| 摘要 |
PURPOSE:To enable to minimize power loss in channel current supply circuits and to make it easier to form the circuit with ICs, by controlling the current to be supplied to the channel in accordance with the channel resistance. CONSTITUTION:Channel current supply circuit LCF which supplies the channel current, is equipped to terminal equipment TE through lines L1 and L2, and line voltage VL between lines L1 and L2 is detected by installing voltage detect circuit DETV using a voltage divider, etc., to this circuit LCF. Moreover, by providing a series resistance and current detect circuit DET1 using operation amplifier, etc., the detecting output from both circuits DETV and DET1 is added to operation circuit CAL and the channel current is decided by obtaining the channel resistance through the operation at circuit CAL. This channel current and the current detected at circuit DET1 are compared with each other through comparator CMP, and power loss in circuit LCF is minimized and the circuit is easily formed with ICs, by controlling power source conversion circuit CONV which supplies the voltage of wire B to lines L1 and L2 after converting the voltage into a prescribed voltage in accordance with the difference in current values compared at comparator CMP. |
