Monthly Archives: May 2016

Switched Micro-Power Supply

In this Article I present my Switched Voltage Converter for the low-power range.

For example it can be mounted on a small PCB with 3 pins that can easily replace regular 78XX regulators. That will become the “simple” Version.


The advanced Version in the image above has some quite impressive features:

  • The nominal output current is 250 mA, which is half of what the simple version can produce due to design reasons.
  • The module is absolutly overload and short-circuit proof.
  • In contrast to the simple version it can Buck and boost the voltage at the same time. The input and output Voltages range from 3V to 35V.
  • The negative output can even create a negative Voltage, though it must be stabilised with an externel Zener Diode.
  • Provides Control Pins for Enable Input and Power-OK Output

And the most important ones, and the reasons why I designed this Discrete Converter is:

  • The Design can be changed and adapted for high voltages using appropriate transistors.
  • The polarity of all semiconductors can be swapped with the opposite ones (NPN to PNP) to build the same converter for negative voltages!

For size reasons there are no output caps onboard and therefore the converter rely on external ones, like 3-pin regulators do too. These are mandatory, starting the circuit without them will immediately destroy it as the stored energy in the coil will induce extreme voltages. (Maybe I’ll fix that in an upcoming smd version of this converter)

I have already used two of these in my MPS-Stack. For example in my Preamp-Module it generates a very stable bipolar supply voltage of + and – 5 Volts independent of the Input Voltage that can be anything from 4 to 35 Volts.