I've got a project that runs 90% of the time from an externally regulated 5v supply attached to VIN. However, the other 10% of the time I need to be able to attach and use the USB, both in cases where that external 5v might be present or might not (ie I need the Teensy to still be able to be powered by USB alone if the external 5v isn't present).
Obviously by default if the external 5v is provided, I can't use the USB connection unless I either cut the on board trace or snip the power line on the USB cable. Cutting the onboard trace means I can no longer power the board with USB alone and I'd prefer not to introduce the requirement of modified USB cables.
If instead I wanted to use a muxer such as the TPS2113A, am I right in thinking that all I need to do is:
The schematic for the Teensy 3.5 indicates that this should work given where VUSB is taken from, but I wasn't sure if there was anything I was missing around how the power selection was dealt with. In such a setup, does it matter in what order power is provided (ie external first then USB or vice versa)?
Obviously by default if the external 5v is provided, I can't use the USB connection unless I either cut the on board trace or snip the power line on the USB cable. Cutting the onboard trace means I can no longer power the board with USB alone and I'd prefer not to introduce the requirement of modified USB cables.
If instead I wanted to use a muxer such as the TPS2113A, am I right in thinking that all I need to do is:
- Cut the onboard trace
- Connect the external 5v supply to one input on the TPS2113A
- Connect VUSB from the board to the other input on the TPS2113A
- Connect the output from the TPS2113A to VIN?
- Setup the rest of the TPS2113A for auto-switching etc.
The schematic for the Teensy 3.5 indicates that this should work given where VUSB is taken from, but I wasn't sure if there was anything I was missing around how the power selection was dealt with. In such a setup, does it matter in what order power is provided (ie external first then USB or vice versa)?