 60Hz? Who chose these numbers, anyway? 

This chapter explains the history of the development of AC power.

Chapter 2: Linear AC/DC Power Supplies

Is there room for linear AC/DC power supplies in the modern world, or are switching power supplies the only answer?

Chapter 3: Apparent, Reactive and Active Power

Taking the analogy of a beer mug: active power is the liquid beer, reactive power is the head of foam and apparent power is the full glass.

This chapter explains the mathematical relationship between “useable electricity” and “wasted electricity”. 

Chapter 4: AC Theory

This chapter on AC theory  covers impedance diagrams, phasors and the importance of the imaginary square root of minus one. 

What is the link between polarized light and Maxwell’s field equation?

Chapter 5: Passive Components

The working lifetime of a power supply is very often limited by the choice of capacitors.  When is a 100µF capacitor not a 100µF capacitor?

This chapter explains the stress factors and how to design an AC/DC converter with more than 20 years’ lifetime.

Chapter 6: Active Components

MosFET, IGBT, SiC or GaN? This chapter covers the fundamentals of power switching transistor behaviour and how to design for high reliability switching.

Chapter 7: Power Factor Correction

Power factor correction is often a regulatory requirement for AC/DC converters. What techniques are available and what are their respective advantages and disadvantages?

Chapter 8:  AC/DC Converter Topologies

This chapter is a comprehensive overview of AC power supply topologies: single-ended, quasi-resonant, two-transistor, interleaved, parallel, half-bridge and full-bridge, single phase and three phase.

If it is not here, you probably don’t need it!

Chapter 9: Transformerless AC Power supplies

Not all AC/DC power supplies need a transformer. What has IoT to do with non-isolated AC/DC converters?

Chapter 10: Wireless power

Power without wires has been an ambition since the time of Tesla. Now with the advent of Qi and other standards, wireless power is moving away from electric toothbrushes and becoming a  very useful power transfer technique.

Chapter 11: Feedback

Chapter 11:

Feedback is the essence of every stable system. How can I design my power supply to react quickly to sudden changes in load or input voltage, but stay smooth when the load is constant?

Why is the optocoupler the weak link in the chain and what alternatives to exist?

Chapter 12:  Low Standby Power Consumption Techniques

Microprocessors have a current consumption that varies by a factor of 100million between full speed and deep sleep modes. How can I design my power supply to deliver full power when needed, but consume as little power as possible when the load is near to zero?

Chapter 13:  Measuring AC

“Wer misst, misst Mist!“ Measuring AC is not so simple as measuring DC. This chapter outlines the different AC measurement techniques and explains why your multi-meter may not be telling you the whole truth.