Voltage regulator

Abstract

Provided is a voltage regulator capable of reducing fluctuation of an output current even when an output terminal thereof is short-circuited. In a case where the output terminal of the voltage regulator is short-circuited, an output current (Iout) of the voltage regulator is limited and fixed to a limit current value. When an output voltage (Vout) of the voltage regulator decreases to have a value equal to or smaller than not a detection voltage value (Vref3) of a reference voltage circuit (34) but a detection voltage value (Vref2) of a reference voltage circuit (31), a second limit operation in which the output voltage (Iout) is further limited to be decreased is set. Further, in a case where the output terminal is short-circuited and then reset, when the output voltage (Vout) has a value equal to or larger than not the detection voltage value (Vref2) but the detection voltage value (Vref3), the second limit operation is canceled.

Description

technical field [0001] The present invention relates to voltage regulators. Background technique [0002] First, a conventional voltage regulator will be described. image 3 is a circuit diagram showing a conventional voltage regulator. Figure 4 It is a graph showing the output voltage with respect to the output current of the conventional voltage regulator. [0003] Here, the output transistor 71 outputs the output voltage Vout according to the input voltage Vin and the control voltage Vc of the amplifier circuit 74 . When the output voltage Vout of the voltage regulator decreases, the output voltage Vout is divided by the voltage dividing circuit 72, and the divided voltage Vfb output by the voltage dividing circuit 72 also decreases. The divided voltage Vfb is compared with the reference voltage Vref1 generated by the reference voltage circuit 73 by the amplifying circuit 74, and when the divided voltage Vfb is smaller than the reference voltage Vref1, the control volt...

AI Technical Summary

Problems solved by technology

[0008] However, when the output voltage Vout is close to the detection voltage value due to the short circuit of the output terminal, the overcurrent protection circuit 75 performs the second limiting operation or releases the second limiting operation on the output current Iout based on one detection voltage value, so the output terminal is short-circuited. When the output current Iout is unstable

At this time, there is a danger that the output current Iout does not become the short-circuit current value but becomes an unexpected current value, causing the output voltage Vout to become 0V.

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