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Regulation in battery chargers

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Full Member level 6
May 10, 2020
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I'm using this Battery charger IC.

What does it mean when one says, "The OUT pins do not offer regulation"?

For example, if the part has a VREG of 4.2V, the IC charges the battery to Vbat. That is Ok. What about the OUT pins? What would be the voltage at the OUT pins when the input supply IN pin is at 5V? And it is said that the OUT pins do not offer regulation?

Does it mean that the OUT pins would provide the same input 5V and provide 4.2V to VBAT pins? But as per the function diagram, there's a pass MOSFET. How to understand this?

From your description, it seems that you are using a dedicated single battery manager. The simplest manager is to ensure that the charging current of the battery is not too high and that the voltage does not exceed the limit when fully charged. Do you need to see the data table for any other functions.

What does it mean when one says, "The OUT pins do not offer regulation"?
It means that the output pin voltage either equals the input voltage or the battery voltage, depending upon which is powering the load.
The charging battery voltage is controlled so that the battery is not overcharged.
Extracted from data sheet:The MCP73871 device employs a constant current/constant voltage (CC/CV) charge algorithm with selectable charge termination point. To accommodate new and emerging battery charging requirements, the constant voltage regulation is fixed with four available options: 4.10V, 4.20V, 4.35V or 4.40V. The MCP73871 device also limits the charge current based on the die temperature during high power or high ambient conditions. This thermal regulation optimizes the charge cycle time while maintaining device reliability.

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