LM2671: LM2671

Hello

Can you provide waveforms of your input voltage and the voltage on the VSW node.

Is the "noise" on the output recurrent ??

Thanks

Hello Frank, thanks for the reply, 

I/p waveform as below - and its repeating, 

Regulator O/P waveform as shown below and its repetative 

Regulator o/p noise AC waveform as shown below

                            Please let us know in case of any other details required from our side.  

Hello Frank,

                     This is the VSW point waveform for your reference

Hello

The waveforms you are showing look very strange.

Please double check your set-up.

The waveforms should look closer to those in the data sheet.

Also, please check your component values.

Thanks

Hello Frank ,

                  i have also felt little strange, set up is fine as we are getting 18V along with ringing noise, and output also same, if we are not getting the o/p voltage we would have checked the set up but set up is fine ....and all the components are also fine....  

Hello

Is the repetition rate of the noise the same as the switching frequency of the regulator ?

Thanks

Hello Frank, switching frequency of regulator is 260Khz, but the captured ringing noise frequency is around 83Mhz as shown in the below screen shot 12 nSec (hope i have captured the timing properly) 

Hello

What is the repetition rate of the burst of noise ?

Thanks

Hello Frank, 

For every 268 kHz, burst of noise is repeating, below screen shot is for your reference

Hello

That is at the switching frequency.  So, it seems like

noise is getting into your output.

It may be a PCB layout issue, such as grounding.

Can you give us images of your PCB layout.

Also, it could be switching pulse getting through the inductor.

You could try a small ceramic capacitor on the output to shunt the noise.

Thanks