Lithium battery protection based on-board PTC (positive temperature coefficient) protection circuit

Abstract

The invention discloses a lithium battery protection based on-board PTC (positive temperature coefficient) protection circuit which comprises multiple resistor-capacitor units, a PTC overcurrent thermal protector, a control protection chip and an MOS (metal oxide semiconductor) switching circuit. Two output ends of a load are connected with the first end of the control protection chip and the first end of the MOS switching circuit respectively, the second end of the control protection chip is connected with the second end of the MOS switching circuit, the third end of the control protection chip is connected with the first end of the PTC overcurrent thermal protector, the second end of the PTC overcurrent thermal protector is connected with the first end of a lithium cell, and the third end of the MOS switching circuit is connected with the second end of the lithium cell. After a PTC thermistor is added to the circuit, the PTC thermistor can still provide protection for faults such as overcharge, overcurrent, short circuit and overtemperature even though a primary protection path fails or temperature rises highly, and security problems cannot be caused under the condition that the battery is misused or abused.

Description

technical field [0001] The invention relates to a lithium battery protection board circuit to realize circuit overcurrent temperature protection, in particular to a PTC protection circuit based on a lithium battery protection board. Background technique [0002] Early batteries used fuses or bimetallic strips as secondary protection devices for overcurrent, short circuit, and overtemperature. However, because battery overcurrent and other faults are often temporary and do not mean permanent damage to the battery, the disadvantage of non-recoverable fuse increases the quality assurance cost of the battery manufacturer; although the bimetal can be self-recovery, it will not Stop action / recovery will lead to early fatigue and wear of the contacts and then adhesion and loss of protection. In addition, the bimetal sheet has a large volume and weight for the demanding requirements of the battery volume and weight of the portable device. The polymer PTC has advantages in providing...

AI Technical Summary

Problems solved by technology

Although the primary protection is generally considered to be reliable, the protection IC or MOS-FET may be damaged when the electrostatic discharge voltage is too high or the temperature is too high, and the integrated circuit will oscillate when it is short-circuited, and most IC+MOS-FET circuits are charging The detection of discharge overcurrent is indirect, and it cannot guarantee that overcurrent protection will be provided under all working conditions of the battery, and the reliability of protection is also reduced.

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