Under-voltage and over-voltage protection circuit for power supply circuit
A technology of undervoltage and overvoltage, power supply circuit, which is applied in the direction of emergency protection circuit device, protection against undervoltage or no voltage, protection against overvoltage, etc., to reduce manufacturing cost, high reliability, and structure simple effect
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Embodiment 1
[0030] Such as figure 1 Shown is an undervoltage and overvoltage protection circuit for a power supply circuit according to the first embodiment of the present invention, which is coupled to an external power supply and an external circuit, and includes a protection unit 101 and a control unit 102, wherein,
[0031] The protection unit 101 is coupled to the external power supply and the control unit 102, and is used to clamp or divide the supply voltage when the external power supply is under-voltage or over-voltage. The current corresponding to the processed voltage is sent to the control unit 102;
[0032] The control unit 102 is coupled to the protection unit 101 and an external circuit, and is configured to receive the current sent by the protection unit 101 to supply power to the external circuit. At the same time, when the protection unit 101 receives When the current value of is less than the minimum shut-off current value, the coupling with the external circuit is turned of...
Embodiment 2
[0041] Now combined Figure 2 to 4 , The specific application of the undervoltage and overvoltage protection circuit for the power supply circuit is described:
[0042] Such as figure 2 As shown in the prior art, in the switching power supply control circuit, although the switching power supply control device of model DPA423 is used to turn off or turn on the whole circuit, the overvoltage or undervoltage of the input voltage will cause the DPA423 Failure or even damage. Therefore, undervoltage and overvoltage protection circuits are added to the circuit structure. image 3 Shown.
[0043] Practical applications, image 3 The actual circuit corresponding to the circuit block diagram shown is as follows Figure 4 Shown is the actual circuit corresponding to the undervoltage and overvoltage protection circuit 20 for the power supply circuit in a specific application, where:
[0044] R1 and R4 are voltage divider resistors, R2, R3 and R5 are current-limiting resistors, D3 is a voltag...
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