TPS7A4533: TPS7A4533 PSRR vs Drop Out Voltage

Hi John,

Looking at the data for this graph, I was not able to find the output voltage used. I was able to find that the input voltage was 2.7V, the output capacitance was 10uF, the input capacitance was 0uF, and the load current was 750mA. We also do not have any additional curves for lower drop out voltages.

Thanks,

Alek Kaknevicius

Hi Alex,

Thanks for your reply but I need more info.  PSRR is highly dependent on Vin-Vout and I have a customer who wants to operate very close to the specified drop out voltage.   I need to provide some guidance to the customer on how close he can get to the drop out before he runs into major issues with PSRR.  If we have a figure in the data sheet that demonstrates PSRR or ripple rejection its critical that the we know how close the LDO is operating with respect to its drop out voltage.  Please let me know who I can talk further with about this?

Thanks, John Garrett TI-AFA

Hi John,

Can you provide me the customer parameters and what measurements it would be helpful for the customer to have? That way I can go down into the lab and collect this data.

Thanks,

Alek Kaknevicius

Hi Alex,

Thank you!

The basic requirements are using the TPS7A4533 to power a OCXO with Vout = 3.3V @ 600mA. They presently have Vinmin = 4.2V but they would like to operate down to Vinmin = 3.8V but that depends on PSRR.

Thanks again, John Garrett, TI-AFA

Hi John,

Thank you for the information about your application. I needed to order an EVM to take the measurement so please allow some time for me to take the measurement.

Very Respectfully,
Ryan

Hi John,

I apologize for the delay in shipping.  Here is PSRR across frequency and headroom.

Very Respectfully,

Ryan