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Original question:

TPS40322: Multiphase operation and switching frequency selection

TPS40322: Multiphase operation and switching frequency

Arun Gomathi R
Prodigy 70 points
Part Number: TPS40322

Tool/software:

Hi, 

As per the datasheet, considering the max values of HRDV & LDRV pull up & down resistances and a Rg of 5 ohms & VDD = 5V,

1. HDRV source current = 4.9/(2.5+5) = 0.65A
2. HDRV sink current = 4.9/(1.6+5) = 2.33A
3. LDRV source current = 4.9/(2.5+0) = 1.96A
4. LDRV sink current = 4.9/(1.3+0) = 3.78A

Are the above calculations are correct?

And to consider the junction temperature rise based on the power dissipation of the controller, there is no specific graphs in the datasheet for HRDV & LDRV gate currents vs Junction Temperature. 

Request your support on this concern.

Regards,
Arun Gomathi R
Hardware Design Engineer
DATA PATTERNS INDIA LTD
Chennai.

  • 0
    TI__Mastermind 28200 points

    The divers supply voltage is BP = 6.5V typical. So in your calculation 4.9V should be 6.5V.

    The junction temperature should be calculated based on device power dissipation and junction to ambient thermal resistance

    Device power dissipation is Pd = (Idd + 2*Qg*Fsw)*Vdd.

    Qg is the power FET gate charge

    Fsw is the switching Frequency 

    Vdd is the device supply voltage

    Idd is the device supply current

    Tj - Ta = Pd*RθJA

    Regards