| 摘要 |
PURPOSE:To prevent fluctuation due to the temperature of an output voltage with a low level from occurring, and to keep the stable operation of a circuit, by providing the circuit to compensate the characteristic fluctuation of a clamping circuit due to the temperature. CONSTITUTION:It is assumed that a current on a resistance R4 is decided by a resistance ratio between the resistances R4 and R5 in a room temperature, and thereby, the low level voltage of a node 3 is set at the optimum value. At the time of a temperature rise, a voltage VBE between the base and the emitter of a transistor Q5 is lowered, but since the forward biased voltage of a diode D1 is also lowered with the temperature rise as much as the VBE, the current on the R5 is reduced, and the current on the R4 is increased. Therefore, a voltage drop by the R4 is increased, and the voltage of an N5 is lowered. In other words, since the share of the voltage drop of the VBE of the Q5 due to the temperature rise can be compensated by the increase of the voltage drop in the R4, no fluctuation in the low level voltage of the N3 is generated. Thus, it is possible to keep the low level voltage at a regulated level regardless of the fluctuation of the temperature.
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