Onion 3.3v regulator circuit
-
Hello, im trying to make a standalone onion2 (no dock) talk to an arduino pro mini 5v.
for this I'm using an L7805 to power the arduino from 12v and a MIC29300 to power the onion omega2 from 12v. the problem I'm having is that for some reason the out of the MIC29300 is the same as the input voltage, so if I hook it to 12v the out is 12 and is I connect to 5v the output is 5V. I am not sure at all what I'm doing wrong here.
here is a schematic of what I'm doing
https://www.dropbox.com/s/qh4wb9zhonag675/Screenshot 2017-10-05 20.03.18.png?dl=0
and this is the datasheet for the mic29300 http://ww1.microchip.com/downloads/en/DeviceDoc/20005685A.pdf
-
@Luis-Morales only things i can think of is you have a bad regulator or have hooked it up incorrectly. do you have a photo of the actual setup?
-
Thanks, @Douglas-Kryder here is a few photos of the breadboard right now https://www.dropbox.com/sh/rrgg7mb535oul9t/AABMZ4gXkZdYkg5Nf-pnihHwa?dl=0
I tested with 3 different regulators I have 6.
-
@Luis-Morales said in Onion 3.3v regulator circuit:
I'm using ... a MIC29300 to power the onion omega2 from 12v. the problem I'm having is that for some reason the out of the MIC29300 is the same as the input voltage, so if I hook it to 12v the out is 12 and is I connect to 5v the output is 5V. I am not sure at all what I'm doing wrong here.
The minimum load current of MIC29300 is 10 mA.
Put a max 330 Ohm resistor (or a LED with a suitable serial resistor) to the 3.3V output.
-
ah! I did not see that, now it's working perfectly, thank you very much @György-Farkas
-
hmm still think I'm doing something wrong somewhere, with the led everything is fine, but as soon as I powerup the omega2, the regulator starts getting super hot, using a kitchen probe it reached 70 degrees C in about 5 mins and it kept rising.
-
Do not skip essential components specified by the IC datasheet.
It needs a 0.1uF input capacitor (for stability) and
one output capacitor (minimum of 10 uF.)
They have to be as closed to the IC as possible.
-
@Luis-Morales said in Onion 3.3v regulator circuit:
hmm still think I'm doing something wrong somewhere, with the led everything is fine, but as soon as I powerup the omega2, the regulator starts getting super hot, using a kitchen probe it reached 70 degrees C in about 5 mins and it kept rising.
To make 3.3V for Omega2(+) with an LDO (eg MIC29300) in TO-220 package without heatsink in "normal" room temperature you should use stabilized 5V -10%...+10% input voltage. Using Vin 12V MIC29300 needs a proper heatsink.
-
@György-Farkas I was hoping to use a single power supply for this project, I'm using the arduino for a few analog sensors, the omega runs the main logic for everything and offer a server to manage the solution, I also want to power a few 12V motors hence why I'm using a 12v 2amp power supply. I am in fact using a heatsink in both regulators with a bit of thermal paste on them
a heatsink like this one
if I supply 5v to the 3.3v regulator them the one that gets super hot 70+ centigrade is the 5v regulator (both regulator I have with a heatsink.)
@ccs-hello I am in fact using the capacitor as specified by the datasheet.
-
well after some more research, i am going to drop the linear regulator for step-down buck switching regulators. i will update the schematic and share my final solution when i have it working.
