| 摘要 |
<p>PURPOSE:To protect a digital transmission equipment against the application of overcurrent over the normal operating current by inserting an overcurrent limit circuit comprising a FET having a constant current characteristic to a pre-stage of a DC-DC conversion section. CONSTITUTION:The overcurrent limit circuit 10 having the FET with the constant current characteristic is provided, while being inserted to a power supply line from connecting points 30, 31 to the DC-DC conversion section 11 in the digital transmission equipment provided with the DC-DC conversion section 11 energized remotely via connection points 30, 31 to a digital communication line, a reception section 12 and a transmission section 13 operated by the power supply from the DC-DC conversion section 11 and receiving/transmitting a signal to the digital communication line, a hybrid transformer 16 and a signal processing section 14 operated by the power supply from the DC-DC conversion section 11 and applying an input/output signal to the reception section 12 and the transmission section 13. The overcurrent limit FET 10 protects the DC-DC conversion section 11 from being destroyed by the flowing of the overcurrent in case an overvoltage is applied between the connection points 30, 31 to the digital communication line.</p> |
