| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a constant-voltage power supply circuit capable of high-speed switching of an output voltage. <P>SOLUTION: An output transistor 6 is connected between a power terminal 2 and an output terminal 3. A voltage detection circuit 7 is connected between the output terminal 3 and a ground terminal 4 and divides, with a ratio k (k≥0) which changes according to an inputted voltage switching signal Vsel, the voltage between the output terminal 3 and the ground terminal 4 in the ratio of k:1 so as to generate a first voltage Va and a second voltage Vb at the ground terminal 4 side. The second voltage Vb has the same polarity as that of the first voltage, and its absolute value is equal to or less than the absolute value of the first voltage. A control circuit 8 detects an error between the first voltage Va and a reference voltage Vref being a standard of a voltage generated at the output terminal 3, and controls the output transistor 6 so as to decrease the absolute value of the error. A discharge circuit 9 is connected between the output terminal 3 and the ground terminal 4 and discharges an electrical charge from the output terminal 3 to the ground terminal 4 when the absolute value of the second voltage Vb is greater than the absolute value of the reference voltage Vref. <P>COPYRIGHT: (C)2013,JPO&INPIT |
