In particular, FIG. 6 is a circuit diagram of a discharge circuit 600 for reducing an unknown period of the voltage measured at the reference point K1 described with reference to FIG. 4, and FIG. 7 is a circuit diagram of a discharge circuit 700 for removing an unknown period of the voltage measured at the reference point K1.
Referring to FIG. 6, the discharge circuit 600 may include a DC power supply unit 131, a discharge control terminal 132, a first switch 133, a capacitor 134, a second switch 135, a third switch 137, and a discharge check terminal 136.
The DC power supply unit 131, the discharge control terminal 132, the first switch 133, the capacitor 134, and the second switch 135 are substantially the same as those of FIGS. 2 and 3.
The discharge circuit 600 of FIG. 6 may further include the third switch 137, in addition to the discharge circuit 130 of FIGS. 2 and 3.
The third switch 137 may be a FET.
A gate terminal G of the third switch 137 is connected to a drain terminal of the second switch 135 and one end of the third resistor R3.
A source terminal S of the third switch 137 is grounded
