| 摘要 |
PURPOSE:To prevent the breakdown caused by the heat loss of a feeding transistor(TR) by turning of a TR by an overcurrent preventing circuit to form a current loop between the 1st and 2nd current feeding circuits and generating a voltage drop through a resistor. CONSTITUTION:Since an R-line resistor is turned to '0' at the time of grounding, a current I3 is allowed to flow into an overcurrent detecting circuit 12. The voltage drop of a resistor R28 is increased by the current I3, a TR13 is turned on, a voltage drop is generated in a resistor R29 by a current I5' flowing into the TR13, and then a TR10 is turned on. When the TR10 is turned on a current IC3 flows from the 1st current circuit 10 through a resistor R26. The current flows through R22 R23 R26 TR10 R30 R20 R21 power supply VBB in loop. When a current I5 is allowed to flow impressed to the resistor 21 a voltage drop is generated, voltage impressed to the resistor 21 is reduced and a current I1 for grounding is reduced. |
