TJA1100 dimensions of capacitances of the PI-filters

[jerrry]

Hi NXP-community,

I have a question about the PI-filters and their dimensions of the capacitances.

In the application-hints of TJA1100 there are shown two figures, firure 6 and figure 13.

The capacitance right to the supply coming from the LDO, what is the dimension? Are them the 22µF shown in figure 13 or not? So if they are, then my PI-filter will be build this way:  supply(3V3) -> cap(22µ) -> ferrite -> cap(470n) ? (f.e.VDDA(3V3)).

Am I correct? So I only unsure aboiut the cap after the LDO.

Thanks in advance.

Jerrry

[TomasVaverka]

Hi Jerome,

Yes, the 22uF electrolytic capacitor at the voltage regulator output is recommended to reflect the buffering needs of the TJA1100. A higher value may be needed when also considering the buffering needs of your MCU.

Best regards,

Tomas

PS: If this answer helps to solve your question, please mark it as "Correct". Thank you.

[jerrry]

Hi Tomas,

thank you for your response. I added a PI-filter to every supply pin and dimensioned the capacitance for every filter input 10µF. Summed up I now have a bit more than the recommended 22µF. So for every pin (instead of the 1V8) this PI setup (LDO -> 3V3 -> cap(10µF) -> ferrite -> cap(recommended).

Thanks again and best regards.

Jerrry