Using TLVH431 for SMPS with Vout=36V?

[schnell]

Hello,

I wish to use the TLVH431 to get opto-isolated feedback in an SMPS.

The problem is that this SMPS has an output voltage of 36V, and the maximum allowable cathode voltage of TLVH431 is 20V.

Do you think that it is possible to use the TLVH431 here?

Is it right that all I have to do is simply put a 20V zener in series with RS inn the following schematic?
-and then I am safe?

SCHEMATIC:

http://i51.tinypic.com/30skly9.jpg

TLVH431 DATASHEET:

http://focus.ti.com/lit/ds/symlink/tlvh431.pdf

RELEVANT ARTICLE:
Article: Biasing the TL431 for improved output impedance :

http://powerelectronics.com/mag/50107.pdf

 

[OperaHouse]

That would work or you could form a voltage divider with RS to minus prior to the opto. This would be a cheaper option since the current through the LED would be very low.

 

[Comcokid]

I believe I have seen 'somewhere' a circuit for the 431 used as a opto feedback in a higher voltage SMPS application.

The TLV431, TL431, LT431 family is large and there are many application circuits. The last two above are rated for a max of 36 volts (Fairchild and Linear Tech). maybe someone makes a "HV" version as this is a very popular shunt regulator.