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CN-122001188-A - Control circuit and control method of power switch tube and switch power supply

CN122001188ACN 122001188 ACN122001188 ACN 122001188ACN-122001188-A

Abstract

The application discloses a control circuit and a control method of a power switch tube and a switch power supply, and belongs to the technical field of switch power supplies. The control circuit of the power switch tube comprises a first P-type MOS tube, a first N-type MOS tube and a driving circuit, wherein a source electrode of the first P-type MOS tube is connected with a power supply voltage node, a drain electrode of the first P-type MOS tube is connected with a driving end of the power switch tube, a drain electrode of the first N-type MOS tube is connected with the power supply voltage node, the source electrode of the first N-type MOS tube is connected with the driving end of the power switch tube, the driving circuit is respectively connected with a grid electrode of the first P-type MOS tube and a grid electrode of the first N-type MOS tube, and when a control signal of the power switch tube is a conducting signal and a power supply voltage of the power supply voltage node is smaller than a reference voltage, the first P-type MOS tube is driven to be conducted, and when the control signal of the power switch tube is a conducting signal and the power supply voltage is larger than or equal to the reference voltage, voltage loss generated due to threshold loss of the power switch tube is reduced, and driving capability of the driving circuit is improved when the power supply voltage is smaller.

Inventors

  • CHEN ZHIJUN
  • ZHANG HUI

Assignees

  • 成都智融微电子有限公司

Dates

Publication Date
20260508
Application Date
20241104

Claims (12)

  1. 1. A control circuit for a power switching tube, comprising: The source electrode of the first P-type MOS tube is electrically connected with the power supply voltage node, and the drain electrode of the first P-type MOS tube is electrically connected with the driving end of the power switch tube; The drain electrode of the first N-type MOS tube is electrically connected with the power supply voltage node, and the source electrode of the first N-type MOS tube is electrically connected with the driving end of the power switch tube; The driving circuit is respectively and electrically connected with the grid electrode of the first P-type MOS tube and the grid electrode of the first N-type MOS tube, and is configured to drive the first P-type MOS tube to be conducted when the control signal of the power switch tube is a conducting signal and the power voltage of the power voltage node is smaller than a reference voltage, and drive the first N-type MOS tube to be conducted when the control signal of the power switch tube is a conducting signal and the power voltage of the power voltage node is larger than or equal to the reference voltage.
  2. 2. The control circuit of claim 1, wherein the control circuit further comprises: And the output end of the clamping circuit is electrically connected with the grid electrode of the first P-type MOS tube and is configured to clamp the grid electrode voltage of the P-type MOS tube to be larger than or equal to a first threshold voltage.
  3. 3. The control circuit of claim 2, wherein the clamp circuit comprises: a reference voltage node, the voltage of the reference voltage node being less than the voltage of the supply voltage node; The drain electrode of the second N-type MOS tube is electrically connected with the output end of the reference voltage node, and the source electrode of the second N-type MOS tube is electrically connected with the grid electrode of the first P-type MOS tube; a reference current circuit configured to provide a first current; And the voltage conversion circuit is configured to convert the first current into a first voltage and apply the first voltage to the grid electrode of the second N-type MOS tube when the control signal of the power switch tube is a conduction signal.
  4. 4. A control circuit according to claim 3, wherein the reference current circuit comprises: the non-inverting input end of the comparator is used for being connected with the target voltage; the driving end of the first switching tube is electrically connected with the output end of the comparator; The first end of the first resistor is electrically connected with the negative phase input end of the comparator and the first end of the first switching tube respectively, and the second end of the first resistor is electrically connected with the grounding node; The input end of the first current mirror unit is electrically connected with the second end of the first switching tube, and the output end of the first current mirror unit is electrically connected with the input end of the voltage conversion circuit; The voltage conversion circuit includes: The first end of the second resistor is electrically connected with the power supply voltage node, and the second end of the second resistor is electrically connected with the output end of the first current mirror unit; The grid electrode of the second P type MOS tube is electrically connected with the second end of the second resistor, the drain electrode of the second P type MOS tube is electrically connected with the grounding node, and the source electrode of the second P type MOS tube is electrically connected with the grid electrode of the second N type MOS tube; And the output end of the power supply circuit is electrically connected with the source electrode of the second P-type MOS tube and the grid electrode of the second N-type MOS tube respectively, and is configured to provide power supply current when the control signal of the power switch tube is a conduction signal.
  5. 5. The control circuit according to any one of claims 1 to 4, wherein the driving circuit includes: the input end of the comparison circuit is electrically connected with the power supply voltage node, and the comparison circuit is configured to generate a first driving signal when the power supply voltage of the power supply voltage node is smaller than a reference voltage; the first input end of the logic circuit is electrically connected with the output end of the comparison circuit, the second input end of the logic circuit is used for being connected with the control signal of the power switch tube, and the logic circuit is configured to generate a second driving signal when the first driving signal is received and the control signal of the power switch tube is a conducting signal; The power supply end of the drive enhancing circuit is used for being connected with a first current source, the input end of the drive enhancing circuit is electrically connected with the output end of the logic circuit, the output end of the drive enhancing circuit is electrically connected with the grid electrode of the first P-type MOS tube, and the drive enhancing circuit is configured to respond to the second drive signal to drive the first P-type MOS tube to be conducted.
  6. 6. The control circuit of claim 5, wherein the logic circuit comprises: The first input end of the AND gate is electrically connected with the output end of the comparison circuit, and the second input end of the AND gate is used for accessing the control signal of the power switch tube; and the input end of the first NOT gate is electrically connected with the output end of the AND gate, and the output end of the first NOT gate is electrically connected with the input end of the drive enhancing circuit.
  7. 7. The control circuit of claim 5, wherein the drive enhancing circuit comprises: the first end of the second switching tube is used for being connected with the first current source, and the second switching tube is configured to be conducted when the control signal of the power switching tube is a conducting signal and the power supply voltage is smaller than the reference voltage; The input end of the second current mirror unit is electrically connected with the second end of the second switching tube, and the output end of the second current mirror unit is electrically connected with the input end of the clamping circuit and the grid electrode of the first P-type MOS tube respectively; The first end of the third switching tube is used for being connected with the first current source, and the third switching tube is configured to be turned on when the control signal of the power switching tube is an off signal and/or the power supply voltage is greater than or equal to the reference voltage; And the input end of the third current mirror unit is electrically connected with the second end of the third switch tube, and the output end of the third current mirror unit is electrically connected with the grid electrode of the first P-type MOS tube.
  8. 8. The control circuit of claim 7, wherein the drive circuit further comprises: The input end of the fourth current mirror unit is electrically connected with the first current source; The first end of the fourth switching tube is electrically connected with the output end of the fourth current mirror unit, and the driving end of the fourth switching tube is electrically connected with the output end of the comparison circuit and is configured to be turned on in response to the first driving signal; The input end of the fifth current mirror unit is electrically connected with the second end of the fourth switching tube, the first output end of the fifth current mirror unit is electrically connected with the first end of the second switching tube, and the second output end of the fifth current mirror unit is electrically connected with the first end of the third switching tube; a third resistor, the first end of the third resistor being electrically connected to the supply voltage node, the second end of the third resistor; The first end of the fifth switching tube is electrically connected with the power supply voltage node, and the second end of the fifth switching tube is electrically connected with the grid electrode of the first P-type MOS tube; and a sixth switching tube, wherein a first end of the sixth switching tube is electrically connected with a second end of the third resistor and a driving end of the fifth switching tube respectively, a second end of the sixth switching tube is electrically connected with an output end of the second current source, and the sixth switching tube is configured to be conducted when the power supply voltage is greater than or equal to the reference voltage.
  9. 9. The control circuit according to any one of claims 1 to 4, wherein the control circuit of the power switching tube further comprises: The drain electrode of the third N-type MOS tube is electrically connected with the driving end of the power switch tube, the source electrode of the third N-type MOS tube is electrically connected with the grounding node, the grid electrode of the third N-type MOS tube is electrically connected with the driving circuit, and the driving circuit is configured to drive the third N-type MOS tube to be conducted when the control signal of the power switch tube is an off signal.
  10. 10. The control method of the power switch tube is characterized in that the driving end of the power switch tube is respectively and electrically connected with the drain electrode of the first P-type MOS tube and the source electrode of the first N-type MOS tube, and the source electrode of the first P-type MOS tube and the drain electrode of the first N-type MOS tube are electrically connected with a power supply voltage node, and the control method comprises the following steps: When a conduction signal of the power switch tube is received and the voltage of the power supply voltage node is smaller than a reference voltage, controlling the first P-type MOS tube to be conducted and controlling the first N-type MOS tube to be turned off; And when receiving a conduction signal of the power switch tube and the power voltage of the power voltage node is larger than or equal to the reference voltage, controlling the first N-type MOS tube to be conducted and controlling the first P-type MOS tube to be turned off.
  11. 11. The control method according to claim 10, characterized in that the control method further comprises: And when receiving the turn-off signal of the power switch tube, controlling the first P-type MOS tube and the first N-type MOS tube to be turned off.
  12. 12. A switching power supply comprising a power switching tube and a control circuit according to any one of claims 1-11, said control circuit being electrically connected to the drive end of said power switching tube.

Description

Control circuit and control method of power switch tube and switch power supply Technical Field The application belongs to the technical field of switching power supplies, and particularly relates to a control circuit and a control method of a power switch tube and a switching power supply. Background In a flyback switching power supply, an external power tube plays a role of a switch to control the power supply conversion process so as to control the on-off of current, thereby realizing the conversion and output of voltage. The driving circuit of the external power tube generally needs to be connected with a power supply voltage, and the power supply voltage is applied to the external power tube according to a set switching time sequence. At present, when the voltage value of the power supply voltage is small, the driving circuit is prone to have a problem of insufficient driving capability, and switching efficiency is reduced. Disclosure of Invention The present application aims to solve at least one of the technical problems existing in the prior art. Therefore, the application provides a control circuit and a control method of a power switch tube and a switch power supply, wherein when a first P-type MOS tube is conducted, a power supply voltage is directly used for driving the power switch tube, so that voltage loss generated by threshold loss of the power tube in a driving circuit is reduced, and driving capability of the driving circuit is improved. In a first aspect, the present application provides a control circuit for a power switching tube, including: The source electrode of the first P-type MOS tube is electrically connected with the power supply voltage node, and the drain electrode of the first P-type MOS tube is electrically connected with the driving end of the power switch tube; The drain electrode of the first N-type MOS tube is electrically connected with the power supply voltage node, and the source electrode of the first N-type MOS tube is electrically connected with the driving end of the power switch tube; the driving circuit is respectively and electrically connected with the grid electrode of the first P-type MOS tube and the grid electrode of the first N-type MOS tube, and is configured to drive the first P-type MOS tube to be conducted when the control signal of the power switch tube is a conducting signal and the power voltage of the power voltage node is smaller than the reference voltage, and drive the first N-type MOS tube to be conducted when the control signal of the power switch tube is a conducting signal and the power voltage of the power voltage node is larger than or equal to the reference voltage. According to the control circuit of the power switch tube, when the control signal of the power switch tube is a conduction signal and the power voltage of the power voltage node is smaller than the reference voltage, the driving circuit drives the first P-type MOS tube to conduct, the drain electrode of the first P-type MOS tube is electrically connected with the driving end of the power switch tube, the voltage transmitted to the driving end of the power switch tube through the first P-type MOS tube is not influenced by the conduction threshold value between the grid electrode and the source electrode of the first P-type MOS tube, and when the first P-type MOS tube is conducted, the power voltage is directly used for driving the power switch tube, so that the voltage loss caused by the threshold loss of the power tube in the driving circuit is reduced, and the driving capability of the driving circuit is improved. According to one embodiment of the application, the control circuit further comprises: and the output end of the clamping circuit is electrically connected with the grid electrode of the first P-type MOS tube and is configured to clamp the grid electrode voltage of the first P-type MOS tube to be larger than or equal to the first threshold voltage. According to one embodiment of the present application, a clamp circuit includes: a reference voltage node having a voltage less than a voltage of the power supply voltage node; the drain electrode of the second N-type MOS tube is electrically connected with the output end of the reference voltage node, and the source electrode of the second N-type MOS tube is electrically connected with the grid electrode of the first P-type MOS tube; a reference current circuit configured to provide a first current; and the voltage conversion circuit is configured to convert the first current into the first voltage and apply the first voltage to the grid electrode of the second N-type MOS tube when the control signal of the power switch tube is an on signal. According to one embodiment of the application, a reference current circuit includes: the non-inverting input end of the comparator is used for accessing the target voltage; the driving end of the first switching tube is electrically connected with the output end of the comparato