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TPS61088: About relationship between PCB area and thermal

Tsukui Yusuke
Guru 21930 points
Part Number: TPS61088

Hi,

Could you tell me about relationship between PCB area and thermal.
Customers are trying to use TPS61088 under the following conditions.

Vin：3.0~4.2V
Vout：5.0V
Iout：4.5A

Customers simulate using Webench.
However, because the actual board size is 20mm × 30mm, customers are concerned about heat issues.
Could you give your advice on the following questions?

1.Customers are requesting additional information beyond the Thermal Information in the data sheet.
   And Customers want thermal information on the actual board size as much as possible.
   Could you give me information about the relationship between PCB size (20mm × 30mm) and thermal?

2.Please tell me the specifications and size information of the PCB used by Webench.

Regards,
Yusuke

  • 0
    TI__Mastermind 40080 points

    Dear Sir,

    The pcb size in the webench is at least > 3mmX7mm.

    Your output power is really big, its very close to the maximum output capability of TPS61088. So for the 2mmX3mm small size, please use at least a 4-layer board to handle the thermal. The copper thickness at least 1oZ.

  • 0 in reply to Helen chen
    Guru 21930 points

    Hi Helen,

    Thank you for your response.
    >The pcb size in the webench is at least > 3mmX7mm.
    >So for the 2mmX3mm small size, 
    Isn't the answer here 30mmX70mm and 20mmX30mm instead of 3mmX7mm and 20mmX30mm?

    I have one more question.
    >Your output power is really big, its very close to the maximum output capability of TPS61088. 
    What did you judge ”Your output power is really big, its very close to the maximum output capability” based on?
    Could you give me additional information about the criteria and calculation method?

    Regards,
    Yusuke

  • 0 in reply to Tsukui Yusuke
    TI__Mastermind 40080 points

    Dear Sir,

    Yes, it should be 30mmX70mm.

    For the TPS61088, its peak switch current is about 10A. in this applicaiton, Ipeak=1.2*Vo*Io/(Vinmin*eff.), it is very close to the 10A.

  • 0 in reply to Helen chen
    Guru 21930 points

    Hi Helen,

    Thank you for your kind support.
    I told your advice to the customer.
    >So for the 2mmX3mm small size, please use at least a 4-layer board to handle the thermal. The copper thickness at least 1oZ.
    I received a question from a customer about this.

    １．”4-layer board”
    This intention is to improve heat dissipation by passing vias through the 4-layer board.
    Is this understanding correct?

    ２．”The copper thickness at least 1oZ”
    Should one ounce copper thickness be applied to all layers?
    Please tell me a detailed image.


    Could you give me your advice?

    Regards,
    Yusuke

  • 0 in reply to Tsukui Yusuke
    TI__Mastermind 40080 points

    Dear Sir,

    Please check my answer below:

    １．”4-layer board”
    This intention is to improve heat dissipation by passing vias through the 4-layer board.
    Is this understanding correct?  

    Answer: Yes. Please refer to the layout of the TPS61088 datasheet.

    ２．”The copper thickness at least 1oZ”
    Should one ounce copper thickness be applied to all layers?
    Please tell me a detailed image.

    Answer: Yes. at least 1oz to all 4 layers.