PCA9306-Q1: the way to handle of EN and Vref pin

Yamamoto-san,

Thank you for your questions.

Answer 1) We recommend 200k ohm pull up on the node that shorts VREF2 and EN together because the VREF2 pin is regulated to a voltage of roughly VREF1 + 0.7V. This is the voltage that is then applied to the EN pin. THis is important for voltage translation to properly bias the translation gates for an open drain setup. The 200k value is not a hard requirement, merely a recommendation, but it done so to cut down on power consumption. You should be able to use values ranging from the ballpark of 10k to 500k without issue, but we find that 200k is a good middle-ground value to go with.

Answer 2) Yes, you can use 47k without issues, just note that you will see roughly 4x the power consumption values from the VDPU rail.

Answer 3) I do not know what you mean by RC filter. I think you are referring to the decoupling cap. Keeping the standard recommended capacitor size is sufficient. The point of the capacitor is mainly for decoupling at the VREF/EN node to clean up any noise from the translation.

Dear Jonathan,

about your answer 3;
My customer will use 100 pF capacitor.
Is this the standard recommended size?

Best regards,

Yamamoto-san,

Yes. 100pF is standard practice for a decoupling capacitor and would be suitable in this application, as well.