Hi, I need some power mgt advice:
My current project is a daughterboard that attaches to the back of a Pocket Operator drum machine.
The PO is a 3.3v device; it presents power and ground pads on the back, and my board routes
its 3.3v pad to Vin and Gnd on the Teensy 3.2 on my board, and that powers the Teensy.
(I believe this is a direct connection to the two AA batteries on the back of the PO.)
This setup also lets me power the PO with the Teensy's regulated
supply. Or so I thought. It all worked great on the breadboard!
Actually it works just fine when the PO doesn't have its 2xAAA batteries
installed. But when it does have its batteries installed, I'm finding
that the power regulator chip on the teensy is getting red hot,
which is no good. I guess maybe the regulator is just a little bit higher
voltage than the PO batteries, and is "charging" them?
For a future versions of this board, I'm wondering how I can attain
my preferred power nirvana, which would be:
-- if USB is present, it powers both teensy and the PO
-- if PO batteries are present, they power both teensy and the PO
-- if both power sources are present, both are powered & nothing catches fire.
I've read the PRJC page on working with battery and USB side by side,
splitting the 5v and 3.3v sections of the board with a knife and then
bridging them with a diode. I'm not sure that would work with this
situation, tho, where I actually do want to be able to send current back to the PO --
just a limited current. Is there a favorite circuit or chip
to solve this sort of problem? Or can it all be accomplished with
the right diodes?
All advice much appreciated & thanks for being a great resource!
-mykle-
My current project is a daughterboard that attaches to the back of a Pocket Operator drum machine.
The PO is a 3.3v device; it presents power and ground pads on the back, and my board routes
its 3.3v pad to Vin and Gnd on the Teensy 3.2 on my board, and that powers the Teensy.
(I believe this is a direct connection to the two AA batteries on the back of the PO.)
This setup also lets me power the PO with the Teensy's regulated
supply. Or so I thought. It all worked great on the breadboard!
Actually it works just fine when the PO doesn't have its 2xAAA batteries
installed. But when it does have its batteries installed, I'm finding
that the power regulator chip on the teensy is getting red hot,
which is no good. I guess maybe the regulator is just a little bit higher
voltage than the PO batteries, and is "charging" them?
For a future versions of this board, I'm wondering how I can attain
my preferred power nirvana, which would be:
-- if USB is present, it powers both teensy and the PO
-- if PO batteries are present, they power both teensy and the PO
-- if both power sources are present, both are powered & nothing catches fire.
I've read the PRJC page on working with battery and USB side by side,
splitting the 5v and 3.3v sections of the board with a knife and then
bridging them with a diode. I'm not sure that would work with this
situation, tho, where I actually do want to be able to send current back to the PO --
just a limited current. Is there a favorite circuit or chip
to solve this sort of problem? Or can it all be accomplished with
the right diodes?
All advice much appreciated & thanks for being a great resource!
-mykle-