CN111181383B - Power switch circuit - Google Patents
Power switch circuit Download PDFInfo
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- CN111181383B CN111181383B CN201811330775.XA CN201811330775A CN111181383B CN 111181383 B CN111181383 B CN 111181383B CN 201811330775 A CN201811330775 A CN 201811330775A CN 111181383 B CN111181383 B CN 111181383B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
- H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
- H02M3/06—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using resistors or capacitors, e.g. potential divider
- H02M3/07—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using resistors or capacitors, e.g. potential divider using capacitors charged and discharged alternately by semiconductor devices with control electrode, e.g. charge pumps
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
- H03K17/04—Modifications for accelerating switching
- H03K17/041—Modifications for accelerating switching without feedback from the output circuit to the control circuit
- H03K17/04106—Modifications for accelerating switching without feedback from the output circuit to the control circuit in field-effect transistor switches
Abstract
The invention discloses a power switch circuit, which comprises a switch circuit and a capacitor. The switch circuit is coupled between the input end and the output end of the power switch circuit and comprises a first switch unit and a second switch unit. The first switch unit and the second switch unit are coupled to the charge pump. The first end of the capacitor is coupled to a node between the first switch unit and the second switch unit, and the second end of the capacitor is coupled to the first switch unit, the second switch unit, the charge pump and the charging circuit. When a load is coupled to the power switch circuit, the charging circuit charges the capacitor. When the load is started, the charge pump only needs to pull up the voltage of the second end of the capacitor by a small amount, so that the first switch unit and the second switch unit can be quickly turned on to provide the power to the load.
Description
Technical Field
The present invention relates to a power switch circuit, and more particularly, to a power switch circuit with a fast response speed.
Background
Generally, the main function of the power switch circuit is to transfer the power provided by the power supply to the load. When the load is to be started, the power switch circuit needs to form a path to enable the load to receive the power provided by the power supply at the moment of starting the load. During the operation of the load, if an abnormal condition occurs (e.g., the load draws excessive current, the current supplied by the power supply is excessive …, etc.), the power switch circuit needs to be opened in real time to protect the load and its own circuit. Therefore, the speed of response of the power switching circuit is important.
Disclosure of Invention
In order to improve the above-mentioned problem and achieve the effect of increasing the response speed of the circuit, the invention provides a power switch circuit with a faster response speed.
The power switch circuit provided by the invention has an input end and an output end, wherein the input end of the power switch circuit is used for receiving a supply power, the output end of the power switch circuit is used for being coupled with a load, and the power switch circuit comprises a switch circuit and a capacitor. The switch circuit is coupled between the input terminal and the output terminal of the power switch circuit, and includes a first switch unit and a second switch unit, wherein the first switch unit and the second switch unit are coupled to a charge pump. The first end of the capacitor is coupled to a node between the first switch unit and the second switch unit, and the second end of the capacitor is coupled to the first switch unit, the second switch unit, the charge pump and a charging circuit. When the output end of the power switch circuit is coupled with the load but the load is not started, the charging circuit charges the capacitor in advance, so that the voltage of the capacitor is a first voltage. Then, when the load is started, the charge pump charges the voltage of the capacitor from the first voltage to a second voltage sufficient to turn on the first switch unit and the second switch unit, so as to allow the power provided by the power supply to be transferred to the load.
In an embodiment of the power switch circuit provided by the invention, the first switch unit includes a first transistor and a first bidirectional switch. The first bidirectional switch is connected in parallel with the capacitor and coupled to the control end of the first transistor. The first end of the first transistor is coupled to the input end of the power switch circuit, and the second end of the first transistor is coupled to the first bidirectional switch and the first end of the capacitor. The second switching unit includes a second transistor and a second bidirectional switch. The second bidirectional switch is connected in parallel with the capacitor and coupled to the control end of the second transistor. The first end of the second transistor is coupled to the second bidirectional switch and the first end of the capacitor, and the second end of the second transistor is coupled to the output end of the power switch circuit.
When the load is started, the first bidirectional switch and the second bidirectional switch are controlled to enable the control end of the first transistor and the control end of the second transistor and the first end of the capacitor to be conducted, and then the control end of the first transistor and the control end of the second transistor are of second voltage which is enough to conduct the first transistor and the second transistor so as to transfer the power provided by the power supply to the load.
In other embodiments of the power switch circuit provided in the present invention, the power switch circuit may further include a plurality of protection circuits, such as: a reverse current blocking circuit, a current limiting circuit, or an overcurrent protection circuit …. In the present invention, the first bidirectional switch in the first switch unit or the second bidirectional switch in the second switch unit can be controlled by the control signals generated by the protection circuits, so that the control end of the first transistor in the first switch unit or the control end of the second transistor in the second switch unit and the second end of the capacitor are turned on, and the first transistor or the second transistor is further controlled to be turned off, thereby achieving different circuit protection objectives, such as: reverse current is blocked, and the circuit is prevented from being damaged by overlarge current.
Preferably, the first switch unit includes a first transistor and a first bidirectional switch, the first bidirectional switch is connected in parallel to the capacitor and coupled to a control terminal of the first transistor, a first terminal of the first transistor is coupled to the input terminal of the power switch circuit, and a second terminal of the first transistor is coupled to the first bidirectional switch and the first terminal of the capacitor;
the second switch unit includes a second transistor and a second bidirectional switch, the second bidirectional switch is connected in parallel to the capacitor and coupled to a control terminal of the second transistor, a first terminal of the second transistor is coupled to the second bidirectional switch and a first terminal of the capacitor, and a second terminal of the second transistor is coupled to an output terminal of the power switch circuit.
Preferably, when the load is started, the first bidirectional switch and the second bidirectional switch are controlled so that the control terminal of the first transistor and the control terminal of the second transistor and the second terminal of the capacitor are conducted, and then the voltage of the control terminal of the first transistor and the control terminal of the second transistor is equal to the second voltage, so that the first transistor and the second transistor are conducted to transfer the power provided by the power supply to the load.
Preferably, the power switching circuit further includes a first protection circuit, and the first protection circuit includes:
a first operational amplifier having an inverting input coupled to the input of the power switch circuit, a non-inverting input coupled to the output of the power switch circuit, and an output coupled to the second bidirectional switch of the second switch unit;
the first operational amplifier outputs a first control signal according to a voltage difference between a voltage of an input terminal of the power switch circuit and a voltage of an output terminal of the power switch circuit, and the second bidirectional switch is controlled by the first control signal.
Preferably, in the process of the load operation, if a voltage difference between the voltage at the input terminal of the power switch circuit and the voltage at the output terminal of the power switch circuit is less than or equal to a first predetermined voltage difference, the second bidirectional switch is controlled to keep the control terminal of the second transistor and the first terminal of the capacitor turned on according to the first control signal, so as to turn on the second transistor, and if the voltage difference between the voltage at the input terminal of the power switch circuit and the voltage at the output terminal of the power switch circuit is greater than the first predetermined voltage difference, the second bidirectional switch is controlled to turn on the control terminal of the second transistor and the second terminal of the capacitor according to the first control signal, so as to turn off the second transistor.
Preferably, the power switching circuit further includes a second protection circuit, and the second protection circuit includes:
a second operational amplifier, an inverting input terminal of which is coupled to the first terminal of the capacitor, a non-inverting input terminal of which is coupled to the output terminal of the power switch circuit, and an output terminal of which is coupled to the second bidirectional switch of the second switch unit;
the second operational amplifier outputs a second control signal according to a voltage difference between a voltage of the first end of the capacitor and a voltage of the output end of the power switch circuit, and the second bidirectional switch is controlled by the second control signal.
Preferably, in the process of the load operation, if a voltage difference between the voltage of the first end of the capacitor and the voltage of the output end of the power switch circuit is less than or equal to a second predetermined voltage difference, the second bidirectional switch is controlled to keep the control end of the second transistor and the first end of the capacitor turned on according to the second control signal, so as to turn on the second transistor, and if the voltage difference between the voltage of the first end of the capacitor and the voltage of the output end of the power switch circuit is greater than the second predetermined voltage difference, the second bidirectional switch is controlled to turn on the control end of the second transistor with the second end of the capacitor according to the second control signal, so as to turn off the second transistor.
Preferably, the power switching circuit further includes a third protection circuit, and the third protection circuit includes:
a sense transistor; and
a comparator, an inverting input terminal of which receives a threshold current, a non-inverting input terminal of which is coupled to the input terminal of the power switching circuit through the sense transistor, and an output terminal of which is coupled to the first bidirectional switch in the first switching unit;
wherein the comparator compares the threshold current with a current supplied from the power supply to output a third control signal, and the first bidirectional switch is controlled by the third control signal.
Preferably, during the load operation, if the current provided by the power supply is less than or equal to the threshold current, the first bidirectional switch is controlled to make the control terminal of the first transistor and the first terminal of the capacitor remain on according to the third control signal to turn on the first transistor, and if the current provided by the power supply is greater than the threshold current, the first bidirectional switch is controlled to make the control terminal of the first transistor turn on with the second terminal of the capacitor according to the third control signal to turn off the first transistor.
Preferably, the first protection circuit is a reverse current blocking circuit.
Preferably, the second protection circuit is a reverse current blocking circuit.
Preferably, the third protection circuit is a current limiting circuit or an overcurrent protection circuit.
Because the power switch circuit provided by the invention is provided with the capacitor, and the capacitor is charged in advance when the load is not started, when the load is started and in the process of load operation, the first switch circuit or the second switch circuit can be quickly responded by controlling the first bidirectional switch and the second bidirectional switch, and the first switch circuit or the second switch circuit is switched on or off. Therefore, compared with a common power switch circuit, the power switch circuit provided by the invention has a faster response speed.
Drawings
FIG. 1 is a block diagram illustrating a power switch circuit in an exemplary embodiment of the invention.
Fig. 2 is a circuit diagram of the power switching circuit of fig. 1.
Fig. 3 is a circuit diagram showing a power switching circuit according to another exemplary embodiment of the invention.
Fig. 4 is a circuit diagram showing a power switching circuit according to another exemplary embodiment of the invention.
Detailed Description
Various exemplary embodiments will be described more fully hereinafter with reference to the accompanying drawings, in which some exemplary embodiments are shown. The inventive concept may, however, be embodied in many different forms and should not be construed as limited to the exemplary embodiments set forth herein. Rather, these exemplary embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the inventive concept to those skilled in the art. Like numbers refer to like elements throughout.
It will be understood that, although the terms first, second, third, etc. may be used herein to describe various components or elements, these components or elements should not be limited by these terms. These terms are only used to distinguish one element or component from another element or component. Thus, a first component or element discussed below could be termed a second component or element without departing from the teachings of the present invention.
Referring to fig. 1, fig. 1 is a block diagram illustrating a power switch circuit according to an exemplary embodiment of the invention.
As shown IN fig. 1, the power switch circuit provided by the present invention has an input terminal IN and an output terminal OUT. The input terminal IN of the power switch circuit is used for receiving a power supply, and the output terminal OUT of the power switch circuit is used for coupling a load or other various functional chips.
The power switch circuit provided by the invention mainly comprises a switch circuit 10 and a capacitor 20. The switch circuit 10 is coupled between the input terminal IN and the output terminal OUT of the power switch circuit. The switching circuit 10 includes a first switching unit 12 and a second switching unit 14. The first switch unit 12 and the second switch unit 14 are both coupled to the charge pump CP and the charging circuit PRE.
The main feature of the power switch circuit provided by the present invention is that a capacitor 20 is provided. A first terminal ca of the capacitor 20 is coupled to the node n between the first switch unit 12 and the second switch unit 14, and a second terminal cb of the capacitor 20 is coupled to the first switch unit 12, the second switch unit 14, the charge pump CP and the charging circuit PRE. The capacitor 20 is provided to improve the operation speed of the power switching circuit in various aspects.
Referring to fig. 2, fig. 2 is a circuit diagram of the power switch circuit of fig. 1.
As shown in fig. 2, the first switching unit 12 includes a first transistor T1 and a first bidirectional switch SW 1. The first bidirectional switch SW1 is connected in parallel to the capacitor 20 and coupled to the control terminal of the first transistor T1. A first terminal (drain as shown IN fig. 2) of the first transistor T1 is coupled to the input terminal IN of the power switch circuit, and a second terminal (source as shown IN fig. 2) of the first transistor T1 is coupled to the first bidirectional switch SW1 and the first terminal ca (node n) of the capacitor 20.
The second switching unit 14 includes a second transistor T2 and a second bidirectional switch SW 2. The second bidirectional switch SW2 is connected in parallel to the capacitor 20 and is coupled to the control terminal of the second transistor T2, a first terminal (source as shown in fig. 2) of the second transistor T2 is coupled to the second bidirectional switch SW2 and the first terminal ca (node n) of the capacitor 20, and a second terminal (drain as shown in fig. 2) of the second transistor T2 is coupled to the output terminal OUT of the power switch circuit.
As further shown in fig. 2, the current source supplying the reference current IREF1 is coupled to the output terminal OUT of the power switch circuit through the switch S and coupled to the load through the output terminal OUT. The on and off of the switch S is controlled by an enable signal EN _ PRE. Before the load and the power switch circuit are started, the voltage at the first end ca of the capacitor 20 is the same as the voltage at the second end cb of the capacitor 20, i.e., the voltage across the capacitor 20 is zero.
First, before the load is activated, the system terminal provides an enable signal EN _ PRE to turn on the switch S to allow the reference current IREF1 to flow to the output terminal OUT through the switch S, so as to confirm that there is a conducting path between the power switch circuit and the load, and if the line is not shorted, when the reference current IREF1 flows OUT from the output terminal OUT to the load, one or both of the charging circuit PRE and the charge pump CP of the power switch circuit are activated, and the capacitor 20 is precharged simultaneously or sequentially, so that the node CAP has the first voltage.
As described above, in the present embodiment, the power switching circuit is provided with the capacitor 20, the charging circuit PRE, and the charge pump CP. Before the load is started, the voltage of the node CAP is already charged to the first voltage by the charging circuit PRE and the charge pump CP. Therefore, when the load is started by charging the load with the reference current IREF1 to reach a voltage threshold, the charge pump CP only needs to pull up the voltage of the node CAP from the first voltage to the second voltage.
If the capacitor 20 is not provided (and the charging circuit PRE is not required), the charge pump CP must pull up the voltage at the node CAP from zero to a voltage value sufficient to turn on the first transistor T1 and the second transistor T2, i.e., the second voltage, when the load is started.
In contrast, the time taken to pull up the voltage of the node CAP from the first voltage to the second voltage is shorter than the time taken to pull up the voltage of the node CAP from zero to the second voltage. Therefore, the capacitor 20 of the present embodiment facilitates to quickly turn on the first switch unit 12 and the second switch unit 14, and increases the operation speed of the power switch circuit from the non-activated state to the activated state of the load.
Referring to fig. 3, fig. 3 is a circuit diagram showing a power switch circuit according to another exemplary embodiment of the invention.
The power switch circuit in fig. 3 and the power switch circuit in fig. 2 have similar circuit structures and operation principles, and therefore only the differences between the circuit structures and the operation principles will be described in the following description.
The difference between the power switching circuit in fig. 3 and the power switching circuit in fig. 2 is that the power switching circuit in fig. 3 further includes a first protection circuit 30 a. The first protection circuit 30a includes a first operational amplifier 32 a.
As shown IN FIG. 3, the inverting input terminal of the first operational amplifier 32a is coupled to the input terminal IN of the power switch circuit, the non-inverting input terminal of the first operational amplifier 32a is coupled to the output terminal OUT of the power switch circuit, and the output terminal of the first operational amplifier 32a is coupled to the second bidirectional switch SW2 of the second switch unit 14.
In fig. 3, the first protection circuit 30a can provide a Reverse Current Blocking (RCB) circuit protection function.
During the load operation, the first operational amplifier 32a outputs the first control signal CON1 according to the voltage difference between the voltage at the input terminal IN of the power switch circuit and the voltage at the output terminal OUT of the power switch circuit, so as to control the second bidirectional switch SW 2.
If the voltage difference between the voltage at the input terminal IN of the power switch circuit and the voltage at the output terminal OUT of the power switch circuit is less than or equal to a first predetermined voltage difference (or approaches zero), it means that no reverse current will flow back from the load terminal to the power supply terminal. Accordingly, the first control signal CON1 outputted from the first operational amplifier 30a controls the second bidirectional switch SW2 to keep the control terminal of the second transistor T2 and the first terminal ca (i.e., the node n) of the capacitor 20 turned on, so as to keep the connection between the power supply connected to the input terminal IN and the load connected to the output terminal OUT.
Conversely, if the voltage difference between the voltage at the input terminal IN of the power switch circuit and the voltage at the output terminal OUT of the power switch circuit is greater than a first predetermined voltage difference, it means that a reverse current will flow from the load terminal back to the power supply terminal. Thus, the first control signal CON1 outputted from the first operational amplifier 30a controls the second bidirectional switch SW2 to turn on the control terminal of the second transistor T2 and the second terminal cb of the capacitor 20, so as to turn off the second transistor T2, thereby forming an open circuit between the load and the power supply and preventing reverse current from flowing back from the load terminal to the power supply terminal.
In addition, another difference between the power switching circuit in fig. 3 and the power switching circuit in fig. 2 is that the power switching circuit in fig. 3 further includes a third protection circuit 40. As shown in fig. 3, the third protection circuit 40 includes a sense transistor ST and a comparator 42. The inverting input terminal of the comparator 42 receives the threshold current IREF2, the non-inverting input terminal of the comparator 42 is coupled to the input terminal IN of the power switch circuit through the sense transistor ST, and the output terminal of the comparator 42 is coupled to the first bidirectional switch SW1 of the first switch unit 12.
In fig. 3, the third Protection circuit 40 can provide a Current Limiting (CL) or Over Current Protection (OCP) circuit Protection function according to different circuit designs in practical operation.
During load operation, the comparator 42 can obtain the current provided by the power supply through the sense transistor ST. Then, the comparator 42 compares the threshold current IREF2 with the current provided by the power supply and outputs a third control signal CON3 to control the first bidirectional switch SW1 accordingly. For example, the threshold current IREF2 is set according to the safety current of the power switch circuit, and the definition of the safety current is well known to those skilled in the art, and therefore will not be described in detail herein.
If the current provided by the power supply is smaller than or equal to the threshold current IREF2, the difference in the definition of the threshold current IREF2 may indicate that the current provided by the power supply is still within the current range that can be carried by the power switch circuit, or that the current provided by the power supply does not damage the load. At this time, the third control signal CON2 outputted by the comparator 42 controls the first bidirectional switch SW1 to make the control terminal of the first transistor T1 and the first terminal ca (i.e., the node n) of the capacitor 20 remain on, so that the connection between the power supply connected to the input terminal IN and the load connected to the output terminal OUT is maintained on.
Conversely, if the current provided by the power supply is greater than IREF2, the difference in the definition of IREF2 may indicate that the current provided by the power supply is beyond the range of current that can be carried by the power switch circuit, or that the current provided by the power supply may damage the load. Then, the third control signal CON3 outputted by the comparator 42 controls the first bidirectional switch SW1 to turn on the control terminal of the first transistor T1 and the second terminal cb of the capacitor 20 to turn off the second transistor T2, so as to form an open circuit between the load and the power supply, thereby preventing the power switch circuit or the load from being damaged due to an excessive current carried by the load.
In this case, since the power switch circuit cannot receive power from the power supply, the second transistor T2 in the second switch unit 14 is also turned off.
Finally, referring to fig. 4, fig. 4 is a circuit diagram showing a power switch circuit according to another exemplary embodiment of the invention.
The power switch circuit in fig. 4 and the power switch circuit in fig. 3 have similar circuit structures and operation principles, and therefore only the differences between the circuit structures and the operation principles will be described in the following description.
The power switching circuit in fig. 4 and the power switching circuit in fig. 3 differ in that the power switching circuit in fig. 4 is not provided with the first protection circuit 30a, but is provided with the second protection circuit 30 b. The second protection circuit 30b includes a second operational amplifier 32 b. As shown in fig. 4, the inverting input terminal of the second operational amplifier 32b is coupled to the first terminal ca of the capacitor 20, the non-inverting input terminal of the second operational amplifier 32b is coupled to the output terminal OUT of the power switch circuit, and the output terminal of the second operational amplifier 32b is coupled to the second bidirectional switch SW2 of the second switch unit 14.
Similar to the first protection circuit 30a in fig. 3, in fig. 4, the second protection circuit 30b may provide a Reverse Current Blocking (RCB) circuit protection function.
During the load operation, the second operational amplifier 32b outputs the second control signal CON2 according to a voltage difference between the voltage of the first terminal ca of the capacitor 20 (i.e., the voltage of the node n) and the voltage of the output terminal OUT of the power switch circuit, so as to control the second bidirectional switch SW 2.
If the voltage difference between the voltage at the node n and the voltage at the output terminal OUT of the power switch circuit is less than or equal to the second predetermined voltage difference (or approaches zero), it means that no reverse current will flow back from the load terminal to the power supply terminal. Accordingly, the second control signal CON2 outputted from the second operational amplifier 30b controls the second bidirectional switch SW2 to keep the control terminal of the second transistor T2 and the first terminal ca (i.e., node) of the capacitor 20 turned on, so as to keep the connection between the power supply connected to the input terminal IN and the load connected to the output terminal OUT. Conversely, if the voltage difference between the voltage at the node n and the voltage at the output terminal OUT of the power switch circuit is greater than the second predetermined voltage difference, it means that a reverse current will flow from the load terminal to the power supply terminal. Thus, the second control signal CON2 outputted by the second operational amplifier 30b controls the second bidirectional switch SW2 to turn on the control terminal of the second transistor T2 and the second terminal cb of the capacitor 20, so as to form an open circuit between the load and the power supply, thereby preventing the reverse current from flowing back from the load terminal to the power supply terminal.
That is, the circuit structure of the power switch circuit IN fig. 4 is similar to that of the power switch circuit IN fig. 3, but the difference between the two is that IN the circuit structure of the power switch circuit IN fig. 3, the inverting input terminal of the first operational amplifier 32a is coupled to the input terminal IN of the power switch circuit, and IN the circuit structure of the power switch circuit IN fig. 4, the inverting input terminal of the second operational amplifier 32b is coupled to the first terminal ca (node n) of the capacitor 20.
IN short, IN the circuit structure of the power switch circuit IN fig. 3, the first protection circuit 30a generates the first control signal CON1 to prevent the reverse current from flowing back from the load terminal to the power supply terminal by determining the voltage difference between the voltage at the input terminal IN of the power switch circuit and the voltage at the output terminal OUT of the power switch circuit, and IN the circuit structure of the power switch circuit IN fig. 4, the second protection circuit 30b generates the second control signal CON2 to prevent the reverse current from flowing back from the load terminal to the power supply terminal by determining the voltage difference between the voltage at the first terminal ca of the capacitor 20 (i.e., the voltage at the node n) and the voltage at the output terminal OUT of the power switch circuit.
[ possible effects of examples ]
In summary, the main feature of the power switch circuit provided by the present invention is that, since the power switch circuit is provided with the capacitor, and the capacitor is pre-charged when the load is not started, when the load is started, the charge pump only needs to pull up the voltage at the second end of the capacitor by a small amount, so that the first switch unit and the second switch unit can be rapidly turned on to transmit the power provided by the power supply to the load. Furthermore, during the operation of the load, the reverse current can be prevented from flowing back from the load end to the power supply end.
Finally, while in the foregoing specification, the present inventive concept has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the present inventive concept as defined by the following claims.
Claims (12)
1. A power switching circuit having an input terminal and an output terminal, wherein the input terminal of the power switching circuit is configured to receive a power supply, and the output terminal of the power switching circuit is configured to be coupled to a load, the power switching circuit comprising:
a switch circuit coupled between an input terminal and an output terminal of the power switch circuit, and including a first switch unit and a second switch unit, wherein the first switch unit and the second switch unit are coupled to a charge pump; and
a capacitor, a first end of which is coupled to a node between the first switch unit and the second switch unit, and a second end of which is coupled to the first switch unit, the second switch unit, the charge pump and a charging circuit;
when the load is not started up but the output end of the power supply switch circuit is coupled with the load, the charging circuit charges the capacitor in advance so that the voltage of the capacitor is a first voltage, and when the load is started up, the charge pump charges the voltage of the capacitor from the first voltage to a second voltage which is enough to turn on the first switch unit and the second switch unit so as to allow the power provided by the power supply to be transferred to the load.
2. The power switch circuit as claimed in claim 1, wherein the first switch unit comprises a first transistor and a first bi-directional switch, the first bi-directional switch is connected in parallel to the capacitor and coupled to a control terminal of the first transistor, a first terminal of the first transistor is coupled to an input terminal of the power switch circuit, and a second terminal of the first transistor is coupled to the first bi-directional switch and a first terminal of the capacitor;
the second switch unit includes a second transistor and a second bidirectional switch, the second bidirectional switch is connected in parallel to the capacitor and coupled to a control terminal of the second transistor, a first terminal of the second transistor is coupled to the second bidirectional switch and a first terminal of the capacitor, and a second terminal of the second transistor is coupled to an output terminal of the power switch circuit.
3. The power switch circuit of claim 2, wherein when the load is activated, the first bi-directional switch and the second bi-directional switch are controlled such that the control terminal of the first transistor and the control terminal of the second transistor and the second terminal of the capacitor conduct, and the voltage of the control terminal of the first transistor and the control terminal of the second transistor is equal to the second voltage, such that the first transistor and the second transistor conduct to transfer the power provided by the supply power to the load.
4. The power switching circuit of claim 2, further comprising a first protection circuit, and wherein the first protection circuit comprises:
a first operational amplifier having an inverting input coupled to the input of the power switch circuit, a non-inverting input coupled to the output of the power switch circuit, and an output coupled to the second bidirectional switch of the second switch unit;
the first operational amplifier outputs a first control signal according to a voltage difference between a voltage of an input terminal of the power switch circuit and a voltage of an output terminal of the power switch circuit, and the second bidirectional switch is controlled by the first control signal.
5. The power switching circuit of claim 4 wherein during operation of said load, if the voltage difference between the voltage at the input end of the power switch circuit and the voltage at the output end of the power switch circuit is less than or equal to a first preset voltage difference, the second bidirectional switch is controlled to make the control end of the second transistor and the first end of the capacitor keep conducting according to the first control signal so as to conduct the second transistor, and if the voltage difference between the voltage of the input end of the power switch circuit and the voltage of the output end of the power switch circuit is greater than the first preset voltage difference, according to the first control signal, the second bidirectional switch is controlled to enable the control end of the second transistor to be conducted with the second end of the capacitor instead, so that the second transistor is turned off.
6. The power switching circuit of claim 2, wherein the power switching circuit further comprises a second protection circuit, and the second protection circuit comprises:
a second operational amplifier, an inverting input terminal of which is coupled to the first terminal of the capacitor, a non-inverting input terminal of which is coupled to the output terminal of the power switch circuit, and an output terminal of which is coupled to the second bidirectional switch of the second switch unit;
the second operational amplifier outputs a second control signal according to a voltage difference between a voltage of the first end of the capacitor and a voltage of the output end of the power switch circuit, and the second bidirectional switch is controlled by the second control signal.
7. The power switch circuit as claimed in claim 6, wherein during the operation of the load, if the voltage difference between the voltage of the first terminal of the capacitor and the voltage of the output terminal of the power switch circuit is less than or equal to a second predetermined voltage difference, the second bidirectional switch is controlled to keep the control terminal of the second transistor and the first terminal of the capacitor conducting according to the second control signal, so as to turn on the second transistor, and if the voltage difference between the voltage of the first terminal of the capacitor and the voltage of the output terminal of the power switch circuit is greater than the second predetermined voltage difference, the second bidirectional switch is controlled to turn on the control terminal of the second transistor with the second terminal of the capacitor according to the second control signal, so as to turn off the second transistor.
8. The power switching circuit of claim 2, wherein the power switching circuit further comprises a third protection circuit, and the third protection circuit comprises:
a sense transistor; and
a comparator, an inverting input terminal of which receives a threshold current, a non-inverting input terminal of which is coupled to the input terminal of the power switching circuit through the sense transistor, and an output terminal of which is coupled to the first bidirectional switch in the first switching unit;
wherein the comparator compares the threshold current with a current supplied from the power supply to output a third control signal, and the first bidirectional switch is controlled by the third control signal.
9. The power switch circuit of claim 8, wherein during operation of the load, if the current provided by the power supply is less than or equal to the threshold current, the first bi-directional switch is controlled to maintain the control terminal of the first transistor and the first terminal of the capacitor conductive according to the third control signal to turn on the first transistor, and if the current provided by the power supply is greater than the threshold current, the first bi-directional switch is controlled to change the control terminal of the first transistor to be conductive with the second terminal of the capacitor conductive according to the third control signal to turn off the first transistor.
10. The power switching circuit of claim 4, wherein the first protection circuit is a reverse current blocking circuit.
11. The power switching circuit of claim 6, wherein said second protection circuit is a reverse current blocking circuit.
12. The power switching circuit of claim 8 wherein said third protection circuit is a current limiting circuit or an overcurrent protection circuit.
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| CN201811330775.XA CN111181383B (en) | 2018-11-09 | 2018-11-09 | Power switch circuit |
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| CN201811330775.XA CN111181383B (en) | 2018-11-09 | 2018-11-09 | Power switch circuit |
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| CN111181383B true CN111181383B (en) | 2021-01-26 |
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| CN114172363B (en) * | 2020-09-10 | 2023-11-03 | 瑞昱半导体股份有限公司 | charge pump device |
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