Part Number: TPS43061
I measured excessive ringing at the output of the EVM and wanted your help to either correct a possible mistake in the way I'm testing it or to provide clarification to understand the discrepancy I see against the documentation.
Another observation is that a board sitting at ambient temperature seems to have smaller ringing than that of a board with which I loaded the output with higher current, even for a short period of time. Would the MOSFET's or the chip temperatures have an influence in the results?
This experiment is for confirming an observation from a customer, who seems to have reached comparable findings with the ones I tested with the TPS43061EVM-198. I made sure to reproduce the nominal values of input voltage and load to eliminate possible issues with the compensation in the circuit. I therefore applied 9V to the input and measured a well-regulated 15VDC on the output as expected. I have applied different loads and made sure to use a calibrated tip&barrel oscilloscope probe to collect the data.
The documentation for the EVM estimates that the voltage ripple should be in the order of 70mV when operating in CCM and about 10mV when operating in DCM. Page 8 of the EVM user's guide represents in Figure 9 a ringing of 16V (!!!) peak to peak, which makes me wonder if the indication of 10V/div should actually have been 10mV/div. My measurement however is the following with a load of 1A (CCM):
I appreciate any comments you might have about these findings. Thank you!