Patent ID: 7840194

Claim:
A transmitting circuit for a serial transmission interface that receives a transmitting data signal to generate a pair of transmitting signals, comprising: a first resistor unit controlled by a control signal, wherein the first resistor unit has a predetermined impedance value while the control signal is enabled, or has a high-impedance value while the control signal is disabled; a first switch unit connected to the first resistor unit and controlled by the transmitting data signal, wherein the connecting node of the first switch unit and the first resistor unit is defined as a first terminal; a second resistor unit controlled by the control signal, wherein the second resistor unit has the predetermined impedance value while the control signal is enabled or has the high impedance value while the control signal is disabled; a second switch unit connected to the second resistor unit and controlled by the reverse signal of transmitting data signal, wherein the connecting node of the second switch unit and the second resistor unit is defined as a second terminal; and an auto-detection circuit for generating the control signal according to a reference signal; wherein the pair of transmitting signals are output from the first terminal and the second terminal, and the pair of transmitting signals are determined by the transmitting data signal while the control signal is enabled, or the pair of transmitting signals are at a high impedance state without output from the first terminal and the second terminal while the control signal is disabled.