LM5022: LM5022: PMP20551 Reference Design T1

Jerome Herzog

Prodigy 50 points

Part Number: LM5022
Other Parts Discussed in Thread: LMV431

Hello,

in the Design (http://w*ww.ti.com/lit/df/tidrqf9/tidrqf9.pdf there is T1 (750316708) from Würth.

The truns ratio pri1 to sec is 3:1.

Vin: 12 to 60V.

The secondary winding is defined by 12V. So if 60V is at Vin I get 20V on secondary. Is this a failure?
If I need 48V on the secondary and got 24V on Vin, do I need a ratio of 1:2 for primary winding 1 to secondary winding?

Kind Regards

over 5 years ago

0 Youhao Xi over 5 years ago

TI__Guru 74430 points

Hi Jerome,

Thank you for posting. No matter what your turns ratio is, if your output is greater than the feedback setting of 12V (by the LMV431), something is wrong with your circuit.

If you want to get 48V Vout, and your VIN=24V, you don't have to have a turns ratio of 1:2. Please refer to the follow doc and calculator for flyback designs.

http://www.ti.com/lit/pdf/slyy062

http://www.ti.com/tool/flybuck-flyback-design-calc

Thanks,

Youhao Xi

Power management

Power management forum

LM5022: LM5022: PMP20551 Reference Design T1