LM20146MHEVAL: SW waveforms

kura

Genius 4740 points

Part Number: LM20146MHEVAL
Other Parts Discussed in Thread: LM20146

We got SW waveforms using with LM20146MHEVAL.

Condition is

Vin:5.0V,Iout:1A CR mode EVM is default

Vin:5.4V,Iout:1A CR mode EVM is default

Please see the point of red circle at page2 in attached file.(Vin:5.4V,Iout:1A)

Please let us know the reason why these waveform was seen at EVM.

Does this waveform cause any problem ?

LM20146MHEVAL.pptx

over 5 years ago

0 JohnTucker over 5 years ago

TI__Guru**** 191445 points

Kura,

This is an unmodified EVM, correct? I will look into this, but please be patient. I will have to order an EVM and it may be after the new year. I will try my best to get you an answer this week though.

0 kura over 5 years ago in reply to JohnTucker

Genius 4740 points

John-san

Thank you for your reply.

Yes,this is an unmodified EVM.

0 JohnTucker over 5 years ago in reply to kura

TI__Guru**** 191445 points

Kura,

I could not duplicate your results.

Vin = 5 V, Iout = 1 A:

Vin = 5.4 V, Iout = 1 A:

0 kura over 5 years ago in reply to JohnTucker

Genius 4740 points

John-san

Thank you for your support.

In light load condition,attached waveform is found.

Vin:5.4V Iout:0.5A CR mode,unmodified EVM

Please check attached.

0 JohnTucker over 5 years ago in reply to kura

TI__Guru**** 191445 points

Kura-san,

LM20146 uses diode emulation mode. The low side switch is not turned on when the inductor current falls below 0 A. Your waveforms show classic non-synchronous Discontinuous Conduction Mode (DCM) operation. That waveform is normal.

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LM20146MHEVAL: SW waveforms