Other Parts Discussed in Thread: TPS62750,
Hi team,
I have a general question about interpreting the USB 2.0 spec regarding current limiting. I see that section 9.2.5.1 Power Budgeting it states that "USB devices shall limit the power they consumer from Vbus to one unit load (i.e. 100mA) or less until configured." With enumeration this can be increased to 500mA.
My question is for peripheral devices that are not hubs (usb powered mouse for example), is it required to guarantee this current limit with external hardware, like the TPS2140, or the TPS62750? Or if the designer can ensure the load will never exceed 100mA before enumeration and 500mA after enumeration can this hardware be omitted? For example, the start-up max current is 50mA and after enumeration the system can fully power up to 200mA load. In this case can no current limit switch be used and still meet the USB 2.0 specification?
If my understanding is correct, then the TPS2140 and TPS62750 would mostly be targeted at USB hubs or other applications where the load currents are unknown and could exceed the limit.
Thank you for the insight,
Nate
