Buck circuit ripple test oscilloscope settings problem

dianhang

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Buck circuit ripple test oscilloscope settings problem

The buck circuit outputs 3.6V, and the output ripple is tested with an oscilloscope. When the oscilloscope is set to 500mV/div, the ripple voltage is 80mv; when the oscilloscope is set to 200mV/div, the ripple voltage is 32mv. Which parameter is reasonable, or which gear is more appropriate?

qwqwqw2088

The oscilloscope uses AC coupling, and the probe ground wire should be as short as possible.

dianhang

qwqwqw2088 posted on 2021-3-9 15:44 When using AC coupling for oscilloscope, the probe ground wire should be as short as possible

Yeah, yes.

Spring loaded ground clip for AC coupling bandwidth limited to 20Mhz

I just want to know, different gears, the ripple will be different

qwqwqw2088

dianhang posted on 2021-3-9 16:12 Yes, the AC coupling bandwidth is limited to 20Mhz. I just want to know if the ripple will be different in different gears...

It can only be said that the ripple should be the same when measured at different small ranges, and the error is not large.

Can be in a smaller gear

If the range is large, the noise floor of the oscilloscope will be large

1nnocent

Then 200mV/div is definitely reasonable. If you are measuring a 66cm piece of wood and you are given a ruler with 1 decimeter and 1 centimeter scales respectively, which one do you think is more accurate?

dianhang

1nnocent posted on 2021-4-2 15:07 Then 200mV/div is definitely reasonable. If you measure a 66cm piece of wood with a ruler with 1dm and 1cm scales respectively, which one do you think is more accurate...

Thank you for your answer