many outputs SMPS

Posted by: ilkintacan on 10/07/2013

Hello,

I need below outputs. Must I use two seperate SMPS or can I design a single one? because PI Expert design program dont support such channels. I want to use LNK362/362.

+5V(250mA), +12V(30mA), -12V(30mA) these outputs will have same GND

+6V(30mA),+6V(30mA), +6V(30mA), +6V(30mA) these outputs will have floating GNDs

Thank you in advance.

Comments

Let me understand. You need to design a power supply with total seven outputs,

Three outputs (+5,+12.-12) with common return right?

Four outputs (6V each) to be isolated from the rest of the outputs and from each other, am I right?

If this is your case then you can have a power supply in flyback topology. The flyback transformer will have the 3common-RETURN output windings stacked in series.

The other 4 outputs will be parallel windings. Then you take each of the 6V from each of these isolated windings.

You do not need to tell PI expert that your four six-volts outputs are isolated. You can just enter six volts output as any other output. A the time to wind your transformer you just separate the 6V outputs and wind in parallel windings.

Keep in mind that your regulation is going to be very poor because you have many outputs. If your output loads going to be constant, then should be easier to tune the circuit to have your desired voltage. But, if your will have some loads to be maximum while others loads are zero, then regulation may be a challenge. It depends on your specifications for output regulation

Thank you this is useful information that I can design 4x6V output as 1 floating 6V output in PIExpert.

But in what current?

6V and total 4 channel's current or 6V and single channel current but when I construct it I will wind extra 3 same winding. If second is true, will transformer be enough for extra 3 windings?

Best Regards

This is what I would do if I were in your case.

Design a transformer with all the outputs you need. For the 6VOUT use 300mA load. The program will give you an oversized core and oversized wire gauges. This is design 1

Then you create another design. (Design 2).This design does not include the 6 VOUTs. Only include the other 3 outputs.

For you final design, you use the wires sizes recommended in design 2 for your 3 outputs in series and use the core from design 1. The 6Vout will be 4 wires. Each wire will be 4 sizes smaller that the recommended size from design 1.