Li-ion Charger board selection for 5V step-up converter application

TECHNICAL SUPPORT Batteries & Power
1

Customer:

I’m building a 5V power supply for a controller using Li-ion batteries. The batteries have a protection circuit built in. I need to understand which charger board is correct for this application: the standard Li-ion Charger or the Li-ion Charger with Protection. It seems the one with protection has redundant protection since the battery already includes it. For the standard charger board, the step-up converter (which provides the 5V output) connects in parallel to the battery using the board’s pins - is that correct?

Originally submitted via email support on 3 February 2025. Migrated to the forum for community visibility.

2

Soldered Support:

You can use both variants. The one with protection just adds additional protection on the charger side. The li-ion batteries have a small chip near the connector that provides protection, with OUT + and - pins that become active if the protection threshold is breached. The standard charger board without protection works well for this application. For your step-up converter to 5V, yes, it connects in parallel to the battery using the board’s pins. The battery voltage will range from approximately 4.2V to 3.5V, so the step-up converter is necessary to maintain stable 5V output.