| 摘要 |
PURPOSE:To suppress the increase in electric power consumed in an IC and to prevent the heat generation and the resulting temperature rise of the IC, by suppressing the rise in an applied DC voltage when an excessive electric power is supplied without exerting any influence upon an AC electric characteristic, and shunting part of a supplied current to an external element. CONSTITUTION:When the voltage applied between the base and emitter of a transistor (TR) 13 is higher than an enough voltage (about 0.7V to turn on the TR, the TR13 turns on to suppress an increase in the power consumption in the IC constituting a telephone set circuit by the effect of the suppression of a rise in the DC voltage between terminals 8a and 8b and the effect of the shunting of part of the electric power to an external element 9. On the other hand, the AC voltage developed between the base 4 and emitter of the TR13 by the AC voltage applied between the terminals 8a and 8b is short-circuited by a capacitor 12 to hold the impedance between both terminals high, so almost no influence is exerted upon the AC characteristics of the telephone set circuit. |
