Need some help to design a unipolar power supply

[classelectronics]

I need some help to create a power supply.

I need to design a unipolar 9V power supply with a current limit of 5A. The input voltage will be 12V DC. Also when the 4A output current starts to be reached, I need to limit the current.

Any help?

Best Regards.

 

[BradtheRad]

It is feasible to drop 3V with a transistor or IC regulator. However you waste 15W at 5A.

To have efficiency you're probably looking at a buck converter. Although your output spec is 4A or 5A max, the inductor may have waveforms with peaks upwards of 6-8A going through it.

It gets complicated when you want to regulate output voltage, and at the same time to limit current.

 

[d123]

Hi,

Maybe for a pass device you could look at, for example and just as examples, ST Micros or OnSemis (Infineons) low VCE resistance BJTS, they and other manufacturers may have pass device solutions that don't require a large gate voltage like a MOSFET might for those currents, maybe... And if you're designing it yourself, then current limiting is as simple as "Googling" the term to find transistor or op amp circuit designs and app notes.

2N5684 (PNP), 2N5686 (NPN) "High-Current Complementary Silicon Power Transistors" may be a suitable fit, SOA and Vbe, and seemingly Vce fit your needs.