increase PSRR for LDO vs Buck?

Hello,

Thank you for your question.  In general, LDO's will be lower efficiency versus buck converters.  However, most switching converters will have higher output voltage ripple, and higher integrated noise. Can you provide a little more about your application and your PSRR requirements? Do you also have ripple and noise requirements?

Hi Steve,

• 100mA output min
• good low load regulation
• Vout 0.7-4.5V adjustable
• PSSR > 40dB between 100KHz - 2MHz

I know cout can be increased to improve PSRR on buck, but I am not sure if it can be equivalent performance to LDO. I just want guidance on different factors to look into as most buck datasheets do not specify PSRR and LDOs do.

Thanks,

Connie

Hi Steve,

Is there any part that may fit the requirement above that can sink current?

Thanks,

Connie

Connie,

Please allow me to look into this a bit more.  Most of our DC/DC buck converters do not provide the PSRR in the datasheet, but data may be available. Some of the modules do provide the information, such as the TPS826721, but it does not meet the PSRR requirements  you describe without a post-regulation LDO.  Can you also provide what input voltage you need? And you need to sink and source current?  Can you describe the application in more detail?