This button cell battery charger circuit project, is designed using U2401B IC and some other common electronic components.
This button cell battery charger circuit is powered from a 9V adapter and can charge between one and five batteries. D1 is a protection diode, while R1 and C1 decouples the power line charge processor IC1 D3 is a protection against reverse polarity. R4 limits the load current to 5 mA. During pulse charging through R4 and R5 circulating current of 0.5 mA. Determine the value of C2 during charging. After connecting to the network adapter, batteries will be charged with maximum current for a period of time (Table 1) followed by pulse charging (which is always 1/10 of the maximum current load).