Control circuit for multi-output switching converter

1 . A control circuit, for controlling a switching converter with a primary switch, an energy storage component and a plurality of rectifiers, the control circuit comprising:

a sample and hold circuit, configured to sample and hold a power source winding voltage provided by a power source winding of the energy storage component during when any one of the plurality of rectifiers is on, and to provide a sample&hold voltage based thereon; and

a feedback circuit, configured to receive the sample&hold voltage and a power supply voltage for supplying power to the control circuit to maintain an operation of the control circuit, and to provide a feedback voltage based on the power supply voltage and the sample&hold voltage, for controlling the primary switch; and

wherein the feedback circuit comprises:

a first scaling circuit, configured to receive the power supply voltage, and to provide a first scaling voltage which is a product of the power supply voltage and a first scale factor;

a second scaling circuit, configured to receive the sample&hold voltage, and to provide a second scaling voltage which is a product of the sample&hold voltage and a second scale factor; and

an operational circuit, configured to receive the first scaling voltage and the second scaling voltage, and based on the first scaling voltage and the second scaling voltage, the operational circuit provides the feedback voltage which is a sum of the first scaling voltage and the second scaling voltage.

2 . The control circuit of claim 1 , further comprising:

an error amplifier, configured to receive the feedback voltage and a reference voltage, and based on an amplified error between the feedback voltage and the reference voltage, the error amplifier provides a compensation signal; and

a pulse control circuit, configured to receive the compensation signal, and based on the compensation signal, the pulse control circuit provides a switching control signal to control the primary switch.

3 . The control circuit of claim 1 , wherein:

both the first scale factor and the second scale factor are constants having values between 0 and 1, and a sum of the first scale factor and the second scale factor is 1.

4 . A switching converter having with a flyback topology, comprising:

a primary switch, coupled to a primary winding of an energy storage component;

a sample and hold circuit, configured to sample and hold a power source winding voltage provided by a power source winding of the energy storage component, and to provide a sample&hold voltage based thereon; and

a feedback circuit, configured to receive the sample&hold voltage and a power supply voltage for supplying power to a control circuit for controlling the primary switch, and to provide a feedback voltage based on the power supply voltage and the sample&hold voltage, for controlling the primary switch; and

wherein the feedback circuit comprises:

a first scaling circuit, configured to receive the power supply voltage, and to provide a first scaling voltage which is a product of the power supply voltage and a first scale factor:

a second scaling circuit, configured to receive the sample&hold voltage, and to provide a second scaling voltage which is a product of the sample&hold voltage and a second scale factor; and

an operational circuit, configured to receive the first scaling voltage and the second scaling voltage, and based on the first scaling voltage and the second scaling voltage, the operational circuit provides the feedback voltage which is a sum of the first scaling voltage and the second scaling voltage.

5 . The switching converter of claim 4 , further comprising:

an error amplifier, configured to receive the feedback voltage and a reference voltage, and based on an amplified error between the feedback voltage and the reference voltage, the error amplifier provides a compensation signal; and

a pulse control circuit, configured to receive the compensation signal, and based on the compensation signal, the pulse control circuit provides a switching control signal to control the primary switch.

6 . The switching converter of claim 4 , further comprising:

the energy storage component, having the primary winding, the power source winding, and at least two secondary windings, wherein the primary switch is coupled to the primary winding; and

at least three rectifiers of the plurality of rectifiers, coupled respectively to the power source winding and the at least two secondary windings, wherein the rectifier coupled to the power source winding has a first terminal coupled to the power source winding to receive the power source winding voltage, and a second terminal configured to provide the power supply voltage.

7 . The switching converter of claim 4 , wherein:

both the first scale factor and the second scale factor are constants having values between 0 and 1, and a sum of the first scale factor and the second scale factor is 1.

8 . A control circuit for a switching converter having a flybuck topology with an energy storage component, a primary switch and a rectifier, the control circuit comprising:

a sample and hold circuit, configured to sample and hold a primary winding voltage provided by a primary winding of the energy storage component during when the rectifier is on, and to provide a sample&hold voltage based thereon;

a feedback circuit, configured to receive a power supply voltage for supplying power to the control circuit to maintain an operation of the control circuit, and the sample&hold voltage, and to provide a feedback voltage based on the power supply voltage and the sample&hold voltage for controlling the primary switch; and

wherein the feedback circuit comprises:

a first scaling circuit, configured to receive the power supply voltage, and to provide a first scaling voltage which is a product of the power supply voltage and a first scale factor;

a second scaling circuit, configured to receive the sample&hold voltage, and to provide a second scaling voltage which is a product of the sample&hold voltage and a second scale factor; and

an operational circuit, configured to receive the first scaling voltage and the second scaling voltage, and based on the first scaling voltage and the second scaling voltage, the operational circuit provides the feedback voltage which is a sum of the first scaling voltage and the second scaling voltage.

9 . The control circuit of claim 8 , further comprising:

an error amplifier, configured to receive the feedback voltage and a reference voltage, and based on an amplified error between the feedback voltage and the reference voltage, the error amplifier provides a compensation signal; and

a pulse control circuit, configured to receive the compensation signal, and based on the compensation signal, the pulse control circuit provides a switching control signal to control the primary switch.

10 . The control circuit of claim 8 , wherein:

both the first scale factor and the second scale factor are constants having values between 0 and 1, and a sum of the first scale factor and the second scale factor is 1.