Excuse me, what is the circuit? How can I see it without the picture? You can understand the principle of single cell protection board
1.
When the battery charging voltage reaches the set value VC, 4.125-4.300 V (the specific voltage of the overload protection point depends on the chip manufacturer's settings, the manufacturer's application can select the IC chip according to the specific parameters and battery requirements), as shown in the figure above: when the VD1 and Cout pins reach a low level, the MOS tube T1 is cut off and charging stops when the cell voltage drops to VCR3.6-4.2V; the specific recovery voltage of overload protection depends on the integrated circuit, and the integrated voltage is included in the basic parameter design), Cout produces a high level, the MOS tube T1 is turned on, and charging continues. value to avoid frequent jumps.
2. Working principle of over-discharge protection and over-discharge protection recovery
During the battery discharge process, when the cell voltage is discharged and drops to the value set VD (2.1 -2.45V, overdischarge protection point voltage generally cannot be designed and can only be set by different chip manufacturers). When the output voltage VD2 is low, after a short delay, Dout becomes low, T2 is cut off and the discharge stops. When the battery is put into charge, the internal OR gate is reversed, causing T2 to go to again to prepare for the next discharge.
3. Overcurrent and short circuit protection
When the battery discharges, when the charging circuit current exceeds the set value or is short circuited, the voltage applied to the MOS tube T2 will increase, the levelu of sense resistor R3 will produce a voltage drop after reaching the potential value set by the integrated circuit, cout2 will become a low level, the MOS tube T2 will be turned off, and the power will be cut off. The overcurrent value can be obtained by changing R3 to obtain the desired overcurrent value.
The above is the basic principle of battery protection board management for a single battery. This is very simple since the protection point voltage of different materials is different, as well as the protection point voltage and current of each manufacturer. are also different, so the products on the market There are many lithium battery protection IC chips, various major solutions, including mobile power solutions, etc. As a person engaged in the lithium battery industry, it is more important to understand what materials and battery materialsterie IC prices for which the chip parameters on the market are used, to be chosen according to different process requirements, which is based on the accumulation of experience.
This article comes from Shenzhen Maifeng Electronic Technology website