Current sensing of LM25117

lee 84680

Other Parts Discussed in Thread: LM25117, LM25116, LM5119

I try to use LM25117 for high input voltage POL, but using Rs between bottom FET source to GND is costly.

So I am wondering if LM25117 can allow CS pin connects to SW pin to sense bottom FET Rdson instead.

Please advise me, Thanks.

0 EricLee over 13 years ago

Hi Soo

Unfortunately, LM25117 is not designed for Rdson sensing which requires to connect CS pin to SW. Please check LM25116 which allows Rdson sensing.

Regards,

Eric

0 lee 84680 over 13 years ago in reply to EricLee

Hi Eric,

I have more questions on LM25117.

The IC has CM pin, so can this pin be used for current share of modules used this IC?

In adjustable output design, OCP range turns out wide range, so can any compensation voltage signal be added to CS pin to minimize this error?

Thanks.

0 EricLee over 13 years ago in reply to lee 84680

Hi Soo

Usually, current sharing between multiphase modules can be done by sharing COMP (Please refer LM5119).

CM can be used as a portion of your current sharing circuit, but CM itself doesn't have any feature to make the current sharing happened.

There was an idea which compensating current limit variation by changing RAMP signal dynamically, but I have not tried yet.

Regards,

Eric

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