AM5726: VDDA33V_USB decoupling capacitors

UNA

Part Number: AM5726

Hi,

I have a question about capacitor value of VDDA33V_USB power line.
A 0.1uF, 0.001uF, 10uF capacitors are mounted on the evaluation board, is it possible to remove this 10uF capacitor if USB function is not used?
My customer is considering whether it can reduce the capacitor to care for the inrush current.

Best regards,
H.U

over 7 years ago

0 Biser Gatchev-XID over 7 years ago

TI__Guru**** 393215 points

Hi,

See processors.wiki.ti.com/.../AM57xx_Schematic_Checklist

0 UNA over 7 years ago in reply to Biser Gatchev-XID

Mastermind 7980 points

Hi Biser,

The checklist does not describe the capacitor when USB is not used, so are you say that decoupling capacitor is unnecessary when USB is not used?

Best regards,
H.U

0 Biser Gatchev-XID over 7 years ago in reply to UNA

TI__Guru**** 393215 points

From the checklist, what I mean is:

"AM572x/AM571x: Connect VDDA33V_USB1 or VDDA33V_USB2 terminal to any 3.3-V power supply. If the system does not have a 3.3-V power supply, these terminals may be connected to ground."

0 UNA over 7 years ago in reply to Biser Gatchev-XID

Mastermind 7980 points

Hi Biser,

It seems my explanation was not clear enough.

If peripherals other than USB function use 3.3V power rails.
In that case, I think that it is necessary to connect VDDA33V_USB1 or VDDA33V_USB2 to those 3.3V power rail.
Please tell me about capacitor requirements in that case.

"AM572x/AM571x: Connect VDDA33V_USB1 or VDDA33V_USB2 terminal to any 3.3-V power supply. If the system does not have a 3.3-V power supply, these terminals may be connected to ground."

Best Regards,
H.U

0 -DK- over 7 years ago in reply to UNA

TI__Mastermind 27890 points

Hello H.U.,
If you are not using USB at all, you can connect these pins directly to any 3.3V as per the schematic checklist recommendation. Decoupling is not required.

I've updated the Wiki to reflect this as I think this may be a common question that we were not specifically addressing.

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AM5726: VDDA33V_USB decoupling capacitors