Applying voltage to VBUS before VCC

[Andrew Mowry]

In my design I have a load switch that supplies power to VCC. The result is that voltage is applied to VCC 0.6 mS after 5V is applied to VBUS, because the load switch takes that much time to turn on. Will that be a problem? Thanks!

[Priyanka]

Hi Andrew,

That should be fine. Are you working with a custom hardware based on 52840 SoC or with the 52840DK?

Best Regards,

Priyanka

[Andrew Mowry]

Great, thank you! I am working with a custom board using the ISP1807 module.

[Priyanka]

Ah okay. Supplying the voltage to VBUS before VCC is okay because the VBUS input is used for a regulator, and this regulator is used by the USB peripheral in order to supply voltage to the data lines. This regulator is switched on only after the peripheral is configured. So it's fine.

[Andrew Mowry]

Great, thanks again for your help!