USB and battery power source

[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]

Is GND of the LP2985-33 connected to USB GND?

Damn right !Oops

Everything good now !What about the rest of circuit,is it a good design ?

[Vcky_electro]

Is GND of the LP2985-33 connected to USB GND?

Nice..

[Kasper]

Is my design good to avoid leakage into the battery ?

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.