UCC28740: Ultra Low Noise SMPS

Ram Kumar

Part Number: UCC28740

We are working on ultra low noise SMPS using UCC28740 PSU.pdfI am having issue with feedback circuit of SMPS design , We want to know the best values of R11 ,R20 ,R37,R38,R40 ,C23,C24, to suppress the noise at 5.5KHZ and other frequencies below 1uV.( Pl refer graph)

Feedback circuit and Noise graph is attached “

over 7 years ago

0 Benjamin Lough over 7 years ago

TI__Mastermind 27145 points

Hi Ram,

Thanks for your interest in UCC28740. By noise, are you referring to noise on the output voltage?

Best Regards,
Ben Lough

0 Ram Kumar over 7 years ago in reply to Benjamin Lough

Prodigy 235 points

Yes you are right.I am referring to the output noise at the 5V output voltage.

0 Benjamin Lough over 7 years ago in reply to Ram Kumar

TI__Mastermind 27145 points

Hi Ram,

Thank you for the additional information. You could add some ceramic capacitors in parallel to C14 with the goal being to drive down the output impedance in the 5kHz to 20kHz range. Another option is to tune the damping of your pi filter.

These application notes might be useful to you:
www.ti.com/.../slyt720.pdf.
www.ti.com/.../snva538.pdf

Best Regards,
Ben Lough

Power management

Power management forum

UCC28740: Ultra Low Noise SMPS