CN108667294B - Switch circuit and electronic device - Google Patents
Switch circuit and electronic device Download PDFInfo
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- CN108667294B CN108667294B CN201810216657.XA CN201810216657A CN108667294B CN 108667294 B CN108667294 B CN 108667294B CN 201810216657 A CN201810216657 A CN 201810216657A CN 108667294 B CN108667294 B CN 108667294B
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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
- H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
- H02M3/158—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load
- H02M3/1584—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load with a plurality of power processing stages connected in parallel
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Abstract
The invention provides a switching circuit which comprises a first feedback circuit, a second feedback circuit and a selection control circuit. The first feedback circuit is used for enabling the output end of the power supply circuit to output a first voltage. The second feedback circuit is used for enabling the power supply voltage output end to output a second voltage. The selection control circuit enables one of the first feedback circuit and the second feedback circuit to work according to the switching signal, when the first feedback circuit is selected to work, the voltage output end of the selection control circuit is disconnected with the voltage input end, and when the second feedback circuit is selected to work, the voltage output end of the selection control circuit is connected with the voltage input end, so that the voltage output by the power supply voltage output end is converted into the second voltage from the first voltage. The invention also provides an electronic device. The switching circuit and the electronic device can control the output voltage to be switched on and off rapidly according to the switching signal output by the program control circuit, obtain the low-ripple constant-voltage output of the power supply and meet the time sequence requirement of the electronic device.
Description
Technical Field
The present disclosure relates to power switching devices, and particularly to a switching circuit and an electronic device.
Background
With the development of electronic technology, more and more electronic devices are widely used in various fields, and the requirements of the electronic devices on power supply devices are also increased correspondingly. The output of the power supply device also needs to be controlled by program according to the time sequence requirement of the electronic device. The existing controllable on-off power supply designs are of two types, and reference can be made to fig. 1 and fig. 2 respectively.
As shown in fig. 1, the first design is that a Mos transistor switch circuit is arranged in the left frame, a DC-DC power supply is arranged in the right frame, and the switch circuit determines whether to output a power supply voltage to the DC-DC power supply according to a switch signal, so that the DC-DC power supply outputs the voltage VOUT. As shown in fig. 2, the second design is that a DC-DC power supply is arranged in the left frame, a Mos transistor switch circuit is arranged in the right frame, the DC-DC power supply outputs a voltage to the switch circuit, and the switch circuit determines whether to output the voltage VOUT according to a switch signal.
However, with the first design, the switch circuit is at the front stage of the DC-DC power supply, and although the input terminal of the DC-DC power supply is controlled to be turned on or off, since the output capacitor of the DC-DC power supply is an energy storage element and the capacitance value is generally large, there is a problem of discharge time, the problem of fast power on/off of the output of the rear stage cannot be guaranteed; for the second design, the output of the switching power supply can be quickly turned on and off at the rear stage of the DC-DC power supply, but since the on-state voltage of the MOS transistor changes with the change of the output current (for example, fig. 3 is a relationship curve between the on-state voltage and the reverse current of the MOS transistor SD), the voltage of the front stage and the rear stage of the MOS transistor changes, which results in the change of the output voltage and fails to provide stable voltage output.
Disclosure of Invention
In view of the above, the present invention provides a switch circuit for solving the problems that the output voltage cannot be controlled to be switched on and off rapidly and the stable voltage output cannot be provided.
Specifically, an embodiment of the present invention provides a switching circuit including a first feedback circuit, a second feedback circuit, and a selection control circuit. The first end of the first feedback circuit is connected with the input end of the power supply circuit, the second end of the first feedback circuit is connected with the output end of the power supply circuit, and the first feedback circuit is used for enabling the output end of the power supply circuit to output a first voltage. The first end of the second feedback circuit is connected with the input end of the power supply circuit, the second end of the second feedback circuit is connected with the output end of the power supply voltage, and the second feedback circuit is used for enabling the output end of the power supply voltage to output a second voltage. The selection control circuit comprises a signal control input end, a first control output end, a second control output end, a voltage input end and a voltage output end, the signal control input end of the selection control circuit receives a switching signal output by the program control circuit, the first control output end of the selection control circuit is connected with the third end of the first feedback circuit, the second control output end of the selection control circuit is connected with the third end of the second feedback circuit, the voltage input end of the selection control circuit is connected with the output end of the power circuit, the voltage output end of the selection control circuit is connected with the power supply voltage output end, the selection control circuit enables one of the first feedback circuit and the second feedback circuit to work according to the switching signal output by the program control circuit, when the first feedback circuit is selected to work, and when the second feedback circuit is selected to work, the voltage output end of the selection control circuit is connected with the voltage input end of the selection control circuit, so that the voltage output by the power supply voltage output end is converted into the second voltage from the first voltage.
Further, the first feedback circuit includes a first resistor, a second resistor, and a first switching element. The first end of the first resistor is connected with the second end of the first feedback circuit. The first switch element is connected with the second end of the first resistor, the second switch element is connected with the first end of the first feedback circuit, and the first control end of the first switch element is connected with the third end of the first feedback circuit. And the first end of the second resistor is connected with the second path end of the first switching element, and the second end of the second resistor is grounded.
Further, the first switching element is an N-type MOS transistor.
Further, the second feedback circuit includes a second resistor, a third resistor, and a second switching element. And the first end of the third resistor is connected with the second end of the second feedback circuit. And the third path end of the second switching element is connected with the second end of the third resistor, the fourth path end of the second switching element is connected with the first end of the second feedback circuit, and the second control end of the second switching element is connected with the third end of the second feedback circuit. And the first end of the second resistor is connected with the fourth path end of the second switching element, and the second end of the second resistor is grounded.
Further, the second switching element is an N-type MOS transistor.
Further, the selection control circuit includes a third switching element, a fourth switching element, and a fourth resistor. The third control end of the third switching element is respectively connected with the signal control input end and the second control output end of the selection control circuit, the fifth path end of the third switching element is connected with the first control output end of the selection control circuit, and the sixth path end of the third switching element is grounded. A fourth control end of the fourth switching element is connected with a fifth path end of the third switching element, a seventh path end of the fourth switching element is connected with a voltage input end of the selection control circuit, and an eighth path end of the fourth switching element is connected with a voltage output end of the selection control circuit. A first end of the fourth resistor is connected to a seventh path end of the fourth switching element, and an eighth end of the fourth resistor is connected to a fourth control end of the fourth switching element.
Further, the third switching element is an N-type MOS transistor, and the fourth switching element is a P-type MOS transistor.
Further, the selection control circuit includes a fifth resistor, a first end of the fifth resistor is connected to the third control end of the third switching element, and a second end of the fifth resistor is grounded.
Further, the selection control circuit includes a first capacitor, a first end of the first capacitor is connected to the seventh path end of the fourth switching element, and a second end of the first capacitor is grounded.
The embodiment of the invention also provides an electronic device which comprises the switch circuit.
The technical scheme provided by the embodiment of the invention has the following beneficial effects:
the switching circuit and the electronic device provided by the embodiment of the invention can control the output voltage to be quickly switched on and off according to the switching signal output by the program control circuit, obtain the low-ripple constant-voltage output of the power supply, have the advantages of flexible control, high stability of the output voltage and the like, and meet the time sequence requirement of the electronic device.
In order to make the aforementioned and other objects, features and advantages of the invention comprehensible, preferred embodiments accompanied with figures are described in detail below.
Drawings
Fig. 1 is a circuit diagram of a first conventional controllable on-off power supply circuit.
Fig. 2 is a circuit diagram of a second conventional controllable on-off power supply circuit.
Fig. 3 is a relationship curve of the conduction voltage and the reverse current of the MOS transistor SD.
Fig. 4 is a circuit diagram of the switch circuit according to the first embodiment of the invention.
Fig. 5 is a circuit diagram of a switch circuit according to a second embodiment of the invention.
Detailed Description
To further clarify the technical measures and effects of the present invention adopted to achieve the intended purpose, the following detailed description is given of specific embodiments, methods, steps, structures, features and effects of the switch circuit and the electronic device according to the present invention with reference to the accompanying drawings and preferred embodiments.
The foregoing and other aspects, features and advantages of the invention will be apparent from the following more particular description of preferred embodiments, as illustrated in the accompanying drawings. While the invention has been described in connection with specific embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention.
First embodiment
Fig. 4 is a circuit diagram of the switch circuit according to the first embodiment of the invention. As shown in fig. 4, an embodiment of the present invention provides a switching circuit including a first feedback circuit 100, a second feedback circuit 200, and a selection control circuit 300. The first terminal 101 of the first feedback circuit 100 is connected to the feedback input terminal 401 of the power circuit 400, the second terminal 102 of the first feedback circuit 100 is connected to the output terminal 402 of the power circuit 400, and the first feedback circuit 100 is configured to enable the output terminal 402 of the power circuit 400 to output the first voltage V1. The first terminal 201 of the second feedback circuit 200 is connected to the feedback input terminal 401 of the power circuit 400, the second terminal 202 of the second feedback circuit 200 is connected to the supply voltage output terminal 501, and the second feedback circuit 200 is configured to enable the supply voltage output terminal 501 to output the second voltage V2. The selection control circuit 300 comprises a signal control input end 301, a first control output end 302, a second control output end 303, a voltage input end 304 and a voltage output end 305, the signal control input end 301 of the selection control circuit 300 receives a switching signal SW output by the program control circuit, the first control output end 302 of the selection control circuit 300 is connected with the third end 103 of the first feedback circuit 100, the second control output end 303 of the selection control circuit 300 is connected with the third end 203 of the second feedback circuit 200, the voltage input end 304 of the selection control circuit 300 is connected with the output end 402 of the power supply circuit 400, and the voltage output end 305 of the selection control circuit 300 is connected with the power supply voltage output end 501. The selection control circuit 300 operates one of the first feedback circuit 100 and the second feedback circuit 200 according to the switching signal SW output by the programmable circuit received by the signal control input terminal 301, when the first feedback circuit 100 is selected to operate, the voltage output terminal 305 of the selection control circuit 300 is disconnected from the voltage input terminal 304 of the selection control circuit 300, and when the second feedback circuit 200 is selected to operate, the voltage output terminal 305 of the selection control circuit 300 is connected with the voltage input terminal 304 of the selection control circuit 300, so that the voltage output by the supply voltage output terminal 501 is converted from the first voltage V1 to the second voltage V2.
Specifically, the switching circuit of the embodiment of the present invention may include, but is not limited to, two sets of feedback circuits, which are the first feedback circuit 100 and the second feedback circuit 200, respectively. The first end 101 of the first feedback circuit 100 is connected to the feedback input end 401 of the power circuit 400, and the second end 102 of the first feedback circuit 100 is connected to the output end 402 of the power circuit 400, so that the power circuit 400 receives the power voltage at the power input end 403 thereof and starts to operate, and then the first feedback circuit 100 can generate a corresponding feedback voltage, and the power circuit 400 receives the feedback voltage and outputs the corresponding voltage at the output end 402 thereof, so that the first feedback circuit 100 obtains a new feedback voltage, and the process is repeated, so that the output end 402 of the power circuit 400 outputs a stable voltage, i.e., the first voltage V1. Similarly, the first end 201 of the second feedback circuit 200 is connected to the feedback input terminal 401 of the power circuit 400, the second end 202 of the second feedback circuit 200 is connected to the supply voltage output terminal 501, and the second end 202 of the second feedback circuit 200 is also connected to the output terminal 402 of the power circuit 400 through the selection control circuit 300, so that the power circuit 400 can generate a corresponding feedback voltage through the second feedback circuit 200 after receiving the supply voltage at the power input terminal 403 of the power circuit and starts to operate, the power circuit 400 receives the feedback voltage and outputs a corresponding voltage at the output terminal 402 of the power circuit, and the supply voltage output terminal 501 also outputs a corresponding voltage, so that the first feedback circuit 100 obtains a new feedback voltage, and the cycle is repeated, so that the supply voltage output terminal 501 outputs a stable voltage, that is, the second voltage V2.
In this embodiment, the selection control circuit 300 receives the switch signal SW output by the program control circuit, and selects one of the first feedback circuit 100 and the second feedback circuit 200 to operate according to the switch signal SW, for example, after the power supply circuit 400 receives a power supply voltage at the power supply input terminal 403 and starts to operate, when the switch signal SW is at a low level, the selection control circuit 300 selects the first feedback circuit 100 to operate, the first feedback circuit 100 enables the output terminal 402 of the power supply circuit 400 to output a stable first voltage V1, the input voltage terminal 304 of the selection control circuit 300 is connected to the output terminal 402 of the power supply circuit 400, the input voltage terminal 304 of the selection control circuit 300 receives the stable first voltage V1, and at this time, the voltage output terminal 305 of the selection control circuit 300 is disconnected from the voltage input terminal 304 of the selection control circuit 300, and the voltage output terminal 501 of the power supply voltage is zero.
When the switch signal SW changes from the low level to the high level, the selection control circuit 300 selects the second feedback circuit 200 to operate, and at this time, the voltage output terminal 305 of the selection control circuit 300 is conducted with the voltage input terminal 304 of the selection control circuit 300, so that the power supply voltage output terminal 501 receives the voltage output by the power supply circuit 400 at the output terminal 402 thereof, i.e., the first voltage V1 through the selection control circuit 300; meanwhile, the second feedback circuit 200 may enable the power circuit 400 to output a corresponding regulated voltage at the output terminal 402 thereof through the selection control circuit 300, and the supply voltage output terminal 501 may also output a corresponding regulated voltage, i.e., the second voltage V2, through the selection control circuit 300. Therefore, when the switch signal SW changes from low level to high level, the voltage output by the supply voltage output terminal 501 jumps directly from zero to the first voltage V1 and gradually changes to the second voltage V2, so that the output voltage can be switched on quickly. When the first voltage V1 and the second voltage V2 are nearly equal, the power supply low-ripple constant-voltage output can be realized.
When the switch signal SW changes from high level to low level, the selection control circuit 300 selects the first feedback circuit 100 to operate, the voltage output terminal 305 of the selection control circuit 300 is disconnected from the voltage input terminal 304 of the selection control circuit 300, and the power supply voltage output terminal 501 is not connected to any capacitor, so that the output voltage of the power supply voltage output terminal 501 immediately becomes zero, and the rapid disconnection of the output voltage can be realized.
The technical scheme provided by the embodiment of the invention has the following beneficial effects:
the switching circuit can control the output voltage to be rapidly switched on and off according to the switching signal SW output by the program control circuit, obtains the power supply low-ripple constant voltage output, has the advantages of flexible control, high stability of the output voltage and the like, and meets the time sequence requirement of an electronic device.
Second embodiment
Fig. 5 is a circuit diagram of a switch circuit according to a second embodiment of the invention. As shown in fig. 5, the circuit connection diagram of the switching circuit is substantially the same as that of the switching circuit shown in fig. 4, except that: the first feedback circuit 100 includes a first resistor R1, a second resistor R2, and a first switching element Q1. The first terminal R1A of the first resistor R1 is connected to the second terminal 102 of the first feedback circuit 100. The first pass terminal T1 of the first switching element Q1 is connected to the second terminal R1B of the first resistor R1, the second pass terminal T2 of the first switching element Q1 is connected to the first terminal 101 of the first feedback circuit 100, and the first control terminal K1 of the first switching element Q1 is connected to the third terminal 103 of the first feedback circuit 100. A first terminal R2A of the second resistor R2 is connected to the second path terminal T2 of the first switching element Q1, and a second terminal R2B of the second resistor R2 is grounded. The second feedback circuit 200 includes a second resistor R2, a third resistor R3, and a second switching element Q2. The first terminal R3A of the third resistor R3 is connected to the second terminal 202 of the second feedback circuit 200. The third terminal T3 of the second switching element Q2 is connected to the second terminal R3B of the third resistor R3, the fourth terminal T4 of the second switching element Q2 is connected to the first terminal 201 of the second feedback circuit 200, and the second control terminal K2 of the second switching element Q2 is connected to the third terminal 203 of the second feedback circuit 200. A first terminal R2A of the second resistor R2 is connected to the fourth pass terminal T4 of the second switching element Q2, and a second terminal R2B of the second resistor R2 is grounded. The selection control circuit 300 includes a third switching element Q3, a fourth switching element Q4, and a fourth resistor R4. The third control terminal K3 of the third switching element Q3 is connected to the signal control input terminal 301 and the second control output terminal 303 of the selection control circuit 300, respectively, the fifth path terminal T5 of the third switching element Q3 is connected to the first control output terminal 302 of the selection control circuit 300, and the sixth path terminal T6 of the third switching element Q3 is grounded. The fourth control terminal K4 of the fourth switching element Q4 is connected to the fifth path terminal T5 of the third switching element Q3, the seventh path terminal T7 of the fourth switching element Q4 is connected to the voltage input terminal 304 of the selection control circuit 300, and the eighth path terminal T8 of the fourth switching element Q4 is connected to the voltage output terminal 305 of the selection control circuit 300. A first terminal R4A of the fourth resistor R4 is connected to the seventh path terminal T7 of the fourth switching element Q4, and an eighth terminal of the fourth resistor R4 is connected to the fourth control terminal K4 of the fourth switching element Q4.
The first switching element Q1 of the present embodiment may be, but is not limited to, an N-type MOS transistor, the second switching element Q2 may be, but is not limited to, an N-type MOS transistor, the third switching element Q3 may be, but is not limited to, an N-type MOS transistor, the fourth switching element Q4 may be, but is not limited to, a P-type MOS transistor, for example, the N-type MOS transistor may be replaced by an NPN-type transistor, and the P-type MOS transistor may be replaced by a PNP-type transistor, and the like.
Specifically, the first group of feedback circuits includes a first resistor R1, a second resistor R2 and a first switching element Q1, wherein the first terminal R1A of the first resistor R1 is connected to the second terminal 102 of the first feedback circuit 100, and the second terminal 102 of the first feedback circuit 100 is connected to the output terminal 402 of the power supply circuit 400, the first terminal R1A of the first resistor R1 is connected to the output terminal 402 of the power supply circuit 400, furthermore, the second end R1B of the first resistor R1 is connected to the first end T1 of the first switch element Q1, the second end T2 of the first switch element Q1 is connected to the first end R2A of the second resistor R2, the second end R2B of the second resistor R2 is grounded, the second end T2 of the first switch element Q1 is further connected to the first end 101 of the first feedback circuit 100, and the first terminal 101 of the first feedback circuit 100 is connected to the feedback input 401 of the power supply circuit 400, the second path terminal T2 of the first switching element Q1 is connected to the feedback input terminal 401 of the power supply circuit 400. After the power supply circuit 400 receives the power supply voltage Vin at the power supply input terminal 403 and starts to operate, when the first control terminal K1 of the first switching element Q1 is at a high level, the first switching element Q1 is turned on, so that the first resistor R1, the first switching element Q1 and the second resistor R2 form a feedback loop of the power supply circuit 400, the first feedback circuit 100 can generate a corresponding feedback voltage, the power supply circuit 400 receives the feedback voltage and outputs the corresponding voltage at the output terminal 402 thereof, so that the first feedback circuit 100 obtains a new feedback voltage, and the loop is repeated, so that the output terminal 402 of the power supply circuit 400 outputs a stable voltage, i.e., the first voltage V1.
The second group of feedback circuits includes a second resistor R2, a third resistor R3 and a second switching element Q2, wherein a first terminal R3A of the third resistor R3 is connected to the second terminal 202 of the second feedback circuit 200, and the second terminal 202 of the second feedback circuit 200 is connected to the supply voltage output terminal 501, the first terminal R3A of the third resistor R3 is connected to the supply voltage output terminal 501, the second terminal R3B of the third resistor R3 is connected to the third pass terminal T3 of the second switch element Q2, the fourth pass terminal T4 of the second switch element Q2 is connected to the first terminal R2A of the second resistor R2, the second terminal R2B of the second resistor R2 is grounded, the second pass terminal T2 of the second switch element Q2 is further connected to the first terminal 201 of the second feedback circuit 200, while the first terminal 201 of the second feedback circuit 200 is connected to the feedback input 401 of the power supply circuit 400, the second path terminal T2 of the second switching element Q2 is connected to the feedback input terminal 401 of the power supply circuit 400. After the power supply circuit 400 receives the power supply voltage Vin at the power supply input terminal 403 and starts to operate, the second feedback circuit 200 may generate a corresponding feedback voltage, and the power supply circuit 400 receives the feedback voltage and outputs a corresponding voltage at the output terminal 402, so that the power supply voltage output terminal 501 also outputs a corresponding voltage, and the first feedback circuit 100 obtains a new feedback voltage, and this is repeated, so that the power supply voltage output terminal 501 outputs a stable voltage, i.e., the second voltage V2.
The selection control circuit 300 includes a third switching element Q3, a fourth switching element Q4, and a fourth resistor R4, wherein the seventh path terminal T7 of the fourth switching element Q4 is connected to the output terminal 402 of the power supply circuit 400, and the voltage of the seventh path terminal T7 of the fourth switching element Q4 is equal to the voltage of the output terminal 402 of the power supply circuit 400. The eighth path terminal T8 of the fourth switching element Q4 is connected to the supply voltage output terminal 501, the fourth control terminal K4 of the fourth switching element Q4 is connected to the fifth path terminal T5 of the third switching element Q3, the third control terminal K3 of the third switching element Q3 is connected to the signal control input terminal 301 and the second control output terminal 303 of the selection control circuit 300, respectively, the fifth path terminal T5 of the third switching element Q3 is connected to the first control output terminal 302 of the selection control circuit 300, and the sixth path terminal T6 of the third switching element Q3 is connected to the ground.
After the power supply circuit 400 starts to operate after the power supply input terminal 403 of the power supply circuit receives the power supply voltage Vin, when the switching signal SW is at a low level, the third control terminal K3 of the third switching element Q3 receives the low level of the switching signal SW, so that the third switching element Q3 is turned off, the fourth control terminal K4 of the fourth switching element Q4 receives the high level output by the output terminal 402 of the power supply circuit 400 through the fourth resistor R4, so that the fourth switching element Q4 is turned off, and similarly, the first control terminal K1 of the first switching element Q1 receives the high level output by the output terminal 402 of the power supply circuit 400 through the fourth resistor R4, so that the first switching element Q1 is turned on. Meanwhile, the second control terminal K2 of the second switching element Q2 receives the low level of the switching signal SW, so that the second switching element Q2 is turned off. At this time, the power circuit 400 causes the output terminal 402 of the power circuit 400 to output the stable first voltage V1, which can be determined by the first resistor R1 and the second resistor R2, through the feedback effect of the first feedback circuit 100.
After the power supply circuit 400 receives the power supply voltage Vin at the power supply input terminal 403 and starts operating, when the switch signal SW is at a high level, the third control terminal K3 of the third switch element Q3 receives the high level of the switch signal SW, so that the third switch element Q3 is turned on, the fourth control terminal K4 of the fourth switch element Q4 is grounded through the turned-on third switch element Q3, and the fourth control terminal K4 of the fourth switch element Q4 is at a low level, so that the fourth switch element Q4 is turned on; similarly, when the first control terminal K1 of the first switching element Q1 is grounded through the turned-on third switching element Q3, the first control terminal K1 of the first switching element Q1 is at a low level, and the first switching element Q1 is turned off. Meanwhile, the second control terminal K2 of the second switching element Q2 receives the high level of the switching signal SW, so that the second switching element Q2 is turned on. At this time, the power supply circuit 400 enables the supply voltage output terminal 501 to output the stable second voltage V2, which can be determined by the third resistor R3 and the second resistor R2, through the feedback effect of the second feedback circuit 200. Therefore, only one of the first feedback circuit 100 and the second feedback circuit 200 operates at the same time.
Therefore, when the switching signal SW changes from the low level to the high level, the fourth switching element Q4 changes from off to on accordingly. When the fourth switching element Q4 is turned off, the seventh path terminal T7 of the fourth switching element Q4 receives the voltage output from the power circuit 400 at the output terminal 402, which rises and stabilizes at the first voltage V1. When the fourth switching element Q4 is turned on, the voltage at the eighth path terminal T8 of the fourth switching element Q4 momentarily jumps from zero to the first voltage V1 at the seventh path terminal T7 of the fourth switching element Q4 plus the tube voltage drop of the first switching element Q1, i.e., is approximately equal to the first voltage, at this time, the voltage output terminal 305 of the selection control circuit 300 is turned on with the voltage input terminal 304 of the selection control circuit 300, and the supply voltage Vsupply output by the supply voltage output terminal 501 may momentarily jump from zero to the first voltage V1. The power supply circuit 400 utilizes the feedback effect of the second feedback circuit 200 to make the supply voltage output terminal 501 finally and stably output the second voltage V2, i.e., the supply voltage Vsupply output by the supply voltage output terminal 501 is converted from the first voltage V1 to the second voltage V2. In the conversion process, when the second voltage V2 is approximately equal to the first voltage V1, the output voltage ripple is very small, and the output current of the supply voltage output terminal 501 increases or decreases, so that the tube voltage drop of the fourth switching element Q4 changes, and the supply voltage Vsupply output by the supply voltage output terminal 501 also slightly changes, and is finally stabilized at the second voltage V2, thereby realizing the constant voltage output. In addition, in the embodiment of the present invention, since the supply voltage output terminal 501 is connected to the fourth switching element Q4, and the supply voltage output terminal 501 is not connected to any capacitor, the output voltage Vsupply of the supply voltage output terminal 501 may jump at a corresponding instant according to the on-off change of the fourth switching element Q4, so that the selection control circuit 300 may correspondingly turn on and off the fourth switching element Q4 according to the switching signal output by the program control circuit, and the voltage output on-off speed of the supply voltage output terminal 501 is very fast.
In an embodiment of the invention, the selection control circuit 300 may include, but is not limited to, a fifth resistor R5, a first terminal R5A of the fifth resistor R5 is connected to the third control terminal K3 of the third switching element Q3, a second terminal R5B of the fifth resistor R5 is grounded, and the fifth resistor R5 may be used to prevent current from burning out the switching element due to an over-voltage.
In an embodiment of the present invention, the selection control circuit 300 may include, but is not limited to, a first capacitor C1, a first terminal C1A of the first capacitor C1 is connected to a seventh path terminal T7 of the fourth switching element Q4, a second terminal C1B of the first capacitor C1 is grounded, and the first capacitor C1 may be used to filter and store the voltage output by the power circuit 400.
The switching circuit of the embodiment of the invention can control the rapid on-off of the output voltage according to the switching signal SW output by the program control circuit, and obtain the low-ripple constant-voltage output of the power supply, has the advantages of flexible control, high stability of the output voltage and the like, and meets the time sequence requirement of an electronic device.
Third embodiment
The embodiment of the invention also provides an electronic device which comprises the switch circuit of the embodiment. The electronic device can be any electronic product or equipment such as a mobile phone, a tablet computer, a notebook computer, a netbook, a game machine, a television, a VCD, a DVD, a navigator, a camera, a video camera, a recording pen, an MP3, an MP4, a PSP and the like, and can also be any intermediate product comprising an external double-voltage input selection switch circuit.
The switching circuit and the electronic device provided by the embodiment of the invention can control the rapid on-off of the output voltage according to the switching signal SW output by the program control circuit, obtain the low-ripple constant-voltage output of the power supply, have the advantages of flexible control, high stability of the output voltage and the like, and meet the time sequence requirement of the electronic device.
Although the present invention has been described with reference to the preferred embodiments, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (8)
1. A switching circuit comprising a first feedback circuit (100), a second feedback circuit (200) and a selection control circuit (300);
the first end (101) of the first feedback circuit (100) is connected with a feedback input end (401) of a power supply circuit (400), the second end (102) of the first feedback circuit (100) is connected with an output end (402) of the power supply circuit (400), and the first feedback circuit (100) is used for enabling the output end (402) of the power supply circuit (400) to output a first voltage (V1);
a first end (201) of the second feedback circuit (200) is connected with a feedback input end (401) of the power supply circuit (400), a second end (202) of the second feedback circuit (200) is connected with a supply voltage output end (501), and the second feedback circuit (200) is used for enabling the supply voltage output end (501) to output a second voltage (V2);
the selection control circuit (300) comprises a signal control input end (301), a first control output end (302), a second control output end (303), a voltage input end (304) and a voltage output end (305), the signal control input end (301) of the selection control circuit (300) receives a switching Signal (SW) output by a program control circuit, the first control output end (302) of the selection control circuit (300) is connected with the third end (103) of the first feedback circuit (100), the second control output end (303) of the selection control circuit (300) is connected with the third end (203) of the second feedback circuit (200), the voltage input end (304) of the selection control circuit (300) is connected with the output end (402) of the power supply circuit (400), and the voltage output end (305) of the selection control circuit (300) is connected with the power supply voltage output end (501), the selection control circuit (300) enables one of the first feedback circuit (100) and the second feedback circuit (200) to work according to the switching Signal (SW) output by the program control circuit, when the first feedback circuit (100) is selected to operate, the voltage output terminal (305) of the selection control circuit (300) is disconnected from the voltage input terminal (304) of the selection control circuit (300), when the second feedback circuit (200) is selected to work, the voltage output end (305) of the selection control circuit (300) is conducted with the voltage input end (304) of the selection control circuit (300), whereby the voltage output by the supply voltage output (501) is converted from the first voltage (V1) to the second voltage (V2), the selection control circuit (300) includes a third switching element (Q3), a fourth switching element (Q4), and a fourth resistor (R4);
a third control terminal (K3) of the third switching element (Q3) is respectively connected with the signal control input terminal (301) and the second control output terminal (303) of the selection control circuit (300), a fifth pass terminal (T5) of the third switching element (Q3) is connected with the first control output terminal (302) of the selection control circuit (300), a sixth pass terminal (T6) of the third switching element (Q3) is grounded, and the third switching element (Q3) is an N-type MOS transistor;
a fourth control terminal (K4) of the fourth switching element (Q4) is connected to a fifth path terminal (T5) of the third switching element (Q3), a seventh path terminal (T7) of the fourth switching element (Q4) is connected to a voltage input terminal (304) of the selection control circuit (300), an eighth path terminal (T8) of the fourth switching element (Q4) is connected to a voltage output terminal (305) of the selection control circuit (300), and the fourth switching element (Q4) is a P-type MOS transistor;
a first terminal (R4A) of the fourth resistor (R4) is connected to a seventh path terminal (T7) of the fourth switching element (Q4), and an eighth terminal of the fourth resistor (R4) is connected to a fourth control terminal (K4) of the fourth switching element (Q4).
2. The switching circuit according to claim 1, wherein the first feedback circuit (100) comprises a first resistor (R1), a second resistor (R2), and a first switching element (Q1);
a first terminal (R1A) of the first resistor (R1) is connected to a second terminal (102) of the first feedback circuit (100);
a first pass terminal (T1) of the first switching element (Q1) is connected to the second terminal (R1B) of the first resistor (R1), a second pass terminal (T2) of the first switching element (Q1) is connected to the first terminal (101) of the first feedback circuit (100), and a first control terminal (K1) of the first switching element (Q1) is connected to the third terminal (103) of the first feedback circuit (100);
a first end (R2A) of the second resistor (R2) is connected with a second path end (T2) of the first switch element (Q1), and a second end (R2B) of the second resistor (R2) is grounded.
3. The switching circuit according to claim 2, wherein the first switching element (Q1) is an N-type MOS transistor.
4. The switching circuit according to claim 1, wherein the second feedback circuit (200) comprises a second resistor (R2), a third resistor (R3), and a second switching element (Q2);
a first terminal (R3A) of the third resistor (R3) is connected to a second terminal (202) of the second feedback circuit (200);
a third pass terminal (T3) of the second switching element (Q2) is connected to the second terminal (R3B) of the third resistor (R3), a fourth pass terminal (T4) of the second switching element (Q2) is connected to the first terminal (201) of the second feedback circuit (200), and a second control terminal (K2) of the second switching element (Q2) is connected to the third terminal (203) of the second feedback circuit (200);
a first terminal (R2A) of the second resistor (R2) is connected to a fourth pass terminal (T4) of the second switching element (Q2), and a second terminal (R2B) of the second resistor (R2) is grounded.
5. The switching circuit according to claim 4, wherein the second switching element (Q2) is an N-type MOS transistor.
6. The switch circuit according to claim 1, characterized in that the selection control circuit (300) comprises a fifth resistor (R5), a first terminal (R5A) of the fifth resistor (R5) being connected to the third control terminal (K3) of the third switching element (Q3), a second terminal (R5B) of the fifth resistor (R5) being connected to ground.
7. The switching circuit according to claim 1, wherein the selection control circuit (300) comprises a first capacitor (C1), a first terminal (C1A) of the first capacitor (C1) being connected to a seventh path terminal (T7) of the fourth switching element (Q4), a second terminal (C1B) of the first capacitor (C1) being connected to ground.
8. An electronic device, characterized in that the electronic device comprises a switching circuit according to any one of claims 1 to 7.
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| CN201810216657.XA CN108667294B (en) | 2018-03-16 | 2018-03-16 | Switch circuit and electronic device |
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| CN201810216657.XA CN108667294B (en) | 2018-03-16 | 2018-03-16 | Switch circuit and electronic device |
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| CN102117087B (en) * | 2009-12-31 | 2016-01-13 | 意法半导体研发(深圳)有限公司 | Adjust the method for signal, power supply, power-supply controller of electric and system |
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| CN1794738A (en) * | 2005-11-09 | 2006-06-28 | 杭州华为三康技术有限公司 | Feeding circuit, method of providing different feed voltage and front end feed device |
| CN201122423Y (en) * | 2007-12-04 | 2008-09-24 | 英华达(上海)电子有限公司 | Backlight power supply circuit |
| CN101860188A (en) * | 2010-06-07 | 2010-10-13 | 鸿富锦精密工业（深圳）有限公司 | Switch power supply circuit |
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