TPS54202EVM-716: TPS54202

Skylar Li

Part Number: TPS54202EVM-716

I tested TPS54202EVM today, and I changed the output voltage from 5V to 3.3V by adjusting the feedback resistance. . I don't understand where I circled out with a red line because not every square waves have spikes .

over 1 year ago

0 Zixu Wang over 1 year ago

TI__Expert 8100 points

Hi Skylar,

I will make further analysis and give you response by tomorrow!

BRs

Zixu

0 Zixu Wang over 1 year ago

TI__Expert 8100 points

Hi Skylar,

Which part in shown waveforms confuse you? Spikes in falling edge or marked ringing period?

Could you make more specific explanations?

BRs

Zixu

0 Skylar Li over 1 year ago in reply to Zixu Wang

TI__Intellectual 760 points

I dont't understand that not every square waves have spikes

0 Zixu Wang over 1 year ago in reply to Skylar Li

TI__Expert 8100 points

Hi Skylar,

For falling edge in each period, it is obvious to observe spikes of undershoot.

What does "not every square waves" mean?

BRs

Zixu

+1 Zixu Wang over 1 year ago in reply to Skylar Li

TI__Expert 8100 points

Hi Skylar,

I suppose you must want to know why the marked ringing appears every 3 cycles.

This is related with load current. For extreme low current, single pulse will charge enough energy for load, meaning that there exists time for shutdown of High Side FET, Low Side FET and body diode of Low Side FET. This will cause ringing in each switching period.

However, when load current increases to some value, single pulse would not provide enough energy to load, which make several consecutive pulses to provide enough energy and then the inductor would have time for no current flowing through. This is the reason behind shown waveform.

Hope my explanation would be helpful!

BRs

Zixu

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TPS54202EVM-716: TPS54202