CN115189573A - Switch converter and control circuit thereof - Google Patents

Switch converter and control circuit thereof Download PDF

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Publication number
CN115189573A
CN115189573A CN202210747311.9A CN202210747311A CN115189573A CN 115189573 A CN115189573 A CN 115189573A CN 202210747311 A CN202210747311 A CN 202210747311A CN 115189573 A CN115189573 A CN 115189573A
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voltage
switch
signal
control
control circuit
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CN202210747311.9A
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Inventor
马勋
郑鹏
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Beijing Eswin Computing Technology Co Ltd
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Beijing Eswin Computing Technology Co Ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of DC power input into DC power output
    • H02M3/02—Conversion of DC power input into DC power output without intermediate conversion into AC
    • H02M3/04—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters
    • H02M3/10—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M3/155—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/156—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
    • H02M3/158—Conversion of DC power input into DC power output without intermediate conversion into AC by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load
    • H02M3/1582—Buck-boost converters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/0048—Circuits or arrangements for reducing losses
    • H02M1/0054—Transistor switching losses
    • H02M1/0058—Transistor switching losses by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
    • H02M1/088—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the simultaneous control of series or parallel connected semiconductor devices
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/32—Means for protecting converters other than automatic disconnection
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/36—Means for starting or stopping converters
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Dc-Dc Converters (AREA)

Abstract

The application discloses switch converter and control circuit thereof, switch converter include main switch and synchronous switch, and control circuit includes: the bias module is used for generating bias voltage according to the input voltage and the enabling signal and providing the bias voltage to the control end of the synchronous switch; the switch control module is used for generating a switch control signal according to the enable signal, and the switch control signal is used for controlling the conduction and the disconnection of the main switch and the synchronous switch; during the active level of the enable signal, the bias module adjusts the output voltage of the switching converter to the input voltage; during the inactive level of the enable signal, the switch control module adjusts the output voltage from the input voltage to a target voltage, the target voltage being greater than the input voltage or less than the input voltage. This application control synchronous switch switches on in order to adjust output voltage to input voltage when just starting, and voltage feedback signal is less when avoiding direct start leads to error amplifier to be in unbalanced state to avoid arousing surge current and output voltage overshoot.

Description

Switch converter and control circuit thereof
Technical Field
The application relates to the technical field of switching power supplies, in particular to a switching converter and a control circuit thereof.
Background
With the rapid development of electronic products, the requirements for the performance of power management chips in the fields of computers, communications, consumer electronics, and the like are increasing. DC-DC switching power supplies are widely used in a variety of application scenarios, such as wide input and wide load range conditions.
A BOOST (BOOST) converter has an output voltage higher than an input voltage, and the BOOST converter regulates the output voltage by comparing a feedback voltage of the output voltage with a reference voltage mainly through an error amplifier. In the starting process of the traditional boost converter, because no voltage exists on the output capacitor, the output voltage rises from zero and is far smaller than the target voltage, the error amplifier is in an unbalanced state, so that the inductive current directly rises to the peak current controlled by the clamping voltage, and the load current is very small at the moment, so that the surge current and even the output voltage overshoot can be caused, and the device is damaged.
Disclosure of Invention
In order to solve the above technical problem, the present application provides a switching converter and a control circuit thereof, which avoid causing surge current and output voltage overshoot.
According to a first aspect of the present disclosure, there is provided a control circuit of a switching converter, the switching converter including a main switch and a synchronous switch, the control circuit including: the bias module is used for generating a bias voltage according to an input voltage and an enable signal and providing the bias voltage to the control end of the synchronous switch; the switch control module is used for generating a switch control signal according to the enable signal, wherein the switch control signal is used for controlling the conduction and the disconnection of the main switch and the synchronous switch; wherein the bias module adjusts an output voltage of the switching converter to the input voltage during an active level of the enable signal; the switch control module adjusts the output voltage from the input voltage to a target voltage during an inactive level of the enable signal, wherein the target voltage is greater than the input voltage or less than the input voltage.
Optionally, when the enable signal is at an active level, the bias module is turned on, and the switch control module generates the switch control signal according to an internal logic signal to control the main switch to be turned off.
Optionally, when the enable signal is at an inactive level, the bias module is turned off, and the switch control module generates the switch control signal according to a voltage feedback signal, a soft start voltage, and a reference voltage, where the switch control signal is used to control the main switch and the synchronous switch to be alternately turned on and off.
Optionally, when the enable signal is at an active level, the switch control signal controls the main switch to be turned off, and the bias voltage controls the synchronous switch to be turned on, so that the input voltage charges the capacitor through the inductor.
Optionally, during the active level of the enable signal, the soft-start voltage follows the voltage feedback signal until an initial value is reached, wherein the initial value is the voltage feedback signal when the output voltage reaches the input voltage.
Optionally, during the inactive level of the enable signal, the soft start voltage is stepped up from an initial value until a preset threshold is reached.
Optionally, when the soft-start voltage is smaller than a preset threshold, the switch control module generates the switch control signal according to the voltage feedback signal and the soft-start voltage.
Optionally, when the soft-start voltage reaches a preset threshold, the switch control module generates the switch control signal according to the voltage feedback signal and the reference voltage.
Optionally, the biasing module comprises: a first transistor, a second transistor, a first resistor, and a third transistor sequentially connected in series between an input voltage and a ground terminal; the control end of the first transistor receives an enable signal through the inverter; the control end of the second transistor is connected with a node between the second transistor and the first resistor, and outputs the bias voltage; the control terminal of the third transistor receives the enable signal.
Optionally, the switch control module comprises: the positive phase input end of the error amplifier receives the voltage feedback signal, the first negative phase input end of the error amplifier receives the soft start voltage, the second negative phase input end of the error amplifier receives the reference voltage, and the output end of the error amplifier outputs an error amplification signal; a fourth transistor connected between a non-inverting input terminal and a first inverting input terminal of the error amplifier, a control terminal of the fourth transistor receiving the enable signal; the pulse width modulation unit is connected with the output end of the error amplification signal and generates a pulse width modulation signal according to the error amplification signal; the control logic unit generates the switch control signal according to the pulse width modulation signal or the internal logic signal; and the soft start unit is connected with the first inverting input end of the error amplifier and used for generating a soft start voltage.
Optionally, during an inactive level of the enable signal, when the soft start voltage is less than a preset threshold, the error amplifier generates an error amplification signal according to a voltage feedback signal and the soft start voltage; when the soft start voltage reaches a preset threshold value, the error amplifier generates an error amplification signal according to a voltage feedback signal and the reference voltage; the control logic unit generates the switch control signal according to the pulse width modulation signal.
Optionally, during an active level of the enable signal, the fourth transistor is turned on, the non-inverting input terminal and the first inverting input terminal of the error amplifier are shorted, and the control logic unit generates the switch control signal according to an internal logic signal.
According to a second aspect of the present disclosure, there is provided a switching converter comprising: the circuit comprises a main switch, a synchronous switch, an inductor and a capacitor; the sampling resistor is connected between the output voltage and a grounding end, and a sliding end of the sampling resistor outputs a voltage feedback signal; and the control circuit described above.
The application discloses switch converter and control circuit thereof controls synchronous switch to conduct when just starting so as to adjust output voltage to input voltage, and the smaller error amplifier that leads to of voltage feedback signal is in unbalanced state when avoiding direct start to avoid arousing surge current and output voltage overshoot.
Further, after the output voltage reaches the input voltage, the main switch and the synchronous switch are alternately switched on, the error amplifier generates an error amplification signal according to the voltage feedback signal and the soft start voltage which rises in the step shape, and when the soft start voltage rises to a preset threshold value, the error amplifier is switched to generate the error amplification signal according to the voltage feedback signal and the reference signal, so that the inductive current can be stably improved, and the generation of surge current is avoided.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure.
Drawings
Fig. 1 shows a schematic structural diagram of a switching converter provided according to an embodiment of the present application;
fig. 2 shows waveforms of signals of the switching converter provided according to the embodiment of the application.
Detailed Description
To facilitate an understanding of the present disclosure, the present disclosure will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present disclosure are set forth in the accompanying drawings. However, the present disclosure may be embodied in different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
When a boost converter in the prior art is started, a power switch tube is suddenly turned on, and surge current and output voltage overshoot may occur due to sudden change of an on-resistance, so that a device is damaged. According to the method, the boost converter is subjected to segmented soft start, the output capacitor is charged firstly, so that the output voltage is slowly increased to the input voltage, and the overshoot of surge current and output voltage caused by direct start is avoided; and then generating a control signal according to an error signal between a voltage feedback signal representing the output voltage and a ramp voltage to control the power switch tube of the boost converter to be alternately conducted, wherein the ramp voltage slowly rises from the value of the input voltage to gradually stabilize the inductive current of the boost converter, and then generating the control signal according to the error signal between the voltage feedback signal representing the output voltage and a reference voltage to avoid the generation of surge current.
Fig. 1 shows a schematic structural diagram of a control circuit of a switching converter provided according to an embodiment of the present application. As shown in fig. 1, the switching converter includes a main switch Mn, a synchronous switch Mp, an inductor L, a capacitor Cout, and a control circuit 100.
The inductor L and the main switch Mn are connected in series between an input voltage Vin and a ground terminal. The synchronous switch Mp and the output capacitor Cout are connected in series between a node Lx between the inductor L and the main switch Mn and a ground terminal.
The control circuit 100 is connected to the control terminals of the main switch Mn and the synchronous switch Mp to control the on and off of the main switch Mn and the synchronous switch Mp.
The control circuit 100 includes a bias module 110 and a switch control module 120.
The bias module 100 is configured to generate a bias voltage according to an input voltage Vin and an enable signal EN, and provide the bias voltage to a control terminal of the synchronous switch Mp.
The switch control module 120 is configured to generate a switch control signal VG according to the enable signal EN, where the switch control signal VG is used to control on and off of the main switch Mn and the synchronous switch Mp.
In this embodiment, during the active level of the enable signal EN, the bias module 110 adjusts the output voltage Vout of the switching converter 100 to the input voltage Vin; during the inactive level of the enable signal EN, the switch control module 100 adjusts the output voltage Vout from the input voltage Vin to a target voltage, wherein the target voltage is greater than the input voltage Vin or less than the input voltage Vin. The switching converter in the present embodiment is described by taking a boost circuit as an example, but the switching converter is not limited to this, and may include, for example, a step-down circuit, a step-up/step-down circuit, or the like. If the switching converter 100 is a boost circuit, the output voltage is increased from 0V to an input voltage Vin, and then increased to a target voltage, i.e., the target voltage is greater than the input voltage.
During the active level (e.g., high level) of the enable signal EN, the switch control signal VG controls the main switch Mn to be turned off, and the bias voltage controls the synchronous switch Mp to be turned on so that the input voltage Vin charges the capacitor Cout through the inductor L.
When the enable signal EN is at an active level, the bias module 110 is turned on, and the switch control module 120 generates the switch control signal VG according to an internal logic signal to control the main switch Mn to be turned off. During the active level of the enable signal EN, the bias module 110 adjusts the output voltage Vout of the switching converter 100 to the input voltage Vin, where the output voltage Vout is the same as the input voltage Vin.
When the enable signal EN is at an inactive level, the bias module 110 is turned off, and the switch control module 120 generates the switch control signal VG according to the voltage feedback signal VFB, the soft-start voltage Vss, and the reference voltage Vref, wherein the switch control signal VG is used for controlling the main switch Mn and the synchronous switch Mp to be alternately turned on and off. During the inactive level of the enable signal EN, the switch control module 120 adjusts the output voltage Vout from the input voltage Vin to a target voltage. Referring to fig. 1, the bias module 110 includes a first transistor M1, a second transistor M2, a first resistor R1, and a third transistor M3 sequentially connected in series between an input voltage Vin and a ground terminal.
Wherein, a node between the second transistor M2 and the first resistor R1 outputs a bias voltage; the control terminal of the first transistor M1 receives the enable signal EN via the inverter; the control end of the second transistor M2 is connected with a node between the second transistor M2 and the first resistor R1; a control terminal of the third transistor M3 receives the enable signal EN.
In the present embodiment, the first transistor M1 and the second transistor M2 are P-type field effect transistors (PMOS transistors), and the third transistor M3 is an N-type field effect transistor (NMOS transistor).
Referring to fig. 2, during the active level period (period from 0 to t 2) of the enable signal, the first transistor M1 is turned on, the third transistor M3 is turned on, the input voltage Vin forms a current path via the first transistor M1, the second transistor M2, the first resistor R1 and the third transistor M3, the control terminal of the second transistor M2 is connected to the source terminal thereof, and the node between the second transistor M2 and the first resistor R1 outputs the bias voltage. The switch control module 120 generates a switch control signal VG according to the internal logic signal to control the main switch Mn to turn off, and the control terminal of the synchronous switch Mp receives the bias voltage, operates in a saturation region, and charges the capacitor Cout through its own on-resistance. The magnitude of the bias voltage may be adjusted by adjusting the aspect ratio of the second transistor M2 or the resistance value of the first resistor R.
Since the overdrive voltage (the absolute value of the difference between the gate-source voltage Vgs and the threshold voltage Vthp) of the synchronous switch Mp is small and the on-resistance thereof is large, the inductor L does not generate a surge current.
Under the condition that the input voltage Vin is kept unchanged, the capacitor Cout is continuously charged in the period from 0 to t1, the source-drain voltage of the synchronous switch Mp is gradually reduced along with the continuous rising of the output voltage Vout, and the charging current I L Rises first and then decreases, so the output voltage Vout rises smoothly until it is equal to the input voltage. Charging time:
Figure BDA0003717311800000061
IL = MI may be obtained, where I is the current flowing through the first transistor M1 in the bias module 110;
Figure BDA0003717311800000062
is the width-to-length ratio of the second transistor M2;
Figure BDA0003717311800000063
is the width-to-length ratio of the fourth transistor M4; m is the ratio of the width-to-length ratios of the fourth transistor M4 to the second transistor M2.
Figure BDA0003717311800000064
Wherein, vgs M2 Is the gate-source voltage of the second transistor; can obtain
Figure BDA0003717311800000065
According toFormula I L *t1＝Cout*Vin；
The charging time can be obtained
Figure BDA0003717311800000066
During the period from t1 to t2, the output voltage Vout is always kept consistent with the input voltage Vin.
In this embodiment, the enable signal EN is a chip internal timing signal, and the enable signal EN is at an active level (e.g., high level) when the chip is started, and becomes an inactive level (e.g., low level) after a certain time period through the timer.
Referring to fig. 1, the control circuit 120 includes an error amplifier 121, a fourth transistor M4, a pulse width modulation unit 122, a control logic unit 123, and a soft start unit 124.
The error amplifier 121 has a positive phase input end receiving the voltage feedback signal VFB, a first negative phase input end receiving the soft start voltage Vss, a second negative phase input end receiving the reference voltage Vref, and an output end outputting the error amplification signal EA.
The fourth transistor M4 is connected between the non-inverting input terminal and the first inverting input terminal of the error amplifier 121, and has a control terminal receiving the enable signal EN.
In the present embodiment, during the active level of the enable signal EN, the fourth transistor M4 is turned on, and the soft-start voltage Vss follows the voltage feedback signal VFB until it reaches an initial value, where the initial value is the voltage feedback signal VFB when the output voltage Vout reaches the input voltage Vin. The non-inverting input terminal and the first inverting input terminal of the error amplifier 121 are shorted, and the control logic unit 123 generates the switch control signal VG according to the internal logic signal to control the turn-off of the main switch Mn.
A soft-start unit 124 is connected to the first inverting input of the error amplifier for generating a soft-start voltage Vss.
During the inactive level of the enable signal EN, the fourth transistor M4 is turned off, and the soft-start unit 124 generates the soft-start voltage Vss, which is stepped up from an initial value until a preset threshold value is reached.
When the soft-start voltage Vss is less than the preset threshold, the error amplifier 121 generates an error amplification signal EA according to the voltage feedback signal VFB and the soft-start voltage Vss, that is, the switch control module 120 generates the switch control signal VG according to the voltage feedback signal VFB and the soft-start voltage Vss.
When the soft-start voltage Vss reaches a preset threshold, the error amplifier 121 generates an error amplification signal EA according to a voltage feedback signal VFB and the reference voltage Vref, that is, the switch control module 120 generates the switch control signal VG according to the voltage feedback signal VFB and the reference voltage Vref.
In the process that the soft start voltage reaches the preset threshold value, the peak current of the inductor L can be stably improved along with the rise of the soft start voltage Vss. When the soft-start voltage Vss reaches the threshold voltage, the error amplifier 121 switches to compare the voltage feedback signal VFB with the reference voltage Vref, so that the output voltage Vout can be adjusted more accurately, and the output voltage Vout can reach the target output voltage.
The pulse width modulation unit 122 is connected to an output end of the error amplification signal, and generates a pulse width modulation signal PWM according to the error amplification signal.
The control logic unit 123 generates the switch control signal VG according to the internal logic signal or the pulse width modulation signal PWM.
During the active level of the enable signal, the control logic unit 123 generates the switch control signal according to the internal logic signal to control the main switch Mn to be turned off; during the inactive level of the enable signal, the control logic unit 123 generates the switch control signal according to the pulse width modulation signal PWM to control the main switch Mn and the synchronous switch Mp to be alternately turned on. During the period from t2 to t3, the main switch Mn and the synchronous switch Mp are alternately switched on, namely when the main switch Mn is switched on, the synchronous switch Mp is switched off, and the inductor L is charged at the moment; when the main switch Mn is turned off, the synchronous switch Mp is turned on, and the inductor current IL continues to flow through the synchronous switch Mp to charge the capacitor Cout until the next cycle.
The application discloses switch converter and control circuit thereof, control synchronous switch work in the saturation region so that output voltage slowly rises to input voltage when just starting, and the less error amplifier that leads to of voltage feedback signal is in unbalanced state when avoiding direct start to avoid arousing surge current and output voltage and overshoot.
Further, after the output voltage reaches the input voltage, the main switch and the synchronous switch are alternately switched on, the error amplifier generates an error amplification signal according to the voltage feedback signal and the soft start voltage which rises in the step shape, and when the soft start voltage rises to a preset threshold value, the error amplifier is switched to generate the error amplification signal according to the voltage feedback signal and the reference signal, so that the inductive current can be stably improved, and the generation of surge current is avoided.
It should be noted that the numerical values in this document are only used for exemplary illustration, and in other embodiments of the present disclosure, other numerical values may be sampled to implement the present disclosure, and the present disclosure is not limited to this, which should be set reasonably according to actual situations.
Finally, it should be noted that: it should be understood that the above examples are only for clearly illustrating the present disclosure, and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. This need not be, nor should it be exhaustive of all embodiments. And obvious variations or modifications of the invention as herein taught are within the scope of the present disclosure.
It is also to be understood that the terms and expressions employed herein are used as terms of description and not of limitation, and that the embodiment or embodiments of the specification are not limited to those terms and expressions. The use of such terms and expressions is not intended to exclude any equivalents of the features shown and described (or portions thereof), and it is recognized that various modifications may be made which are within the scope of the claims. Other modifications, variations, and alternatives are also possible. Accordingly, the claims should be looked to in order to cover all such equivalents.

Claims (13)

1. A control circuit for a switching converter, the switching converter including a main switch and a synchronous switch, the control circuit comprising:
the bias module is used for generating a bias voltage according to an input voltage and an enable signal and providing the bias voltage to the control end of the synchronous switch;
the switch control module is used for generating a switch control signal according to the enable signal, wherein the switch control signal is used for controlling the conduction and the disconnection of the main switch and the synchronous switch;
wherein the bias module adjusts an output voltage of the switching converter to the input voltage during an active level of the enable signal; the switch control module adjusts the output voltage from the input voltage to a target voltage during an inactive level of the enable signal, wherein the target voltage is greater than the input voltage or less than the input voltage.
2. The control circuit of claim 1, wherein the bias module is turned on when the enable signal is active, and the switch control module generates the switch control signal according to an internal logic signal to control the main switch to be turned off.
3. The control circuit of claim 1, wherein the bias module is turned off when the enable signal is inactive, and the switch control module generates the switch control signal according to a voltage feedback signal, a soft-start voltage, and a reference voltage, wherein the switch control signal is used for controlling the main switch and the synchronous switch to be alternately turned on and off.
4. The control circuit of claim 1, wherein the switch control signal controls the main switch to be turned off when the enable signal is active, and the bias voltage controls the synchronous switch to be turned on to charge the input voltage to the capacitor via the inductor.
5. The control circuit of claim 3, wherein during the active level of the enable signal, the soft-start voltage follows the voltage feedback signal until an initial value is reached, wherein the initial value is the voltage feedback signal when the output voltage reaches the input voltage.
6. The control circuit of claim 5, wherein the soft-start voltage is stepped up from an initial value until a preset threshold is reached during an inactive level of the enable signal.
7. The control circuit of claim 6, wherein the switch control module generates the switch control signal according to the voltage feedback signal and the soft-start voltage when the soft-start voltage is less than a preset threshold.
8. The control circuit of claim 6, wherein the switch control module generates the switch control signal according to the voltage feedback signal and the reference voltage when the soft-start voltage reaches a preset threshold.
9. The control circuit of claim 1, wherein the bias module comprises:
a first transistor, a second transistor, a first resistor, and a third transistor sequentially connected in series between an input voltage and a ground terminal;
the control end of the first transistor receives an enable signal through the inverter;
the control end of the second transistor is connected with a node between the second transistor and the first resistor, and outputs the bias voltage;
the control terminal of the third transistor receives the enable signal.
10. The control circuit of claim 1, wherein the switch control module comprises:
the positive phase input end of the error amplifier receives the voltage feedback signal, the first negative phase input end of the error amplifier receives the soft start voltage, the second negative phase input end of the error amplifier receives the reference voltage, and the output end of the error amplifier outputs an error amplification signal;
a fourth transistor connected between a non-inverting input terminal and a first inverting input terminal of the error amplifier, a control terminal of the fourth transistor receiving the enable signal;
the pulse width modulation unit is connected with the output end of the error amplification signal and generates a pulse width modulation signal according to the error amplification signal;
the control logic unit generates the switch control signal according to the pulse width modulation signal or the internal logic signal;
and the soft start unit is connected with the first inverting input end of the error amplifier and used for generating a soft start voltage.
11. The control circuit of claim 10, wherein the error amplifier generates an error amplification signal according to a voltage feedback signal and the soft-start voltage when the soft-start voltage is less than a preset threshold during the inactive level of the enable signal;
when the soft start voltage reaches a preset threshold value, the error amplifier generates an error amplification signal according to a voltage feedback signal and the reference voltage;
the control logic unit generates the switch control signal according to the pulse width modulation signal.
12. The control circuit of claim 10, wherein during an active level of the enable signal, the fourth transistor is turned on, the non-inverting input terminal and the first inverting input terminal of the error amplifier are shorted, and the control logic unit generates the switch control signal according to an internal logic signal.
13. A switching converter, comprising:
the circuit comprises a main switch, a synchronous switch, an inductor and a capacitor;
the sampling resistor is connected between the output voltage and a grounding end, and a sliding end of the sampling resistor outputs a voltage feedback signal;
a control circuit as claimed in any one of claims 1 to 12.
CN202210747311.9A 2022-06-28 2022-06-28 Switch converter and control circuit thereof Pending CN115189573A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN118380981A (en) * 2024-03-29 2024-07-23 北京华电众信技术股份有限公司 Surge suppression circuit and network equipment

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN118380981A (en) * 2024-03-29 2024-07-23 北京华电众信技术股份有限公司 Surge suppression circuit and network equipment

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