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TPS53015: Questions about Figure 18 of the datasheet

Kazuhiko Hirano
Genius 11573 points
Part Number: TPS53015

Hello,

My customer has some questions about TPS53015 as follows.

Q1
How customers can calculate or decide R2, R5, R9 and C12 values of Figure 18 of the datasheet.

Q2
What are R7 and D1 for at Figure 18 of the datasheet?
How to determine those values?

Beat regards,

K.Hirano

  • 0
    TI__Mastermind 28620 points

    Hello Hirano, , 

    Question1: 

    • Select an R2 value between 10 kΩ and 100 kΩ and use Equation 11 to calculate R1.
    • R5 is the BST  resistor use ~5.11ohms 
    • R9 and C12 are the snubber circuit. You can use the same value as the EVM and the datasheet, they are already been calculated for you. If you wnat to know how they are calculated, please look into this  

    Power Tips: Calculate an R-C snubber in seven steps - Power management - Technical articles - TI E2E support forums

    Question2:

    R7 and D1 that is voltage clamping circuit to protect the device from reverse  voltages on the SW pin to GND.  The SW is rated NOT to go outside the abs max of -300mV to 30V. 

    SO any reverse voltage outside that range risk damaging the device, and thus that circuit is recommended to clamp the SW voltage. For D1, we typicall look into the reverse voltage the forward voltage that we want to protect against  

    Thanks! 

    Tahar

  • 0 in reply to Tahar Allag
    TI__Genius 11573 points

    Tahar,

    Thank you for your responses.
    For R2, you and datasheet say between 10kohms to 100Kohms.
    But, looking at Figure 18 or EVM Users Guide, R2 is 10ohms, not 10Kohms.
    Which is correct, ohms or Kohms?

    Best regards,

    K.Hirano

  • +1 in reply to Kazuhiko Hirano
    TI__Mastermind 28620 points

    Hi Hirano, 

    I see where the confusion is, in your question above, you are referring to Figure 18 in page 17. R2 in there is the HS FET gate resistor that needs to be 10ohms 

    The datasheet we are talking about R2 in equation 11 in page 19. that is the Rbottom of the feedback network that needs to be 10K to 100K and uses equation 11 to calculate R1 based on the desire VOUT. 

    I guess the datasheet should not refer to two R2's that are used for two different purposes

    Sorry for that confusion. 

    Thanks! 

    Tahar

  • 0 in reply to Tahar Allag
    TI__Genius 11573 points

    Tahar,

    I see, thanks a lot!

    Best regards,

    K.Hirano