What protective measures does lithium battery have?

The lithium battery protection plate varies according to the use of IC, voltage, etc., and the circuits and parameters are different. The following is explained by DW01 with MOS tube 8205 A:

1. The normal working process of the lithium battery protection plate is:

When the core voltage is between 2.5 V and 4.3 V, the first and third feet of the DW01 output high levels(equal to the supply voltage), and the second leg voltage is 0V. At this point, the first foot and third foot voltages of the DW01 will be increased to the fifth and fourth feet of the 8205 A, respectively. The two electronic switches in the 8205 A will be in the state of conduction because their G poles are connected to the voltage from the DW01, that is, the two electronic switches. Both are on. At this point, the negative electrode of the core is equivalent to a direct connection with the P-end of the protective plate, and the protective plate has a voltage output.

2. Protection plate over discharge protection control principle:

When the core is discharged through an external load, the voltage of the core will slowly decrease, while the DW01 interior will monitor the core voltage in real time through the R1 Resistor. When the core voltage drops to about 2.3 V, the DW01 will think that the core voltage is In the state of over discharge voltage, The output voltage of the first leg is immediately disconnected, so that the first leg voltage becomes 0V, and the switch tube in the 8205 A is turned off because there is no voltage in the fifth leg. At this point, the B-of the core and the P-of the protection plate are disconnected. That is, the discharge loop of the core is cut off and the core will stop discharging. The protective plate is in an over-discharge state and remains in place. After the P and P of the protective plate are indirectly charged, the DW01 immediately stops the overdischarge state after the B-detection of the charging voltage, and re-outputs Gaodianya in the first leg, so that the overdischarge control tube in the 8205 A is turned on. That is, the B of the core and the P of the protection plate are reconnected, and the core is directly charged by the charger.

3. Protection plate overcharge protection control principle:

When the battery is charged normally through the charger, the voltage of the core will increase with the increase of the charging time. When the core voltage rises to 4.4 V, the DW01 will assume that the core voltage is in overcharged voltage and immediately disconnects. The output voltage of the third foot, The third leg voltage is changed to 0V, and the switch tube in 8205 A is closed due to the absence of voltage in the fourth leg. At this point, the B-of the core and the P-of the protection plate are disconnected. That is, the charging circuit of the core is cut off and the core will stop charging. The protective panel is overcharged and remains in place. After waiting for the P and P of the protective plate to indirectly discharge the load, although the overcharge control switch tube is turned off at this time, the internal diode is in the same direction as the discharge loop, so the discharge loop can discharge. When the voltage of the core is placed below 4.3 V, the DW01 stops the overcharge protection state and re-outputs the overcharge control tube in the third leg, so that the overcharge control tube in the 8205 A is turned on, that is, the B of the core and the protection plate P-Again connected, The core can also perform normal charging and discharging.

4. Protection board short circuit protection control principle:

As shown in the figure, in the process of external discharge of the protective plate, the two electronic switches in the 8205 A are not completely equivalent to two mechanical switches, but are equivalent to two resistors with very small resistors, and are called 8205 A. Internal resistance, The conduction resistance of each switch is approximately 30m \ U03a9, which is approximately 60m \ U03a9. The voltage added to the G pole is actually directly controlling the size of the conduction resistance of each switch tube when the G pole voltage is greater than 1V. The conduction internal resistance of the switch tube is small(several tens of millieures), which is equivalent to the closure of the switch. When the G-pole voltage is less than 0.7 V, the conduction internal resistance of the switch tube is very large(a few MΩ), which is equivalent to the switch disconnection. Voltage UA is the voltage generated by the conduction resistance and discharge current of 8205 A. When the load current increases, UA must increase because UA 0.006L? The IUA, also known as the 8205A tube pressure drop, UA can simply indicate the magnitude of the discharge current. When it rises to 0.2 V, it is considered that the load current reaches the limit, so the output voltage of the first foot is stopped, the discharge control tube in the first foot voltage is turned off to 0V, and the discharge loop in the 8205 A is cut off. Discharge discharge control tube. In other words, the maximum current allowed by the DW01 is 3.3 A, which implements overcurrent protection.

5. Short circuit protection control process:

Short circuit protection is a limit form of over current protection. Its control process and principle are the same as over current protection. Short circuit is only equivalent to adding a small resistance(about 0Ω) between PP-so that the load current of the protective plate instantly reaches more than 10A, and the protective plate is immediately protected by current.

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