TWM651963U - Control circuit for controlling blocking switch of power converter - Google Patents

Abstract

A control circuit for controlling a blocking switch of a power converter is provided. The control circuit includes a controller and a discharge switch circuit. The controller includes control pins. The control pin is coupled to a control terminal of the blocking switch. The controller controls a switching operation of the blocking switch through the control pin. A first terminal of the discharge switch circuit is coupled to an output terminal of the blocking switch. A second terminal of the discharge switch circuit is coupled to a reference low voltage. A control terminal of the discharge switch circuit is coupled to the control pin. The controller turns off the blocking switch and turns on the discharge switch circuit. The controller turns on the blocking switch and turns off the discharging switch circuit.

Description

Control circuit for controlling blocking switch of power converter

The present invention relates to a control circuit, and in particular to a control circuit for controlling a blocking switch of a power converter.

Generally speaking, a power converter can output the output power provided by the power converter through a blocking switch. Generally, if there is no load, the blocking switch is turned off. Based on the specification of Vsafe0V, the blocking switch is allowed to be turned on only when the voltage value at the output end of the blocking switch is lower than a specified value (eg, 0~0.8 volts). It should be noted that under no load conditions the voltage value at the output of the blocking switch decreases very slowly.

It can be seen from this that how to pull down the voltage value at the output end of the blocking switch while the blocking switch is turned off is one of the research focuses of those skilled in the art.

The invention provides a control circuit for controlling the blocking switch of a power converter, which can pull down the voltage value at the output end of the blocking switch during the period when the blocking switch is turned off.

The control circuit created in this new type includes a controller and a discharge switch circuit. The controller includes control pins. The control pin is coupled to the control end of the blocking switch. The controller controls the switching operation of the blocking switch through the control pin. The first terminal of the discharge switch circuit is coupled to the output terminal of the blocking switch. The second terminal of the discharge switch circuit is coupled to the reference low voltage. The control terminal of the discharge switch circuit is coupled to the control pin. The controller opens the blocking switch and conducts the discharge switch circuit. The controller turns on the blocking switch and turns off the discharging switch circuit.

Based on the above, the controller turns off the blocking switch and turns on the discharge switch circuit. In this way, during the period when the blocking switch is turned off, the discharge switch circuit is turned on to pull down the voltage value at the output end of the blocking switch.

Some embodiments of the present invention will be described in detail with reference to the drawings. The component symbols cited in the following description will be regarded as the same or similar components when the same component symbols appear in different drawings. These embodiments are only part of the invention and do not disclose all possible implementation modes of the invention. Rather, these embodiments are merely examples within the scope of the patent application for this novel creation.

Please refer to FIG. 1 , which is a schematic diagram of a blocking switch and a control circuit according to a first embodiment of the present invention. FIG. 1 shows a blocking switch SWB of the power converter and a control circuit 100 for controlling the blocking switch SWB. In this embodiment, the control circuit 100 includes a controller 110 and a discharge switch circuit 120 . Controller 110 includes control pins 111 . The control pin 111 is coupled to the control terminal TC of the blocking switch SWB. The controller 110 controls the switching operation of the blocking switch SWB through the control pin 111 .

For example, the blocking switch SWB can be implemented by an N-type field effect transistor (FET) (but the invention is not limited to this). The blocking switch SWB is, for example, an NMOS field effect transistor. The input terminal TI of the blocking switch SWB receives the output power supply VCC. The controller 110 provides a control signal SC having a first voltage level (eg, a high voltage level) to the control terminal TC of the blocking switch SWB through the control pin 111, thereby turning on the blocking switch SWB. Therefore, the blocking switch SWB will transmit the output power VCC to the output terminal TO (eg, Vbus terminal) of the blocking switch SWB. The controller 110 provides a control signal SC having a second voltage level (eg, a low voltage level) to the control terminal TC of the blocking switch SWB through the control pin 111, thereby turning off the blocking switch SWB. Therefore, blocking the switch SWB does not transfer the output power VCC to the output terminal TO.

In this embodiment, the first terminal of the discharge switch circuit 120 is coupled to the output terminal of the blocking switch SWB. The second terminal of the discharge switch circuit 120 is coupled to the reference low voltage VSS. The control terminal of the discharge switch circuit 120 is coupled to the control pin 111 . The controller 110 turns off the blocking switch SWB and turns on the discharge switch circuit 120. Therefore, during the period when the blocking switch SWB is turned off, the discharge switch circuit 120 connects the output terminal TO of the blocking switch SWB to the reference low voltage VSS. In addition, the controller 110 turns on the blocking switch SWB and turns off the discharging switch circuit 120 .

It is worth mentioning here that when the blocking switch SWB is turned off, the discharge switch circuit 120 is turned on. In this way, during the period when the blocking switch SWB is turned off, the discharge switch circuit 120 is turned on to quickly pull down the voltage value VO at the output terminal TO of the blocking switch SWB. Furthermore, the discharge switch circuit 120 is turned on to use the reference low voltage VSS to pull down the voltage value VO at the output terminal TO of the blocking switch SWB.

In this embodiment, the voltage value of the reference low voltage VSS may be determined based on the conduction voltage difference between the first terminal of the discharge switch circuit 120 and the second terminal of the discharge switch circuit 120 and the standard value. For example, based on the Vsafe0V specification, during the period when the blocking switch SWB is turned off, the voltage value VO must be lower than the specification value (for example, 0~0.8 volts) before the blocking switch SWB can be turned on again. When the discharge switch circuit 120 is turned on, the turn-on voltage difference between the first terminal of the discharge switch circuit 120 and the second terminal of the discharge switch circuit 120 is equal to, for example, 0.8 volts. Therefore, the voltage value of the reference low voltage VSS is lower than 0 volts. For another example, the conduction voltage difference between the first terminal of the discharge switch circuit 120 and the second terminal of the discharge switch circuit 120 is equal to 0.6 volts, for example. Therefore, the voltage value of the reference low voltage VSS is less than 0.2 volts.

In this embodiment, the controller 110 provides a control signal SC having a first voltage level (eg, a high voltage level) through the control pin 111 to turn on the blocking switch SWB. Therefore, the discharge switch circuit 120 is turned off in response to the control signal SC having the first voltage level. In addition, the controller 110 provides a control signal SC having a second voltage level (eg, a low voltage level) through the control pin 111 to turn off the blocking switch SWB. Therefore, the discharge switch circuit 120 is turned on in response to the control signal SC having the second voltage level.

Please refer to FIG. 2 , which is a schematic diagram of a blocking switch and a control circuit according to a second embodiment of the present invention. The blocking switch SWB can be implemented by an N-type field effect transistor (but the present invention is not limited to this). In this embodiment, the control circuit 200 includes a controller 110 and a discharge switch circuit 220 . The controller 110 controls the switching operation of the blocking switch SWB through the control pin 111 . The implementation details of the controller 110 have been clearly explained in the embodiment of FIG. 1 and will not be repeated here.

In this embodiment, the discharge switch circuit 220 includes a P-type field effect transistor T1. The source of the P-type field effect transistor T1 is used as the first terminal of the discharge switch circuit 220 . The drain electrode of the P-type field effect transistor T1 is used as the second terminal of the discharge switch circuit 220 . The gate of the P-type field effect transistor T1 is used as the control terminal of the discharge switch circuit 220 . In other words, the source of the P-type field effect transistor T1 is coupled to the output terminal TO of the blocking switch SWB. The drain of the P-type field effect transistor T1 is coupled to the reference low voltage VSS. The gate of the P-type field effect transistor T1 is coupled to the control pin 111 .

In this embodiment, the controller 110 provides the control signal SC with a high voltage level to turn on the blocking switch SWB. At this time, the P-type field effect transistor T1 is turned off in response to the control signal SC having a high voltage level. The discharge switch circuit 220 does not discharge the voltage value VO located at the output terminal TO of the blocking switch SWB.

The controller 110 provides the control signal SC with a low voltage level to turn off the blocking switch SWB. At this time, the P-type field effect transistor T1 is turned on in response to the control signal SC having a high voltage level. Therefore, the P-type field effect transistor T1 can use the reference low voltage VSS to pull down the voltage value VO at the output terminal TO of the blocking switch SWB.

Discharge switch circuit 220 also includes resistor R1. The first terminal of the resistor R1 is coupled to the first terminal of the discharge switch circuit 220 . In other words, the first terminal of the resistor R1 is coupled to the output terminal TO of the blocking switch SWB and the source of the P-type field effect transistor T1. The second terminal of the resistor R1 is coupled to the control pin 111 . In other words, the first end of the resistor R1 is coupled to the control terminal TC of the blocking switch SWB and the gate of the P-type field effect transistor T1.

Please refer to FIG. 3 , which is a schematic diagram of a blocking switch and a control circuit according to a third embodiment of the present invention. The blocking switch SWB can be implemented by an N-type field effect transistor (but the present invention is not limited to this). In this embodiment, the control circuit 300 includes a controller 110 and a discharge switch circuit 320 . The controller 110 controls the switching operation of the blocking switch SWB through the control pin 111 . The implementation details of the controller 110 have been clearly explained in the embodiment of FIG. 1 and will not be repeated here.

In this embodiment, the discharge switch circuit 320 includes a PNP bipolar junction transistor (BJT) T2. The emitter of the PNP bipolar transistor T2 serves as the first terminal of the discharge switch circuit 320 . The collector of the PNP bipolar transistor T2 serves as the second terminal of the discharge switch circuit 320 . The base of the PNP bipolar transistor T2 is used as the control terminal of the discharge switch circuit 320 . In other words, the emitter of the PNP bipolar transistor T2 is coupled to the output terminal TO of the blocking switch SWB. The collector of PNP bipolar transistor T2 is coupled to the reference low voltage VSS. The base of bipolar transistor T2 is coupled to control pin 111 .

In this embodiment, the controller 110 provides the control signal SC with a high voltage level to turn on the blocking switch SWB. At this time, the PNP bipolar transistor T2 is turned off in response to the control signal SC having a high voltage level. The discharge switch circuit 320 does not discharge the voltage value VO at the output terminal TO of the blocking switch SWB.

The controller 110 provides the control signal SC with a low voltage level to turn off the blocking switch SWB. At this time, the PNP bipolar transistor T2 is turned on in response to the control signal SC having a high voltage level. Therefore, the PNP bipolar transistor T2 can use the reference low voltage VSS to pull down the voltage value VO at the output terminal TO of the blocking switch SWB.

Discharge switch circuit 320 also includes resistor R1. The first terminal of the resistor R1 is coupled to the first terminal of the discharge switch circuit 220 . In other words, the first terminal of the resistor R1 is coupled to the output terminal TO of the blocking switch SWB and the emitter of the PNP bipolar transistor T2. The second terminal of the resistor R1 is coupled to the control pin 111 . In other words, the first terminal of the resistor R1 is coupled to the control terminal TC of the blocking switch SWB and the base of the bipolar transistor T2.

To sum up, the controller turns off the blocking switch through the control pin, and turns on the discharge switch circuit through the control pin. In this way, during the period when the blocking switch is turned off, the discharge switch circuit is turned on to pull down the voltage value at the output end of the blocking switch. In addition, the controller can control the switching operation of the blocking switch and the switching operation of the discharge switch circuit only through the control pin.

Although the embodiments of the present invention have been disclosed above, they are not intended to limit the invention. Anyone with ordinary knowledge in the technical field can make some modifications and changes without departing from the spirit and scope of the invention. Therefore, the scope of protection of this new creation shall be determined by the scope of the patent application attached.

100, 200, 300: control circuit 110:Controller 111:Control pin 120, 220, 320: Discharge switch circuit R1: Resistor SC: control signal SWB: blocking switch T1: P-type field effect transistor T2: Bipolar transistor TC: control terminal of blocking switch TI: Input terminal of blocking switch TO: Block the output of the switch VCC: output power VO: The voltage value at the output terminal of the blocking switch VSS: reference low voltage

FIG. 1 is a schematic diagram of a blocking switch and a control circuit according to the first embodiment of the present invention. FIG. 2 is a schematic diagram of a blocking switch and a control circuit according to a second embodiment of the present invention. FIG. 3 is a schematic diagram of a blocking switch and a control circuit according to a third embodiment of the present invention.

100:Control circuit

110:Controller

111:Control pin

120: Discharge switch circuit

SC: control signal

SWB: blocking switch

TC: control terminal of blocking switch

TI: Input terminal of blocking switch

TO: Block the output of the switch

VCC: output power

VO: The voltage value at the output terminal of the blocking switch

VSS: reference low voltage

Claims (10)

A control circuit for controlling a blocking switch of a power converter, comprising: Controllers, including: A control pin coupled to the control end of the blocking switch, wherein the controller controls the switching operation of the blocking switch through the control pin; and Discharge switch circuit, the first terminal of the discharge switch circuit is coupled to the output terminal of the blocking switch, the second terminal of the discharge switch circuit is coupled to the reference low voltage, and the control terminal of the discharge switch circuit is coupled to on the control pin, wherein the controller turns off the blocking switch and turns on the discharge switch circuit, and The controller turns on the blocking switch and turns off the discharge switch circuit. The control circuit of claim 1, wherein the discharge switch circuit is turned on to use the reference low voltage to pull down the voltage value at the output end of the blocking switch. The control circuit of claim 1, wherein the controller provides a control signal with a first voltage level through the control pin to turn on the blocking switch, and provides a second voltage through the control pin. level of the control signal to turn off the blocking switch. The control circuit of claim 3, wherein the discharge switch circuit is turned on in response to the control signal having the second voltage level. The control circuit of claim 3, wherein the discharge switch circuit is turned off in response to the control signal having the first voltage level. The control circuit as claimed in claim 3, wherein the blocking switch is an N-type field effect transistor. The control circuit as claimed in claim 6, wherein: the first voltage level is a high voltage level, and The second voltage level is a low voltage level. The control circuit as claimed in claim 6, wherein the discharge switch circuit includes: P-type field effect transistor, the source of the P-type field effect transistor is used as the first terminal of the discharge switch circuit, and the drain of the P-type field effect transistor is used as the third terminal of the discharge switch circuit. On both ends, the gate of the P-type field effect transistor is used as the control end of the discharge switch circuit. The control circuit as claimed in claim 8, wherein the discharge switch circuit further includes: A resistor, a first end of the resistor is coupled to the first end of the discharge switch circuit, and a second end of the resistor is coupled to the control pin. The control circuit as claimed in claim 5, wherein the discharge switch circuit includes: PNP bipolar transistor, the emitter of the PNP bipolar transistor is used as the first terminal of the discharge switch circuit, and the collector of the PNP bipolar transistor is used as the second terminal of the discharge switch circuit, The base of the PNP bipolar transistor is used as the control terminal of the discharge switch circuit.

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