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TPS22990 max Cload

Kai Hsiao
Guru 12675 points

Other Parts Discussed in Thread: TPS22990

Dear Sir 

May I know max Cload for 5Vin in TPS22990 

Datasheet just describe 10uF test result ,but we may have 50uF Cload and 5mS soft start delay 

I can't make sure TPS22990 could be use large cap

Thanks 

  • 0
    TI__Genius 15800 points

    Hi Kai,

    Using the inrush current equation in the TPS22990 datasheet (I_INRUSH = C_OUT x 0.8 x V_IN / t_R), an inrush current of 40mA is expected for t_R = 5ms and C_OUT = 5V.  When the device is first turning on, VIN=5V and VOUT=0V, so the total power being dissipated across the load switch is V x I, or 5V x 40mA.  This means that 200mW is being dissipated across the device.

    The junction-to-ambient thermal resistance for the device (R_thetaJA) is 51.4C/W, so for every watt of power the device heats up 51.4 degrees.  For 200mW of power, the device only heats up about 10 degrees.  Even with 100uF of capacitance, 400mW of power would be dissipated across the device and it would only heat up about 20C.

    Aside from the output capacitance, what is the value of the current load being driven by the device?  This can increase the power dissipation during turn on and cause the device to heat up more.

    Thanks,

    Alek Kaknevicius