Low Parasitic Current `Half ON' Operation of Battery Protection IC

Parasitic diode is frequently employed in integrated power devices, and causes parasitic leakage current. Large leakage current may cause troubles, such as latch up, malfunction of analogue circuit and increase in consumption power. In a single chip Li-ion battery protection IC, new operation method to charge a battery without using the parasitic diode is devised. To detect current direction precisely, only half of the bi-directional switches are turned on. We call it 'half on' operation. This operation suppresses parasitic current and heat generation. The parasitic current is reduced from a few milli-amperes to a few nano- amperes. Chip temperature during charging can be lowered from 190 to 65 degrees Celsius.