LM5157EVM-FLY: output current

Hi Youhao,

I can draw more than 75mA on EVM?

Jason

Hi Jason,

How much more do you want to draw?  For any individual output yes you can draw more current if the other outputs are under the rated load. If you want to draw more currents from all output rails at the same time, the circuit may enter current limit, causing the output voltage drops.  If this happens, you will need to change to a larger transformer and also use a smaller current sense resistor, to support your higher power.  

You may refer to our design calculator to help you design.  The link is here: https://www.ti.com/lit/zip/snvr508

Thanks,

Youhao

Hi Youhao,

Got it,

one thing I don't very understand is how to decide the output current  magnitude. where limit the output current.

Jason

Hi Jason,

Flyback transformer is basically coupled inductor.  You need to convert all loads into the main output rail (via transformer turns ratio), then you can decide the max power.  The design calculator should help you in this matter: converting the EVM to a single output rail.

Thanks,

Youhao

Hi Youhao,

Got it, thanks.

Jason