CN117251012A - Voltage switching circuit and power supply system using the same - Google Patents
Voltage switching circuit and power supply system using the same Download PDFInfo
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- CN117251012A CN117251012A CN202210649728.1A CN202210649728A CN117251012A CN 117251012 A CN117251012 A CN 117251012A CN 202210649728 A CN202210649728 A CN 202210649728A CN 117251012 A CN117251012 A CN 117251012A
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- 101100112673 Rattus norvegicus Ccnd2 gene Proteins 0.000 description 13
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- 238000010586 diagram Methods 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
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- 230000001360 synchronised effect Effects 0.000 description 2
- 239000003990 capacitor Substances 0.000 description 1
- 230000006854 communication Effects 0.000 description 1
- 238000010280 constant potential charging Methods 0.000 description 1
- 238000010277 constant-current charging Methods 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
Classifications
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
- G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
- G05F1/10—Regulating voltage or current
- G05F1/46—Regulating voltage or current wherein the variable actually regulated by the final control device is dc
- G05F1/56—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices
- G05F1/561—Voltage to current converters
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- General Physics & Mathematics (AREA)
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- Direct Current Feeding And Distribution (AREA)
Abstract
The application discloses a voltage switching circuit and a power supply system using the same. The voltage switching circuit for selectively transmitting a voltage applied to a first input terminal and a second input terminal to an output terminal, includes: a first transistor connected between the first input terminal and the output terminal; a second transistor connected between the second input terminal and the output terminal; and the switching module is connected with the grid electrodes of the first transistor and the second transistor and is used for controlling one of the first transistor and the second transistor to be conducted according to the voltage difference between the first input voltage of the first input terminal and the second input voltage of the second input terminal, and the voltage loss of a diode is omitted through channel conduction of the transistor so as to reduce the working voltage of a chip and the overall power of a system.
Description
Technical Field
The present invention relates to the technical field of power management systems, and more particularly, to a voltage switching circuit and a power system using the same.
Background
With the popularization of wireless charging technology, wireless charging receiving chips are widely applied to various portable electronic devices such as mobile phones and wireless bluetooth headsets. Such a device having a wireless charging function generally has two charging modes, one is wireless charging by a wireless charger and the other is wired charging by a power adapter. The wireless charging may generate high voltage at the receiving end in the communication process, and if the two charging modes are performed simultaneously, the high voltage may reach the power adapter through the power channel, so that the adapter is damaged and even safety problems are caused. Therefore, the two charging modes are reasonably switched by adopting a power supply switching mode in the product so as to achieve the aim of safe charging.
Fig. 1 shows a circuit schematic of a conventional voltage switching circuit 100, which includes transistors M1 and M2. The diodes D1 and D2 are substrate diodes of the transistors M1 and M2, respectively, the first terminals of the transistors M1 and M2 receive the input voltages Vin1 and Vin2, respectively, the control terminals of the transistors M1 and M2 are electrically connected to each other, and the second terminals of the transistors M1 and M2 are electrically connected to each other and output a voltage vin_h. The conventional scheme uses the substrate diodes D1 and D2 of the transistors M1 and M2 to realize unidirectional conduction to perform voltage switching, and selects a higher input voltage to supply power to other modules inside the chip. However, this approach generates a drop in diode voltage inside the chip, which is detrimental to the chip's operating voltage and also consumes the overall power of the system. In addition, the diode is forward biased, so that latch-up is easy to occur, and the system stability is poor.
Disclosure of Invention
In view of the above problems, an object of the present invention is to provide a voltage switching circuit and a power supply system using the same, which can automatically turn on a corresponding transistor when a voltage difference between voltages at input terminals is greater than a turn-on threshold of the transistor, and remove voltage loss of a diode by channel conduction of the transistor, so as to reduce an operating voltage of a chip and an overall power of the system.
According to an aspect of an embodiment of the present invention, there is provided a voltage switching circuit for selectively transmitting a voltage applied to a first input terminal and a second input terminal to an output terminal, including: a first transistor connected between the first input terminal and the output terminal; a second transistor connected between the second input terminal and the output terminal; and a switching module connected with the gates of the first transistor and the second transistor for controlling one of the first transistor and the second transistor to be turned on according to a voltage difference between a first input voltage of the first input terminal and a second input voltage of the second input terminal.
Optionally, when the first input voltage is greater than the second input voltage and the voltage difference between the first input voltage and the second input voltage is greater than the on threshold of the first transistor, the first transistor is turned on; when the second input voltage is larger than the first input voltage and the voltage difference between the second input voltage and the first input voltage is larger than the conduction threshold value of the second transistor, the second transistor is turned on.
Optionally, the switching module includes: the cathode of the Zener diode is connected with the output terminal, the anode of the Zener diode is connected with the first end of the resistor, and the second end of the resistor is grounded; a third transistor having a gate connected to the zener diode and an intermediate node of the resistor, a drain connected to the second input voltage, and a source connected to the gate of the first transistor; and a fourth transistor having a gate connected to the zener diode and an intermediate node of the resistor, a drain connected to the first input voltage, and a source connected to the gate of the second transistor.
Optionally, the third transistor and the fourth transistor are clamp transistors, and gate-source voltage clamps of the first transistor and the second transistor may be respectively located in a safe voltage range.
Optionally, the third transistor and the fourth transistor are always in an on state.
Optionally, the first to fourth transistors are implemented by P-type transistors, respectively.
According to another aspect of an embodiment of the present invention, there is provided a power supply system for charging a battery, including: the voltage switching circuit can be used for receiving a first input voltage provided by the power adapter; a wireless charging receiving circuit for providing a second input voltage to the voltage switching circuit by receiving energy emitted by the wireless charger, the voltage switching circuit selectively transmitting the first input voltage or the second input voltage to an output terminal; and a battery charge management circuit for managing the charge of the battery according to the voltage of the output terminal of the voltage switching circuit.
In summary, the voltage switching circuit of the present invention can automatically turn on the corresponding transistor when the voltage difference between the voltages of the input terminals is greater than the on threshold of the transistor by the mutual control of the gates of the two transistors, and removes the voltage loss of the diode by the channel conduction of the transistor, so as to reduce the working voltage of the chip and the overall power of the system, and therefore, the latch-up effect caused by the forward bias of the diode will not occur.
In addition, the voltage switching circuit also comprises a clamping transistor, so that the gate-source voltage of the transistor can be clamped in a safe voltage range when the voltage difference between the voltages of the input terminals is overlarge, and the damage of the transistor is avoided.
Drawings
The above and other objects, features and advantages of the present invention will become more apparent from the following description of embodiments of the present invention with reference to the accompanying drawings, in which:
FIG. 1 shows a circuit schematic of a conventional voltage switching circuit;
FIG. 2 shows a schematic circuit diagram of a voltage switching circuit according to an embodiment of the invention;
fig. 3 shows a schematic configuration of a power supply system for wired and wireless charging according to an embodiment of the present invention.
Detailed Description
Various embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. The same reference numbers will be used throughout the drawings to refer to the same or like parts. For clarity, the various features of the drawings are not drawn to scale. Furthermore, some well-known portions may not be shown.
It should be understood that in the following description, "circuit" refers to an electrically conductive loop formed by at least one element or sub-circuit through electrical or electromagnetic connection. When an element or circuit is referred to as being "connected to" another element or being "connected between" two nodes, it can be directly coupled or connected to the other element or intervening elements may be present, the connection between the elements may be physical, logical, or a combination thereof. In contrast, when an element is referred to as being "directly coupled to" or "directly connected to" another element, it means that there are no intervening elements present between the two.
The invention may be embodied in various forms, some examples of which are described below.
Fig. 2 shows a circuit schematic of a voltage switching circuit 200 according to an embodiment of the invention. Fig. 3 shows a schematic configuration diagram of a power supply system 300 for wired and wireless charging, in which the voltage switching circuit 200 in fig. 2 is installed. The power supply system 300 includes a wireless charge receiving circuit 320, a battery charge management circuit 330, and a voltage switching circuit 200.
An output terminal of the power adapter 301 is connected to an input terminal of the voltage switching circuit 200, and supplies an input voltage Vin1 to the voltage switching circuit 200. An output terminal of the wireless charging receiving circuit 320 is connected to an input terminal of the voltage switching circuit 200, and provides an input voltage Vin2 to the voltage switching circuit 200 by receiving energy emitted from the wireless charger 302. The voltage switching circuit 200 is configured to compare the input voltages Vin1 and Vin2, and obtain a voltage vin_h at the output terminal according to the higher voltage of the input voltages Vin1 and Vin2. An input terminal of the battery charge management circuit 330 is connected to an output terminal of the voltage switching circuit 200, and an output terminal of the battery charge management circuit 330 is connected to the battery 303 for performing charge management on the battery 303 according to the voltage vin_h. The configuration of the voltage switching circuit 200 will be described in detail below with reference to fig. 2.
As shown in fig. 2, the voltage switching circuit 200 includes input terminals 201 and 202, an output terminal 203, transistors M1 and M2, and a switching module 210. Wherein the input terminals 201 and 202 are for receiving input voltages Vin1 and Vin2, respectively, and the voltage switching circuit 200 is for selectively transmitting voltages applied to the input terminal 201 and the input terminal 202 to the output terminal 203. The transistors M1 and M2 are implemented, for example, by P-type transistors, the transistor M1 being connected between the input terminal 201 and the output terminal 203, the transistor M2 being connected between the input terminal 202 and the output terminal 203, the switching module 210 being connected to the gates of the transistors M1 and M2 for controlling one of the transistors M1 and M2 to be turned on in accordance with a voltage difference between the input voltage Vin1 of the input terminal 201 and the input voltage Vin2 of the input terminal 202.
Specifically, the switching module 210 includes a zener diode Dz, a resistor R1, and transistors M3 and M4. The cathode of the zener diode Dz is connected to the output terminal 203, the anode is connected to the first end of the resistor R1, and the second end of the resistor R1 is grounded. The transistors M3 and M4 are implemented, for example, by P-type transistors, the gate of the transistor M3 being connected to the intermediate node of the zener diode Dz and the resistor R1, the source of the transistor M3 being connected to the gate of the transistor M1, and the drain of the transistor M3 being connected to the input voltage Vin2. The gate of the transistor M4 is connected to the intermediate node of the zener diode Dz and the resistor R1, the source of the transistor M4 is connected to the gate of the transistor M2, and the drain of the transistor M4 is connected to the input voltage Vin1.
The operating principle of the voltage switching circuit 200 of the present embodiment is as follows: when the input voltage Vin1 is greater than the input voltage Vin2, the substrate diode D1 of the transistor M1 is turned on, the substrate diode D2 of the transistor M2 is turned off, and the voltage vin_h=vin 1-VD1 of the output terminal 203 is the voltage drop of the substrate diode D1. In addition, the gate voltages v_g3 (G4) =vin_h-Vz of the transistors M3 and M4, where Vz is the zener voltage of the zener diode Dz, and since the gate voltages of the transistors M3 and M4 are lower than the voltage vin_h by one zener voltage, the transistors M3 and M4 are always in the on state, the transistor M3 transmits the input voltage Vin2 to the gate of the transistor M1, the transistor M4 transmits the input voltage Vin1 to the gate of the transistor M2, that is, the gate voltage v_g1=v2 of the transistor M1 at this time, the gate voltage v_g2=v1 of the transistor M2, and since the source voltage v_s1=vjh=v1-VD of the transistor M1, when vjh_vjv_2=vjvjv_m1, where vth_m1 is the channel of the transistor M1 is the on threshold value of the transistor M1, the voltage vjv_h=1 of the final output terminal 203 is in the off state, where vjv_vjv=vjv_2 is the gate voltage of the transistor M2.
Similarly, when the input voltage Vin2 is greater than the input voltage Vin1, the substrate diode D2 of the transistor M2 is turned on, the substrate diode D1 of the transistor M1 is turned off, and at this time, the voltage vin_h=vin 2-VD2 of the output terminal 203, where VD2 is the voltage drop of the substrate diode D2. Similarly, the gate voltages v_g3 (G4) =vin_h-Vz of the transistors M3 and M4, where Vz is the zener voltage of the zener diode Dz, and since the gate voltages of the transistors M3 and M4 are lower than the voltage vin_h by one zener voltage, the transistors M3 and M4 are always in the on state, the transistor M3 transmits the input voltage Vin2 to the gate of the transistor M1, the transistor M4 transmits the input voltage Vin1 to the gate of the transistor M2, that is, the gate voltage v_g1=v2 of the transistor M1, the gate voltage v_g2=v1 of the transistor M2, and since the source voltage v_s2=vjvjh=v2-VD of the transistor M2, when vjh-vjvjvjv_2-vjvjv > vjv 2-vjv 2, where vjv_m2 is the on threshold of the transistor M2, the voltage vjv_vjv 2 of the transistor M2 is the channel of the transistor M2, and the voltage vjv_vjv=vjv 2 of the transistor M1 is the gate voltage v_vjv=vjv 2.
As can be seen from the above, the voltage switching circuit 200 of the present invention can automatically turn on the corresponding transistor when the voltage difference between the input voltages Vin1 and Vin2 is greater than the on threshold of the transistor by the way of controlling the gates, and the voltage loss of the diode is removed by the channel conduction of the transistor, so as to reduce the working voltage of the chip and the overall power of the system, and therefore, the latch-up effect caused by the forward bias of the diode will not occur.
In addition, the transistors M3 and M4 in the embodiment of the present invention may also be used as clamping transistors, so that when the voltage difference between the input voltages Vin1 and Vin2 is too large, the gate-source voltages of the transistors M1 and M2 are clamped within a safe voltage range (for example, 5V, and the gate withstand voltages of most high-voltage transistors do not exceed 5V), thereby avoiding damage to the transistors M1 and M2. Taking the clamping of the transistor M3 as an example, since the transistor M3 is a P-type transistor and the transistor M3 is always in an on state, the source voltage of the transistor M3 cannot be lower than the gate voltage, and the gate voltage v_g3=vin_h-vz=v1-VD 1-Vz of the transistor M3, so when the input voltage Vin1-Vin2> 5V, the source voltage of the transistor M3 (i.e. the gate voltage of the transistor M1) becomes vjn 1-VD1-vz+vth_m3, wherein vth_m3 is the threshold voltage of the transistor M3, thereby clamping the gate-source voltage of the transistor M1 within 5V of the safety range and avoiding the damage of the transistor M1.
With continued reference to fig. 3, the wireless charging receiving circuit 320 includes an LC dual resonant circuit, an ASK modulation circuit, an FSK demodulation circuit, and a synchronous rectification filter circuit, which are formed by coils and capacitors. The energy sent by the wireless charger is received through the LC double-resonance circuit and is converted into direct current through the synchronous rectification filter circuit to work by the wireless charging receiving module. The ASK modulation circuit is used for transmitting data to the wireless charger by the wireless charging receiving end. The FSK demodulation circuit is used for receiving data sent to the wireless charging receiving end by the wireless charger.
The battery charge management circuit 330 performs trickle, constant current and constant voltage charging on the battery, and monitors the voltage, current and temperature of the battery in real time, so as to prevent the battery from being damaged by excessive charge and discharge or over-temperature.
It should be noted that, the wireless charging receiving circuit 320 and the battery charging management circuit 330 in the present invention are common circuits in the art, and will not be described in detail herein.
In summary, the voltage switching circuit of the present invention can automatically turn on the corresponding transistor when the voltage difference between the voltages of the input terminals is greater than the on threshold of the transistor by the mutual control of the gates of the two transistors, and removes the voltage loss of the diode by the channel conduction of the transistor, so as to reduce the working voltage of the chip and the overall power of the system, and therefore, the latch-up effect caused by the forward bias of the diode will not occur.
In addition, the voltage switching circuit also comprises a clamping transistor, so that the gate-source voltage of the transistor can be clamped in a safe voltage range when the voltage difference between the voltages of the input terminals is overlarge, and the damage of the transistor is avoided.
In the above description, well-known structural elements and steps have not been described in detail. Those of ordinary skill in the art will understand that the corresponding structural elements and steps may be implemented by various technical means. In addition, in order to form the same structural elements, those skilled in the art can also devise methods which are not exactly the same as the methods described above. In addition, although the embodiments are described above separately, this does not mean that the measures in the embodiments cannot be used advantageously in combination.
Embodiments in accordance with the present invention, as described above, are not intended to be exhaustive or to limit the invention to the precise embodiments disclosed. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, to thereby enable others skilled in the art to best utilize the invention and various modifications as are suited to the particular use contemplated. The scope of the invention should be determined by the following claims.
Claims (7)
1. A voltage switching circuit for selectively transmitting a voltage applied to a first input terminal and a second input terminal to an output terminal, comprising:
a first transistor connected between the first input terminal and the output terminal;
a second transistor connected between the second input terminal and the output terminal; and
and the switching module is connected with the gates of the first transistor and the second transistor and is used for controlling one of the first transistor and the second transistor to be conducted according to the voltage difference between the first input voltage of the first input terminal and the second input voltage of the second input terminal.
2. The voltage switching circuit of claim 1, wherein the first transistor is turned on when the first input voltage is greater than the second input voltage and a voltage difference therebetween is greater than a turn-on threshold of the first transistor;
when the second input voltage is larger than the first input voltage and the voltage difference between the second input voltage and the first input voltage is larger than the conduction threshold value of the second transistor, the second transistor is turned on.
3. The voltage switching circuit of claim 2, wherein the switching module comprises:
the cathode of the Zener diode is connected with the output terminal, the anode of the Zener diode is connected with the first end of the resistor, and the second end of the resistor is grounded;
a third transistor having a gate connected to the zener diode and an intermediate node of the resistor, a drain connected to the second input voltage, and a source connected to the gate of the first transistor; and
and the grid electrode of the fourth transistor is connected with the zener diode and the middle node of the resistor, the drain electrode of the fourth transistor is connected with the first input voltage, and the source electrode of the fourth transistor is connected with the grid electrode of the second transistor.
4. A voltage switching circuit according to claim 3 wherein the third and fourth transistors are clamp transistors operable to clamp gate-source voltages of the first and second transistors, respectively, within a safe voltage range.
5. The voltage switching circuit of claim 4 wherein the third transistor and the fourth transistor are always in an on state.
6. The voltage switching circuit of claim 3, wherein the first through fourth transistors are implemented by P-type transistors, respectively.
7. A power supply system for charging a battery, comprising:
the voltage switching circuit of any of claims 1-6 operable to receive a first input voltage provided by a power adapter;
a wireless charging receiving circuit for providing a second input voltage to the voltage switching circuit by receiving energy emitted by the wireless charger, the voltage switching circuit selectively transmitting the first input voltage or the second input voltage to an output terminal; and
and the battery charge management circuit is used for carrying out charge management on the battery according to the voltage of the output terminal of the voltage switching circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210649728.1A CN117251012A (en) | 2022-06-09 | 2022-06-09 | Voltage switching circuit and power supply system using the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210649728.1A CN117251012A (en) | 2022-06-09 | 2022-06-09 | Voltage switching circuit and power supply system using the same |
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| Publication Number | Publication Date |
|---|---|
| CN117251012A true CN117251012A (en) | 2023-12-19 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210649728.1A Pending CN117251012A (en) | 2022-06-09 | 2022-06-09 | Voltage switching circuit and power supply system using the same |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117811371A (en) * | 2024-02-28 | 2024-04-02 | 杰华特微电子股份有限公司 | Maximum input voltage selection output circuit, method and chip using same |
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2022
- 2022-06-09 CN CN202210649728.1A patent/CN117251012A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117811371A (en) * | 2024-02-28 | 2024-04-02 | 杰华特微电子股份有限公司 | Maximum input voltage selection output circuit, method and chip using same |
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