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.
Note that the dignity of these components is the high switching frequency – 260 kHz, allowing the use of inductors and capacitors small denominations, to achieve high efficiency and small size of the converter. Under normal conditions, the efficiency is 90%, and in some cases, can reach even up to 96%. Both devices are protected against overcurrent and overheating.
LM2671 has a number of additional features such as soft start and the opportunity to work with an external generator. The latter allows to synchronize multiple converters, which significantly reduces the noise created by them and ensure compliance with any requirements of electromagnetic compatibility (EMC). Shown in Figure converter provides output voltages of 5V and current up to 500mA. Schottky diode D1 must withstand reverse voltages of at least 45V and a maximum forward current of 3 A.
