Anybody is using LTC4088 for LiPo charging?

I just can't get a working lipo charger with load sharing.
I want to be able to charge the battery while my Teensy is kept happy with 3.3V, then unplug the USB cable and see no interruption in power. Just like every phone in the world.

Somehow this turned into weeks of research and wasted time and money. I either get 2.8V while charging or with USB unplugged, or the reversed, depending on the design I use.

I just found this chip, which is supposed to do all this perfectly: http://www.analog.com/media/en/technical-documentation/data-sheets/4088fb.pdf

Did anybody have it working? I need 3.3V on the output with a 3.7V LiPo single cell battery, all the common things. I'm just trying to save some time and frustration here. Don't really want to "try this...". Please say if you get it working or not, or maybe some other design what you really have working for 3.3V.

Thanks.

If you are looking for something simple, see TP4056 (with protection IC) and MCP1700 regulator. LTC4088 seems to be very complex.

About Teensy, specifically, perhaps a dedicated forum can help better.

PJRC (Teensy) Forum

Welcome to the PJRC (Teensy) Forum.

https://forum.pjrc.com/

I recently purchased an "18650 shield V3" from Banggood. I've not used it much but I have it operating with a resistor load on the bench for some time now. I'm interested in the 5V output but the board has 3 output each for 3.3 Volts. I just measured them and they are 3.31 volts.

The board requires a 5V input for charging the battery and because the 3.3 volt regulators are connected to the battery there is absolutely no loss of output voltage when the input is disconnected.

The only limitation I've found is it will only draw 600 ma from the 5V source. This current must charge the battery and supply the output, so if your output draw is greater that 600 ma you will not be charging the battery.

The only slightly technical thing you would need to do the use the board is solder wires on the 3.3V outputs. The output connector is for 5V only.

John

AndyBelov, it looks like you’re fed up with this, but it seems a shame to go searching for complicated solutions when load sharing is fairly simple - just adding a P-channel mosfet, a diode, and a resistor. I’ll attach an example circuit which uses a boost regulator to produce 5V, but for 3.3V you could replace that with a 3.3V LDO with something like 0.2V dropout voltage or less. But why don’t you post the circuit that’s giving you 2.8V, and see if someone can offer a solution.

JohnRob, I thought those shields did not include load sharing. Do you have a schematic for the one you bought from Banggood (and a link to that shield)?