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I'm making a power-supply circuit for some MCUs using a battery charging-discharging protect module MH-CD42 (both input and output is 5 V).

The module's datasheet says it has a 0.3 seconds switch time when connecting or disconnecting the DC power input, so I use a 10 F super capacitor to make sure those MCUs don't power off due to power loss. But when I power the circuit, it triggers the module's overcurrent protection (2.1 A).

I have tried to add a resistor between the module and the capacitor, but it still doesn't work.

Here are my circuits, with and without resistor.

Without resistor

With resistor

What should I add or how can I change my circuit to solve the problem?

Object Unknown
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    Without knowing which exact module you are using, answers would be speculative at best. Please update the question with the exact module you are using. – Adam Lawrence Jun 22 '23 at 12:03
  • @AdamLawrence Question updated.The module is called MH-CD42 – Object Unknown Jun 23 '23 at 06:08
  • How much voltage drop do you accept on the load side? – Jens Jun 23 '23 at 21:24
  • @Jens The loads are one ESP8266 Module and one Arduino Mega 2560 Rev3. I think 4.2 V is enough, so maybe less than 0.8 V, or I can add a DC to DC boost module to solve the votage drop. – Object Unknown Jun 24 '23 at 12:09
  • If you can accept 0.8 V drop, you may charge the capacitor via 50-100 ohm and connect a Schottky diode parallel to the charge resistor in discharge direction. This way the capacitor charging current is much lower. During takeover the capacitor feeds the load via diode. A boost converter allows a smaller capacitor. – Jens Jun 26 '23 at 00:32
  • @Jens Do you mean change my circuit to this one [Citcuit 1](https://github.com/UnknownObject000/TemporyPictures/blob/main/circuit-01.png) or this one [Circuit 2](https://github.com/UnknownObject000/TemporyPictures/blob/main/circuit-02.png)? – Object Unknown Jun 26 '23 at 06:34
  • I meant Circuit 2 – Jens Jun 26 '23 at 15:54

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