An output detection feedback section ( 5 ) for controlling the power supply output voltage of a converter unit ( 4 ) in response to an error signal Ve has an error amplifier ( 26 ) for outputting the error signal Ve, a phase compensation circuit ( 41 ), a state detection circuit ( 42 ), and a response compensation circuit ( 43 ) for setting the voltage of a capacitor ( 29 ) of the phase compensation circuit ( 41 ) to a predetermined value. When output voltage is switched, the output voltage is fixed at the predetermined value in a DC manner while a transitional response of the error signal (Ve) is accelerated, so that the output voltage is changed at a high speed to a desired value and the overshoot and undershoot are suppressed around the desired value.
1. A power supply, comprising:
a converter unit for transforming power supply input voltage to a predetermined power supply output voltage based on an error signal, and
an output detection feedback section for outputting the error signal according to the power supply output voltage,
the output detection feedback section comprising:
an error amplifier for outputting the error signal obtained by amplifying a voltage difference between a reference voltage and an output detection voltage obtained from the power supply output voltage,
a phase compensation circuit having a circuit of a capacitor and a resistor to compensate a phase of the error amplifier,
a state detection circuit for outputting a state signal indicating whether the voltage difference between the output detection voltage and the reference voltage is within a predetermined range, and
a response compensation circuit for inputting thereinto the state signal, and setting a voltage of the capacitor of the phase compensation circuit to a predetermined value when the voltage difference between the output detection voltage and the reference voltage is beyond the predetermined range.
2. The power supply according to claim 1 , wherein the response compensation circuit sets the resistor of the phase compensation circuit at a high resistance when the voltage difference between the reference voltage and the output detection voltage is beyond the predetermined range.
3. A power supply, comprising:
a converter unit for transforming power supply input voltage to a predetermined power supply output voltage based on an error signal, and
an output detection feedback section for outputting the error signal according to the power supply output voltage,
the output detection feedback section comprising:
an error amplifier for outputting the error signal obtained by amplifying a voltage difference between a reference voltage and an output detection voltage obtained from the power supply output voltage,
a phase compensation circuit having a circuit of a capacitor and a resistor to compensate a phase of the error amplifier,
a state detection circuit for outputting a state signal indicating whether the voltage difference between the output detection voltage and the reference voltage is within a predetermined range, and
a response compensation circuit for setting a voltage of the capacitor of the phase compensation circuit to a predetermined value for a predetermined period of time, when the voltage difference between the output detection voltage and the reference voltage is changed from a value beyond the predetermined range to a value within the predetermined range.
4. The power supply according to claim 1 , wherein the state detection circuit comprises a comparator for outputting the state signal activated when the output detection voltage is higher than the reference voltage by a predetermined voltage or more.
5. The power supply according to claim 3 , wherein the state detection circuit comprises a comparator for outputting the state signal activated when the output detection voltage is higher than the reference voltage by a predetermined voltage or more.
6. The power supply according to claim 1 , wherein the state detection circuit comprises a comparator for outputting the state signal activated when the output detection voltage is lower than the reference voltage by a predetermined voltage or more.
7. The power supply according to claim 3 , wherein the state detection circuit comprises a comparator for outputting the state signal activated when the output detection voltage is lower than the reference voltage by a predetermined voltage or more.
8. The power supply according to claim 1 , wherein the state detection circuit comprises:
a first comparator for outputting a first signal activated when the output detection voltage is higher than the reference voltage by a predetermined voltage or more,
a second comparator for outputting a second signal activated when the output detection voltage is lower than the reference voltage by the predetermined voltage or more, and
a logic circuit for outputting the state signal activated when one of the first signal and the second signal is active.
9. The power supply according to claim 3 , wherein the state detection circuit comprises:
a first comparator for outputting a first signal activated when the output detection voltage is higher than the reference voltage by a predetermined voltage or more,
a second comparator for outputting a second signal activated when the output detection voltage is lower than the reference voltage by the predetermined voltage or more, and
a logic circuit for outputting the state signal activated when one of the first signal and the second signal is active.
10. The power supply according to claim 1 , wherein the output detection feedback section comprises an output switching circuit for changing input voltage to the error amplifier in response to a switching signal for switching the output voltage.
11. The power supply according to claim 3 , wherein the output detection feedback section comprises an output switching circuit for changing input voltage to the error amplifier in response to a switching signal for switching the output voltage.
12. The power supply according to claim 1 , wherein the output detection feedback section comprises an output switching circuit for changing input voltage to the error amplifier in response to a switching signal for switching the output voltage, and
the output switching circuit comprises a resistor having one end connected to a node of the detection resistor and an input terminal of the error amplifier, and a switch circuit for selecting and applying a predetermined direct-current voltage to the other end of the resistor in response to the switching signal.
13. The power supply according to claim 3 , wherein the output detection feedback section comprises an output switching circuit for changing input voltage to the error amplifier in response to a switching signal for switching the output voltage, and
the output switching circuit comprises a resistor having one end connected to a node of the detection resistor and an input terminal of the error amplifier, and a switch circuit for selecting and applying a predetermined direct-current voltage to the other end of the resistor in response to the switching signal.
14. A power supply according to claim 1 , wherein the phase compensation circuit is a series circuit of the capacitor and the resistor.
15. A power supply according to claim 3 , wherein the phase compensation circuit is a series circuit of the capacitor and the resistor.