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.

Navigation

[0] Message Index

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod