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DRV8912-Q1: Operating temperature of DRV8912

Huanfeng Ren
Prodigy 70 points
Part Number: DRV8912-Q1

Dear team,

My customer meet some problems while using DRV8912-Q1.

He is considering parallel all channels to generate 6A output current.

He combines the parallel resistance and parameter of junction-to-ambient thermal resistance to calculate the operating temperature.

 

T=I2R×RθJA=62×0.25×30.2=271.8℃

 

Could you please help me to analyze whether his calculate idea is correct?

Is the operating temperature normal?

Many thanks!

BR,

Huanfeng.

  • 0
    TI__Mastermind 45075 points

    Hi Huanfeng,

    Calculation is not correct. Please refer to Datasheet 9.3 .1 Power dissipation.

    Assuming all 12 channel in parallel (I do not think this is reasonable way, I recommend different device), PFB(9.3.1.1) is followings.

    P_FBCONT = (Irms)^2 * (Rdson highside + Rdson + lowside)

    Then : Irms=6A. DRV8912 has 6-Full bridges(12 half bridges) --> Rdson high + Rdson low = 0.75ohm/6 +0.75ohm/6 = 0.25ohm

    P_FBCONT= 6*6*0.25 = 9W

    Tj = 9W * 30.2 + 27C(room temp) = 298.8C. This Tj is too high.

    Device hit thermal shut down (175C).  It does not work at all. 

    By the way, if customer want to driver 6A motor, DRV8243Q1, DRV8244Q1, DRV8245Q1 is good one to take a look. If customer need 6A contiouse(>10sec), DRV8245Q1 is one to pick up.

    regards

    Shinya Morita