CN111900864A - Control circuit and control method of switch circuit - Google Patents

Abstract

The present invention provides a control circuit and a control method for a switch circuit. The control circuit includes a first module and a second module, and the first module and the second module cooperate to control the switch circuit; the first module is the control loop of the switch circuit, the second module provides auxiliary control for the switch circuit; when the conduction time of the first switch tube of the switch circuit reaches the threshold time, the control circuit detects the load size of the switch circuit, when the switch circuit When the load is less than the first threshold, the second module is turned off; the first switch tube is connected to the input end or the output end of the switch circuit. The invention can effectively reduce the power consumption of the control circuit and improve the efficiency at light load.

Description

Control circuit and control method of switch circuit

technical field

The invention relates to the field of power electronics, in particular to a control circuit and a control method of a switch circuit.

Background technique

The control circuit of the switch circuit includes some devices with high power consumption and devices with normal power consumption. When the control circuit works, all circuits in the control circuit work normally no matter what mode the switch circuit operates. However, in some cases, the high power consumption device in the control circuit does not need to work normally, and it will not affect the control of the switching circuit. In these cases, if the high power consumption device continues to work normally, it will bring a lot of Unnecessary energy loss.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a control circuit and a control method of a switch circuit for reducing the power consumption of the control circuit, which can solve the problem of high power consumption of the control circuit.

In order to achieve the above object, the present invention provides a control circuit of a switch circuit, comprising a first module and a second module, the first module and the second module cooperate to control the switch circuit; the first module is The control loop of the switch circuit, the second module provides auxiliary control for the switch circuit; when the conduction time of the first switch tube of the switch circuit reaches the threshold time, the control circuit detects the load size of the switch circuit; when the switch circuit load When the value is less than the first threshold, the second module is turned off; the first switch tube is connected to the input end or the output end of the switch circuit.

Optionally, the first module includes a detection circuit, and when the conduction time of the first switch tube reaches a threshold time, the detection circuit detects the voltage drop of the first switch tube or the current of the first switch tube, and when the first switch tube is turned on, the detection circuit detects the voltage drop or current of the first switch tube. When the voltage drop or the current of the first switch tube is less than the corresponding threshold, the second module is turned off; the voltage drop of the first switch tube or the current of the first switch tube represents the size of the load.

Optionally, the detection circuit further detects a rate of change of the output voltage, and when the rate of change is greater than a second threshold or the voltage drop of the first switch tube is greater than a third threshold, the second module is turned on.

Optionally, the first module further includes the main control comparator; when the switch circuit works in the discontinuous conduction mode, the main control comparator current is greater than the threshold current to ensure fast load transient response; After the first switch tube and the second switch tube are both turned off for a first time, the current flowing through the main control comparator is reduced, and the second switch tube is connected to the first switch tube; the main control comparator The control signal is compared with the ramp signal for controlling the switching state of the switching circuit.

Optionally, the second module includes a zero-crossing comparator, an overcurrent protector and a timer.

Optionally, the first module further includes an error amplifier, an undervoltage lockout circuit, a bandgap reference circuit and a bias circuit.

The present invention also provides a control method for a switch circuit, based on the control circuit, including a first module and a second module, the first module and the second module cooperate to control the switch circuit, and the first module realizes the switch Loop control of the circuit and provide bias current, the second module provides auxiliary control for the switch circuit; when the conduction time of the first switch tube of the switch circuit reaches the threshold time, the control circuit detects the load size of the switch circuit; When the load of the switch circuit is less than the first threshold, the second module is turned off; the first switch tube is connected to the input end or the output end of the switch circuit.

Optionally, when the conduction time of the first switch tube reaches the threshold time, the voltage drop of the first switch tube or the current of the first switch tube is detected, and when the voltage drop of the first switch tube or the current of the first switch tube is less than the corresponding threshold value , the second module is turned off; the voltage drop of the first switch tube or the current of the first switch tube represents the size of the load.

Optionally, the rate of change of the output voltage is detected, and when the rate of change is greater than a second threshold or the voltage drop of the first switch tube is greater than a third threshold, the second module is turned on.

Compared with the prior art, the present invention has the following advantages: the control circuit of the present invention includes a first module and a second module, the first module is a control loop of the switch circuit, and the second module provides auxiliary control for the switch circuit ; When the conduction time of the first switch tube of the switch circuit reaches the threshold time, the control circuit detects the load size of the switch circuit; when the switch circuit load is less than the first threshold value, the second module is turned off; the first switch tube Connect to the input or output of the switch circuit. The invention can effectively reduce the power consumption of the control circuit and improve the efficiency at light load.

Description of drawings

Fig. 1 is the control circuit principle diagram of the switch circuit of the present invention;

Detailed ways

The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, but the present invention is not limited to these embodiments. The present invention covers any alternatives, modifications, equivalent methods and arrangements made within the spirit and scope of the present invention.

In order to give the public a thorough understanding of the present invention, specific details are described in detail in the following preferred embodiments of the present invention, and those skilled in the art can fully understand the present invention without the description of these details.

The invention is described in more detail by way of example in the following paragraphs with reference to the accompanying drawings. It should be noted that, the accompanying drawings are all in a relatively simplified form and in an inaccurate scale, so as to facilitate and clearly assist in explaining the purpose of the embodiments of the present invention.

As shown in FIG. 1, a schematic diagram of the control circuit of the switch circuit of the present invention is shown. The control circuit includes a first module and a second module. The first module is a module that needs to work normally, and the second module is a high-voltage module. Power consumption module. The first module and the second module cooperate to control the switch circuit, the first module is a control loop of the switch circuit and provides a reference voltage and a bias current; the second module provides auxiliary control for the switch circuit. The second module includes a timer, a zero-crossing comparator, an overcurrent protector, and the like. The first module includes a bandgap reference circuit and a bias circuit, an undervoltage lockout circuit, an error amplifier, a main control comparator and a detection circuit, etc. The detection circuit further includes an output voltage change rate detection circuit, a first switch tube voltage A drop detection circuit and a first switch tube detection circuit, etc., the first switch tube is connected to the input end or the output end of the switch circuit. For example, when the switch circuit is a step-down circuit, the first switch tube is a main power tube and is connected to the input end of the switch circuit; when the switch circuit is a boost circuit, the second switch tube is a synchronous rectifier tube , connected to the output of the switching circuit.

When the switch circuit works in the discontinuous conduction mode, when both the first switch tube and the synchronous rectifier tube of the switch circuit are turned off, the second module is controlled to be turned off, and the first module works normally; When both the first switch tube and the synchronous rectifier tube are turned off for a certain period of time, the current flowing through the main control comparator is reduced; the main control comparator compares the main control signal with the ramp signal to drive the switch circuit .

When the first switch tube of the switch circuit is on during the on time, the load size is detected, and when the load is less than the first threshold, the second module is turned off. The detection circuit detects the voltage drop of the first switch tube or the current of the first switch tube. When the first switch tube is turned on for a period of time and the voltage drop of the first switch tube is greater than the threshold voltage, or the current of the first switch tube is less than the threshold current, the detection circuit detects the voltage drop of the first switch tube or the current of the first switch tube. The second module is turned off; the voltage drop of the first switch tube or the current of the first switch tube represents the size of the load. The detection circuit also detects the rate of change of the output voltage of the switch circuit, and when the rate of change is greater than the second threshold or the voltage drop of the first switch tube is greater than the third threshold, the second module is turned on.

The above-mentioned embodiments do not constitute a limitation on the protection scope of the technical solution. Any modifications, equivalent replacements and improvements made within the spirit and principles of the above-mentioned embodiments shall be included within the protection scope of this technical solution.

Claims (9)

1. A control circuit for a switching circuit, characterized by: the circuit comprises a first module and a second module, wherein the first module and the second module cooperatively control the switch circuit; the first module is a control loop of the switch circuit, and the second module provides auxiliary control for the switch circuit; when the conduction time of a first switch tube of the switch circuit reaches threshold time, the control circuit detects the load of the switch circuit; when the load of the switching circuit is smaller than a first threshold value, the second module is switched off; the first switch tube is connected with the input end or the output end of the switch circuit.

2. The control circuit of the switching circuit according to claim 1, characterized in that: the first module comprises a detection circuit, when the conduction time of the first switch tube reaches a threshold time, the detection circuit detects a first switch tube voltage drop or a first switch tube current, and when the first switch tube voltage drop or the first switch tube current is smaller than a corresponding threshold, the second module is turned off; the first switch tube voltage drop or the first switch tube current is characterized by the load size.

3. The control circuit of the switching circuit according to claim 2, characterized in that: the detection circuit also detects the change rate of the output voltage, and the second module is started when the change rate is larger than a second threshold or the first switch tube voltage drop is larger than a third threshold.

4. A control circuit of a switching circuit according to claim 1, 2 or 3, characterized in that: the first module further comprises the master comparator; when the switching circuit works in an intermittent conduction mode, the current of the master control comparator is larger than the threshold current so as to ensure quick load transient response; when the first switch tube and the second switch tube are both turned off for a first time, reducing the current flowing through the master control comparator, wherein the second switch tube is connected with the first switch tube; and the master control comparator compares the master control signal with the ramp signal and is used for controlling the switching state of the switching circuit.

5. The control circuit of the switching circuit according to any one of claims 3, characterized in that: the second module comprises a zero-crossing comparator, an overcurrent protector and a timer.

6. The control circuit of the switching circuit according to claim 5, characterized in that: the first module further comprises an error amplifier, an under-voltage locking circuit, a band-gap reference circuit and a bias circuit.

7. A control method of a switch circuit is based on a control circuit and comprises a first module and a second module, wherein the first module and the second module cooperatively control the switch circuit, and the control method is characterized in that: the first module realizes loop control of the switch circuit and provides bias current, and the second module provides auxiliary control for the switch circuit; when the conduction time of a first switch tube of the switch circuit reaches threshold time, the control circuit detects the load of the switch circuit; when the load of the switching circuit is smaller than a first threshold value, the second module is switched off; the first switch tube is connected with the input end or the output end of the switch circuit.

8. The control method of the switching circuit according to claim 7, characterized in that: when the conduction time of the first switch tube reaches threshold time, detecting the voltage drop of the first switch tube or the current of the first switch tube, and when the voltage drop of the first switch tube or the current of the first switch tube is smaller than the corresponding threshold, turning off the second module; the first switch tube voltage drop or the first switch tube current is characterized by the load size.

9. The control method of the switching circuit according to claim 8, characterized in that: and detecting the change rate of the output voltage, and when the change rate is greater than a second threshold or the first switch tube voltage drop is greater than a third threshold, starting the second module.

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