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TPS563257: Schematics Review

Nachiketh Karanth
Intellectual 530 points
Part Number: TPS563257

Hello,

Requesting to review the schematics of TPS563257DRLR, Vin, Vout and Iout are mentioned in the document along with schematic.

Link of the document is provided below.

/cfs-file/__key/communityserver-discussions-components-files/196/TPS563257DRLR.pdf

Regards,

Nachiketh

  • 0
    TI__Mastermind 20980 points

    Hi Nachiketh,

    Thanks for reaching out! I will check and get back to you soon.

    BRs

    Lucia

  • 0 in reply to Lucia Gao
    TI__Mastermind 20980 points

    Hi Nachiketh,

    Would you mind sharing me the application of TPS563257? For schematic review comments, please kindly change the value of the inductor from 200nH to 680nH.

    Thanks!

    BRs

    Lucia

  • 0 in reply to Lucia Gao
    Intellectual 530 points

    Hello Lucia,

    Its used for a specific voltage rail in FPGA.

    Based on the equation for inductor i got 200nH, can you please explain how you got 680nH.

    Regards,

    Nachiketh

  • 0 in reply to Nachiketh Karanth
    TI__Mastermind 20980 points

    Hi Nachiketh,

    Thanks for sharing! BTW, would you mind sending me your equation? I can help check. Thanks!

    BRs

    Lucia

  • 0 in reply to Lucia Gao
    Intellectual 530 points

    Hello Lucia, 

    This is the equation i used,

    L= ( Vout x ( 1 - ( Vout / Vin ) ) / ( 2 * Freq * NOC(min) )

    where,

    Vout = 0.85V

    Vin = 5V

    Freq = 1.2 MHz

    NOC(min) = 1.5A

    Regards,

    Nachiketh

  • +1 in reply to Nachiketh Karanth
    TI__Mastermind 20980 points

    Hi Nachiketh,

    Thanks for sharing. This equation is to check whether it will trigger NOC. 

    Actually, there are other things need to take into consideration. 

    To calculate the value of the inductor, LIR is used. LIR is a coefficient that represents the amount of inductor ripple current relative to the maximum output current. In every cycle, inductor current is LIR times of max output current from below first equation. The inductor ripple current is filtered by the output capacitor. Therefore, choosing high inductor ripple currents impact the selection of the output capacitor since the output capacitor must have a ripple current rating equal to or greater than the inductor ripple current. A good rule is that LIR is normally from 0.2 to 0.5 for the majority of applications. So inductor can be received with second equation shown below based on this rule.

    Thanks! Kindly let me know if you have any further concern.

    BRs

    Lucia