Abstract: The present disclosure discloses a zero-crossing detection circuit, including: a zero-crossing judgment module, having a first end and a second end, wherein the first end is connected to a power supply and the second end is grounded; a photoelectric coupler, connected to the zero-crossing judgment module; an optocoupler driving module, connected to the photoelectric coupler; and an energy storage capacitor, wherein the energy storage capacitor is configured to provide excitation power for the photoelectric coupler and the optocoupler driving module.

Abstract: The present disclosure discloses a zero-crossing detection circuit, including: a zero-crossing judgment circuit, configured to detect a zero-crossing signal; and an energy storage capacitor, connected to the zero-crossing judgment circuit in parallel, wherein the energy storage capacitor is configured to provide excitation current for the zero-crossing judgment circuit.

Abstract: The present disclosure discloses a zero-crossing detection circuit, including: a zero-crossing judgment module, having a first end and a second end, wherein the first end is connected to a power supply and the second end is grounded; a photoelectric coupler, connected to the zero-crossing judgment module; an optocoupler driving module, connected to the photoelectric coupler; and an energy storage capacitor, wherein the energy storage capacitor is configured to provide excitation power for the photoelectric coupler and the optocoupler driving module.

Abstract: The present disclosure discloses a zero-crossing detection circuit, including: a zero-crossing judgment circuit, configured to detect a zero-crossing signal; and an energy storage capacitor, connected to the zero-crossing judgment circuit in parallel, wherein the energy storage capacitor is configured to provide excitation current for the zero-crossing judgment circuit.

Abstract: A parallel hybrid circuit comprising a transformer, a first matching resistor, a second matching resistor and an echo cancelling circuit. The transformer comprises: a first side, comprising a transmitting coil group and a receiving coil group, wherein the transmitting coil group comprises at least one transmitting coil, wherein the receiving coil group comprises at least one receiving coil; a second side comprising at least one transceiving coil; wherein the transformer receives a transmitting signal and couples the transmitting signal from the first side to the second side via a first turn ratio, and receives a receiving signal from the transceiving line and couples the receiving signal from the second side to the first side via a second turn ratio. The first, second matching resistors are coupled with the transformer in parallel. The echo cancelling circuit is coupled between the transmitting line and the receiving line.

Abstract: A parallel hybrid circuit comprising a transformer, a first matching resistor, a second matching resistor and an echo cancelling circuit. The transformer comprises: a first side, comprising a transmitting coil group and a receiving coil group, wherein the transmitting coil group comprises at least one transmitting coil, wherein the receiving coil group comprises at least one receiving coil; a second side comprising at least one transceiving coil; wherein the transformer receives a transmitting signal and couples the transmitting signal from the first side to the second side via a first turn ratio, and receives a receiving signal from the transceiving line and couples the receiving signal from the second side to the first side via a second turn ratio. The first, second matching resistors are coupled with the transformer in parallel. The echo cancelling circuit is coupled between the transmitting line and the receiving line.

Abstract: A surge protection circuit for a line driver of a communication system includes a positive output pad; a negative output pad; a transistor, comprising a first terminal, a second terminal and a third terminal, the first terminal coupled to the positive output pad, the second terminal coupled to the negative output pad; and a trigger circuit. The trigger circuit includes an inverter, comprising an input terminal and an output terminal, the output terminal coupled to the third terminal of the transistor; and a first RC delay circuit. The first RC delay circuit includes a resistor having a terminal coupled to an input terminal of the inverter, and another terminal coupled to a power supply; and a capacitor having a terminal coupled to the input terminal of the inverter and another terminal coupled to a ground. The transistor is within an integrated circuit.

Abstract: The present invention discloses a surge protection circuit for a line driver. The surge protection circuit includes a transistor, including a first terminal coupled to a positive output pad of the line driver and a second terminal coupled to a negative output pad of the line driver, an inverter, including an output terminal coupled to a third terminal of the transistor, and a first RC circuit, including a resistor having a terminal coupled to an input terminal of the inverter and another terminal coupled to a power supply, and a capacitor having a terminal coupled to the input terminal of the inverter and another terminal coupled to a ground. A first RC time constant of the first RC circuit is substantially equal to or greater than a period of a differential mode surge signal.