Protective circuit for cascade of multiple battery strings

Abstract

The invention provides a protective circuit for cascade of multiple battery strings. The protective circuit comprises a chip port voltage withstand protection circuit. A first resistor of the chip port voltage withstand protection circuit is connected with a battery pack negative terminal and a negative terminal of a first diode. A positive terminal of the first diode is connected with a ground end. A drain terminal of a first NMOS (N-channel metal oxide semiconductor) transistor of the chip port voltage withstand protection circuit is connected with a negative terminal of the first diode, a source terminal and a substrate in the first NMOS transistor are short-circuited and are connected with a battery pack negative terminal detection end, and a gate terminal of the first NMOS transistor is connected with a power terminal. A gate end of a second NMOS transistor of the chip port voltage withstand protection circuit is connected with a control terminal of a charge tube, a source terminal and a substrate in the second NMOS transistor are short-circuited and are connected with the ground end, a drain terminal of the second NMOS transistor is connected with a second resistor, and the second resistor is connected with the power terminal. A gate terminal of a PMOS (p-channel metal oxide semiconductor) transistor of the chip port voltage withstand protection circuit is connected with the drain terminal of the second NMOS transistor, a source terminal and a substrate in the PMOS transistor are short-circuited and are connected with the power terminal, and a drain terminal of the PMOS transistor is connected with a positive terminal of a second diode. A negative terminal of the second diode is connected with a gate terminal of the charge tube. A source terminal and a substrate in the charge tube are short-circuited and are connected with a battery pack negative terminal, and a drain terminal of the charge tube is connected with a drain terminal of a discharge tube. A source terminal and a substrate in the discharge tube are short-circuited and are connected with the ground end, and a gate terminal of the discharge tube is connected with a discharge tube control terminal. Very high positive voltage and very low negative voltage are prevented from entering a battery protection chip, and a safe and reliable multi-string battery protection scheme is formulated.

Description

technical field [0001] The invention relates to the technical field of battery protection, in particular, the invention relates to a protection circuit for multi-string battery cascading. Background technique [0002] Lithium batteries are widely used in electric tools, electric bicycles and other fields, and the total voltage is relatively high, usually exceeding 60V. In the application scheme, the battery protection chip usually has a withstand voltage within 40V. In order to realize the protection of multiple lithium batteries, the battery protection chip of more than 5 lithium batteries is usually produced by cascading multiple chips (IC). For example, the 10-series lithium battery protection board can be implemented by cascading two 5-series lithium battery protection chips, and each chip only needs to withstand the voltage of about 25V from 5 batteries. The withstand voltage of each IC is within 40V, and the total battery voltage can reach up to 60V with 12 cells. ...

AI Technical Summary

Problems solved by technology

[0006] To sum up, in the realization of the multi-cell battery protection scheme, especially when the total battery vol

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