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I am new to PCB design and need help in the battery management part. I am currently designing a PCB which is to be powered by a battery and this battery can be recharged by a micro-USB via a linear charge management controller, MCP73811/2. Can this component also control the flow of current when the microcontroller is being powered by this battery and be charged at the same time or do I need another component for that? Please let me know if I am not clear enough and I thank you in advance.

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  • \$\begingroup\$ Provide a link to the data sheet for the device. \$\endgroup\$
    – Andy aka
    Apr 6, 2020 at 10:18
  • \$\begingroup\$ ww1.microchip.com/downloads/en/devicedoc/22036a.pdf \$\endgroup\$
    – jellybean
    Apr 6, 2020 at 11:20
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    \$\begingroup\$ You also mention a microcontroller - what has this got to do with anything. Be clear. \$\endgroup\$
    – Andy aka
    Apr 6, 2020 at 11:22
  • \$\begingroup\$ The PCB consists of ;mainly the battery, battery charging system (MCP73811/2), a microcontroler and a few sensors. I am thinking of connecting the battery to the microcontroller to power it up and at the same time use the MCP73811/2 to charge it. I am not sure on if it is possible to control the current flow when it is charging and discharging at the same time by only using a MCP73811/2. Hope that it is clear \$\endgroup\$
    – jellybean
    Apr 6, 2020 at 11:31

1 Answer 1

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The charging current to the battery will be partially stolen by the MCU and sensors. You have to decide whether the MCU steals too much or, that what is left is enough to keep the battery floated without slow continuous depletion leading to eventual battery failure.

If you think that might happen, you will need to disconnect the load (MCU and sensors) before this occurs and let the charger put all its charging current into the battery.

Can this component also control the flow of current when the microcontroller is being powered by this battery and be charged at the same time or do I need another component for that?

You will probably need a comparator circuit that monitors battery voltage level and disconnects the MCU before that voltage gets too low for the battery.

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  • \$\begingroup\$ okay thank you very much!! On a separate note, is it better to power up the sensors using the battery or one of the outputs of the microcontroller? \$\endgroup\$
    – jellybean
    Apr 6, 2020 at 11:51
  • \$\begingroup\$ It all depends on the sensor and whether it is analogue and can be used ratiometrically with the MCU's ADC or is it an on/off sensor where it doesn't matter. It also depends on what current is needed by the sensor to operate correctly and what voltage limitations are implied by its data sheet. Having buffers between sensor and MCU also affects the answer. I'd raise a new question if you are not sure. \$\endgroup\$
    – Andy aka
    Apr 6, 2020 at 11:56
  • \$\begingroup\$ Okay i'll raise a new question. Thanks \$\endgroup\$
    – jellybean
    Apr 6, 2020 at 13:06

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