LM5017 Freewheel Diode

Samuel.Loho

Other Parts Discussed in Thread: LM5017

Hello,

I am trying to understand the topology of LM5017. On all of the app notes and datasheet that use LM5017 in the circuit, there is no freewheel diode on the output between the switching output and return path of the switcher.
Most switching regulator in the buck converter topology that I came across use freewheel diode on the output.

I also noticed in the datasheet it was mentioned that there is an internal high voltage diode between the VCC pin and BST pin. Is this the reason that the LM5017 circuit does not require freewheel diode?

Regards

Samuel

over 10 years ago

0 Stephen Oberholzer over 10 years ago

Intellectual 895 points

Samuel,

The freewheeling diode has been replaced with a FET inside the ic.

See page 8 of the datasheet.

Stephan.

0 Samuel.Loho over 10 years ago in reply to Stephen Oberholzer

Prodigy 210 points

Hi Stephan,

Thanks for the answer. That makes sense now. The datasheet mentioned it in the paragraph on page 11: "The LM5017 provides an internal synchronous N-Channel MOSFET rectifier. This MOSFET provides a path for the inductor current to flow when the high-side MOSFET is turned off."

That answer my question now.

Thanks,

Samuel

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LM5017 Freewheel Diode