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AM5718: Recommended decoupling capacitors

unnati yadav
Prodigy 10 points
Part Number: AM5718


Decoupling capacitor recommendation details(Table 2) in http://www.ti.com/lit/pdf/spraby8 is not sufficient. Nowhere, It has mention about type of capacitor (Tantlum/Electrolytic or ceramic). Table 2 doesn't have the details for other power supplies 

(vdda_gpu
vdda_hdmi
vdda_osc
vdda_pcie
vdda_pcie0
vdda_rtc
vdda_sata

vddshv1
vddshv2
vddshv3
vddshv4.and so on).

The AM5718 reference design (http://www.ti.com/lit/df/sprr242/sprr242.pdf) does not follow the above recommendation. Why so? Moreover, capacitor recommendation details in http://www.ti.com/lit/pdf/spraby8 is for AM572X. 

Is there any document where I can refer regarding AM5718 power supply decoupling capacitor recommendation?

regards,

Unnati)

  • 0
    TI__Guru**** 393215 points
    The factory team have been notified. They will respond here.
  • 0 in reply to Biser Gatchev-XID
    TI__Mastermind 46460 points

    Unnati,

    The example capacitors listed are all ceramic SMT chip capacitors.  Decoupling at the higher frequencies requires use of ceramic chip capacitors.

    You referenced the AM571x IDK EVM schematic SPRR242.zip.  This is a good, conservative implementation that should be sufficient as long as good PCB design practices are followed.  It does contain more capacitors than stated in SPRABY8.  The list in SPRABY8 shows the absolute minimum requirement and the PCB implementation must have very low loop inductance for each capacitor.

    A detailed analysis of the decoupling requirements for the VDDSHVxx I/O supplies and the analog VDDA_xxx supplies is not available.  The implementation shown in the AM571x IDK EVM schematic SPRR242.zip is a good model to follow.

    Tom