How much can the capacitance on Vin and +5V be reduce for the PF3000

[ryanmartin]

We are using the PF3000 as a PMIC for a i.mx7 USB 2.0 peripheral device.  The inrush current when connected to Vbus is greater than the USB specification allows.  USB allows for 10uF of bus facing capacitance at a plug event.  The reference design for the PF3000 uses (2) 47uF capacitors at both the Vin and +5V rails.  can this be reduce to 10uF?  what are the tradeoffs?

thanks,

ryan

[reyes]

Hi Ryan,

Yes, you can reduce this capacitor to 10uF, the effects that you might see would be that, depending on how clean is the power signal in your design, with lower capacitance on this point you will have higher voltage spikes since the voltage charge will be quicker, but I don’t think this could be a problem using 10uF capacitor.

Regards,

Jose

NXP Semiconductors