Do you know if the 5528’s USB LDO has any built-in delay during the power-up sequence (or any other mechanism) to help handle the in-rush current while plugging in the USB cable? I was researching USB power best practices for bus-powered peripherals, and found this from FTDI:
2.4.2 Bulk capacitance vs. inrush current – USB peripheral devices
For bus-powered peripherals, the USB 2.0 specification requires VBUS inrush current limiting equivalent to 10μF capacitance in parallel with a 44Ω load for the following conditions:
- Initial plug-in
- Upon enumeration and power negotiation of a high-power circuit
- Upon resuming from a sleep or suspend condition.
Larger bulk capacitance may be used, provided power is applied with a soft-start method so that the inrush specification is not exceeded. The FTDI FT-series ICs provide a Power Enable (PWREN#) signal to facilitate switching of a P-channel FET. An example soft-start RC circuit with PWREN# is shown in Figure 2.4.
Thanks again!
Paul
