App note: The behavior of electro-magnetic radiation of power inductors in power management


Application note form Würth Elektronik about EM radiation radiated from inductors in DC-DC converters. Link here (PDF)

This Application Note focuses on the Electro-Magnetic (EM) radiation behavior of power inductor(s) in DC-DC converters, which is dependent on several parameters such as ripple current, switching frequency, rise & fall time of a switching device, the core material and its permeability and suggests several design tips to mitigate these EMI effects.

3V3/30V DC/DC converter using SN6505A


Robert Gawron made a 3V3/30V DC/DC converter using SN6505A:

Recently I’v got my samples of SN6505A, it’s a really nice IC, so I decided to make a simple DC/DC converter to get familiar with it. What I like in this chip is that it can operate on input voltage as low as 2,5V – that makes it great for battery devices. It’s also nice, that it’s a very minimalist design – on primary side all what is needed is decoupling capacitor. One disadvantage is that it doesn’t have a feedback loop.
To increase efficiency, SN6505A can operate with more developed versions of transformers, but I used the simplest configuration – one coil on each side.

Project info at Robert Gawron’s blog.

Output voltage control of DC/DC converters


Thomas Fischl writes:

Some applications needs to control the output voltage of a dc/dc converter instead using a fixed output voltage. For example battery chargers has to adjust the output voltage to the current battery level. This page shows how to add such a control function to a buck converter circuit.

Control output via external voltage source
Typically a voltage divider is used in dc converters to adjust the output voltage to the needed feedback voltage. To control the feedback signal by an external voltage source, a third resistor is added to the circuit.

More info at Fischl’s site.