Hi guys,

Why need discharge circuit between SW and GND in buck converter?
Please see following file.

Best regards,
Nazar

 

That depends on what it is,
the individual parts are not specified.
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.
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During the on part of the cycle, the inductor is connected to V+. During the off cycle, you cannot simply disconnect it, you need a path for current to continue flowing. Normally, this is simply a diode to ground, but it could be a MOSFET as well.

Bob

 

I thought it was to make sure that the charge pump that provides the gate voltage for the upper FET can operate.
But I note that the upper FET is drawn wrongly. The source appears to go to V+, but it is drawn as an N channel FET, but the diode is the right way round for a P channel FET.

 

Hi guys,

Why need discharge circuit between SW and GND in buck converter?
Please see following file.

Best regards,
Nazar

If you would kindly provide the chip's denomination, one could check the datasheet. With some likelihood the purpose of the discharge circuit is documented there.