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Original question:

TPS61378-Q1: Schematic Review

TPS61378-Q1: Schematic review

Pawee Jane
Prodigy 60 points
Part Number: TPS61378-Q1

Dear, Team

Could you please help review the schematic?

The spec is as follows : Vin = 6-8.3V, Vout = 14V, Iout(Max) = 1.14A, Efficiency 90%

7510.pdf
Thanks & Best Regards,

  • 0
    TI__Mastermind 34231 points

    Hi Sir,

    Please change capacitor C9 to 1nF. 1uF is too large for compensation network. Other parts look good.

  • 0 in reply to Zack Liu
    Prodigy 60 points

    Thank you for your suggestion.

    If I have 2 options, Details in the table below.

    Can you please advise me a value that can be used in both versions (especially the inductor)?

    Version #1 #2
    Vin (V) 10.8-13.2 6-8.3
    Vout(V) 14 14
    Iout(A) 1.14 1.14

    The table below are from WEBENCH and the RED text is a difference value from 2 versions that I need your advice.

    No.
            Part
    		 WEBENCH
            Unit
    VIN#1 VIN#2
    1 Rfbb 80.6 80.6 kohms
    2 Rfbt 1.33 1.33 Mohms
    3 Rent 787 392 kohms
    4 Renb 100 100 kohms
    5 Ccomp 680 680 pF
    6 Rcomp 59 86.6 kohms
    7 Cbst 100 100 nF
    8 Rilim 20 20 kohms
    9 Cin 10 10 uF
    10 Rpg 100 100 kohms
    11 Coutx 1 1 uF
    12 L1 2.5 1.8 uH
    13 Rt 41.2 18.2 kohms
    14 Cvcc 1 1 uF
    15 Cout 22 22 uF
    16 CoutIso 1.5 1.5 uF

    Version#1

    Version#2

  • 0 in reply to Pawee Jane
    TI__Mastermind 34231 points

    Hi Sir,

    For some unknow reason, I cannot open the google drive files. Could you share the schematic and BOM directly on E2E?

  • 0 in reply to Zack Liu
    Prodigy 60 points

    Yes, please see the attach file below.

    TPS61378 - Sheet1.pdf

    Thank you

  • +1 in reply to Pawee Jane
    TI__Mastermind 34231 points

    You can use 2.2uH inductance for both two cases.

  • 0 in reply to Zack Liu
    Prodigy 60 points

    Dear Team, 

    Different input voltage ( 6V-8.3V , 10.8V-13.2V ) .If I use common values for the discrete components.

    (use 2.2uH inductance from your recommence and other parts use value in Column VIN#2 from table above. VIN#2 -> : Vin = 6V-8.3V ) 

    What would be the expected output when doing so  ? 

    Please let me know if you have any question.

    Thank you

  • 0 in reply to Pawee Jane
    TI__Mastermind 34231 points

    Hello Pawee,

    The output is set by feedback resistors. Vout=(Rfbt/Rfbb+1)*0.8=14V.

  • 0 in reply to Zack Liu
    Prodigy 60 points

    HI Zack,

    I'm sorry to misunderstand you .

    From previously I mean I have 2 versions (2 different input voltage) but both version need the same output(14V ,1.14A).

    So both version have different values for components like Rent, Rcomp, Rt .

    If I need 1 circuit for 2 versions.

    Can I use Rent, Rcomp, Rt : 392K, 86.6K, 19.2K respectively for 2 version?

    No.
           Part
    		 WEBENCH
            Unit
    VIN#1 VIN#2
    1 Rfbb 80.6 80.6 kohms
    2 Rfbt 1.33 1.33 Mohms
    3 Rent 787 392 kohms
    4 Renb 100 100 kohms
    5 Ccomp 680 680 pF
    6 Rcomp 59 86.6 kohms
    7 Cbst 100 100 nF
    8 Rilim 20 20 kohms
    9 Cin 10 10 uF
    10 Rpg 100 100 kohms
    11 Coutx 1 1 uF
    12 L1 2.5 1.8 uH
    13 Rt 41.2 18.2 kohms
    14 Cvcc 1 1 uF
    15 Cout 22 22 uF
    16 CoutIso 1.5 1.5 uF

    Thank you

  • +1 in reply to Pawee Jane
    TI__Mastermind 34231 points

    Hello Pawee,

    You can use 392k for Rent for both circuit. Use 59k for both Circuit. But Rt decides the switching frequency, it's better to follow the WEBENCH recommended value for two different Vin condition.