Research On Key Technology Of Multi Section Lithium Battery Protection Chip

Lithium-ion battery is widely used in portable products due to its excellent properties:high energy density,small size,good environmental protection,long life,low self-discharge rate and no memory effect.With the development of microelectronic technology and improvement of the performance of electronic products,a lithium battery can't meet the voltage and current requirements of electronic products.Therefore,lithium batteries have been used in series and parallel to meet requirements.Due to the unique characteristics of lithium-ion batteries,batteries are vulnerable to damage during charging and discharging.Therefore,corresponding protection circuits should be used when using batteries to prevent lithium batteries from overcharging,over-discharging,overcurrent and short circuiting,which can result in irreversible damage of batteries.When the lithium-ion batteries used in high power applications,we need to consider the balance between each single battery,the reason is that lithium-ion battery factory specifications and different application environment can aggravate the difference between each single battery,in result the battery group had short board effect that lithium battery performance lithium battery group limited to the minimum capacity.In view of the above problems,the main contents of this paper are divided into two aspects:one part is the balance between lithium ion batteries and another part is the protection of lithium-ion batteries including overcharge,over-discharge,discharge overcurrent and short circuit protection.This paper discusses the imbalance problem between the lithium battery due to the factory specifications,the use of the environment and the temperature induced lithium battery;and then continue to study the complete function of 5 lithium batteries protection chip,key modules is comparator module which is used for detecting the voltage and current of the lithium battery is working in a safe area,including the voltage comparator is the main innovation of this paper,different from traditional voltage comparator,and according to the principle of low power,using bipolar transistors instead of MOS tubes,converting the opening voltage of bipolar transistors into the reversal threshold of the comparator and changing the voltage resistance to design different switching thresholds,the circuit structure is simplified and the chip area is reduced,the power consumption of the circuit is reduced,thus the protection function of the circuit is realized;other modules are as follows clock generation module which is used to provide the clock and delay function for the whole chip;The power supply and the reference module:providing power and bias for the whole circuit;logic control module,for digital circuit chip.In this paper,Spectre software is used in the Cadence simulation environment,and the above modules are simulated and verified.