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TMS320F280039: VDD pins & decoupling capacitors

Guillaume Henri
Expert 3976 points
Part Number: TMS320F280039

Hi champs,

 

On a new F280039CSPZ (100 pins) design, in case of using the internal 1.2V reference :

Is it necessary to connect all VDD pins to the same plane as on the first schematics?

Or could the VDD pins have their owns decoupling capacitors as on the second schematics?

 

Indeed the datasheet specifies that “In internal VREG mode, tying the VDD pins together is optional as long as each VDD pin has a capacitor on it.”

but we like to be sure that not connecting them will not cause any performance issue.

Thank you!

Best regards,

Guillaume

 



Schematics 1

Schematics 2

  • 0
    TI__Mastermind 40865 points

    Hi Guillaume,

    Guillaume Henri said:

    Or could the VDD pins have their owns decoupling capacitors as on the second schematics?

     

    Indeed the datasheet specifies that “In internal VREG mode, tying the VDD pins together is optional as long as each VDD pin has a capacitor on it.”

    The 2nd schematic is OK, but would suggest dividing up the total VDD Capacitance we document (10 ~ 26.8uF) across all the VDD pins if the VDD pins are not all connected on the PCB. Currently there is just one 10uF to meet C_VDD TOTAL.

    In summary, recommend following configuration 1 below when VDD pins are not all tied together on the PCB.

    Best,

    Kevin