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USB and battery power source
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jmbinette:
Hi to all,
I built a circuit to power a 3.3v power source using both battery and/or USB cable.
The battery section of my circuit seems to work fine.
the USB section is using a LP2985-33 and I cannot get 3.3v at the output.
instead, I get like 1.7v
My schematic is attached
Any suggestions?
Is my design good to avoid leakage into the battery ?
thanks
ledtester:
Is GND of the LP2985-33 connected to USB GND?
jmbinette:
--- Quote from: ledtester on September 22, 2019, 05:02:00 am ---Is GND of the LP2985-33 connected to USB GND?
--- End quote ---
Damn right !Oops |O
Everything good now !What about the rest of circuit,is it a good design ?
Vcky_electro:
--- Quote from: ledtester on September 22, 2019, 05:02:00 am ---Is GND of the LP2985-33 connected to USB GND?
--- End quote ---
Nice.. :clap:
Kasper:
--- Quote from: jmbinette on September 21, 2019, 11:10:47 pm ---
Is my design good to avoid leakage into the battery ?
--- End quote ---
Check the datasheet for max40200. Does it have reverse current blocking? What happens if Vout is 5V and Vin is 4V? Many regulators have max Vout = Vin and if Vout > Vin, current flows the wrong direction.
Adafruit has some good example circuits of connecting battery and usb I think feather 328P has a good one.
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