Can I use a LNK501 to make a MULTIPLE outputs converter?

[Nicholas]

SMPS Design

can I use a LNK501 to make a MULTIPLE outputs converter?
can't find any AN from Power Integration describe this.
Application of LNK always detect the reflect voltage on the primary winding to form a regulator. If used in MULTIPLE outputs application, what the Vor will be when all the secondary winding reflect a voltage on the primary winding respectively?
thanks!!

 

[wky]

Re: SMPS Design

The Vor should be the same in single or multiple output configuration.

 

[goodboy_pl]

Re: SMPS Design

It is possible to make a flyback SMPS with several ouputs both with primary side(with auxiliary winding) regulation and secondary side (with Ref+Opto).

the output voltages of several winding will track the voltage which the feedback signal was taken; the regulation is better than 10% for awell designed transformer. the fromula is as followiing:

Vout=N(out.n)*((Vout(Aux)+Vdiode)/N(Aux))

thus all output voltage will track the voltage of Auxiliary winding with a simple winding ratio and this is all we need in multi-output SMPS design!

for more info refer to:
**broken link removed**

BEST!

 

[Nicholas]

Re: SMPS Design

It is possible to make a flyback SMPS with several ouputs both with primary side(with auxiliary winding) regulation and secondary side (with Ref+Opto).

the output voltages of several winding will track the voltage which the feedback signal was taken; the regulation is better than 10% for awell designed transformer. the fromula is as followiing:

Vout=N(out.n)*((Vout(Aux)+Vdiode)/N(Aux))

thus all output voltage will track the voltage of Auxiliary winding with a simple winding ratio and this is all we need in multi-output SMPS design!

for more info refer to:
h**p://www.powerint.com/PDFFiles/an22.pdf

BEST!

But there is no Auxiliary winding in basic LNK501 Application. It just sense the reflect voltage on primary winding (Vor = Vsec*Np/Ns) to form a feedback.

 

[goodboy_pl]

Re: SMPS Design

The reflected voltage in primary winding acts like auxiliary winding and even other secondary windings, THUS:
the volatge on other secondary windings is dependent on turns ratio of secondaries, i.e. first design the transformer for single secondary(but with total output power!!!) then find other secondary turn according to basic transformer voltage/turn ratio!

please refer to an22!

BEST!