| 摘要 |
PURPOSE:To attain the detection with high accuracy using the same grounding detection resistor and to apply this circuit with IC constitution, by compensating a difference of the grounding detection resistor based on the difference of a grounding current due to use/non-use state of a terminal, by a load current output. CONSTITUTION:A detecting voltage proportional to a current difference IA-IB between a battery line current IA and a grounding line current IB is applied from a current difference detecting circuit 7 to a comparison circuit, and a voltage difference subtracting a detected voltage proportional to a load current IL out of a reference voltage VREF is applied from a circuit 11 to the comparison circuit 8, respectively. The circuit 8 generates an inverted grounding detecting output when the comparison input is larger than a reference input. Further, the grounding detecting resistor is made the same independently of the use/non-use state of the terminal 1 by determining the decrease compensating component of a grounding current IG depending on the usage state of a subscriber terminal 1 to a prescribed value. |
