Lithium battery protection circuit with current-limiting charging control

Abstract

The invention discloses a lithium battery protection circuit with current-limiting charging control, a lithium battery is connected with a charging adapter for charging, the lithium battery protection circuit comprises a protection module and a current-limiting charging control module, and the current-limiting charging control module adopts a step-down rapid charging and step-up discharging bidirectional controller. In the charging process, the step-down quick charging, boosting and discharging bidirectional controller firstly controls the charging adapter to adaptively input the minimum voltage and then enables the charging adapter to charge at a fixed current in a current-limiting manner, so that the constant-current charging effect is achieved, and when the battery is charged to the charging cut-off voltage set by the step-down quick charging, boosting and discharging bidirectional controller, the charging adapter is switched to the charging cut-off voltage set by the step-down quick charging, boosting and discharging bidirectional controller. The step-down rapid charging and step-up discharging bidirectional controller controls the charging adapter to stop charging, so that the function of current-limiting charging control of the lithium battery circuit is realized. According to the invention, charging overvoltage protection, discharging undervoltage protection, charging overcurrent protection, discharging overcurrent protection and short-circuit protection are realized, and current-limiting charging and self-adaptive charging voltage functions of the charger are realized.

Description

Technical Field

[0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to a lithium battery protection circuit with current limiting charging control. Background Art

[0002] Lithium batteries have the advantages of relatively high energy, long service life, high rated voltage, high power tolerance, very low self-discharge rate, light weight, and strong adaptability to high and low temperatures. However, they have the disadvantages of poor safety and require protection circuits to prevent overcharging, over-discharging, over-current, short circuit, and over-temperature protection.

[0003] The design scheme of lithium battery protection circuit in the prior art has the following problems: the traditional lithium battery protection circuit only has some functions such as protecting the lithium battery from overvoltage, undervoltage, charge and discharge current, but cannot achieve the charger current limiting charging and charger adaptive charging voltage functions. Summary of the invention

[0004] The purpose of the present invention is to provide a lithium battery protection circuit with current limiting charging control, which realizes some protection functions such as charging overvoltage protection, discharging undervoltage protection, charging overcurrent protection, discharging overcurrent protection, short circuit protection and the like.

[0005] The technical solution of the present invention is: A lithium battery protection circuit with current limiting charging control, wherein the lithium battery is charged by a charging adapter, comprises a protection module and a current limiting charging control module, wherein the protection module and the current limiting charging control module are respectively connected to the lithium battery and the charging adapter to realize charging overvoltage protection, discharging undervoltage protection, charging overcurrent protection, discharging overcurrent protection and short circuit protection.

[0006] Preferably, the current limiting charging control module adopts the buck fast charging boost discharging bidirectional controller SC8803.

[0007] Preferably, during the charging process, the buck-fast charging, boost-discharging bidirectional controller SC8803 first controls the charging adapter to adapt to the minimum input voltage, and then limits the current of the charging adapter to charge at a fixed current, thereby playing the role of constant current charging. When the battery is charged to the charging cut-off voltage set by the buck-fast charging, boost-discharging bidirectional controller SC8803, the buck-fast charging, boost-discharging bidirectional controller SC8803 controls the charging adapter to stop charging, thereby realizing the function of current limiting charging control of the lithium battery circuit.

[0008] Preferably, the charging adapter is connected to the lithium battery, the buck fast charging boost discharging bidirectional controller SC8803 and the protection module through the charging and discharging MOS tubes, and the charging and discharging of the charging adapter is controlled by the charging and discharging MOS tubes.

[0009] Preferably, the protection module uses a lithium battery protection chip SC5550FAAB.

[0010] Preferably, the lithium battery is a battery pack with multiple cells connected in series, and the lithium battery protection chip SC5550FAAB collects the voltage of each battery cell to protect charging.

[0011] The advantages of the present invention are: The lithium battery protection circuit with current limiting charging control proposed by the present invention has a protection module and a current limiting charging control module which are respectively connected to the lithium battery and the charging adapter to realize charging overvoltage protection, discharging undervoltage protection, charging overcurrent protection, discharging overcurrent protection and short circuit protection, so as to achieve the functions of charger current limiting charging and charger adaptive charging voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The present invention will be further described below in conjunction with the accompanying drawings and embodiments: Figure 1 The protection module schematic diagram of the lithium battery protection circuit with current limiting charging control of the present invention; Figure 2 This is a schematic diagram of a current limiting charging control module of a lithium battery protection circuit with current limiting charging control of the present invention. DETAILED DESCRIPTION

[0013] The present invention provides a lithium battery protection circuit with current limiting charging control, wherein the lithium battery is charged by a charging adapter, and comprises a protection module and a current limiting charging control module, respectively. Figure 1 , 2 The protection module and the current limiting charging control module are connected to the lithium battery and the charging adapter respectively to achieve charging overvoltage protection, discharging undervoltage protection, charging overcurrent protection, discharging overcurrent protection, and short circuit protection.

[0014] Figure 1 In the embodiment, the charging pin P- of the charging adapter is connected to the negative electrode of the lithium battery through the charging and discharging MOS tube, the charging pin P+ is connected to the positive electrode of the lithium battery through the fuse F1, the protection module and the current limiting charging control module control the charging and discharging of the charging adapter through the charging and discharging MOS tubes Q1-Q4.

[0015] The protection module uses a lithium battery protection chip SC5550FAAB. The lithium battery is a battery pack with multiple cells connected in series. The lithium battery protection chip SC5550FAAB collects the voltage of each battery cell to protect charging.

[0016] The current limiting charging control module adopts the buck-fast charging boost-discharging bidirectional controller SC8803. During the charging process, the buck-fast charging boost-discharging bidirectional controller SC8803 first controls the charging adapter to adapt to the minimum input voltage, and then limits the current of the charging adapter to charge at a fixed current, which plays the role of constant current charging. When the battery is charged to the charging cut-off voltage set by the buck-fast charging boost-discharging bidirectional controller SC8803, the buck-fast charging boost-discharging bidirectional controller SC8803 controls the charging adapter to stop charging, thereby realizing the function of current limiting charging control of the lithium battery circuit.

[0017] The present invention sets a minimum voltage to realize the adapter self-adaptation function, wherein: VINREG=1.226*(1+R34 / R35)=1.226*(1+10 / 1.2)≈11.4V.

[0018] Adapter end charging current: 2.37A.

[0019] IBUS_LIM=1.21*R43 / (R41*RS3); 2.37=1.21*1000 / (R41*0.01); R41=51K.

[0020] Charging current at charging end: 2.37A.

[0021] IBAT_LIM=1.21*R48 / (R42*RS4); 2.37=1.21*1000 / (R42*0.01); R42=51K.

[0022] Charging cut-off voltage: VBAT = 1.22*[1+ (R46+R56) / ( R47+R57)] =1.22*[1+(200+1) / (18+1.8)] =16.9937V.

[0023] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any modifications made according to the spirit of the main technical solution of the present invention should be included in the protection scope of the present invention.

Claims

1. A lithium battery protection circuit with current limiting charging control, wherein the lithium battery is charged by a charging adapter, characterized in that: It includes a protection module and a current limiting charging control module. The protection module and the current limiting charging control module are respectively connected to the lithium battery and the charging adapter to achieve charging overvoltage protection, discharging undervoltage protection, charging overcurrent protection, discharging overcurrent protection and short circuit protection.

2. The lithium battery protection circuit with current limiting charging control according to claim 1, characterized in that: The current limiting charging control module adopts the buck fast charging boost discharging bidirectional controller SC8803.

3. The lithium battery protection circuit with current limiting charging control according to claim 2, characterized in that: During the charging process, the buck-fast charging, boost-discharging bidirectional controller SC8803 first controls the charging adapter to adapt to the minimum input voltage, and then limits the current of the charging adapter to charge at a fixed current, thereby playing the role of constant current charging. When the battery is charged to the charging cut-off voltage set by the buck-fast charging, boost-discharging bidirectional controller SC8803, the buck-fast charging, boost-discharging bidirectional controller SC8803 controls the charging adapter to stop charging, thereby realizing the current limiting charging control function of the lithium battery circuit.

4. The lithium battery protection circuit with current limiting charging control according to claim 3, characterized in that: The charging adapter is connected to the lithium battery, the buck fast charging, boost discharging bidirectional controller SC8803 and the protection module through the charging and discharging MOS tubes, and controls the charging and discharging of the charging adapter through the charging and discharging MOS tubes.

5. The lithium battery protection circuit with current limiting charging control according to claim 4, characterized in that: The protection module adopts the lithium battery protection chip SC5550FAAB.

6. The lithium battery protection circuit with current limiting charging control according to claim 5, characterized in that: The lithium battery is a battery pack with multiple units connected in series, and the lithium battery protection chip SC5550FAAB collects the voltage of each battery unit to protect the charging.

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