This is the 3/4 series battery protection solution with 2nd protection feature and cell balancing function. It is equipped with high durability and reliability to face with high voltage and extreme current situation. The single HY2540 can provide 3/4 series cells with overvoltage, undervoltage and overcurrent /short circuit protection. Together with the HY2514 for each cell, which could provide the 2nd protection and cell balancing functions, the solution can meet the high safety regulation requirement and also limit the part counts as more as possible. So a simplified protection board is available easily.