reverse battery protection

Answer 1

Reverse battery protection was to prevent damage to the circuit that used the battery as the power source when the battery was connected in reverse in the direct current system. The following are a few common battery protection methods:

** 1. Use a relay and a relay to make a reverse protection circuit **
1. ** Circuit Connection and Working Principle **
- He connected the battery to the relay and the coil, connected the battery to the relay, and connected the battery to the relay coil. He used a light bulb to replace the circuit.
- When the positive and negative poles of the battery were correctly connected, the positive voltage passed through the relay coil through the relay coil, then passed through the coil to the negative pole, and then the contact was pulled in. The circuit obtained a positive voltage and worked normally.
- When the positive and negative connections were reversed, the relay coil would have no current, so it would not be pulled in, and the circuit would not supply power to protect the circuit components behind it. After the positive and negative were reconnected, the circuit would continue to work.

** 2. Use MOS tubes as reverse protection for the battery **
- ** P-Channel Metal-Coupled Devices **
- ** Basic Connection **: The MOS tube is connected to the positive pole of the battery (drain-the positive pole of the battery, power supply-the positive pole of the power supply, grid-the negative pole of the battery, or ground).
- ** Principle of operation **: When the battery voltage is present, the current will flow to the Body Diode. If the battery voltage is higher than the forward bias voltage of the body, the body will be turned on. At this time, the voltage level in the source of the Metalifu is the battery voltage minus the body voltage drop. Since the gate of the Metal-Channel Devices is connected to the negative terminal of the battery or to ground, the voltage applied to the gate-to-source will be negative. Once the gate-to-source voltage requirement of each Metal-Channel Device Data Table is met, the P-Channel Metal-Channel Devices will activate, the channel will be closed, and the current will flow to it instead of to the Body Diode.
- ** Basic requirements **:
- The basic electrical connections must be made according to the recommendations.
- In terms of gate-source threshold voltage, in order to turn on the P-channel semiconductor, the difference between the battery voltage and the body conductor had to be higher than-1V (different mosfetts had different requirements). For low-voltage systems, it was best to choose a mos with a very low gate-to-source threshold voltage.
- The maximum gate-source voltage specifications of the Metalgate must not be reached, or it will be damaged.
- The drain current rating of a consecutively connected drain must be higher than the actual current flowing into it.
- In terms of rated power, the calculated power consumption must be lower than the rated value of the device (for example, a device with a rated power dissipation of 8.3W at 25°C, the actual calculated power consumption must be lower than this value and leave a margin). At the same time, pay attention to the operating temperature range.
- ** N-Channel Metal-Coupled Devices **
- ** Basic Connection **: The Ruoyun is connected to the negative pole of the battery (drain-the negative pole of the battery, source-the negative pole of the device or ground, grid-the positive pole of the battery).
- ** Working principle **: During the circuit start-up period, the current flows from the positive terminal of the battery to the device, then to the body junction, and finally to the negative terminal of the battery. The body junction is turned on when it is forward-biased. At this time, the gate-source voltage is positive, and the Ruoyun begins to turn on, and the current will flow to the channel instead of the body junction.
- ** Basic requirements **:
- The basic electrical connections must be made according to the recommendations.
- In terms of gate-source threshold voltage, it was not enough to just use a positive voltage to bias the gate to the source. It must meet the required level. For low-voltage systems, it was best to choose a Metal-Doped Circuit with a very low gate-to-source threshold voltage.
- Pay attention to the maximum grid-source voltage rating.
- The current rating shall meet the requirements of the data sheet.

** 3. Other methods **
It can also use series connection of the two, the rectify bridge, and the MOS protection.(specify gate, source, drain), fuse +TVS (When the voltage is greater than a certain value, such as 5.6V, it can dissipate a large amount of power and absorb the instantaneous high current caused by the instantaneous high voltage pulse. The fuse can choose a self-restoring fuse. When the current becomes very large, the resistance will also become very large, and it will recover after a period of time.) Connecting a large capacity at the back end could prevent the back-end circuit from being impacted (for example, when the 5V circuit suddenly connected to the 12V power supply, there was a time difference in the TVS's connection, and the large capacity could make the voltage slowly climb).
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