LMR16030: Output spike at hot swap from 24v battery connector.

Jeff,

The PMIC has a max supply voltage of 6V and the scope shots show the spike going up to about 5.4V. This should not cause damage.

Could this spike be noise coupled into the scope probe? Are you using the tip-and-barrel method or a differential probe?

You can confirm that the spike is coming from the LMR16030 by observing the SW node while the spike occurs.

-Sam

Hi Samuel,

     Thanks for your quickly response.  

     1. It's for sure that they were using tip-and-barrel method to measurement output voltage of LMR16030.

     2. I will advice customer to increase oscilloscope trigger point and measurement SW pin at the same time.

Thanks again

Jeff Chen

Jeff,

Thanks and let me know when you hear back.

-Sam

Hi Samuel,

     Picture 1 and picture 2 were testing at connector plug into.  Picture 3 was testing at connector unplug . 

Please give me some advice.

Thnaks

CH1(BLUE)      : SWITCH NODE

CH2(YELLOW) :  VOUT

Jeff,

The high-side FET is on because the part is in dropout. It appears as though the part does not react quickly enough when VIN rises and VOUT shoots up. But there's also a ringing around 170kHz as shown in your zoomed-in picture. This ringing does not appear to be affected by the switch node. I'd like to find the cause of this ringing since it is what's causing the overvoltage. Can you modify the output capacitors and inductor to see if this resonant frequency changes or reduces?

Please also share the schematic and layout.

Thank you,

-Sam