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I'm trying to power a simple circuit (0.25 mA LED) that will be used both when connected to a USB charging cable and by a single 3.7 C Li-ion cell (when disconnected).

Between the available hardware and online resources, it seems the TP4056 is far more popular than the MCP73831. But according to my understanding, the TP4056 risks damaging the Li-ion cell if the load is being used while charging.

Only the MCP73831 has built-in load sharing, and I would assume most use cases would want this functionality, so I'm perplexed why this module isn't more popular and widely available when the TP4056 seems to require additional circuit design and assembly.

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    \$\begingroup\$ Neither the TP4056 nor the MCP73831 ICs have "load sharing" built in. It's up to the designers of the modules built around them to decide whether they include it or not. \$\endgroup\$
    – Finbarr
    Jul 17, 2022 at 19:55

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The MCP73831 ought to be popular for 0.5A users at $0.76 (1) but is more expensive in $/A.

The TP4056 at 1.0A is more popular with 5 finished boards for $2/ea.

In order to charge battery and an external load or "load sharing" there must be 2 current sensors in order to know when to cutoff charge to the battery and allow the battery to relax some few % SoC before a brief recharge.

Neither IC does load sharing, so if loads are added externally to battery they can burn the battery from overcharge time. They must use external parts to subtract the external load current or some other means to regulate the voltage such as linear or DCDC converter. Since the battery voltage is often not the logic voltage. This is done in all mobiles and laptops.

But it is perfect for charge only purposes.

The TP4056 does have thermal sensing for cells which include a thermistor which is a practical safe measure.

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  • \$\begingroup\$ But what about the load sharing issue? \$\endgroup\$
    – Josh Ruchty
    Jul 17, 2022 at 18:59
  • \$\begingroup\$ Thanks very much. Although I think we're only talking about the ICs, I also see there are charging boards (such as these tinyurl.com/55wbkwdc) that include the DW01A and FS8205 ICs . Do these charging boards accomplish safe load sharing so that I can put a load on the circuit while charging the battery? Or do I still need to supplement these boards with the schottky p-mosfet circuit? \$\endgroup\$
    – Josh Ruchty
    Jul 23, 2022 at 15:22

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