TPS22918-Q1: TPS22918-Q1

Hello User,

To calculate the inrush current with your capacitance you would use the equation I = Cout*(Vout/dt)

Our device can limit the slew rate by changing the capacitance value on the CT pin. The equation for that is: SR = 0.55 * CT +30  (uS/V)

The dt in the first equation can be found by multiplying the SR by your input voltage.

An example calculation using 100pF: 

SR = 0.55*100+30 = 85 uS/V

dt = 85 uS/V * 5 = 425 uS

I = 200*10^(-6) * (5/(425*10^(-6)) = 2.35 A

By changing your CT value and limiting your slew rate you can reduce the inrush current.

Regards,

Kalin Burnside

Hello User,

I apologize for missing the original thread and assuming your question. 

The 200uF max is determined from the current allowed to flow through the internal QOD resistance when the device is disabled. It's based off certain rules that need to be followed for the QOD circuity and if exceeded it can have an effect on the long term reliability of the device. If you need to go beyond 200uF in your design then you must use an external resistor to limit the current flow.

Regards,

Kalin Burnside