Custom Teensy3.2

Status
Not open for further replies.
D

dsepshn

New member
Forgive me if this is a silly question. I'm a bit of a rookie here. :)
I'm working on a schematic (Based on the teensy 3.2) and am curious about a few things. My project will be powered by a lipo battery (3.7v) and I was wondering if the LP38691 is needed? I noticed the the Teensy 3.1 and LC do not have this. Is it just for protection from a higher volt source? I also noticed the the 3.1 and 3.2 have the same microcontroller (MK20DX256VLH7), but the 3.2 does not use the VREGIN pin and the 3.1 does. Is that not how the micro controller receives power? Again, might be a silly question :)
And lastly, the VBAT, is that necessary to connect to if I'm not using it?

I apologize if these questions have been asked, I've been looking for a few days and have not found the answers.

Thanks,
~Wes
 
I've seen posted a few times that VBAT is REQUIRED. Try BING or some other search thing perhaps against "PJRC Teensy ..." - there are many posts. They might not answer your other questions - but will give you better background for starters.
 
You can use either the chip's regulator, or an external 3.3V regulator. We started using an external one on Teensy 3.2 because the TI chip with 10V max input is much more rugged and supports higher current.

Yes, VBAT needs to be connected to 3.3V. The default startup code tries to init the RTC and will crash if the RTC is unpowered.
 
@PaulStoffregen
Thanks for the help!!! And the explanation. Sometimes knowing the right words to search can be a huge help. I wasn't sure what the VREGIN actually was until Paul said "chip's regulator". Now knowing what to search for in the data sheet, I found the USB regulator input max is 6v! Thanks so much!
@Fyod, thanks for the link!
@defragster, I don't know why I always forget about Bing! Need to start using that more!

Thanks
~Wes
 
Status
Not open for further replies.
Back
Top