Serial port protecting circuit of LED display screen control card
A technology of LED display screen and protection circuit, which is applied in the direction of emergency protection circuit device, emergency protection circuit device for limiting overcurrent/overvoltage, circuit device, etc., and can solve the problem of many restrictions on use, poor interference tolerance, and flexibility Poor performance and other problems, to achieve the effect of reducing production costs, high pressure and current resistance, and small attenuation
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Embodiment 1
[0027] refer to Figure 1-8 , a specific embodiment of the present invention includes that the computer serial port output port PC_TXD is connected to the serial port chip receiving port UART1_TX, the computer serial port input port PC_RXD is connected to the serial port chip sending port UART1_RX, the computer serial port and the serial port chip are connected with a limited voltage chip, and the computer serial port output port There is a first current limiting circuit connected between PC_TXD and the receiving end UART1_TX of the serial port chip, and a second current limiting circuit is connected between the computer serial port input end PC_RXD and the sending end UART1_RX of the serial port chip; For shunting and stepping down, the first current limiting circuit and the second current limiting circuit are used to limit the current passing through the serial port.
[0028] It is worth noting that the voltage limiting chip adopts the PESD12VL2BT chip produced by Philips, a...
Embodiment 2
[0037] refer to Figure 9-10 , this embodiment is based on Embodiment 1, and an isolation circuit is provided between the first current limiting circuit and the first current stabilizing circuit, and between the second current limiting circuit and the second current stabilizing circuit.
[0038] The isolation circuit arranged between the first current limiting circuit and the first current stabilizing circuit includes a first phototransistor Q7, a first light emitting diode D3, and a sixth pull-down resistor R20, and the first current limiting circuit is connected to the first light emitting diode D3. Anode, the negative pole of the first light-emitting diode D3 is grounded, the first light-emitting diode D3 is coupled with the base of the first phototransistor Q7, the collector of the first phototransistor Q7 is connected to the high level Vcc, the emitter of the first phototransistor Q7 The sixth pull-down resistor R20 is grounded, and the first current stabilization circuit...
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