How do charger chips work?

XTAR Light

Well-known member
Apr 26, 2010
You may be curious about how the charger chips work. Let’s find out more. Charger chips were first introduced in the 1980s, and simplified the design of NiMH/Ni-CD chargers, as batteries with these chemistries were difficult to charge. Li-ion is simpler and most modern charging chips also include the protection circuits for charging more safely.

These chips include current and voltage regulation, FET switches and may also contain charge status indicators and cell balancing. There is even a time-out-timer added to most chips for stopping charge, if predictable symptoms don’t occur when charging a flawed battery. Besides, advanced chips feature pre-charging function to wake up an inactive battery, as well as a sleep mode for lowering the housekeeping current of the circuit when the battery is in storage. Some chips also initiate a charge if a parasitic load lowers the battery voltage below a preset threshold while residing in a charger.

As you can see, charger chips are easy and economical to use. While, they have some limitations. Most have a fixed charge algorithm that doesn’t permit fine-tuning for special uses. Chips are made for a given battery, and may not accommodate different chemistries as requested by the user, or read a battery code that may be embedded in a battery holder. It’s difficult for most chips to adjust to an optimal charge current when charging an aging battery with reduced charge acceptance.

Then, microcontrollers offer an alternative to charger chips, though the design cost is higher because of the extra programming time needed. And maybe you could expect more innovations for lower-cost alternative to build better chargers in the future...