TPS54160EVM-230: Voltage at PH node upper than voltage at VIN node in ON State

Luigi Solimene

Part Number: TPS54160EVM-230
Other Parts Discussed in Thread: TPS54160, TINA-TI

Dear all,

I'm working on the board TPS54160EVM-230 to develop a study of magnetic materials for custom inductors. I am interested in reconstructing a simple circuit model of the converter to simulate the current waveforms in the inductor. Measuring with an oscilloscope the waveforms of voltage at the VIN and PH nodes I noticed that the second, contrary to what I expected, was greater than the first in the ON time.

I can't justify this behavior.

Could you tell me if there's anything inside the TPS54160 chip that causes this voltage rise?

Thank you

over 5 years ago

0 JohnTucker over 5 years ago

TI__Guru**** 191445 points

Luigi,

The PH node voltage can be higher than VIN when the circuit is sinking current rather than sourcing current. However that should not happen for a non-synchronous converter like TPS54160. Can you post your waveforms? For your convenience, there are pspice and TINA-TI models available where you can view the switch current waveforms:
www.ti.com/.../toolssoftware

0 Luigi Solimene over 5 years ago in reply to JohnTucker

Prodigy 20 points

Thanks for the answer. I enclose some plots with the waveforms. I would like to emphasize that the inductor I am using works voluntarily in the region of weak saturation.

0 JohnTucker over 5 years ago in reply to Luigi Solimene

TI__Guru**** 191445 points

Luigi,

It must be your test set up. The PH node may temporarily overshoot and ring above VIN, but during the remainder of the on time, PH will be VIN - (Iout * RDSon) for continuous mode operation.

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TPS54160EVM-230: Voltage at PH node upper than voltage at VIN node in ON State