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AN55102 - PSoC® 1 Single Cell Li-Ion Battery Charger with CY8C21x23 | Cypress Semiconductor

AN55102 - PSoC® 1 Single Cell Li-Ion Battery Charger with CY8C21x23

Last Updated: 
Jun 26, 2020

AN55102 presents a Lithium-Ion (Li-Ion) battery charger design, with the smallest, low-cost PSoC® 1 device – CY8C21x23. This application note includes a dedicated PC-based software developed to perform real time charge process monitoring and analysis.


Li-Ion batteries have the greatest capacity to volume ratio and are found in notebooks, pocket PCs, cell phones, and other cutting-edge consumer products.

This application note describes a single cell Li-Ion battery charger for a 500 mAh battery using the smallest and lowest-cost chip in the PSoC family, CY8C21x23.The battery capacity and other battery parameters can easily be changed by modifying corresponding constants in the firmware to support different batteries.

Multiple methods such as, self modulated voltage reference, pin multiplexing, time multiplexing of resources, and code optimization have been used to implement the design in this chip. The charger can be embedded into consumer and home appliances or industrial applications. The production level design can be implemented in an 8-pin CY8C21123 device. The development can be done in CY8C21223 to add the digital communication required for charge monitoring.

Charger structure


Example Project
Supported H/W and S/W Supported PSoC1 Devices
PSoC Designer Version H/W Kit CY8C20xxx CY8C21xxx CY8C22xxx CY8C23xxx CY8C24xxx CY8C27xxx CY8C28xxx CY8C29xxx
Yes 5.4 Custom board   x23, x34