CN113315089B - High-power supply rejection ratio load switching circuit and control method thereof - Google Patents
High-power supply rejection ratio load switching circuit and control method thereof Download PDFInfo
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- CN113315089B CN113315089B CN202110586319.7A CN202110586319A CN113315089B CN 113315089 B CN113315089 B CN 113315089B CN 202110586319 A CN202110586319 A CN 202110586319A CN 113315089 B CN113315089 B CN 113315089B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/20—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess voltage
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/20—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for electronic equipment
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
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Abstract
A load switching circuit with a high power supply rejection ratio and a control method are disclosed. The load switch circuit with the high power supply rejection ratio comprises a load switch, an input voltage feedback circuit, an output voltage feedback circuit and a control circuit, wherein a first end and a second end of the load switch are respectively coupled with a power supply and a load. The control circuit receives an input voltage feedback signal representing an input voltage signal of the load switch and an output voltage feedback signal representing an output voltage signal of the load switch, and adjusts the voltage between the first end and the second end of the load switch to a fixed preset voltage value when the load switch is fully conducted.
Description
Technical Field
Embodiments of the present invention relate to electronic circuits, and more particularly, to a high power rejection ratio load switching circuit and a control method thereof.
Background
In many electronic device applications, it is often desirable to couple a load switch (also known as an electronic fuse) between the power supply system and the load for protective operation of the power supply system or the load. When the system is abnormal, the load switch can cut off the connection between the power supply system and the load in time, so that the aim of protecting the whole system is fulfilled.
However, in some applications sensitive to noise and power supply ripple, the conventional load switch cannot handle the ripple and noise on the input voltage VIN of the load switch, and the system often needs to add other high power supply rejection ratio modules in the circuit to solve the problem of power supply ripple and noise, thereby increasing the cost of the system.
Therefore, it is desirable to provide a load switching circuit and control method with a high power supply rejection ratio that can significantly reduce input voltage ripple.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a load switch circuit with high power supply rejection ratio and a control method thereof, wherein the load switch circuit can remarkably reduce input voltage ripple.
In order to achieve the above object, an aspect of the present invention provides a load switching circuit having a high power supply rejection ratio, comprising: the load switch is provided with a first end, a second end and a control end, wherein the first end is coupled to a power supply, and the second end is coupled to a load; the output voltage feedback circuit is coupled to the second end of the load switch, receives the output voltage signal and generates an output voltage feedback signal representing the output voltage signal; the input voltage feedback circuit is coupled to the first end of the load switch, receives an input voltage signal and generates an input voltage feedback signal representing the input voltage signal; and the operational amplification circuit receives the input voltage feedback signal and the output voltage feedback signal, and generates a first control signal according to the input voltage feedback signal and the output voltage feedback signal, wherein the first control signal is used for adjusting the voltage between the first end and the second end of the load switch to be a fixed preset voltage value when the load switch is completely conducted.
Another aspect of the present invention provides a control method for a high power supply rejection ratio load switching circuit, wherein the load switching circuit includes a load switch having a first end coupled to a power supply and a second end coupled to a load, the control method comprising: sampling an input voltage signal at a first end of a load switch and generating an input voltage feedback signal representing the input voltage signal; sampling an output voltage signal at a second end of the load switch and generating an output voltage feedback signal representing the output voltage signal; judging whether the load switch needs to be turned off or not; and when the load switch does not need to be turned off, generating a control signal according to the output voltage feedback signal and the input voltage feedback signal, wherein the control signal is used for adjusting the voltage values at two ends of the load switch to a fixed preset voltage value.
Drawings
The above, as well as additional purposes, features, and advantages of embodiments of the present invention will become apparent in the following detailed written description and claims upon reference to the accompanying drawings. In the drawings, several possible embodiments of the invention are shown by way of example and not by way of limitation.
Fig. 1 presents a schematic block-diagram of an embodiment of the load switching circuit.
Fig. 2 shows a schematic circuit diagram of a specific embodiment of the load switching circuit of fig. 1.
Fig. 3 presents a schematic block-diagram of a further embodiment of the load switching circuit.
Fig. 4 shows a schematic circuit diagram of a specific embodiment of the load switching circuit of fig. 3.
Fig. 5 shows a schematic circuit diagram of another embodiment of the load switching circuit of fig. 3.
Fig. 6 presents a schematic block-diagram of a further embodiment of the load switching circuit.
Fig. 7 presents a flow diagram of an embodiment of a method of controlling a load switching circuit.
In the drawings, the same or corresponding reference numerals are used to indicate the same or corresponding elements.
Detailed Description
Specific embodiments of the invention will be described in detail below, it being noted that the embodiments described herein are for illustration only and are not intended to limit the invention. The invention is intended to cover any alternatives, modifications, equivalents, and variations that fall within the spirit and scope of the invention. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to one of ordinary skill in the art that: no such specific details are necessary to practice the invention. In other instances, well-known circuits, materials, or methods have not been described in detail in order not to obscure the invention.
Fig. 1 shows a functional block diagram of an embodiment of a load switching circuit. As shown in fig. 1, the load switching circuit includes a load switch 11, an output voltage feedback circuit 12, an input voltage feedback circuit 13, and a control circuit 14. The load switch 11 has a first end coupled to the power supply circuit via the terminal 1 for receiving the input voltage signal VIN, a second end coupled to the load for providing the output voltage signal VOUT via the terminal 2, and a control end for receiving the control signal DRV. Those of ordinary skill in the art will appreciate that: the load switch 11 may be any suitable controllable semiconductor switching device, such as a Metal Oxide Semiconductor Field Effect Transistor (MOSFET), insulated Gate Bipolar Transistor (IGBT), junction Field Effect Transistor (JFET), etc.
In the embodiment of fig. 1, the output voltage feedback circuit 12 is coupled to the terminal 2, receives the output voltage signal VOUT, and generates the output voltage feedback signal VFB representing the output voltage signal VOUT based on the output voltage signal VOUT.
In the embodiment of fig. 1, the input voltage feedback circuit 13 is coupled to the terminal 1, receives the input voltage signal VIN, and generates the input voltage feedback signal VFF representing the input voltage signal VIN based on the input voltage signal VIN.
The control circuit 14 receives the output voltage feedback signal VFB and the input voltage feedback signal VFF and generates a control signal DRV based on the output voltage feedback signal VFB and the input voltage feedback signal VFF. When the load switch 11 is fully turned on, the control signal DRV is used to control the voltage between the first terminal and the second terminal to be a fixed preset voltage. In one embodiment, when the output voltage feedback signal VFB and/or the input voltage feedback signal VFF are located in the normal voltage interval, the control signal DRV controls the load switch 11 to be fully turned on; when the output voltage feedback signal VFB and/or the input voltage feedback signal VFF are outside the normal voltage interval, the control signal DRV is used to turn off the load switch 11. In one embodiment, a "normal voltage interval" refers to a voltage interval between greater than an under-voltage protection threshold and less than an over-voltage protection threshold. That is, the output voltage feedback signal VFB and/or the input voltage feedback signal VFF is greater than the under-voltage protection threshold and less than the over-voltage protection threshold. In another embodiment, a "normal voltage interval" refers to a voltage interval that is greater than an under-voltage protection threshold. In other embodiments, a "normal voltage interval" may also refer to a voltage interval that is less than the overvoltage protection threshold. In one embodiment, the "fixed preset voltage value" is greater than or equal to the voltage value between the first terminal and the second terminal corresponding to the moment when the load switch 11 is fully turned on. For example, in one embodiment, the load switch is a MOSFET having a first terminal that is the drain of the MOSFET, a second terminal that is the source of the MOSFET, and a control terminal that is the gate of the MOSFET. At this time, the "fixed preset voltage value" is equal to or greater than the value of the source-drain voltage VDS corresponding to the threshold voltage of the MOSFET.
Fig. 2 shows a schematic circuit diagram of a specific embodiment of the load switching circuit of fig. 1. As shown in fig. 2, the output voltage feedback circuit 12 includes a resistor 1201 having a resistance value R1 and a resistor 1202 having a resistance value R2. Resistors 1201 and 1202 are coupled in series between terminal 2 and ground. The voltage at the common node of resistors 1201 and 1202 is the output voltage feedback signal VFB.
The input voltage feedback circuit 13 includes a resistor 1301 having a resistance value R1 and a resistor 1302 having a resistance value R2. Resistors 1301 and 1302 are coupled in series between terminal 1 and ground. The voltage signal at the common node of resistors 1301 and 1302 is the input voltage feedback signal VFF.
The control circuit 14 includes a bias circuit 1401, an operational amplifier 1402, and a comparator 1403. The bias circuit 1401 is configured to provide a bias voltage Δv. In some embodiments, bias circuit 1401 is a voltage source circuit. In other embodiments, the bias circuit 1401 may be a current source circuit. The operational amplifier 1402 has a first input terminal, a second input terminal, and an output terminal. A first end of the operational amplifier 1402 receives an input voltage feedback signal VFF; a second terminal of the operational amplifier 1402 receives the output voltage feedback signal VFB via the bias circuit 1401; the operational amplifier 1402 performs operational amplification on the difference between the output voltage feedback signal VFB and the input voltage feedback signal VFF, which are superimposed with the bias voltage Δv, to generate the first control signal CTRL1. In one embodiment, the first control signal CTRL1 is an analog signal for controlling the voltage between the first terminal and the second terminal of the load switch 11 to be kept constant at kχΔv, where the value of K is related to the resistance of the resistor 1301 being R1 and the resistance of the resistor 1302 being R2.
It should be noted that: it will be appreciated by those skilled in the art that in the embodiment shown in fig. 2, the bias circuit 1401 is illustrated as being coupled between the second terminal of the operational amplifier 1402 and the output voltage feedback circuit 12; in other embodiments, the bias circuit 1401 may also be illustrated as being coupled between the first terminal of the operational amplifier 1402 and the input voltage feedback circuit 13; in still other embodiments, the bias circuit 1401 may be included within the op amp 1402.
Likewise, in the embodiment shown in FIG. 2, a first terminal of the operational amplifier 1402 is illustrated as its inverting input, and a second terminal of the operational amplifier 1402 is illustrated as its non-inverting input. In other embodiments, the first terminal of the operational amplifier 1402 may be a non-inverting input terminal, and the second terminal of the operational amplifier 1402 may be an inverting input terminal. Which are all within the scope of the present invention.
In one embodiment, the voltage threshold signal comprises an over-voltage threshold OVTH. The comparator 1403 is used to determine whether the output voltage feedback signal VFB is greater than the overvoltage threshold OVTH. When the output voltage feedback signal VFB is greater than the overvoltage threshold OVTH, the second control signal CTRL2 is active; and otherwise, the method is invalid. In one embodiment, the logic high state of the second control signal CTRL2 is active.
In another embodiment, the voltage threshold signal may also include an under-voltage threshold UVTH. The comparator 1403 is configured to determine whether the output voltage feedback signal VFB is less than the undervoltage threshold UVTH. When the output voltage feedback signal VFB is smaller than the undervoltage threshold UVTH, the second control signal CTRL2 is active; and otherwise, the method is invalid.
In yet another embodiment, the comparator 1403 is a hysteresis comparator, the voltage threshold signal includes an over voltage threshold OVTH and an under voltage threshold UVTH, and the comparator 1043 is configured to determine whether the output voltage feedback signal VFB is between the over voltage threshold OVTH and the under voltage threshold UVTH. When the output voltage feedback signal VFB is outside the voltage interval of the overvoltage threshold OVTH and the undervoltage threshold UVTH, the second control signal CTRL2 is active; and otherwise, the method is invalid.
It should be noted that, only the judgment between the output voltage feedback signal VFB and the overvoltage threshold OVTH and the undervoltage threshold UVTH is illustrated here, and in other embodiments, the judgment between the input voltage feedback signal VFF and the overvoltage threshold OVTH and/or the undervoltage threshold UVTH may also be performed according to the system requirement. Or, the input voltage feedback signal VFF and the output voltage feedback signal VFB may be undervoltage and/or overvoltage judged according to the system requirement, and the working principle is similar to that of the output voltage feedback signal VFB, and the operation is not illustrated and described here again, and is within the protection scope of the present invention.
In the embodiment shown in fig. 2, the control circuit 14 further includes a drive circuit 1404. The driving circuit 1404 receives the first control signal CTRL1 and the second control signal CTRL2, and generates a driving signal DRV according to the first control signal CTRL1 and the second control signal CTRL2. In one embodiment, the drive signal DRV is used to turn off the load switch 11 when the second control signal CTRL2 is active; when the second control signal CTRL2 is inactive, the driving signal DRV controls the voltage between the first terminal and the second terminal of the load switch 11 to be constant at a fixed preset voltage value based on the first control signal CTRL1.
Fig. 3 presents a schematic block-diagram of a further embodiment of the load switching circuit. In comparison to the load switching circuit of fig. 1, the load switching circuit of fig. 3 further comprises a current sampling circuit 15. A current sampling circuit 15 is coupled to terminal 2, samples the current Ie flowing through the load switch, and generates a current sampling signal Ics representative of the current Ie flowing through the load switch. The control circuit 14 receives the output voltage feedback signal VFB, the input voltage feedback signal VFF, and the current sampling signal Ics, and generates the control signal DRV2 based on the output voltage feedback signal VFB, the input voltage feedback signal VFF, and the current sampling signal Ics. When the current sampling signal Ics is smaller than the overcurrent threshold, the control signal DRV2 is used for controlling the load switch 11 to be turned on and controlling the voltage value between the first end and the second end to be a fixed preset voltage value; when the current sampling signal Ics is greater than the overcurrent threshold, the control signal DRV2 is used to turn off the load switch 11. Similar to the embodiment shown in fig. 1, the "fixed preset voltage value" is greater than or equal to the voltage value between the first terminal and the second terminal corresponding to the moment when the load switch 11 is fully turned on. For example, in an embodiment in which the load switch 11 is a MOSFET, the "fixed preset voltage value" is greater than or equal to the value of the source-drain voltage VDS corresponding to the threshold voltage of the MOSFET.
Fig. 4 shows a schematic circuit diagram of a specific embodiment of the load switching circuit of fig. 3. The output voltage feedback circuit 12 and the input voltage feedback circuit 13 in fig. 4 are identical to the output voltage feedback circuit 12 and the input voltage feedback circuit 13 in fig. 2, and will not be described again here.
In the embodiment shown in fig. 4, the sampling circuit 15 includes a sampling resistor 1501 and an operational amplifier 1502. Wherein the sampling resistor 1501 is connected in series between the second end of the load switch 11 and the terminal 2. The operational amplifier 1502 has a first input terminal, a second input terminal, and an output terminal, wherein the first input terminal and the second input terminal of the operational amplifier 1502 are respectively coupled to two ends of the sampling resistor 1501, and outputs a current sampling signal Ics at the output terminal, wherein the current sampling signal Ics represents a current Ie flowing through the load switch 11.
In the embodiment shown in fig. 4, the control circuit 14 includes a bias circuit 1401, an operational amplifier 1402, an error amplifier 1405, and a drive circuit 1406. The bias circuit 1401 and the operational amplifier 1402 in fig. 4 are the same as the bias circuit 1401 and the operational amplifier 1402 in fig. 2, and will not be described again here. The error amplifier 1405 has a first input terminal, a second input terminal, and an output terminal. A first terminal of the error amplifier 1404 receives the current sample signal Ics; the second end of the error amplifier 1405 receives the current limit threshold Ilimit; the error amplifier 1405 compares the current sampling signal Ics with the current limit threshold Ilimit to generate a third control signal CTRL3. In one embodiment, the third control signal CTRL3 is an analog signal, and when the current sampling signal Ics is less than the current limiting threshold Ilimit, the voltage value between the first terminal and the second terminal of the load switch 11 is controlled to be a "fixed preset voltage value" by the first control signal CTRL1. When the current sampling signal Ics is greater than the current limiting threshold Ilimit, the third control signal CTRL3 is used to adjust the on-resistance of the load switch 11, and further adjust the magnitude of the current Ie flowing through the load switch 11. The third control signal CTRL3 is used to turn off the load switch 11 when the current sampling signal Ics is greater than the current limiting threshold Ilimit for more than a preset period of time.
Fig. 5 shows a schematic circuit diagram of another embodiment of the load switching circuit of fig. 3. In contrast to the load switch circuit shown in fig. 4, the bias circuit 1401 in the load switch circuit shown in fig. 5 is applied to the first terminal of the operational amplifier 1401, where the bias circuit 1401 is illustrated as a current source with a value Ios. In this circuit application, the voltage finally fed to the first terminal of the operational amplifier 1401 is r2× (vin+r1×ios)/(r1+r2), that is: the input voltage feedback signal VFF is equal to r2×vin/(r1+r2), and the current source provides a bias voltage of r1×ios×r2/(r1+r2) to the input voltage feedback signal VFF.
The driving circuit 1406 receives the first control signal CTRL1 and the third control signal CTRL3, and generates a driving signal DRV2 according to the first control signal CTRL1 and the third control signal CTRL3. In one embodiment, when the third control signal CTRL3 is negative, the driving signal DRV2 controls the voltage value between the first terminal and the second terminal of the load switch 11 to be a "fixed preset voltage value" based on the first control signal CTRL 1; when the third control signal CTRL3 is positive, the driving signal DRV2 is used to adjust the on-resistance of the load switch 11; when the third control signal CTRL3 continues to increase to a certain threshold value, the driving signal DRV2 is used to turn off the load switch 11.
Fig. 6 presents a schematic block-diagram of a further embodiment of the load switching circuit. In comparison to the load switching circuit shown in fig. 3, the load switching circuit in fig. 6 further comprises a temperature sampling circuit 16. The temperature sampling circuit 16 may be coupled to a load connected to the terminal 2, sample the temperature of the load, and generate a temperature detection signal Ts representative of the temperature of the load. The control circuit 14 receives the output voltage feedback signal VFB, the input voltage feedback signal VFF, the current sampling signal Ics, and the temperature detection signal Ts, and generates the control signal DRV3 based on the output voltage feedback signal VFB, the input voltage feedback signal VFF, the current sampling signal Ics, and the temperature detection signal Ts. When the current sampling signal Ics is smaller than the overcurrent threshold and the temperature detection signal Ts is smaller than the temperature limiting threshold, the control signal DRV3 is used for controlling the load switch 11 to be turned on and controlling the voltage value between the first end and the second end to be a fixed preset voltage value; when the current sampling signal Ics is greater than the overcurrent threshold or the temperature detection signal Ts is greater than the temperature limiting threshold, the control signal DRV3 is used to turn off the load switch 11.
In the embodiment shown in fig. 1-6, the control circuit 14 controls the voltage between the first terminal and the second terminal of the load switch 11 to a fixed preset voltage value when the system state is normal (the current is not over-current, the output voltage VOUT and the input voltage VIN are not over-voltage or under-voltage, etc. the condition that the user needs to meet the system), so that the output voltage signal VOUT can change along with the change of the input voltage signal VIN, and meanwhile, the ripple of the input voltage VIN can be filtered due to the adjustment of the control circuit, so that the load switch circuits in fig. 1-6 all have a high power supply rejection ratio.
Fig. 7 presents a flow diagram of an embodiment of a method of controlling a load switching circuit. The load switch circuit control method shown in fig. 7 may be used in the load switch circuits shown in fig. 1-6 and other load switch circuits within the scope of the present application, and the load switch circuit control method includes steps 71-75.
Step 71 samples an input voltage signal at the input of the load switch and generates an input voltage feedback signal representative of the input voltage.
Step 72 samples the output voltage signal at the output of the load switch and generates an output voltage feedback signal representative of the output voltage.
Step 74, generating a control signal according to the output voltage feedback signal and the input voltage feedback signal, for adjusting the voltage values of the two ends of the load switch to a fixed preset voltage value. The fixed preset voltage value is any optional voltage value of the voltage between the first end and the second end after the load switch is completely conducted.
Step 75, turning off the load switch. When the condition for determining whether the load switch needs to be turned off is that the current sampling signal is greater than the preset overcurrent threshold, step 75 further includes: the control circuit increases the on-resistance value of the load switch to define the value of the current flowing through the load switch before turning off the load switch. In one embodiment, the load switch is turned off after the current sampling signal continues to exceed the over-current threshold for a preset period of time.
Throughout the specification, references to "one embodiment," "an embodiment," "one example," or "an example" mean: a particular feature, structure, or characteristic described in connection with the embodiment or example is included within at least one embodiment of the invention. Thus, the appearances of the phrases "in one embodiment," "in an embodiment," "one example," or "an example" in various places throughout this specification are not necessarily all referring to the same embodiment or example. Furthermore, the particular features, structures, or characteristics may be combined in any suitable combination and/or sub-combination in one or more embodiments or examples. Moreover, those of ordinary skill in the art will appreciate that the drawings are provided herein for illustrative purposes and that the drawings are not necessarily drawn to scale. It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being "directly connected to" or "directly coupled to" another element, there are no intervening elements present. Like reference numerals designate like elements. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.
While the invention has been described with reference to several exemplary embodiments, it is to be understood that the terminology used is intended to be in the nature of words of description and of limitation. As the present invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, but rather should be construed broadly within its spirit and scope as defined in the appended claims, and therefore all changes and modifications that fall within the meets and bounds of the claims, or equivalences of such meets and bounds are therefore intended to be embraced by the appended claims.
Claims (10)
1. A load switching circuit with a high power supply rejection ratio, comprising:
the load switch is provided with a first end, a second end and a control end, wherein the first end is coupled to a power supply, and the second end is coupled to a load;
the output voltage feedback circuit is coupled to the second end of the load switch, receives the output voltage signal and generates an output voltage feedback signal representing the output voltage signal;
the input voltage feedback circuit is coupled to the first end of the load switch, receives an input voltage signal and generates an input voltage feedback signal representing the input voltage signal, wherein the output voltage signal changes along with the change of the input voltage signal; and
the operational amplification circuit receives the input voltage feedback signal and the output voltage feedback signal, and generates a first control signal according to the input voltage feedback signal and the output voltage feedback signal, and the first control signal is used for adjusting the voltage between the first end and the second end of the load switch to be a fixed preset voltage value when the load switch is completely conducted, wherein the operational amplification circuit comprises a bias circuit for providing a bias voltage, and the ratio of the fixed preset voltage value to the bias voltage is a constant K.
2. The load switch circuit of claim 1, wherein the predetermined voltage value is any one of selectable voltage values of a voltage between the first terminal and the second terminal of the load switch after the load switch is fully turned on.
3. The load switch circuit of claim 1, wherein the load switch is fully conductive when the input voltage signal and/or the output voltage signal does not exceed an overvoltage threshold and/or does not fall below an undervoltage threshold.
4. The load switch circuit of claim 1, wherein the load switch is fully conductive when a current signal flowing through the load switch does not exceed a current limit threshold.
5. The load switching circuit of claim 1, wherein the operational amplification circuit further comprises:
the operational amplifier is provided with a first input end, a second input end and an output end, wherein the first input end of the operational amplifier receives an input voltage feedback signal, the second end of the operational amplifier receives an output voltage feedback signal through a bias circuit, the operational amplifier carries out operational amplification on the difference value between the output voltage feedback signal and the input voltage feedback signal after the bias voltage is overlapped, and a first control signal is generated at the output end of the operational amplifier.
6. The load switching circuit of claim 1, wherein the operational amplification circuit further comprises:
the operational amplifier is provided with a first input end, a second input end and an output end, wherein the first input end of the operational amplifier receives an input voltage feedback signal through the bias circuit, the second input end of the operational amplifier receives an output voltage feedback signal, the operational amplifier carries out operational amplification on the difference value between the input voltage feedback signal and the output voltage feedback signal after the bias voltage is overlapped, and a first control signal is generated at the output end of the operational amplifier.
7. The load switching circuit of claim 5 or 6, wherein the load switching circuit further comprises:
the error amplifier is provided with a first input end, a second input end and an output end, wherein the first input end of the error amplifier receives a current sampling signal representing current flowing through the load switch, the second input end of the error amplifier receives an overcurrent threshold, the error amplifier compares the current sampling signal with the overcurrent threshold and amplifies the difference value of the current sampling signal and the overcurrent threshold to generate a second control signal, and when the current sampling signal is larger than the overcurrent threshold, the first control signal is invalid, and the second control signal is used for adjusting the on-resistance value of the load switch until the load switch is turned off.
8. A control method for a high power supply rejection ratio load switching circuit, wherein the load switching circuit comprises a load switch having a first end coupled to a power supply and a second end coupled to a load, the control method comprising:
sampling an input voltage signal at a first end of a load switch and generating an input voltage feedback signal representing the input voltage signal;
sampling an output voltage signal at a second end of the load switch and generating an output voltage feedback signal representing the output voltage signal, wherein the output voltage signal changes along with the change of the input voltage signal; and
judging whether the load switch needs to be turned off or not; and
when the load switch does not need to be turned off, the operational amplification circuit generates a control signal according to the output voltage feedback signal and the input voltage feedback signal, wherein the control signal is used for adjusting the voltage value between the first end and the second end of the load switch to a fixed preset voltage value, and the operational amplification circuit comprises a bias circuit for providing a bias voltage, and the ratio of the fixed preset voltage value to the bias voltage is a constant K.
9. The control method of claim 8, wherein the step of determining whether the load switch needs to be turned off includes determining whether the input voltage signal and/or the output voltage signal exceeds an over-voltage threshold and/or is below an under-voltage threshold.
10. The control method of claim 8, wherein the step of determining whether the load switch needs to be turned off includes determining whether a current signal flowing through the load switch exceeds a current limit threshold.
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| CN115855289B (en) * | 2023-02-14 | 2023-05-02 | 晶艺半导体有限公司 | Temperature detection module and over-temperature protection circuit |
| CN116346113B (en) * | 2023-05-23 | 2023-08-11 | 晶艺半导体有限公司 | High-precision current-controlled load switch circuit and trimming method thereof |
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