Analyses the effect of mobile phone lithium battery protection board

Source: 2020 - 03 - 24 thus hits: mobile phone lithium battery protection board 1 charge over discharge protection over-current short circuit protection of original mobile phone charge straight flush directly, will automatically open the protection circuit of battery protection board. The positive and negative short circuit batteries, electric spark on the plate. Try a few times, then charge directly. Looking for a 5 v dc power supply, battery of the positive and negative contact the positive and negative of the battery, try a few times, and then use the original charger. The principle of battery protection panel lithium battery protection board according to the IC, voltage and other purposes have different circuit and parameters. The commonly used protection IC 8261, DW01 +, CS213, GEM5018, etc. Among them, seiko series 8261, higher precision, of course also more expensive. The latter are from Taiwan. Main use DW01 + and CS213 secondary market in China. The following is a DW01 + and MOS tube 8205 a ( 8pin) Explanation: the lithium battery protection board normal working process is: when the battery voltage is 2. 5 v ~ 4。 3 v, DW01 first pin (output level Is equal to the power supply voltage) The output voltage of 0 v, the second pin. At this point, the DW01 the voltage of the first 3 feet pin in May 8205 a pin. 8205 a two electronic switch connected to DW01 voltage due to its G, so is in a state of conduction. Two electronic switch is opened. The battery cathode and protection plate p side equivalent for direct communication, protective plate with voltage output. Protection board too loose control principle: when the battery discharge by external load, the battery voltage decreases gradually, through the R1 resistance real-time monitoring DW01 internal voltage. When the battery voltage drop to 2. About 3 v, DW01 will consider battery voltage. When a discharge voltage, output voltage of the first pin closed immediately, make the first pin voltage at 0 v, and the fifth pin pin switch is closed, because there is no voltage fifth pin. At this point, B - cell P - and protection plate Disconnect. In other words, the discharge of the battery circuit is cut off, the battery will cease to discharge. Over discharge protection board, and remain there. When P and P protection voltage protection board indirect charge, when B detected after charging voltage, DW01 immediately stopped discharge state, and on the first pin to output high voltage, opened in 8205 a discharge control tube. In other words, B - of the battery P - and protection plate Reconnect the battery core by the charger directly. Protection board as the overcharge protection control principle: when the battery normal charge, with the increase of charging time, battery voltage will be more and more high. When the battery voltage up to 4. 4 v, DW01 assume that the battery voltage is in a state of charging pressure. Immediately disconnect pin 3 output voltage, pin 3 to 0 v voltage, because there is no voltage on pin 4, so 8205 a switch is closed. At this point, B - cell Disconnect the P - The protection plate and connectivity. That is to say, the battery charging circuit is cut off, will stop charging the battery. Protective plate in the overcharge state and stay there. Until the fender P, P - Indirect discharge load, when the charging control switch is closed, but internal diode and discharge circuit in the same direction, so you can discharge, the discharge circuit, when the battery voltage is less than 4. 3 V, DW01 stop charging protection present situation and the high voltage output pin 3820 5 years charging control tube conduction, B - namely the batteries P - And the protection of plate to reconnect. Battery charge and discharge normally. Protection board short circuit protection control principle: in the process of discharge protection plate, two of the 8205 a electronic switch is not equivalent to two mechanical switch, but the equivalent of two resistance smaller resistance, called the conduction resistance of 8205 a. The electrical resistance of about 30 mu each switch. 03 a9 is about 60 mu 03 a9. The voltage on the G very actually directly controls the conduction resistance of each switch. When the voltage is greater than 1 v g, switch tube conductive resistance is very small, Dozens of milliohm) , which is equivalent to a switch is closed. When the voltage is less than 0. 7 V G, switch tube on resistance is very large, A few meters Ω) , the equivalent of a switch.