This device is intended to charge the 8.4V Li-Ion batteries. The charger has two load modes:

constant current mode (I=900mA) and,

constant voltage mode (V=8.4V). The device detects the end of charge status of the battery and stop the charging. The bad batteries are recognized also and in this situation, the charging doesn’t proceed.

The power element of this charger is a switching voltage stabilizer controlled in closed loop by two different electronic elements:

A differential amplifier – in order to realize the constant-current charging mode;

A threshold voltage comparator – to achieve the constant-voltage charging mode;

A second differential amplifier detects the drop of charging current below 50mA and stops the battery charging;

Another threshold voltage comparator detects the batteries with the voltage below 1.5V and indicates the bad batteries and don’t accept the charging.