Design Of Lithium Battery Charge And Discharge Management Circuit Based On Power Detection

Since the 20 th century,technology has been advancing rapidly and convenient electronic devices have entered various fields.The most representative ones are cell phones and computers,whose energy supply has always been a research hotspot in the academic and industrial fields at home and abroad.lithium battery stands out among rechargeable batteries by virtue of its green and environmental protection,high cycle times,high specific energy density,light mass and no memory effect.The charging method and discharge level of lithium battery will directly affect the number of cycles,and abnormal conditions such as over temperature,over current and over voltage occur in the chip,so it is essential to design management circuits for lithium battery.Based on this research background,this thesis designs a charge and discharge management chip of lithium battery based on power detection to provide a battery management solution for convenient electronic devices.The charge and discharge management chip of lithium battery based on power detection designed in this thesis has the following functions:(1)Input voltage stabilization to supply a "clean" power supply voltage for the post-stage circuit;(2)Status monitoring module to monitor the voltage conditions of the low-noise LDO output,the battery and the load,and generate the corresponding flag signals;(3)Multi-mode charging circuit realizes high efficiency charging of lithium battery by trickle current-short constant current-fixed frequency fast pulse-fixed frequency slow pulse charging;(4)Power detection circuit detects the input power strength,and then selects whether to charge the lithium battery with fixed or variable frequency pulse;the load output power control loop regulates the size of the supplied load power;(5)The internal resistance compensation network detects the internal resistance of the lithium battery during the short constant current charging stage to eliminate its misjudgment of the charging process switching;(6)The protection circuit not only provides precise control of the current and voltage during the discharge of the lithium battery,but also ensures that the chip works within the proper temperature range.In this thesis,The charge and discharge management chip of lithium battery based on power detection is designed with 0.18 μm BCD process,the input voltage range is6-7 V,and the output voltage is 2 V when there is load access.the pre-stage low-noise LDO output voltage is 4.5 V,and the integration noise is lower than 10 μV at different corners;the 50 m Ah lithium battery is replaced by 160 mΩ resistor and 50 μF super capacitor instead,and the internal resistance compensation network realizes the compensation of 160 mΩ internal resistance;the lithium battery reaches the full charge voltage of 4.2 V after trickle current-short constant current-fixed frequency fast pulse-fixed frequency slow pulse charging,where the frequency of fixed-frequency pulse is100 k Hz,and the duty cycle of fast and slow pulse is 75% and 25% respectively.