Lithium battery protection board short circuit protection control principle

Lithium battery protection board, as the name suggests, protects the lithium battery. It has major protection functions such as overcharge protection, overdischarge protection, overcurrent protection, and short circuit protection. It is the core component of the lithium battery. The lithium battery protection board has so many protection functions. Today, the Chinese Chuangfa will learn with you the principle of short-circuit protection control of the lithium battery protection board.

In the process of external discharge of the protection board, the two electronic switches in the 8205A are not completely equivalent to two mechanical switches, but are equivalent to two resistors with very small resistance, and are called The on-resistance of 8205A, the on-resistance of each switch is about 30m\U 03a9 and a total of about 60m\U 03a9. The voltage applied to the G pole actually directly controls the on-resistance of each switch tube Size When the voltage of the G pole is greater than 1V, the internal resistance of the switch tube is very small (tens of milliohms), which is equivalent to the switch closed. When the voltage of the G pole is less than 0.7V, the internal resistance of the switch tube is very large ( A few MΩ), which is equivalent to the switch off. The voltage UA is the voltage generated by the internal resistance of 8205A and the discharge current. When the load current increases, UA will inevitably increase. Because UA0.006L×IUA is also called the tube voltage drop of 8205A, UA can be abbreviated to indicate the size of the discharge current. . When it rises to 0.2V, it is considered that the load current has reached the limit value, so the output voltage of pin 1 is stopped, so that the voltage of pin 1 becomes 0V, the discharge control tube in 8205A is closed, and the discharge circuit of the cell is cut off. Discharge control tube. In other words, the maximum allowable output current of DW01 is 3.3A, which realizes over-current protection.