CN111682869A - Load switch and electronic equipment of anti-backflow current - Google Patents
Load switch and electronic equipment of anti-backflow current Download PDFInfo
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- H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
- H03K17/51—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used
- H03K17/56—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices
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Abstract
The invention provides a load switch and electronic equipment for preventing reverse current, which comprise a P-type power tube, a control selection circuit and a control switch circuit; when the load voltage is greater than the sum of the power supply voltage and the first set voltage, controlling the substrate of the P-type power tube to be electrically connected with the load end, and controlling the grid electrode of the P-type power tube to be electrically connected with the substrate of the P-type power tube; and when the load voltage is less than the sum of the power supply voltage and the second set voltage, controlling the substrate of the P-type power tube to be electrically connected with the power supply voltage end, and controlling the grid electrode of the P-type power tube to be electrically connected with the grounding end. It can be seen that when the load voltage is too large, the substrate of the P-type power tube is controlled to be electrically connected with the load end, and the grid of the P-type power tube is controlled to be electrically connected with the substrate of the P-type power tube so as to control the P-type power tube to be closed, so that no current flows in a path from the load end to the power voltage end, the purpose of preventing the backflow current is achieved, meanwhile, the backflow preventing function of frequently triggering and closing the load switch can be prevented, and the performance of the load switch is improved.
Description
Technical Field
The invention relates to the technical field of load switches, in particular to a load switch capable of preventing reverse current and electronic equipment.
Background
The load switch is a common electronic device in an electronic system, and is mainly used for connecting a power supply and a load to realize connection and isolation between the power supply and the load. The load switch may be integrated with its control circuit, or may be a separate device. However, in practical applications, the output may be higher than the input, for example, the output has interference or the output is touched by high voltage, so that charge may flow back from the output to the input, which may increase the potential of the input and cause system operation disorder. Therefore, the design of the anti-backflow current of the load switch is one of the important research points nowadays.
Disclosure of Invention
In view of this, the invention provides a load switch and an electronic device for preventing reverse current, which effectively solve the technical problems in the prior art, prevent the load switch from generating reverse current, and improve the performance of the load switch.
In order to achieve the purpose, the technical scheme provided by the invention is as follows:
a back-flow prevention load switch, comprising: the power supply comprises a P-type power tube, a control selection circuit and a control switch circuit;
the source electrode of the P-type power tube is electrically connected with a power voltage end, the drain electrode of the P-type power tube is electrically connected with a load end, the substrate of the P-type power tube is electrically connected with the control selection circuit, and the grid electrode of the P-type power tube is electrically connected with the control switch circuit;
the control selection circuit is used for comparing the power supply voltage of the power supply voltage end with the load voltage of the load end and controlling the substrate of the P-type power tube to be electrically connected with the power supply voltage end or the load end; the control switch circuit is used for controlling the grid electrode of the P-type power tube to be electrically connected with the substrate or the grounding end of the P-type power tube according to the comparison result of the power voltage and the load voltage;
when the load voltage is greater than the sum of the power supply voltage and a first set voltage, controlling the substrate of the P-type power tube to be electrically connected with the load end, and controlling the grid electrode of the P-type power tube to be electrically connected with the substrate of the P-type power tube; and controlling the substrate of the P-type power tube to be electrically connected with the power voltage end and controlling the grid electrode of the P-type power tube to be electrically connected with the grounding end until the load voltage is less than the sum of the power voltage and a second set voltage, wherein the first set voltage is greater than the second set voltage.
Optionally, the control selection circuit includes: the comparison module and the selection switch module;
a first input end of the comparison module is connected with the power supply voltage, a second input end of the comparison module is connected with the load voltage, and an output end of the comparison module is electrically connected with a control end of the selection switch module; the comparison module is used for comparing the power supply voltage with the load voltage and outputting a first level control signal when the load voltage is greater than the sum of the power supply voltage and a first set voltage; outputting a second level control signal until the load voltage is less than the sum of the power supply voltage and a second set voltage, wherein the levels of the first level control signal and the second level control signal are opposite in phase;
the first input end of the selection switch module is electrically connected with the power supply voltage end, the second input end of the selection switch module is electrically connected with the load end, and the output end of the selection switch module is electrically connected with the substrate of the P-type power tube; the selection switch module is used for responding to the first level control signal to control the substrate of the P-type power tube to be electrically connected with the load end, and responding to the second level control signal to control the substrate of the P-type power tube to be electrically connected with the power supply voltage end.
Optionally, the comparison module includes a comparator;
the first input end of the comparator is connected to the power supply voltage, the second input end of the comparator is connected to the load voltage, and the output end of the comparator is electrically connected with the control end of the selection switch module.
Optionally, the selection switch module includes: a first transistor and a second transistor, the conduction types of the first transistor and the second transistor being opposite;
the first end of the first transistor is electrically connected with the power supply voltage end, the second end of the first transistor is electrically connected with the substrate of the P-type power tube, and the grid electrode of the first transistor is electrically connected with the output end of the comparison module;
the first end of the second transistor is electrically connected with the load end, the second end of the second transistor is electrically connected with the substrate of the P-type power tube, and the grid electrode of the second transistor is electrically connected with the output end of the comparison module.
Optionally, the selection switch module includes: the switch comprises a third transistor, a fourth transistor and a first inverter, wherein the conduction types of the third transistor and the fourth transistor are the same;
a first end of the third transistor is electrically connected with the power supply voltage end, a second end of the third transistor is electrically connected with the substrate of the P-type power tube, and a grid electrode of the third transistor is electrically connected with the output end of the comparison module; a first end of the fourth transistor is electrically connected with the load end, a second end of the fourth transistor is electrically connected with the substrate of the P-type power tube, a grid electrode of the fourth transistor is electrically connected with an output end of the first phase inverter, and an input end of the first phase inverter is electrically connected with an output end of the comparison module;
or, a first end of the third transistor is electrically connected to the power supply voltage end, a second end of the third transistor is electrically connected to the substrate of the P-type power transistor, a gate of the third transistor is electrically connected to an output end of the first inverter, and an input end of the first inverter is electrically connected to an output end of the comparison module; the first end of the fourth transistor is electrically connected with the load end, the second end of the fourth transistor is electrically connected with the substrate of the P-type power tube, and the grid electrode of the fourth transistor is electrically connected with the output end of the comparison module.
Optionally, the control switch circuit includes: a logic gate module and a second inverter;
a first input end of the logic gate module is connected with an enabling signal, a second input end of the logic gate module is electrically connected with an output end of the comparison module, and an output end of the logic gate module is electrically connected with an input end of the second phase inverter; the logic gate module is used for responding to the first level control signal and outputting a turn-off signal, and responding to the second level control signal and outputting a turn-on signal;
the output end of the second inverter is electrically connected with the grid electrode of the P-type power tube, and the power supply end of the second inverter is electrically connected with the substrate of the P-type power tube; the second inverter is used for responding to the turn-off signal to control the grid electrode of the P-type power tube to be electrically connected with the substrate of the P-type power tube, and responding to the turn-on signal to control the grid electrode of the P-type power tube to be electrically connected with the grounding end of the second inverter.
Optionally, the control switch circuit further includes: a buffer and a third inverter;
the input end of the buffer is connected with the enabling signal, the output end of the buffer is electrically connected with the input end of the third phase inverter, and the output end of the third phase inverter is electrically connected with the first input end of the logic gate module.
Optionally, when the first level control signal is a high level signal and the enable signal is a high level signal, the logic gate module includes: a fourth inverter and an AND gate;
a first input end of the AND gate is connected with the enabling signal; the input end of the fourth inverter is electrically connected with the output end of the comparison module, and the output end of the fourth inverter is electrically connected with the second input end of the AND gate;
correspondingly, the invention also provides electronic equipment which comprises the load switch for preventing the backflow current.
Compared with the prior art, the technical scheme provided by the invention at least has the following advantages:
the invention provides a load switch and electronic equipment for preventing reverse current, comprising: the power supply comprises a P-type power tube, a control selection circuit and a control switch circuit; when the load voltage is greater than the sum of the power supply voltage and a first set voltage, controlling the substrate of the P-type power tube to be electrically connected with the load end, and controlling the grid electrode of the P-type power tube to be electrically connected with the substrate of the P-type power tube; and controlling the substrate of the P-type power tube to be electrically connected with the power voltage end and controlling the grid electrode of the P-type power tube to be electrically connected with the grounding end until the load voltage is less than the sum of the power voltage and a second set voltage. It can be seen that when the load voltage is too large, the substrate of the P-type power tube is controlled to be electrically connected with the load end, and the grid of the P-type power tube is controlled to be electrically connected with the substrate of the P-type power tube, so that the P-type power tube is controlled to be closed, a path from the load end to the power voltage end has no current, the purpose of preventing the backflow of the current is achieved, and the load switching performance is improved.
The first set voltage and the second set voltage are equivalent to hysteresis voltage, namely the backflow prevention function of the load switch is triggered only when the load voltage is greater than the sum of the power supply voltage and the first set voltage, and the backflow prevention function of the load switch is closed only when the load voltage is less than the sum of the power supply voltage and the second set voltage, so that the backflow prevention function of the load switch can be prevented from being triggered and closed frequently, and the practicability of the load switch is improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a load switch for preventing a back-flow current according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of another load switch for preventing reverse current according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of another load switch for preventing reverse current according to an embodiment of the present invention;
fig. 4 is a schematic structural diagram of another load switch for preventing reverse current according to an embodiment of the present invention;
fig. 5 is a schematic structural diagram of another load switch for preventing reverse current according to an embodiment of the present invention;
fig. 6 is a schematic structural diagram of another load switch for preventing reverse current according to an embodiment of the present invention;
fig. 7 is a schematic structural diagram of another load switch for preventing reverse current according to an embodiment of the present invention;
fig. 8 is a schematic structural diagram of another load switch for preventing reverse current according to an embodiment of the present invention;
fig. 9 is a voltage diagram of the corresponding end portion in fig. 8.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the 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 invention.
As mentioned in the background, a load switch is a common electronic device in an electronic system, and is mainly used for connecting a power supply and a load to achieve connection and isolation therebetween. The load switch may be integrated with its control circuit, or may be a separate device. However, in practical applications, the output may be higher than the input, for example, the output has interference or the output is touched by high voltage, so that charge may flow back from the output to the input, which may increase the potential of the input and cause system operation disorder. Therefore, the design of the anti-backflow current of the load switch is one of the important research points nowadays.
Based on this, the embodiment of the invention provides a load switch capable of preventing reverse current and electronic equipment, which effectively solve the technical problems in the prior art, prevent the load switch from generating reverse current, and improve the performance of the load switch.
To achieve the above object, the technical solutions provided by the embodiments of the present invention are described in detail below, specifically with reference to fig. 1 to 9.
Referring to fig. 1, a schematic structural diagram of a load switch for preventing reverse current provided in the present invention is shown, wherein the load switch includes: the P-type power tube P0, the control selection circuit 100 and the control switch circuit 200, and the D1 and D2 are parasitic diodes.
The source electrode of the P-type power tube P0 is electrically connected to the power voltage terminal IN, the drain electrode of the P-type power tube P0 is electrically connected to the load terminal OUT, the substrate bulk of the P-type power tube P0 is electrically connected to the control selection circuit 100, and the gate electrode of the P-type power tube P0 is electrically connected to the control switch circuit 200.
The control selection circuit 100 is configured to compare magnitudes of a power voltage Vin at the power voltage terminal IN and a load voltage Vout at the load terminal OUT, and control a substrate bulk of the P-type power transistor P0 to be electrically connected to the power voltage terminal IN or to be electrically connected to the load terminal OUT; and the control switch circuit 200 is used for controlling the gate of the P-type power transistor P0 to be electrically connected with the substrate bulk or the ground terminal GND of the P-type power transistor P0 according to the comparison result between the power supply voltage Vin and the load voltage Vout.
When the load voltage Vout is greater than the sum of the power supply voltage Vin and a first set voltage, controlling the substrate bulk of the P-type power tube P0 to be electrically connected with the load end OUT, and controlling the gate of the P-type power tube P0 to be electrically connected with the substrate bulk of the P-type power tube P0; and controlling the substrate bulk of the P-type power tube P0 to be electrically connected with the power voltage terminal IN and controlling the gate of the P-type power tube P0 to be electrically connected with the ground terminal GND until the load voltage Vout is less than the sum of the power voltage Vin and a second set voltage, wherein both the first set voltage and the second voltage are greater than 0, and the first set voltage is greater than the second set voltage.
It can be understood that in the technical solution provided in the embodiment of the present invention, when the load voltage is greater than the sum of the power supply voltage and the first set voltage, the substrate of the P-type power transistor is controlled to be electrically connected to the load terminal, and the gate of the P-type power transistor is controlled to be electrically connected to the substrate of the P-type power transistor; when the load voltage is less than the sum of the power supply voltage and a second set voltage, controlling the substrate of the P-type power tube to be electrically connected with the power supply voltage end, and controlling the grid electrode of the P-type power tube to be electrically connected with a grounding end; and then keeping the substrate of the control P-type power tube electrically connected with the power supply voltage end, and electrically connecting the grid of the control P-type power tube with the grounding end until judging that the load voltage is greater than the sum of the power supply voltage and the first set voltage again, electrically connecting the substrate of the control P-type power tube with the load end, and electrically connecting the grid of the control P-type power tube with the substrate of the control P-type power tube. It can be seen that when the load voltage is too large, the substrate of the P-type power tube is controlled to be electrically connected with the load end, and the grid of the P-type power tube is controlled to be electrically connected with the substrate of the P-type power tube, so that the P-type power tube is controlled to be closed, a path from the load end to the power voltage end has no current, the purpose of preventing the backflow of the current is achieved, and the load switching performance is improved.
The first setting voltage and the second setting voltage provided by the embodiment of the invention are equivalent to hysteresis voltage, namely the anti-backflow function of the load switch is triggered when the load voltage is greater than the sum of the power supply voltage and the first setting voltage, and the anti-backflow function of the load switch is closed until the load voltage is less than the sum of the power supply voltage and the second setting voltage, so that the anti-backflow function of the load switch can be prevented from being triggered and closed frequently, and the practicability of the load switch is improved.
Referring to fig. 2, which is a schematic structural diagram of another load switch for preventing reverse current according to an embodiment of the present invention, the control selection circuit 100 according to an embodiment of the present invention includes: a comparison module 110 and a selection switch module 120.
A first input end of the comparison module 110 is connected to the power voltage Vin, a second input end of the comparison module 110 is connected to the load voltage Vout, and an output end of the comparison module 110 is electrically connected to a control end of the selection switch module 120; the comparing module 110 is configured to compare the power supply voltage Vin with the load voltage Vout, and output a first level control signal when the load voltage Vout is greater than a sum of the power supply voltage Vin and a first set voltage; until the load voltage Vout is less than the sum of the power supply voltage Vin and a second set voltage, a second level control signal is output, the levels of the first level control signal and the second level control signal are inverted, and then the comparison module 110 keeps outputting the second level control signal until the comparison module 110 judges that the load voltage Vout is greater than the sum of the power supply voltage Vin and the first set voltage again, and outputs the first level control signal.
A first input end of the selection switch module 120 is electrically connected to the power supply voltage terminal IN, a second input end of the selection switch module 120 is electrically connected to the load terminal OUT, and an output end of the selection switch module 120 is electrically connected to the substrate bulk of the P-type power transistor P0; the selection switch module 120 is used for controlling the substrate bulk of the P-type power transistor P0 to be electrically connected to the load terminal OUT IN response to the first level control signal, and controlling the substrate bulk of the P-type power transistor P0 to be electrically connected to the supply voltage terminal IN response to the second level control signal.
The following describes specific circuit structures of the comparison module and the selection switch module according to the embodiment of the present invention with reference to the drawings. Referring to fig. 3, which is a schematic structural diagram of another load switch for preventing reverse current according to an embodiment of the present invention, the comparison module 110 according to an embodiment of the present invention includes a comparator CMP.
A first input terminal of the comparator CMP is connected to the power voltage Vin, a second input terminal of the comparator CMP is connected to the load voltage Vout, and an output terminal of the comparator CMP is electrically connected to the control terminal of the selection switch module 120.
As shown in fig. 3, the selection switch module 120 provided in the embodiment of the present invention may include: a first transistor M1 and a second transistor M2, wherein the conduction types of the first transistor M1 and the second transistor M2 are opposite, that is, when the first transistor M1 is an N-type transistor, the second transistor M2 is a P-type transistor; or when the first transistor M1 is a P-type transistor, the second transistor M2 is an N-type transistor.
A first terminal of the first transistor M1 is electrically connected to the power supply voltage terminal IN, a second terminal of the first transistor M1 is electrically connected to the substrate bulk of the P-type power transistor P0, and a gate of the first transistor M1 is electrically connected to the output terminal of the comparison module 110.
A first terminal of the second transistor M2 is electrically connected to the load terminal OUT, a second terminal of the second transistor M2 is electrically connected to the substrate bulk of the P-type power transistor P0, and a gate of the second transistor M2 is electrically connected to the output terminal of the comparison module 110.
It can be understood that, the conduction types of the first transistor and the second transistor provided in the embodiment of the present invention are opposite, so that the gate of the first transistor and the gate of the second transistor are both electrically connected to the output end of the comparison module, and the comparison module can control the second transistor to turn off when the first transistor is turned on, and control the first transistor to turn off when the second transistor is turned on. When the comparison module outputs a first level control signal, the second transistor is controlled to be switched on and the first transistor is controlled to be switched off so as to control the substrate of the P-type power tube to be electrically connected with the load end; and when the comparison module outputs a second level control signal, the first transistor is controlled to be switched on and the second transistor is controlled to be switched off so as to control the substrate of the P-type power tube to be electrically connected with the power supply voltage end.
In an embodiment of the present invention, the conduction types of the transistors included in the switch module provided in the embodiment of the present invention may also be the same. Referring to fig. 4, which is a schematic structural diagram of another load switch capable of preventing reverse current, the selection switch module 120 provided in the embodiment of the present invention includes: the third transistor M3, the fourth transistor M4 and the first inverter INV1, and the third transistor M3 and the fourth transistor M4 are of the same conduction type, i.e., the third transistor M3 and the fourth transistor M4 may both be N-type transistors, or the third transistor M3 and the fourth transistor M4 may both be P-type transistors.
A first end of the third transistor M3 is electrically connected to the power supply voltage terminal IN, a second end of the third transistor M3 is electrically connected to the substrate bulk of the P-type power transistor, and a gate of the third transistor M3 is electrically connected to the output terminal of the comparison module 110; a first end of the fourth transistor M4 is electrically connected to the load terminal OUT, a second end of the fourth transistor M4 is electrically connected to the substrate bulk of the P-type power transistor P0, a gate of the fourth transistor M4 is electrically connected to an output end of the first inverter INV1, and an input end of the first inverter INV1 is electrically connected to an output end of the comparison module 110.
It can be understood that, the conduction types of the third transistor and the fourth transistor provided in the embodiment of the present invention are the same, so that a first inverter is electrically connected between the gate of the fourth transistor and the output terminal of the comparison module, so as to ensure the purpose that the comparison module controls the fourth transistor to turn off when controlling the third transistor to turn on, and controls the third transistor to turn off when controlling the fourth transistor to turn on.
It should be noted that, the first inverter provided in the embodiment of the present invention may also be electrically connected between the gate of the third transistor and the output terminal of the comparison module, and the gate of the fourth transistor is directly electrically connected to the output terminal of the comparison module, for which, the determination needs to be made according to the specific levels of the first level control signal and the second level control signal, and the specific conduction types of the third transistor and the fourth transistor. That is, the conduction types of the third transistor and the fourth transistor provided in the embodiment of the present invention are the same, the first end of the third transistor is electrically connected to the power supply voltage end, the second end of the third transistor is electrically connected to the substrate of the P-type power transistor, the gate of the third transistor is electrically connected to the output end of the first inverter, and the input end of the first inverter is electrically connected to the output end of the comparison module; the first end of the fourth transistor is electrically connected with the load end, the second end of the fourth transistor is electrically connected with the substrate of the P-type power tube, and the grid electrode of the fourth transistor is electrically connected with the output end of the comparison module.
Referring to fig. 5, which is a schematic structural diagram of another load switch capable of preventing reverse current, the control switch circuit 200 according to the embodiment of the present invention includes: a logic gate module 210 and a second inverter 220.
A signal accessed by a first input end of the logic gate module 210 is an enable signal EN, a second input end of the logic gate module 210 is electrically connected with an output end of the comparison module 110, and an output end of the logic gate module 210 is electrically connected with an input end of the second inverter INV 2; the logic gate module 210 is configured to output a turn-off signal in response to the first level control signal and output a turn-on signal in response to the second level control signal.
The output end of the second inverter INV2 is electrically connected to the gate of the P-type power transistor P0, and the power supply end of the second inverter INV2 is electrically connected to the substrate bulk of the P-type power transistor P0; the second inverter INV2 is configured to control the gate of the P-type power transistor P0 to be electrically connected to the substrate bulk of the P-type power transistor P0 in response to the turn-off signal, and control the gate of the P-type power transistor P0 to be electrically connected to the ground GND of the second inverter INV2 in response to the turn-on signal.
It can be understood that, in the control switch circuit provided in the embodiment of the present invention, when the comparison module outputs the first level control signal, the logic gate module outputs a turn-off signal according to the first level control signal and the enable signal, and the turn-off signal can control the power end of the second inverter to be electrically connected to the gate of the P-type power transistor, so that the gate of the P-type power transistor is electrically connected to the substrate bulk of the P-type power transistor, thereby achieving the purpose of controlling the turn-off of the P-type power transistor; and when the comparison module outputs the second level control signal, the logic gate module outputs a starting signal according to the second level control signal and the enabling signal, and the starting signal can control the grounding end of the second phase inverter to be electrically connected with the grid electrode of the P-type power tube, so that the aim of controlling the conduction of the P-type power tube is fulfilled.
Furthermore, in order to achieve the purpose of controlling the P-type power transistor to be turned on slowly, the control switch circuit provided by the embodiment of the present invention may further include a buffer and other components. Referring to fig. 6, which is a schematic structural diagram of another load switch capable of preventing reverse current provided in the embodiment of the present invention, the control switch circuit 200 provided in the embodiment of the present invention further includes: a Buffer and a third inverter INV 3.
The input end of the Buffer is connected to an enable signal EN, the output end of the Buffer is electrically connected to the input end of the third inverter INV3, the output end of the third inverter INV3 is electrically connected to the first input end of the logic gate module 210, and the output signal of the third inverter INV3 is used as the input signal of the first input end of the logic gate module 210.
It can be understood that the enable signal provided by the embodiment of the present invention is transmitted to the first input terminal of the logic gate module through the buffer and the third inverter, so that the output of the control switch circuit can be slowly changed from a high level to a low level, and the P-type power transistor is slowly turned on, so as to improve the performance of the load switch.
Referring to fig. 7, in a schematic structural diagram of another load switch capable of preventing reverse current provided in an embodiment of the present invention, when the first level control signal is a high level signal and the enable signal EN is a high level signal, the logic gate module 210 includes: a fourth inverter INV4 And an And gate ad;
a first input end of the AND gate And is connected to the enable signal EN; an input end of the fourth inverter INV4 is electrically connected to the output end of the comparing module 110, And an output end of the fourth inverter INV4 is electrically connected to a second input end of the And gate And.
It can be understood that, when the first level control signal provided by the embodiment of the present invention is a high level signal and the enable signal is a high level signal, the first level control signal is inverted by the fourth inverter and then becomes a low level signal, the low level signal and the high level signal of the enable signal are input to the and gate, so that the and gate outputs a low level turn-off signal, and the turn-off signal can control the substrate of the P-type power transistor connected to the power terminal of the second inverter to be electrically connected to the gate of the P-type power transistor, thereby achieving the purpose of controlling the turn-off of the P-type power transistor; and when the second level control signal is a low level signal and the enable signal is a high level signal, the signal input to the and gate is two high level signals, so that the and gate outputs a high level start signal, and the start signal can control the grounding end of the second inverter to be electrically connected with the gate of the P-type power tube, thereby achieving the purpose of controlling the P-type power tube to be started.
A specific load switch operation process provided by the embodiment of the present invention is described below with reference to fig. 8 and 9. Fig. 8 is a schematic structural diagram of another load switch for preventing reverse current according to an embodiment of the present invention, and fig. 9 is a schematic voltage diagram of a corresponding port of fig. 8; fig. 8 illustrates an example in which the load switch includes the comparator CMP, the Buffer, the first to fourth inverters INV1 to INV4, the And gate And, the P-type third transistor M3, the P-type fourth transistor M4, the enable signal being a high level signal, And the first level control signal being a high level signal, which are provided in the above embodiments; and the first inverter INV1 is electrically connected to the fourth transistor M4, the power supply terminal of the Buffer, the power supply terminal of the third inverter INV3, the power supply terminal of the fourth inverter INV4 And the power supply terminal of the And gate And are all electrically connected to the power supply voltage terminal IN, And the power supply terminal of the comparator CMP, the power supply terminal of the first inverter INV1 And the power supply terminal of the second inverter INV2 are all electrically connected to the substrate bulk of the P0.
When the load voltage Vout suddenly appears to be a pulse voltage higher than the power supply voltage, and the load voltage Vout is greater than the sum of the power supply voltage Vin and the first set voltage Vt1 (i.e., at the node S1 in fig. 9), the comparator CMP outputs a high-level first level control signal, which can control the third transistor M3 to turn off, and the first level control signal controls the fourth transistor M4 to turn on after being inverted by the first inverter INV1, so that the substrate bulk of the P-type power transistor P0 is electrically connected to the load terminal OUT. Meanwhile, the And Gate And an outputs a low-level turn-off signal, And the turn-off signal controls the substrate bulk of the P-type power tube P0 electrically connected with the power supply end of the third inverter INV3 to be electrically connected with the Gate of the P-type power tube P0, so that the Gate voltage Gate of the P-type power tube P0 is rapidly raised to the voltage at the substrate bulk, the P-type power tube P0 is turned off, And no current flows from the load end OUT to the power supply voltage end IN, thereby achieving the purpose of preventing the reverse flow of current.
The load voltage Vout continues to rise, the voltage of the substrate bulk and the Gate voltage of the P-type power tube P0 follow the load voltage Vout, and the P-type power tube P0 keeps being turned off; the load voltage Vout starts to drop until the load voltage Vout is less than the sum of the power voltage Vin and the second set voltage Vt2 (i.e., at the node S2 IN fig. 9), the comparator CMP outputs a low level second level control signal, which can control the third transistor M3 to turn on, and the second level control signal controls the fourth transistor M4 to turn off after being inverted by the first inverter INV1, so that the substrate bulk of the P-type power transistor P0 is electrically connected to the power voltage terminal IN. Meanwhile, the And Gate And ad outputs a high-level turn-on signal, which controls the ground GND of the third inverter INV3 to be electrically connected to the Gate of the P-type power transistor P0, so that the Gate voltage Gate of the P-type power transistor P0 starts to decrease, the P-type power transistor P0 starts to be turned on slowly, And the power supply voltage terminal IN is connected to the load terminal OUT for normally transmitting current.
And then keeping the state that the substrate bulk of the P-type power tube P0 is electrically connected with the power voltage terminal IN and the grid of the P-type power tube P0 is electrically connected with the ground terminal GND, and repeating the working process again until the load voltage Vout is greater than the sum of the power voltage Vin and the first set voltage Vt 1.
Correspondingly, the embodiment of the invention also provides electronic equipment, and the electronic equipment comprises the load switch for preventing the backflow current provided by any one of the embodiments.
The embodiment of the invention provides a load switch for preventing backflow current and electronic equipment, comprising: the power supply comprises a P-type power tube, a control selection circuit and a control switch circuit; when the load voltage is greater than the sum of the power supply voltage and a first set voltage, controlling the substrate of the P-type power tube to be electrically connected with the load end, and controlling the grid electrode of the P-type power tube to be electrically connected with the substrate of the P-type power tube; and controlling the substrate of the P-type power tube to be electrically connected with the power voltage end and controlling the grid electrode of the P-type power tube to be electrically connected with the grounding end until the load voltage is less than the sum of the power voltage and a second set voltage. It can be seen that when the load voltage is too large, the substrate of the P-type power tube is controlled to be electrically connected with the load end, and the grid of the P-type power tube is controlled to be electrically connected with the substrate of the P-type power tube, so that the P-type power tube is controlled to be closed, a path from the load end to the power voltage end has no current, the purpose of preventing the backflow of the current is achieved, and the load switching performance is improved.
The first setting voltage and the second setting voltage provided by the embodiment of the invention are equivalent to hysteresis voltage, namely the anti-backflow function of the load switch is triggered when the load voltage is greater than the sum of the power supply voltage and the first setting voltage, and the anti-backflow function of the load switch is closed until the load voltage is less than the sum of the power supply voltage and the second setting voltage, so that the anti-backflow function of the load switch can be prevented from being triggered and closed frequently, and the practicability of the load switch is improved.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (9)
1. A load switch for preventing reverse current, comprising: the power supply comprises a P-type power tube, a control selection circuit and a control switch circuit;
the source electrode of the P-type power tube is electrically connected with a power voltage end, the drain electrode of the P-type power tube is electrically connected with a load end, the substrate of the P-type power tube is electrically connected with the control selection circuit, and the grid electrode of the P-type power tube is electrically connected with the control switch circuit;
the control selection circuit is used for comparing the power supply voltage of the power supply voltage end with the load voltage of the load end and controlling the substrate of the P-type power tube to be electrically connected with the power supply voltage end or the load end; the control switch circuit is used for controlling the grid electrode of the P-type power tube to be electrically connected with the substrate or the grounding end of the P-type power tube according to the comparison result of the power voltage and the load voltage;
when the load voltage is greater than the sum of the power supply voltage and a first set voltage, controlling the substrate of the P-type power tube to be electrically connected with the load end, and controlling the grid electrode of the P-type power tube to be electrically connected with the substrate of the P-type power tube; and controlling the substrate of the P-type power tube to be electrically connected with the power voltage end and controlling the grid electrode of the P-type power tube to be electrically connected with the grounding end until the load voltage is less than the sum of the power voltage and a second set voltage, wherein the first set voltage is greater than the second set voltage.
2. The anti-back-flow load switch of claim 1, wherein the control selection circuit comprises: the comparison module and the selection switch module;
a first input end of the comparison module is connected with the power supply voltage, a second input end of the comparison module is connected with the load voltage, and an output end of the comparison module is electrically connected with a control end of the selection switch module; the comparison module is used for comparing the power supply voltage with the load voltage and outputting a first level control signal when the load voltage is greater than the sum of the power supply voltage and a first set voltage; outputting a second level control signal until the load voltage is less than the sum of the power supply voltage and a second set voltage, wherein the levels of the first level control signal and the second level control signal are opposite in phase;
the first input end of the selection switch module is electrically connected with the power supply voltage end, the second input end of the selection switch module is electrically connected with the load end, and the output end of the selection switch module is electrically connected with the substrate of the P-type power tube; the selection switch module is used for responding to the first level control signal to control the substrate of the P-type power tube to be electrically connected with the load end, and responding to the second level control signal to control the substrate of the P-type power tube to be electrically connected with the power supply voltage end.
3. The anti-back-flow load switch of claim 2, wherein the comparison module comprises a comparator;
the first input end of the comparator is connected to the power supply voltage, the second input end of the comparator is connected to the load voltage, and the output end of the comparator is electrically connected with the control end of the selection switch module.
4. The anti-back-flow load switch of claim 2, wherein the selection switch module comprises: a first transistor and a second transistor, the conduction types of the first transistor and the second transistor being opposite;
the first end of the first transistor is electrically connected with the power supply voltage end, the second end of the first transistor is electrically connected with the substrate of the P-type power tube, and the grid electrode of the first transistor is electrically connected with the output end of the comparison module;
the first end of the second transistor is electrically connected with the load end, the second end of the second transistor is electrically connected with the substrate of the P-type power tube, and the grid electrode of the second transistor is electrically connected with the output end of the comparison module.
5. The anti-back-flow load switch of claim 2, wherein the selection switch module comprises: the switch comprises a third transistor, a fourth transistor and a first inverter, wherein the conduction types of the third transistor and the fourth transistor are the same;
a first end of the third transistor is electrically connected with the power supply voltage end, a second end of the third transistor is electrically connected with the substrate of the P-type power tube, and a grid electrode of the third transistor is electrically connected with the output end of the comparison module; a first end of the fourth transistor is electrically connected with the load end, a second end of the fourth transistor is electrically connected with the substrate of the P-type power tube, a grid electrode of the fourth transistor is electrically connected with an output end of the first phase inverter, and an input end of the first phase inverter is electrically connected with an output end of the comparison module;
or, a first end of the third transistor is electrically connected to the power supply voltage end, a second end of the third transistor is electrically connected to the substrate of the P-type power transistor, a gate of the third transistor is electrically connected to an output end of the first inverter, and an input end of the first inverter is electrically connected to an output end of the comparison module; the first end of the fourth transistor is electrically connected with the load end, the second end of the fourth transistor is electrically connected with the substrate of the P-type power tube, and the grid electrode of the fourth transistor is electrically connected with the output end of the comparison module.
6. The anti-back-flow load switch of claim 2, wherein the control switch circuit comprises: a logic gate module and a second inverter;
a first input end of the logic gate module is connected with an enabling signal, a second input end of the logic gate module is electrically connected with an output end of the comparison module, and an output end of the logic gate module is electrically connected with an input end of the second phase inverter; the logic gate module is used for responding to the first level control signal and outputting a turn-off signal, and responding to the second level control signal and outputting a turn-on signal;
the output end of the second inverter is electrically connected with the grid electrode of the P-type power tube, and the power supply end of the second inverter is electrically connected with the substrate of the P-type power tube; the second inverter is used for responding to the turn-off signal to control the grid electrode of the P-type power tube to be electrically connected with the substrate of the P-type power tube, and responding to the turn-on signal to control the grid electrode of the P-type power tube to be electrically connected with the grounding end of the second inverter.
7. The anti-back-flow load switch of claim 6, wherein the control switch circuit further comprises: a buffer and a third inverter;
the input end of the buffer is connected with the enabling signal, the output end of the buffer is electrically connected with the input end of the third phase inverter, and the output end of the third phase inverter is electrically connected with the first input end of the logic gate module.
8. The load switch of claim 6, wherein when the first level control signal is a high level signal and the enable signal is a high level signal, the logic gate module comprises: a fourth inverter and an AND gate;
a first input end of the AND gate is connected with the enabling signal; the input end of the fourth phase inverter is electrically connected with the output end of the comparison module, and the output end of the fourth phase inverter is electrically connected with the second input end of the AND gate.
9. An electronic device, characterized in that the electronic device comprises the reverse current prevention load switch of any one of claims 1-8.
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| CN202010636539.1A CN111682869B (en) | 2020-07-03 | 2020-07-03 | Anti-backflow current load switch and electronic equipment |
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| CN202010636539.1A CN111682869B (en) | 2020-07-03 | 2020-07-03 | Anti-backflow current load switch and electronic equipment |
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Cited By (1)
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|---|---|---|---|---|
| CN117240277A (en) * | 2023-11-15 | 2023-12-15 | 浙江地芯引力科技有限公司 | Substrate selection circuit and electronic equipment |
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| CN111682869B (en) | 2024-02-09 |
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