ADP7142 / LT3088: Choice of Rset bypass capacitor

Just refer to the datasheet on what type of capacitor should you use on your design when using these parts. There is a Capacitor Selection guide on the Applications Information section (page 14) of the datasheet.

Regards,

Nino

As far as I have understood the data sheet , there is apacitor selection only for the Input and Output Capacitor, but not for the noise reduction capacitor CNR on page 15.

Will a Metallized Polyester (PET) Capacitors (e.g. MKS2) have a better performance than a X7R ?

In cases like these you can consult the schematic/BOM of the respective evalKit and take the used components as guideline. LT3088 (DC2279A) for example uses a ceramic type COG at ISET:

Thanks for the hint looking into EvalBords too!

Interesting that in the LT3088 data sheet for most of the specs a 0.1 µF for  C3 (=Cset) is used and not the 0.01 µF used in the EvalKit

In the ADP7142 UserGuide (UG-616) a MLCC is used for the noise reduction capacitor. For a 1 µF as it is used in the data sheet, a X7R will probably be the choice.
Neglecting size and price, still the question for me if a metallized polyester with it advantages like the lower dependency of capacitance on DC bias will be abetter, equivalent or worse choice..

Normally we go with SMD components only and look for most space saving solutions, hence ceramic MLCC like X7R are a valid choice for those apps. As ISET voltage level is quite low (and fixed) the biasing effect on ceramic caps might be neglectable.

You are right, when looking at a typical 1µF 50V X7R MLCC, I do not see a capacitance drop at 1.2 V, hence using a MLCC will bei the choice.

The circuit is for 32V Vin (24 VAC rectified and smoothed) and 24V Vout. For these voltages, using  4.7 (or even higher) µF input and output cap may be necessary considering the X7R biasing effect?
Organic Polymer of this capacitnace have a higher ESR compared to the X7R as far as I remember and be a worse choice I guess..