T3.5 Schematic Question: purpose of L1 and D1

[Electric Potato]

Hey guys,

Anybody know the purpose of L1 and D1 circled in red below on the T3.5 schematic?



I've built a number of custom T3.2's and would like to make a custom T3.5, just curious as to the function of these 2 components since the T3.2 schematic is otherwise basically the same in that area.

Thanks!

 

[PaulS]

The purpose of the ferrite is additional high-frequency filtering of the incoming DC voltage [being either the USB voltage or the external voltage on pin Vin].
The diodes are there as protection against reverse voltage when powered by the Vin pin.

Paul

 

[Electric Potato]

Okay cool, thank you Paul!

 

[PaulStoffregen]

Yup, that's it.

The ferrite bead also helps prevent any high frequency noise on Teensy's power line from escaping out the USB cable.