Switching regulator with improved power supply voltage variation response
View Patent ↗Provided is a switching regulator having an improved power supply voltage variation response characteristic while maintaining the stability of an output voltage to oscillation. An output resistance of an error amplifier is adjusted by a power supply voltage variation response improving circuit to allow a gain of the error amplifier to change.
1. A switching regulator control IC, comprising:
an error amplifier for comparing an output voltage from a switching regulator with a reference voltage and amplifying a voltage difference therebetween to perform feedback control; and
an output control circuit connected with an output of the error amplifier, for keeping a gain of the error amplifier constant for a predetermined period after a power supply voltage varies, the output control circuit comprising:
an output resistance circuit; and
a power supply voltage variation response improving circuit connected to the output resistance circuit and comprising:
a power supply voltage increase regulation circuit for detecting a power supply voltage increase; and
a power supply voltage decrease regulation circuit for detecting a power supply voltage decrease,
wherein the power supply voltage variation response improving circuit is configured to control the output resistance circuit for keeping a gain of the error amplifier constant for a predetermined period after a power supply voltage varies.
2. A switching regulator, comprising:
a power supply, a switching element, and an inductor which are connected in series; and
a switching regulator control IC according to claim 1 for monitoring the output voltage and controlling the switching element based on the monitored output voltage.
3. The switching regulator control IC of claim 1 , where the output resistance circuit comprises:
a first resistor and a second resistor connected in parallel; and
an N-type MOS transistor connected to the first resistor and comprising a gate connected to an output of the power supply voltage variation response improving circuit.
4. The switching regulator control IC of claim 3 , wherein the power supply voltage variation response improving circuit is configured to put the N-type MOS transistor in an off state for the predetermined period when the power supply voltage is in a variation state.
5. The switching regulator control IC of claim 3 , the power supply voltage variation response improving circuit further comprising:
a NOR circuit comprising:
a first input connected to an output of the power supply voltage increase regulation circuit;
a second input connected to an output of the power supply voltage decrease regulation circuit; and
an output, wherein the output of the NOR circuit is the output of the power supply voltage variation response improving circuit connected to the gate of the N-type MOS transistor.
6. The switching regulator control IC of claim 1 , wherein the power supply voltage increase regulation circuit is configured to output a High-level output when the power supply voltage increases, and wherein the power supply voltage decrease regulation circuit is configured to output a High-level output when the power supply voltage decreases.
7. A switching regulator control IC, comprising:
a dividing resistor portion for receiving an output voltage from a switching regulator and generating a dividing voltage based on the output voltage;
a reference voltage circuit for generating a reference voltage;
an error amplifier for amplifying a voltage difference between the dividing voltage and the reference voltage;
an output resistance circuit for switching a gain of the error amplifier between a low-frequency region of the output voltage and a high-frequency region thereof, where the output resistance circuit comprises:
a first resistor and a second resistor connected in parallel; and
an N-type MOS transistor connected to the first resistor and comprising a gate connected to an output of the power supply voltage variation response improving circuit;
a power supply voltage variation response improving circuit connected with the output resistance circuit and comprising:
a power supply voltage increase regulation circuit and
a power supply voltage decrease regulation circuit,
wherein the power supply voltage variation response improving circuit is configured to put the N-type MOS transistor in an off state for a predetermined period when the power supply voltage is in a variation state;
a triangular wave generating circuit for generating a triangular wave voltage; and
a PWM comparator for comparing a voltage outputted from the error amplifier with the triangular wave voltage to generate a PWM signal,
wherein the power supply voltage variation response improving circuit controls the output resistance circuit to keep the gain of the error amplifier constant after a power supply voltage varies.
8. A switching regulator control IC according to claim 7 ,
wherein the output resistance circuit comprises:
a first resistor and a second resistor which are connected in parallel; and
a capacitor and a switch circuit which are connected in series with the second resistor, and
wherein the switch circuit is controlled by the power supply voltage variation response improving circuit.
9. A switching regulator control IC according to claim 8 , wherein the switch circuit is caused to be off by the power supply voltage variation response improving circuit for a predetermined period after the power supply voltage varies.
10. A switching regulator, comprising:
a power supply, a switching element, and an inductor which are connected in series; and
a switching regulator control IC according to claim 7 for monitoring the output voltage and controlling the switching element based on the monitored output voltage.
11. The switching regulator control IC of claim 7 , the power supply voltage variation response improving circuit further comprising:
a NOR circuit comprising:
a first input connected to an output of the power supply voltage increase regulation circuit;
a second input connected to an output of the power supply voltage decrease regulation circuit; and
an output, wherein the output of the NOR circuit is the output of the power supply voltage variation response improving circuit connected to the gate of the N-type MOS transistor.
12. The switching regulator control IC of claim 7 , wherein the power supply voltage increase regulation circuit is configured to output a High-level output when the power supply voltage increases, and wherein the power supply voltage decrease regulation circuit is configured to output a High-level output when the power supply voltage decreases.