| 摘要 |
PROBLEM TO BE SOLVED: To provide a termination circuit for communication equipment that maintains a normal operating state even when a power supply is accidentally interrupted and does not generate a radio noise with small power consumption. SOLUTION: The termination circuit for communication equipment 2 consists of a transistor(TR) 19 being a switching element, a diode 21 acting as a reverse flow prevention circuit, a diode 23 acting as a voltage drop circuit, an OR circuit 24, an integration circuit 26, a reference voltage generating circuit 29 acting as a switching control means and a waveform shaping circuit 31. When the level of a transmission line 3 is at a high level, the level of the transmission line 3 drives the reference voltage generating circuit 29 and the waveform shaping circuit 31, stores electric charges in a circuit 28 in the integration circuit 26, and when the transmission line 3 goes from a high level to a low level, the electric charges stored in the capacitor 28 are discharged to drive the reference voltage generating circuit 29 and the waveform shaping circuit 31. The reference voltage generating circuit 29 and the waveform shaping circuit 31 linearly and gradually increase/decrease a current flowing through the TR 19 when the level of the transmission line 3 is subjected to change as their control so that the current waveform of the current flowing through the transmission line 3 is trapezoidal resulting in reduction in the radio noise.
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