POWER SUPPLY Switching 12V for CAR by SG3525

Switchmode Preamp Supply For Cars
DescriptionThe extreme simplicity of this design is thanks to the circuitry inside the SG3525 controller IC. The two outputs have dual switching transistors, and these can be used to create a full bridge forward converter switchmode supply with the absolute minimum of external parts. As shown in Figure 1, the supply is unregulated. While this may seem to be a fundamentally bad idea, the car supply is actually reasonably well regulated at 13.8V, and this means that the output of the supply will not fluctuate very much.

Since opamps are very tolerant of supply variations (especially if they are fairly low frequency), this means that the inductors that are used in nearly all switching converters can be eliminated. Inductors (and associated flyback diodes) must be used if the supply is regulated, and in the interests of simplicity, I did not want to go that way.

This entry was posted on Wednesday, August 1st, 2007 at 9:57 pm and is filed under switching power supply. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.