TP4056 to LD33V regulator: Voltage between OUT terminals dropping to 3.3V

Projects General Guidance
1

Hi,

My circuitry runs at 3.3 V and I want to have both power and battery source options.
In my use case, I want to switch to 3.7 battery only when power is not there at my module.
I am using TP4056 for charging this battery. So, I plan to connect a 3.3V regulator to the OUT terminals (OUT+/OUT-).

My expectation is that if battery is not sufficiently charged OUT voltage comes from the mains. (I see it is 4.13V when battery is not connected.), and when battery is connected it will switch to 3.7 V. So a regulator connected to the OUT terminals will give me constant 3.3V.

But, I am observing that when I connect 3.3V regulator to OUT+ terminals, the volatage across OUT+ and OUT- is dropping to 3.3V and the regulator output is further dropping to 2.6V.

Can someone help me solve this puzzle ?
Is comparator on TP4056 playing any role here ? Does it consider voltage across OUT terminals as well?

Please help.

Thanks in advance.

2

You need to post a schematic of your circuit with all the part numbers on it.

3

Most voltage regulators need some voltage difference between input- and output- voltage. How much? Check regulator specifications.

4

Hi, Thanks for response.

Please find the circuit in attachment.

This is some module which i bought online.
Adding link for reference. (https://www.amazon.in/xcluma-MicroUSB-Lithium-Charging-Protection/dp/B072TDYGMY/ref=sr_1_1?ie=UTF8&qid=1541553301&sr=8-1&keywords=tp4056)

I have attached regulator connection as well.
I am giving the OUT+/OUT- terminals of the TP4056 circuitry to the VIN/GND terminals of the voltage regulator.

Circuit.png
Circuit.png766×307 67.4 KB

VoltageRegulator.png

5

@RailRoader

Yeah, but primary question here is, the the output volatage of the TP4056 module is dropping to 3.3V.
That looks strange to me. Need to understand the TP4056 module though.

6

What does the TP4056 datasheet tell about minimum input voltage, eventualy compared to desired output voltage?

7

It would help if you posted a complete circuit diagram showing how you have it all connected, including the battery.

Do remember the TP4056 is not a power supply, its a battery charger and as such the 'output' voltage will depend on whether a battery is connected or not.