TPS63070EVM-693: Output Ripple Voltage

Hi Sadanori:

Thanks for asking. I have no such graph at hand. Please wait me do a test.

I'll share it today if everything going well.

Hi Minqiu-san,

Thank you for your quick response.

I am looking forward to getting the information from you.

Best regards,
Kato

Hi Minqiu-san,

Thank you for the information.

According the screenshot, is the output ripple voltage less than 30mVpp ?
Could you please meareue the peak to peak voltage just in case ?

Best regards,
Kato

Hi Minqiu-san,

I have an additional question, is the output load which you used the electronic load with the current mode ?

Best regards,
Kato

Hi Minqiu-san,

Thank you for your strong support.

I understood and will contact you if I get additional questions from our customer.

Best regards,
Kato

Hi Minqiu-san,

I just got additional questions as follows.

Q1. Filter Setting for Oscilloscope
Could you please tell me the filter setting for the oscilloscope ?

Q2. Remeasurement
Could you please measure the output ripple voltage with disabling the low pass filter if limiting the bandwidth with the low pass filter ?

Best regards,
Kato

Hi Minqiu-san,

Thank you for the information.

Adding a ferrite bead to the output is a workaround, but should a π-type filter be formed ?
Additionally, please tell me the capacitance value to be added.

Best regards,
Kato

Hi Kato-san:

I didn't add any more caps for EVM.

And may you share the details requirements with us?

Hi Minqiu-san,

The output ripple voltage(620.89mVpp) is higher if disabling the low pass filter with an oscilloscope.
This symptom is consistent with the results measured by our customer with TPS63070EVM-693.
So, could you please tell me the recommended workaround to reduce this ripple noise ?

Best regards,
Kato

Hi Kato:

I'll recommed to add a ferrite bead. Like 100ohm/100MHz. As it depends on the system design and requirement. So I'am not sure the spec is the most suitable one.

A π filter could reduce the noise as well, but it may decrease the efficiency. 

Besides, you could also replace the cap close to Vout pin with smaller size and less parasitic parameters, and add another 10uF with other caps.

Hi Minqiu-san,

Thank you for the information.

I will inform your comments to our customers.

By the way, the output ripple voltage seems to be large, so what is the reason ?

Best regards,
Kato

Hi Minqiu-san,

Thank you for your quick response.

I will suggest our customer to add small size capacitors such as 1nF and 0.1uF.

Best regards,
Kato