| 摘要 |
PURPOSE:To reduce the number of components by utilizing a PN junction between base and emitter of 2 transistors (TRs) being a component of a voltage current conversion circuit as reverse voltage protection mutually. CONSTITUTION:A 1st voltage current conversion circuit being a circuit detecting the polarity consists of a TR 5, a resistor 3 and a polarity detection terminal 7 and a 2nd voltage current conversion circuit consists of a TR 6, a resistor 4 and a polarity detection terminal 8. When a control voltage Vc at the terminal 1 is higher than the level of a terminal 2, the voltage Vc causes a current to flow in a path composed of the resistor 3, the base and emitter of the TR 6 and the resistor 4 to control a collector current from the polarity detection terminal 8. The voltage of the PN junction of the base and emitter of the TR 6 is very small at the same time of the operation above and the PN junction acts like a diode for protecting reverse voltage with respect to the base and emitter of the TR 5. Thus, a diode for reverse voltage protection is not required. |
