LR03 alkaline battery.Technical characteristics of 10-cell series battery pack protection circuit

　　1. Voltage detection function of single cell

　　When the battery is in use and stored, the protection IC needs to detect the voltage of each single cell in real time.

　　2. Overcurrent detection function of battery pack

　　During the use of the battery, the voltage drop on the external switch tube is judged to determine whether the current charging and discharging current of the battery pack exceeds the set maximum current value. The protection IC then determines whether to turn off the battery protection circuit switch to cut off the output. . If the charging and discharging current of the battery pack is in an overcurrent state at this time, after turning off the switch tube, it is necessary to use the detection circuit to determine whether the external load has been removed. When the external load has an impedance of 300 kiloohms or higher, then connect the Turn on the switch.

　　3. Overcharge protection function

　　Lithium-ion batteries are sensitive to charging voltage. When the charging voltage is higher than a certain value, the battery itself may be in danger of exploding. The value of this value depends on the internal materials of the battery. This value of a single battery cell is generally set between 4.15V and 4.35V. After discovering an overcharged battery, the protection IC should immediately turn off the output switch tube. This delay time can be determined by an external capacitor to ensure the accuracy of voltage sampling. After overcharging occurs, the voltage detection module detects that the cell voltage drops to 4V or lower, and then turns on the switch to ensure that the voltage detection of the internal module has a comparator with a hysteresis.

　　4. Over-discharge protection function

　　Lithium-ion batteries have certain requirements for discharge voltage. When the discharge voltage of the cell is lower than a certain value, the cell itself may be damaged beyond recovery. The value of this value depends on the internal materials of the battery. This value of a single battery cell is generally set between 2.3V and 3.0V. After discovering an over-discharged battery, the protection IC should immediately turn off the output switch tube. This delay time can be determined by an external capacitor to ensure the accuracy of voltage sampling. After over-discharge occurs, the voltage detection module detects that the cell voltage rises to 3V or higher, and then turns on the switch to ensure that there is a comparator with hysteresis in the internal module.

　　5. Protect the low power consumption function of the IC

　　The protection IC should keep power consumption as low as possible. It is best to keep the power consumption around 100uA, not too high. When the battery voltage is generally the highest, the power consumption of the protection IC is the largest.

　　Extended functions that a 10-cell battery protection IC should have:

　　6. Protect the automatic balancing function of the IC

　　It is best for the protection IC to have a built-in balancing circuit of about 10mA. When a cell is overcharged, the balancing circuit can automatically determine the cell voltage difference of the battery pack under normal circumstances, and use the balancing circuit to control the battery voltage at a certain level. within the difference range.

　　7.Protect the programmable functions of the IC

　　Because the open circuit voltage of batteries of different types and materials corresponds to different typical SOC values, a rewritable FLASHROM can be integrated inside the protection IC, and the user can input different battery curve parameters according to different battery models.

　　8. Protect the actual power display function of the IC

　　The actual power display function can be set according to the relationship between the open circuit voltage of the lithium-ion battery recorded in the internal RAM and the SOC. The general four-level power display is 20% power, 50% power, 80% power, and more than 95% power. Level four.

　　Generally speaking, the first five functions are common functions that are common to all popular lithium-ion battery protection ICs on the market. The last three functions are already available in some lithium-ion battery protection ICs on the market. 1 or 2 types, but a protection IC that fully possesses these functions has not yet been seen, and the price is generally on the high side.

　　On the basis of the above five basic functions, the last three functions can be expanded to make the protection line truly intelligent.

　　Note: The rated operating current of lithium-ion battery packs used in bicycle batteries is generally 10 amps, and the peak current may reach 20 amps.

　　The two available NMOS models are as follows:

　　IRF1010ES

　　NBD7052L

　　Both NMOSs have strong overcurrent capabilities and retain sufficient margin.

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