| Electronics > Projects, Designs, and Technical Stuff |
| USB and battery power source |
| (1/1) |
| 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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