[moved] Power Supply Design with two USB outputs

[nikhil.medhe]

Hello,

I need to design a 150V - 230V AC input to 5V, 1.5A DC output power supply which has two USB Outputs.
Should I go for the transformerless design or should I include a transformer?
In any of the above cases, what should be the circuit diagram?

I would appreciate your help on this point. Thanks in advance!

- Nikhil

 

[Surendhar M]

Go with the transformer. Step down the input voltage and do the conversion. Use a regulator which is able to provide 5V with 3A, As you said need two USB outputs. So 1.5A for both

 

[nikhil.medhe]

Go with the transformer. Step down the input voltage and do the conversion. Use a regulator which is able to provide 5V with 3A, As you said need two USB outputs. So 1.5A for both

Thank you for the answer! However I have one more query. What should be the specifications of the transformer I should be using?

 

[red_alert]

The transformer could be a 230V/6V (10W). You also need a rectifier bridge, a filtering capacitor and a linear series regulator (LM338 - 5A).

 

[Surendhar M]

I think 230V/6V will be marginal case so better go with 230V/9V or 230V/12V. That should be fine

 

[nikhil.medhe]

I think 230V/6V will be marginal case so better go with 230V/9V or 230V/12V. That should be fine

Thank you very much for your inputs Surendhar! I believe all these specifications will surely work.

 

[red_alert]

Too much power losses in the linear regulator (for 3A current) with 9V/12V AC.

For 6V AC you get ~ 8.4 DC (more than enough for a series regulator).

 

[nikhil.medhe]

Too much power losses in the linear regulator (for 3A current) with 9V/12V AC.

For 6V AC you get ~ 8.4 DC (more than enough for a series regulator).

Do you recommend we use a 230v to 6v transformer in that case?