Switch Mode Power Supplies (SMPS) is now widely used in modern electronic equipment due to its compact design and high efficiency of about 80% or more. The switch-mode regulator circuit presented here has an efficiency of around 85%.
This DC to DC Converter use Max 541 from Maxim, IC1 is a switching regulator that generates a 45-kHz signal that drives the gate of MOSFET Q1 BUZ71A from Motorolla. The source of this power supply comes from a 12V car battery voltage. This DC to DC converter have an output +-15V and 5V.
This Simple switching power supply for 15 Watt can be used to power any load up to 15 … 20 watts and has smaller dimensions than a similar, but with the step-down transformer, operating at a frequency of 50 Hz.
In the typical power supply is used in chip LM2674 company National Semiconductor , for many years engaged in manufacturing and designing components for the pulse transformers. LM2674 can be used instead of a chip LM2671 .
By choosing different versions of chips, you can collect the converter with a constant (3.3, 5 or 12V) or with an adjustable output voltage. The above scheme gives a current of 500 mA.