Lithium battery protection board work principle and let fill short circuit protection

Lithium battery protection board according to the use of IC, the voltage is different, the different circuit and parameters, such as the following to DW01 talking with MOS tube 8205 a: 1. Lithium battery protection board the normal working process is: when the batteries voltage in 2. 5 v to 4. 3 v, DW01 1 foot, foot all output high level (3 Is equal to the power supply voltage) The second foot, voltage of 0 v. DW01 at this time of the first 3, the voltage will be added to the 8205 a, 4, 5, 8205 a within two electronic switch because its G received from DW01 voltage, therefore, are in the conduction state, namely both electronic switch in the open state. The batteries of the cathode and P - protection plate End of directly connected, the protection plate with voltage output. 2. Protection board over discharge protection control principle: when the batteries during discharge, by an external load batteries voltage will reduce slowly, at the same time will be on R1 DW01 internal resistance real-time monitoring batteries voltage, when the batteries voltage drop to about 2. 3 v DW01 will think they are in a discharge voltage batteries voltage, immediately disconnect the output voltage of 1 foot, foot 1 to 0 v voltage, in 8205 a switch tube shut down due to no voltage 5 feet. B - of the batteries and now P - and protection plate In the off state. The batteries discharge circuit is cut off, batteries will cease to discharge. Protection board in the over discharge state and keep. P and P - until the fender By charging voltage on the indirect DW01 through B - Charging voltage detected immediately stopped after discharge, to output high voltage in the first foot, make 8205 a discharge pipe control, within the B - namely the batteries P - and protection plate Back in again, batteries charger directly. 3. Protection board over charging protection control principle: when the battery charger through normal charge, with the increase of charging time, batteries voltage will be more and more high, when the batteries voltage rise to 4. 4 v, DW01 will think they are in a charging voltage batteries voltage, immediately disconnect the output voltage of 3 feet, make 3 feet voltage at 0 v, 8205 a switch tube inside the closed by 4 feet no voltage. B - of the batteries and now P - and protection plate In the off state. The batteries charging circuit is cut off, batteries will be stop charging. Protection board in the charging state and keep. P and P - until the fender After discharge load on indirect, so while charging the control switch tube closed, but its internal diode positive direction and the direction of the discharge circuit of the same, so the discharge circuit to discharge, when the batteries voltage is in less than 4. 3 v, DW01 stopped charging protection status again in 3 feet high output voltage, makes the charging control for 8205 a tube conduction, B - namely the batteries P - and protection board Back in again, batteries and can perform normal charging and discharging. 4. Protection board short circuit protection control principle: as the chart shows, in the process of external discharge protection plate, two in 8205 a electronic switch is not equivalent to two mechanical switch, but is equivalent to two small resistance, and called the conduction resistance of 8205 a, each switch conduction resistance of about 30 m U 03 a9, a total of about 60 m U 03 a9, add in G in the voltage is actually directly control the size of each switch tube on resistance when the voltage is greater than 1 v G, switch tube conduction resistance is small, Dozens of milliohm) , is equal to the switch is closed, when G voltage is less than 0. 7 v, switch tube conduction resistance is very big, A few M Ω) , which is equivalent to a switch. Voltage UA is 8205 a conduction resistance and voltage, discharge current, load current, UA will increase, because UA0. 006L? The IUA is also known as 8205 a pipe pressure drop, UA can indirectly indicates that the size of the discharge current. Up to 0. 2 v think load current when it reached the limit, then stop the output voltage of 1 foot, make feet 1 to 0 v voltage, the discharge control for 8205 a tube closed and cut off the batteries discharge circuit, will shut off discharge control tube. In other words DW01 allowed to output the maximum current is 3. 3 a, has realized the overcurrent protection. 5. Short circuit protection control process: short circuit protection is an extreme form of overcurrent protection, its control process and principle is the same as over current protection, short circuit is equivalent to the P P - Combined with a resistance between small resistance ( About 0 Ω) Make protection plate load current instantaneous amounting to more than 10 a protection plate overcurrent protection immediately.