Fluctuations in smps output.

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Hello there. I created a SMPS design using the tinyswitch 4 integration and your desktop design program. I got 5V and 12 volts from the output of SMPS. However, too much fluctuation occurred in the output voltages. what would you suggest to reduce the amplitudes of these fluctuations?

Hi,
Thank you for using power integrations product.
Can you provide me the schematic?
What is the output voltage and current of this design?
By saying voltage fluctuations, Are you referring to the output ripple?
Do you have waveforms of these fluctuations?

Dear PI-Phlox
I mentioned the output fluctuations in the output voltage.

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150ma loading situation7.93 KB
PI_TNY284_TLV.pdf176.12 KB

Hi eyupozaslan,

Based on your schematic and waveform, only the 5V output is regulated. You can improve the ripple on the 12V by trying the ff:
1. Increase the 12V output capacitance. The 5V has a total of 780uF, while the 12V only has 47uF
2. If you want to improve regulation, you can add a feedback resistor from 12V to R8. Your feedback loop will then become a weighted sum between the 12V and 5V feedback resistors.

There is similiar problem in 5V output.

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5V_output_-170_mA.pdf8.23 KB

Hi,
You can try adjusting the TL431 compensation circuit to type II configuration. In your schematic you are using type I - only C10 between the opamp input and output. Type II will give you better dynamic response.

You can see RDR-295 for an example.