CN113489299B - Switching power supply control circuit and driving chip - Google Patents
Switching power supply control circuit and driving chip Download PDFInfo
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- CN113489299B CN113489299B CN202111035781.4A CN202111035781A CN113489299B CN 113489299 B CN113489299 B CN 113489299B CN 202111035781 A CN202111035781 A CN 202111035781A CN 113489299 B CN113489299 B CN 113489299B
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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
- H02M1/00—Details of apparatus for conversion
- H02M1/32—Means for protecting converters other than automatic disconnection
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/04—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage
- H02H9/045—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage adapted to a particular application and not provided for elsewhere
- H02H9/046—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage adapted to a particular application and not provided for elsewhere responsive to excess voltage appearing at terminals of integrated circuits
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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
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Abstract
The application discloses switching power supply control circuit and driver chip, switching power supply control circuit includes: a driving chip and a discharge circuit; the driving chip and the discharge circuit are matched with other functional devices of the switching power supply control circuit to convert input current into expected output current; the driving chip comprises a feedback pin, a source electrode pin and a drain electrode pin; the discharge circuit is electrically connected with the source electrode pin and the feedback pin; the discharge circuit is used for enabling the difference between the voltage of the feedback pin and the voltage of the source electrode pin to be smaller than a preset value during the turn-off period of a power tube in the driving chip. The invention ensures that the electrostatic discharge device cannot be broken down in the normal operation of the circuit, thereby ensuring the normal operation of the circuit.
Description
Technical Field
The application relates to the field of protection circuits, in particular to a switching power supply control circuit and a driving chip.
Background
Many existing electronic devices receive or output signals through interfaces, and when static electricity exists in the surrounding environment, the static electricity easily damages elements in the electronic devices through the interfaces, so that the electrostatic protection circuits are generally designed at the interfaces of the electronic devices.
In a switching power supply control circuit (e.g., a BUCK circuit), a port of a driver chip thereof is also provided with an electrostatic discharge device (i.e., an ESD device) so that the driver chip is not damaged by static electricity in the environment. In a switching power supply control circuit, a large voltage value is generated due to the fact that current in an inductor cannot suddenly change and the charging and discharging characteristics of a parasitic capacitor exceed the withstand voltage of an electrostatic protection device, so that the electrostatic protection device is broken down, and the reliability of the device in the circuit is seriously damaged.
Therefore, there is a need for a novel switching power supply control circuit to overcome the above-mentioned drawbacks.
Disclosure of Invention
The invention aims to provide a switching power supply control circuit and a driving chip, and aims to solve the technical problem that the voltage at two ends of an electrostatic discharge device is greater than the self withstand voltage in the normal operation of a circuit.
In order to achieve the above object, the present invention provides a switching power supply control circuit, including: a driving chip and a discharge circuit; the driving chip and the discharge circuit are matched with other functional devices of the switching power supply control circuit to convert input current into expected output current; the driving chip comprises a feedback pin, a source electrode pin and a drain electrode pin; the discharge circuit is electrically connected with the source electrode pin and the feedback pin; the discharge circuit is used for enabling the difference between the voltage of the feedback pin and the voltage of the source electrode pin to be smaller than a preset value during the turn-off period of a power tube in the driving chip.
Preferably, the preset value is a breakdown voltage value of an electrostatic discharge device in the driving chip.
Preferably, the feedback pin is electrically connected with the source pin through the discharge circuit; the source electrode pin is electrically connected with the drain electrode pin through the power tube in the driving chip.
Preferably, if the power tube is turned on, the discharge circuit is turned off; if the power tube is disconnected, the discharge circuit is conducted; the discharge circuit is used for increasing the current flowing through the feedback pin during the disconnection period of the power tube.
Preferably, the discharge circuit includes: a shunt resistor; one end of the shunt resistor is electrically connected with the driving chip through the feedback pin; the other end of the shunt resistor is electrically connected with the driving chip through the source electrode pin; when the power tube is turned off, the shunt resistor increases the current flowing through the feedback pin.
Further, the present invention also provides a switching power supply driving chip, which includes: the control circuit, the feedback pin, the source electrode pin, the drain electrode pin, the power tube, the electrostatic discharge device and the discharge circuit are matched with other functional devices of the switching power supply driving chip to drive the power tube; the electrostatic discharge device is electrically connected with the discharge circuit, the discharge circuit is electrically connected with the feedback pin, and the source electrode pin is electrically connected with the drain electrode pin through the power tube; the control circuit generates a control pulse to control the on-off of the power tube; the discharge circuit is used for enabling the difference between the voltage of the feedback pin and the voltage of the source electrode pin to be smaller than a preset value during the turn-off period of the power tube.
Preferably, the discharge circuit comprises a pull-down circuit, the pull-down circuit is connected in parallel with the electrostatic discharge device, and the pull-down circuit comprises a pull-down tube, a pull-down resistor and a control signal receiving end; the pull-down resistor and the pull-down tube are coupled between the pull-down resistor and the source electrode pin in series; the pull-down tube is used for controlling the on-off of the pull-down circuit according to the signal received by the control signal receiving end.
Preferably, the discharge circuit comprises a pull-down circuit, and the pull-down circuit comprises a pull-down tube, a pull-down resistor and a control signal receiving end; the pull-down tube and the electrostatic discharge device multiplex the same field effect transistor; the field effect transistor is coupled between the feedback pin and the source pin; the pull-down resistor is coupled between the control signal receiving end and the source electrode pin; the pull-down tube is used for controlling the on-off of the pull-down circuit according to the signal received by the control signal receiving end.
Preferably, the discharge circuit includes a first pull-down circuit and a second pull-down circuit; the first pull-down circuit comprises a first pull-down tube, a first pull-down resistor and a first control signal receiving end, and the second pull-down circuit comprises a second pull-down tube, a second pull-down resistor and a second control signal receiving end; the first pull-down resistor and the first pull-down tube are coupled in series between the feedback pin and the source pin; a second pull-down tube in the second pull-down circuit and the electrostatic discharge device multiplex the same field effect transistor; the field effect transistor is coupled between the feedback pin and the source pin; the second pull-down resistor is coupled between the second control signal receiving end and the source electrode pin; the first pull-down tube is used for controlling the on-off of the first pull-down circuit according to a signal received by the first control signal receiving end; the second pull-down tube is used for controlling the on-off of the second pull-down circuit according to the signal received by the second control signal receiving end.
Further, the invention also provides a switching power supply control circuit, which comprises any one of the switching power supply driving chips.
The technical effect of the present invention is to provide a switching power supply control circuit and a driving chip, so as to solve the problem that peak voltages larger than the self withstand voltage are generated at two ends of an electrostatic discharge device of a control circuit pin during the switching of the working state of the circuit, thereby protecting each element of the control circuit.
Drawings
The technical solution and other advantages of the present application will become apparent from the detailed description of the embodiments of the present application with reference to the accompanying drawings.
Fig. 1 is a schematic structural diagram of a switching power supply control circuit in the prior art.
Fig. 2 is a diagram of a voltage waveform between a feedback pin and a source pin of a switch circuit in the prior art.
Fig. 3 is a schematic structural diagram of a switching power supply control circuit in embodiment 1 of the present application.
Fig. 4 is a schematic structural diagram of a switching power supply driving chip in embodiment 2 of the present application.
Fig. 5 is a schematic structural diagram of a switching power supply driving chip in embodiment 3 of the present application.
Fig. 6 is a schematic structural diagram of a switching power supply driving chip in embodiment 4 of the present application.
FIG. 7 is a waveform diagram of a control pulse and a trigger pulse according to an embodiment of the present invention.
The figures are labeled as follows:
the circuit comprises a driving chip 1, a parasitic capacitor 2, a freewheeling diode 3, a shunt resistor 4, a sampling diode 5, a direct current input side capacitor 6 and an inductor 7.
A feedback pin 11, a source pin 12, a drain pin 13, a power tube 14 and an electrostatic discharge device 15.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. It is to be understood that the embodiments described are only a few embodiments of the present application and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
The following disclosure provides many different embodiments or examples for implementing different features of the application. In order to simplify the disclosure of the present application, specific example components and arrangements are described below. Of course, they are merely examples and are not intended to limit the present application. Moreover, the present application may repeat reference numerals and/or letters in the various examples, such repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed. In addition, examples of various specific processes and materials are provided herein, but one of ordinary skill in the art may recognize applications of other processes and/or use of other materials.
Fig. 1 is a schematic structural diagram of a switching power supply control circuit in the prior art, and as shown in fig. 1, the switching power supply control circuit includes: the circuit comprises a driving chip 1, a parasitic capacitor 2, a sampling diode 5, a direct current input side capacitor 6 and an inductor 7, wherein the driving chip 1 is provided with a feedback pin 11, a source pin 12 and a drain pin 13.
Illustratively, as shown in fig. 1, the drain pin 13 is electrically connected to the source pin 12 through a power tube inside the driver chip 1, when the power tube is turned on, the source pin 12 is connected to the dc input side capacitor 6 through the power tube, a voltage drop between the dc input side capacitor 6 and the ac output terminal is formed across the inductor 7, and a current passing through the inductor 7 increases.
As shown in fig. 1-2, when the power transistor is turned off, since the current in the inductor 7 cannot change abruptly, and the voltage across the inductor 7 is still positive left and negative right, the inductor 7 will continue to draw current from the source pin 12. In the process that the voltage of the source pin 12 continuously drops, because the parasitic capacitor 2 accumulates charges when the power tube is turned on, the accumulated charges are released when the power tube is turned off, and the voltage is provided for the feedback pin 11. If the voltage drop rate of the source pin 12 is far in excess of the voltage drop rate of the feedback pin 11, a higher voltage spike may occur in the feedback pin 11 relative to the voltage waveform of the source pin 12. This voltage spike may exceed the withstand voltage of the esd protection device connected to the feedback pin 11, causing a great damage to the esd protection device.
The magnitude of the voltage spike is positively correlated with the capacitance of the parasitic capacitor 2, that is, the capacitance of the parasitic capacitor 2 is inversely correlated with the voltage drop speed of the feedback pin 11. In other words, the larger the capacitance of the parasitic capacitor 2, the slower the voltage drop speed of the feedback pin 11, and the larger the difference between the voltage drop speeds of the feedback pin 11 and the source pin 12.
Example 1
Fig. 3 is a schematic circuit diagram of a switching power supply control circuit having a protection structure of the electrostatic discharge device 15 according to an embodiment of the present invention. As shown in fig. 3, the switching power supply control circuit includes: the driving circuit comprises a driving chip 1 and a discharging circuit, wherein the driving chip 1 and the discharging circuit are matched with other functional devices of the switching power supply control circuit to convert an input current into an expected output current. The driving chip 1 includes a feedback pin 11, a source pin 12, and a drain pin 13. The discharge circuit is electrically connected to the source pin 12 and the feedback pin 11. The discharging circuit is used to make the difference between the voltage of the feedback pin 11 and the voltage of the source pin 12 during the turn-off period of the power transistor 14 smaller than a predetermined value.
Further, one end of the feedback pin 11 is electrically connected to one end of the source pin 12 through a discharge circuit, and the source pin 12 is electrically connected to the drain pin 13 through a power tube 14 inside the driver chip 1 and is connected to a ground terminal of the switching power supply.
Illustratively, the power transistor 14 is a MOSFET device.
Illustratively, the preset value is a breakdown voltage value of the electrostatic discharge device 15 in the driving chip 1, and when the voltage value across the electrostatic discharge device 15 is greater than the preset value, the electrostatic discharge device 15 will be broken down.
Further, if the power tube 14 is turned on, the discharge circuit is turned off. If the power tube 14 is off, the discharge circuit is turned on. The discharge circuit is configured to increase a current path from the feedback pin 11 to the ground terminal during a period when the power transistor 14 is turned off.
Further, the switching power supply control circuit further includes: a parasitic capacitance 2. One end of the parasitic capacitor 2 is electrically connected with the driving chip 1 through the feedback pin 11. The other end of the parasitic capacitor 2 is electrically connected with the driving chip 1 through an inductor 7.
Further, the discharge circuit includes: a shunt resistor 4. One end of the shunt resistor 4 is electrically connected with the driving chip 1 through the feedback pin 11. The other end of the shunt resistor 4 is electrically connected with the driving chip 1 through the source electrode pin 12.
Illustratively, when the power tube 14 is conducting, the discharge circuit is open. When the power tube 14 is turned off, the discharge circuit is turned on, and the current path of the feedback pin 11 to the ground terminal is increased.
As can be seen from the above, in the present embodiment, when the discharge circuit is turned on, the parasitic capacitor releases the charges accumulated when the power transistor 14 is turned on, and the output current flows into the discharge circuit, so as to avoid the voltage difference between the voltage of the feedback pin 11 and the voltage of the source pin 12 being too high, and effectively protect the esd protection device 15.
Illustratively, the preset voltage is a maximum voltage value that the electrostatic discharge device 15 can withstand.
The embodiment has the beneficial effect that the voltage spike between the feedback pin 11 and the source pin 12 is removed through the discharge circuit, so that the voltage at the feedback pin 11 does not exceed the withstand voltage value of the electrostatic discharge device 15 electrically connected with the feedback pin, and the electrostatic discharge device 15 is protected. In addition, in this embodiment, the purpose of protecting the electrostatic discharge device 15 is achieved by the shunt resistor 4, and since the resistor element has a low cost and the circuit is simple and easy to connect, the cost of the protection structure of the electrostatic discharge device 15 is reduced to a certain extent.
Example 2
As shown in fig. 4, the present invention also provides a switching power supply driving chip having a protection structure of the electrostatic discharge device 15. The switching power supply driving chip includes: a control circuit, a feedback pin 11, a source pin 12, a drain pin 13, a power tube 14, an electrostatic discharge device 15 and a discharge circuit. The control circuit, the feedback pin 11, the source pin 12, the drain pin 13, the power tube 14 and the electrostatic discharge device 15. The electrostatic discharge device 15 is electrically connected to the discharge circuit, the discharge circuit is electrically connected to the feedback pin 11, and the source pin 12 is electrically connected to the drain pin 13 through the power transistor 14.
The control circuit is configured to generate a control pulse to control the on/off of the power tube 14. The discharge circuit is used for making the difference between the voltage of the feedback pin 11 and the voltage of the source pin 12 smaller than a preset value during the period that the power tube 14 is turned off.
Illustratively, the preset value is a breakdown voltage value of the electrostatic discharge device 15 in the driving chip 1, and when the voltage value across the electrostatic discharge device 15 is greater than the preset value, the electrostatic discharge device 15 will be broken down.
Illustratively, the electrostatic discharge device 15 is a field effect transistor. The static electricity discharge device 15 is used for absorbing static electricity and avoiding the damage of components in the switching power supply driving chip circuit.
Further, the pull-down circuit is connected in parallel with the electrostatic discharge device 15. The pull-down circuit comprises a pull-down resistor, a pull-down tube and a control signal receiving end.
Illustratively, the discharge circuit comprises a pull-down circuit, the pull-down circuit is connected with the electrostatic discharge device in parallel, and the pull-down circuit comprises a pull-down tube, a pull-down resistor and a control signal receiving end of the pull-down tube. The pull-down resistor and the pull-down tube are coupled in series between the pull-down resistor and the source pin 12. The pull-down tube is used for controlling the on-off of the pull-down circuit according to the signal received by the control signal receiving end.
Further, the control signal receiving end is configured to trigger the pull-down tube to conduct according to the received control pulse (for example, a trigger pulse is generated according to a falling edge of the control pulse to trigger the pull-down tube to conduct). The pull-down resistor is configured such that a current flowing through the pull-down circuit is smaller than a current flowing through the electrostatic discharge device when the pull-down resistor is subjected to an ESD test.
Illustratively, as shown in fig. 7, when the power tube 14 is turned off, a control signal receiving end in the pull-down circuit receives a control pulse generated by the control circuit. And the control signal receiving end generates a trigger pulse according to the falling edge of the control pulse, and the trigger pulse indicates to close the pull-down tube to realize the conduction of the pull-down circuit.
Illustratively, the width of the trigger pulse is 200 ns.
Illustratively, when the power tube 14 is turned on, the pull-down tube in the pull-down circuit is turned off, and the pull-down circuit is in an open state. The parasitic capacitance accumulates charges according to a potential difference across it.
Illustratively, when the parasitic capacitance discharges its accumulated charge, it generates a first current that flows into ground via feedback pin 11.
The beneficial effect of this embodiment is that the voltage of the feedback pin 11 is rapidly reduced by the discharge circuit, so as to reduce the difference between the voltage of the feedback pin 11 and the voltage of the source pin 12, and further remove the peak of the voltage between the feedback pin 11 and the source pin 12, so that the voltage at the feedback pin 11 does not exceed the withstand voltage of the electrostatic discharge device 15 electrically connected thereto, that is, the electrostatic discharge device 15 is not broken down during the normal operation of the circuit. When the ESD test is carried out, due to the arrangement of the pull-down resistor in the discharge circuit, the current flowing through the pull-down circuit is smaller than the current flowing through the electrostatic discharge device, and the electrostatic discharge device can be smoothly broken down to protect other devices inside. In addition, the pull-down circuit composed of the pull-down resistor and the pull-down tube is adopted in the embodiment, the pull-down capability of the pull-down circuit can be adjusted, the pull-down time can be controlled within a short time, and extra loss is reduced.
Example 3
As shown in fig. 5, the present invention further provides another switching power supply driving chip having a protection structure of an electrostatic discharge device 15, the structure of the switching power supply driving chip in this embodiment is substantially the same as that of embodiment 2, and its distinctive features are as follows:
the discharging circuit comprises a pull-down circuit, and the pull-down circuit comprises a pull-down tube, a pull-down resistor and a control signal receiving end. Wherein the pull-down tube and the electrostatic discharge device 15 multiplex the same field effect transistor. The field effect transistor is coupled between the feedback pin 11 and the source pin 12. The pull-down resistor is coupled between the control signal receiving terminal and the source pin 12. The pull-down tube is used for controlling the on-off of the pull-down circuit according to the signal received by the control signal receiving end. It should be noted that, since the electrostatic discharge device 15 with the same area generally has a relatively weak ability to bear current, the discharge circuit provided in this embodiment is used in the case where the current peak value of the feedback pin 11 is small.
The embodiment has the advantages that the pull-down circuit and the electrostatic discharge device 15 are multiplexed on the premise of ensuring that the electrostatic discharge device 15 cannot be broken down in the normal work of the circuit, so that the circuit structure is further simplified, and the cost is reduced.
Example 4
As shown in fig. 6, the present invention further provides another switching power supply driving chip having a protection structure of an electrostatic discharge device 15, the structure of the switching power supply driving chip in this embodiment is substantially the same as that of embodiment 2, and its distinctive features are as follows:
the discharge circuit includes a first pull-down circuit and a second pull-down circuit. The first pull-down circuit comprises a first pull-down tube, a first pull-down resistor and a first control signal receiving end, and the second pull-down circuit comprises a second pull-down tube, a second pull-down resistor and a second control signal receiving end.
Further, the first pull-down resistor and the first pull-down tube are coupled in series between the feedback pin 11 and the source pin 12. The second pull-down tube in the second pull-down circuit and the electrostatic discharge device 15 multiplex the same field effect transistor.
Wherein the field effect transistor is coupled between the feedback pin 11 and the source pin 12. The second pull-down resistor is coupled between the second control signal receiving terminal and the source pin 12.
Furthermore, the first pull-down tube is used for controlling the on-off of the first pull-down circuit according to the signal received by the first control signal receiving end. The second pull-down tube is used for controlling the on-off of the second pull-down circuit according to the signal received by the second control signal receiving end.
Because the discharge circuit provided by the embodiment comprises the two pull-down circuits, the discharge capability of the discharge circuit is further enhanced, and the discharge circuit is more suitable for the situation that the current peak value of the feedback pin 11 is large, namely suitable for the scene that the parasitic capacitance accommodating capability is large.
The embodiment has the beneficial effects that on the premise of ensuring that the electrostatic discharge device 15 cannot be broken down in the normal operation of the circuit, the two pull-down circuits connected in parallel are adopted, so that the discharge capacity of the discharge circuit is obviously enhanced.
Example 5
The present invention also provides another switching power supply control circuit having a protection structure of an electrostatic discharge device, and the structure of the switching power supply control circuit in this embodiment is substantially the same as that of the switching power supply control circuit in the prior art described above with reference to fig. 1, and its distinctive features are as follows:
the switching power supply control circuit comprises a resistor connected in parallel between the feedback pin and the source electrode pin.
The embodiment has the advantages that the voltage at the feedback pin cannot exceed the withstand voltage value of the electrostatic discharge device electrically connected with the feedback pin in a mode of connecting the resistor in parallel between the feedback pin and the source pin, the circuit structure is simplified, and the cost is reduced.
Example 6
The present invention also provides another switching power supply control circuit having a protection structure of an electrostatic discharge device, the structure of the switching power supply control circuit in this embodiment is substantially the same as that of the switching power supply control circuit in the prior art described above with reference to fig. 1, and its distinctive features are as follows:
the switching power supply control circuit comprises a capacitor connected in parallel between the feedback pin and the source electrode pin, and the capacitor can bear higher voltage.
The embodiment has the advantages that the voltage at the feedback pin cannot exceed the withstand voltage value of the electrostatic discharge device electrically connected with the feedback pin in a mode of connecting the capacitor in parallel between the feedback pin and the source electrode pin, the circuit structure is simplified, and the cost is reduced.
The invention also provides a switching power supply control circuit which comprises any one of the switching power supply driving chips with the protection structure of the electrostatic discharge device.
In the foregoing embodiments, the descriptions of the respective embodiments have respective emphasis, and for parts that are not described in detail in a certain embodiment, reference may be made to related descriptions of other embodiments.
The principle and the implementation of the present application are explained by applying specific examples, and the above description of the embodiments is only used to help understanding the technical solution and the core idea of the present application; those of ordinary skill in the art will understand that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications or substitutions do not depart from the spirit and scope of the present disclosure as defined by the appended claims.
Claims (10)
1. A switching power supply control circuit, comprising: a driving chip and a discharge circuit;
the driving chip and the discharge circuit are matched with other functional devices of the switching power supply control circuit to convert input current into expected output current;
the driving chip comprises a feedback pin, a source electrode pin and a drain electrode pin;
the discharge circuit is electrically connected with the source electrode pin and the feedback pin;
the discharge circuit is used for enabling the difference between the voltage of the feedback pin and the voltage of the source electrode pin to be smaller than a preset value during the turn-off period of a power tube in the driving chip.
2. The switching power supply control circuit according to claim 1,
the preset value is a breakdown voltage value of the electrostatic discharge device in the driving chip.
3. The switching power supply control circuit according to claim 1,
the feedback pin is electrically connected with the source electrode pin through the discharge circuit;
the source electrode pin is electrically connected with the drain electrode pin through the power tube in the driving chip.
4. The switching power supply control circuit according to claim 1,
if the power tube is conducted, the discharge circuit is disconnected;
if the power tube is disconnected, the discharge circuit is conducted;
the discharge circuit is used for increasing the current flowing through the feedback pin during the disconnection period of the power tube.
5. The switching power supply control circuit according to any one of claims 1 to 4, wherein the discharge circuit includes: a shunt resistor;
one end of the shunt resistor is electrically connected with the driving chip through the feedback pin;
the other end of the shunt resistor is electrically connected with the driving chip through the source electrode pin;
when the power tube is turned off, the shunt resistor increases the current flowing through the feedback pin.
6. A switching power supply driving chip, comprising: the circuit comprises a control circuit, a feedback pin, a source electrode pin, a drain electrode pin, a power tube, an electrostatic discharge device and a discharge circuit;
the control circuit, the feedback pin, the source electrode pin, the drain electrode pin, the power tube, the electrostatic discharge device and the discharge circuit are matched with other functional devices of the switching power supply driving chip to drive the power tube;
the electrostatic discharge device is electrically connected with the discharge circuit, the discharge circuit is electrically connected with the feedback pin, and the source electrode pin is electrically connected with the drain electrode pin through the power tube;
the control circuit generates a control pulse to control the on-off of the power tube;
the discharge circuit is used for enabling the difference between the voltage of the feedback pin and the voltage of the source electrode pin to be smaller than a preset value during the turn-off period of the power tube.
7. The switching power supply driving chip according to claim 6,
the discharging circuit comprises a pull-down circuit, the pull-down circuit is connected with the electrostatic discharge device in parallel, and the pull-down circuit comprises a pull-down tube, a pull-down resistor and a control signal receiving end;
the pull-down resistor and the pull-down tube are coupled between the pull-down resistor and the source electrode pin in series;
the pull-down tube is used for controlling the on-off of the pull-down circuit according to the signal received by the control signal receiving end.
8. The switching power supply driving chip according to claim 6,
the discharging circuit comprises a pull-down circuit, and the pull-down circuit comprises a pull-down tube, a pull-down resistor and a control signal receiving end;
the pull-down tube and the electrostatic discharge device multiplex the same field effect transistor;
the field effect transistor is coupled between the feedback pin and the source pin;
the pull-down resistor is coupled between the control signal receiving end and the source electrode pin;
the pull-down tube is used for controlling the on-off of the pull-down circuit according to the signal received by the control signal receiving end.
9. The switching power supply driving chip according to claim 6,
the discharge circuit comprises a first pull-down circuit and a second pull-down circuit;
the first pull-down circuit comprises a first pull-down tube, a first pull-down resistor and a first control signal receiving end, and the second pull-down circuit comprises a second pull-down tube, a second pull-down resistor and a second control signal receiving end;
the first pull-down resistor and the first pull-down tube are coupled in series between the feedback pin and the source pin;
a second pull-down tube in the second pull-down circuit and the electrostatic discharge device multiplex the same field effect transistor;
the field effect transistor is coupled between the feedback pin and the source pin;
the second pull-down resistor is coupled between the second control signal receiving end and the source electrode pin;
the first pull-down tube is used for controlling the on-off of the first pull-down circuit according to a signal received by the first control signal receiving end; the second pull-down tube is used for controlling the on-off of the second pull-down circuit according to the signal received by the second control signal receiving end.
10. A switching power supply control circuit, characterized in that the switching power supply control circuit comprises a switching power supply driving chip according to any one of claims 6 to 9.
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| US6765372B2 (en) * | 2001-12-14 | 2004-07-20 | Intersil Americas Inc. | Programmable current-sensing circuit providing continuous temperature compensation for DC-DC Converter |
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