CN111277021A

CN111277021A - Load connection identification circuit of switching power supply and multi-port charger

Info

Publication number: CN111277021A
Application number: CN202010219235.5A
Authority: CN
Inventors: 罗月亮
Original assignee: BCD Shanghai Micro Electronics Ltd
Current assignee: BCD Shanghai Micro Electronics Ltd
Priority date: 2020-03-25
Filing date: 2020-03-25
Publication date: 2020-06-12

Abstract

The invention discloses a load connection identification circuit of a switching power supply, which comprises: the ripple detection circuit, the judgment circuit and the control circuit; the ripple signal of the output port of the switching power supply is detected by the arrangement and coupling of the ripple detection circuit, and because whether the output port is connected with the load or not can affect the ripple signal, the judgment circuit can judge whether the output port is connected with the load or not according to the size of the detected ripple signal and output a judgment result to the control circuit, so that the control circuit can identify the load connection state of the output port and correspondingly control the output of the switching power supply; the invention avoids the use of current sampling resistor, can avoid the increase of heating point and system power loss, and improves the system efficiency; and the identification blind area of the output current is reduced, and the identification accuracy of load connection is improved. In addition, the invention also discloses a load connection identification circuit of the multi-port charger, and the circuit also has the beneficial effects.

Description

Load connection identification circuit of switching power supply and multi-port charger

Technical Field

The invention relates to the technical field of power electronics, in particular to a load connection identification circuit of a switching power supply and a multi-port charger.

Background

A charger, also known as a charger and a mobile power supply, is a charging device for providing a stable power supply for an electronic device containing a battery, and is usually composed of a stable power supply (providing a stable working voltage and sufficient current) and necessary control circuits with constant current, voltage limiting and protection functions.

With the rapid popularization of smart devices and smart phones, multi-port smart power distribution chargers (i.e., multi-port chargers) are increasingly favored by users. The power supply port of each switching power supply of the multi-port charger is compatible with the quick charging protocol, and only slight system cost is increased, so that the multi-port charger gradually becomes a very popular product in the market. The main objectives of a multi-port charger are: 1) ensuring safe charging of the load; 2) when the single output port works independently, the output port supports the corresponding fast charging protocol. The "circuit for identifying whether the output port of the charger is connected to the load" is a core element for realizing the multi-port charger. Two types of USB lines are mainstream in the market, namely a Type-C line and a USB-A line. The charger manufacturer cannot ensure whether the USB cable used by the user meets the standard specification. For example, the following steps are carried out: 1) for example, a charging wire without D + and D-is used in the USB-A power supply port, and at the moment, the D + and D-signal channels of the protocol chip (namely, a processor) of the multi-port charger are suspended without signal input; 2) the Type-C power supply port is only connected with a C-to-Lighting line (not connected with a load) which is different from the USB PD protocol, and the multi-port charger can mistakenly think that the load is connected. Therefore, the protocol chip can not judge whether the power supply port (i.e. the output port) of the charger is connected with the load only through the signal lines of D +, D-, CC1 and CC2, and can only judge through measuring the voltage signals or the current signals on the VBUS and GND lines in the USB line.

In the prior art, most of the switching power supplies in the market adopt a conventional identification circuit for judging whether the output of the switching power supply is connected with a load or not by measuring voltage signals at two ends of a current detection resistor, and a schematic diagram of the conventional identification circuit is shown in fig. 1, however, the current sampling resistor (such as R3 in fig. 1) arranged at the output of the switching power supply is used, so that power loss is increased when the system normally works, the efficiency of the system is reduced, and a heating point is added; and the resolution point Iout of the output current (Iout) flowing through the current sampling resistor is equal to Vref/R3, considering the component cost and the component self-error, such as the comparator has a large offset voltage (Voffset), a reference voltage (Vref) error, a current sampling resistor error and noise interference, the resolution point of the output current is about 400mA, that is, when Iout is less than 400mA, the protocol chip cannot judge whether the charger output is connected with a load. Therefore, how to improve the identification accuracy of the switching power supply for the load connection of the output port and improve the system efficiency is a problem which needs to be solved urgently nowadays.

Disclosure of Invention

The invention aims to provide a load connection identification circuit of a switching power supply and a multi-port charger, which is used for identifying the load connection of an output port by utilizing ripple signals detected by a ripple detection circuit in a coupling mode, so that the identification accuracy is improved, and the system efficiency is improved.

In order to solve the above technical problem, the present invention provides a load connection identification circuit for a switching power supply, including:

the ripple detection circuit is coupled to an output port of the switching power supply and used for detecting a ripple signal of the output port, and the ripple detection circuit at least comprises an amplifying circuit and is used for amplifying the ripple signal and generating an amplified signal;

the judging circuit is used for judging whether the output port is connected with a load or not according to the amplified signal;

and the control circuit is used for controlling the output of the switching power supply according to the judgment result of the judgment circuit.

Optionally, the amplifying circuit is a transformer;

a first end of a primary winding of the transformer is connected with a VBUS end or a GND end of the output port, and a second end of the primary winding of the transformer is used for being connected with a load; and the first end and the second end of the secondary winding of the mutual inductor are respectively connected with the first input end and the second input end of the judging circuit in a one-to-one correspondence manner.

Optionally, when the amplified signal is an ac voltage signal, the ripple detection circuit further includes a rectifier circuit, configured to convert the amplified signal into a corresponding dc signal;

the first output end and the second output end of the amplifying circuit are respectively connected with the first input end and the second input end of the judging circuit in a one-to-one correspondence mode through the rectifying circuit.

Optionally, the determining circuit includes: a first resistor and a first switch tube;

the control end of the first switch tube is used as the first input end of the judging circuit and connected with the first output end of the rectifying circuit, the first end of the first switch tube and the first end of the first resistor are connected, the common end of the first switch tube and the first end of the first resistor is connected, the common end of the first switch tube is used as the output end of the judging circuit and connected with the input end of the control circuit, the second end of the first resistor is used for being connected with the preset voltage output end, and the second end of the first switch tube is used as the second input end of the judging circuit and connected with the second output end of the rectifying circuit, and the common end of the first.

Optionally, a first end of the primary winding of the transformer is connected to the VBUS end of the output port.

In addition, the invention also provides a load connection identification circuit of the multi-port charger, which at least comprises a first power supply port and a second power supply port, wherein the first power supply port and the second power supply port are connected through a second switch tube; further comprising: the ripple detection circuit, the judgment circuit and the control circuit;

the ripple detection circuit is coupled to the second power supply port and configured to detect a ripple signal of the second power supply port, and the ripple detection circuit at least includes an amplification circuit configured to amplify the ripple signal and generate an amplified signal;

the judging circuit judges whether the second power supply port is connected with a load or not according to the amplifying signal;

and the control circuit controls the conduction and the cut-off of the second switching tube according to the judgment result of the judgment circuit so as to control the output of the second power supply port.

Optionally, the amplifying circuit is a transformer;

a first end of a primary winding of the transformer is connected with a VBUS end or a GND end of the second power supply port, and a second end of the primary winding of the transformer is used for being connected with a load; and the first end and the second end of the secondary winding of the mutual inductor are respectively connected with the first input end and the second input end of the judging circuit in a one-to-one correspondence manner.

the first output end and the second output end of the amplifying circuit are respectively connected with the first input end and the second input end of the rectifying circuit in a one-to-one correspondence mode, and the first output end and the second output end of the rectifying circuit are respectively connected with the first input end and the second input end of the judging circuit in a one-to-one correspondence mode.

Optionally, the first switching tube is specifically an NPN-type triode;

the base electrode of the NPN type triode is connected with the first output end of the rectifying circuit, the collector electrode of the NPN type triode is connected with the first end of the first resistor, and the emitting electrode of the NPN type triode is grounded.

Optionally, the rectifier circuit includes: the circuit comprises a first diode, a first capacitor and a second resistor;

the anode of the first diode is used as the first input end of the rectifying circuit and connected with the first output end of the amplifying circuit, the cathode of the first diode is respectively connected with the first end of the first capacitor and the first end of the second resistor, the common end of the first diode is used as the first output end of the rectifying circuit, and the second end of the first capacitor and the second end of the second resistor are connected, the common end of the first diode and the second diode is used as the second input end and the second output end of the rectifying circuit.

Optionally, the VBUS terminal of the first power supply port and the VBUS terminal of the second power supply port are connected through the second switch tube.

Optionally, the determining circuit includes: a processor and a switch control circuit;

the first GPIO end of the processor is used as the input end of the control circuit and connected with the output end of the judging circuit, and is used for receiving a first level signal corresponding to the judging result output by the judging circuit; and a second GPIO end of the processor is connected with the control end of the second switch tube through the switch control circuit and is used for outputting a second level signal corresponding to the first level signal to the switch control circuit so as to control the on and off of the second switch tube.

Optionally, the third GPIO terminal of the processor is connected to the VBUS terminal of the second power supply port.

Optionally, the control circuit further includes: a second diode;

and the third GPIO terminal of the processor is connected with the anode of the second diode, and the cathode of the second diode is connected with the VBUS terminal of the second power supply port.

Optionally, the switch control circuit includes: a third resistor, a fourth resistor and a third switching tube;

the first end of the third resistor and the first end of the third switching tube are connected, the common end of the third resistor and the first end of the third switching tube is connected with the control end of the second switching tube, the second end of the third resistor and the first end of the second switching tube are connected, the common end of the third resistor and the first end of the fourth resistor is connected with the second GPIO end of the processor, and the common end of the third resistor and the second end of the fourth resistor is connected with the ground; the first end of the second switch tube is connected with the VBUS end of the first power supply port, and the second end of the second switch tube is connected with the VBUS end of the second power supply port.

The invention provides a load connection identification circuit of a switching power supply, which comprises: the ripple detection circuit is coupled to an output port of the switching power supply and used for detecting a ripple signal of the output port, and the ripple detection circuit at least comprises an amplifying circuit and is used for amplifying the ripple signal and generating an amplified signal; the judging circuit is used for judging whether the output port is connected with the load or not according to the amplified signal; the control circuit is used for controlling the output of the switching power supply according to the judgment result of the judgment circuit;

therefore, the ripple signal of the output port of the switching power supply is detected by the arrangement and coupling of the ripple detection circuit, and because whether the output port is connected with the load or not can affect the ripple signal, the judgment circuit can judge whether the output port is connected with the load or not according to the detected magnitude of the ripple signal and output a judgment result to the control circuit, so that the control circuit can identify the load connection state of the output port and correspondingly control the output of the switching power supply; the invention avoids the use of current sampling resistor, can avoid the increase of heating point and system power loss, and improves the system efficiency; and the identification blind area of the output current is reduced, and the identification accuracy of load connection is improved. In addition, the invention also provides a load connection identification circuit of the multi-port charger, and the load connection identification circuit also has the beneficial effects.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

FIG. 1 is a schematic diagram of a prior art load connection identification circuit for a multi-port charger;

fig. 2 is a block diagram of a load connection identification circuit of a switching power supply according to an embodiment of the present invention;

fig. 3 is a schematic structural diagram of a load connection identification circuit of a multi-port charger according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 2, fig. 2 is a block diagram of a load connection identification circuit of a switching power supply according to an embodiment of the present invention. The load connection identification circuit may include:

the ripple detection circuit 10 is coupled to an OUTPUT port (OUTPUT) of the switching power supply, and is configured to detect a ripple signal at the OUTPUT port, where the ripple detection circuit 10 at least includes an amplifying circuit configured to amplify the ripple signal and generate an amplified signal;

the judging circuit 20 is used for judging whether the output port is connected to the load according to the amplified signal;

and a control circuit 30 for controlling the output of the switching power supply according to the judgment result of the judgment circuit 20.

It can be understood that, when the output port of the switching power supply is connected to the load, the ripple signal (such as ripple voltage and/or ripple current) in the output of the output port of the switching power supply may change, and when the output port of the switching power supply is connected to the load, the ripple voltage output by the output port may become larger, so that the load connection identification circuit of the switching power supply provided in this embodiment determines whether the load is connected to the output port by using the ripple signal (such as ripple voltage and/or ripple current) detected by the ripple detection circuit 10 disposed at the output port of the switching power supply through coupling.

Specifically, the specific location of the ripple detection circuit 10 coupled to the output port of the switching power supply is not limited in this embodiment, for example, the ripple detection circuit 10 may be disposed at a VBUS end of the output port of the switching power supply, that is, a first input end of the ripple detection circuit 10 is connected to the VBUS end of the output port of the switching power supply, and a second input end of the ripple detection circuit 10 is used for being connected to a load; the ripple detection circuit 10 may also be disposed at a GND terminal of an output port of the switching power supply, that is, a first input terminal of the ripple detection circuit 10 is connected to the GND terminal of the output port of the switching power supply, and a second input terminal of the ripple detection circuit 10 is used for being connected to a load. The present embodiment is not limited to this, as long as the ripple detection circuit 10 can couple and detect the ripple signal at the output port of the switching power supply.

Correspondingly, the ripple detection circuit 10 in the present embodiment may include an amplification circuit for amplifying the detected ripple signal. For the specific circuit structure of the amplifying circuit, the specific circuit structure can be set by a designer according to a practical scene and user requirements, for example, the specific circuit structure can be set according to the type of ripple signals required to be detected by the ripple detecting circuit 10, for example, when the ripple signals detected by the ripple detecting circuit 10 are voltage signals (namely, ripple voltages), the amplifying circuit can be a mutual inductor, so that the ripple voltages of the output port of the switching power supply are detected by the mutual inductor through coupling, the detected ripple voltages are amplified, and the amplified signals are output; that is to say, the first end and the second end of the primary winding of the transformer may be respectively used as the first input end and the second input end of the ripple detection circuit 10, that is, the first end of the primary winding of the transformer is connected to the VBUS end or the GND end of the output port of the switching power supply, and the second end of the primary winding of the transformer is used for being connected to the load; the first end and the second end of the secondary winding of the mutual inductor can output amplified signals, namely the first end of the secondary winding of the mutual inductor is connected with the first input end of the judging circuit, and the second end of the secondary winding of the mutual inductor is connected with the second input end of the judging circuit.

Further, when the ripple signal detected by the ripple detection circuit 10 in this embodiment is a ripple voltage, the ripple detection circuit 10 in this embodiment may further include: the rectifying circuit is used for converting the amplified ripple voltage (namely, the amplified signal) output by the amplifying circuit into a corresponding direct current signal so as to be used as the input of the judging circuit 20, and the judging circuit 20 is convenient to use, namely, the first output end and the second output end of the amplifying circuit are respectively connected with the first input end and the second input end of the judging circuit in a one-to-one correspondence manner through the rectifying circuit.

It should be noted that, through the arrangement of the circuit structure, the determining circuit 20 in this embodiment outputs, to the control circuit 30, whether the output port of the switching power supply is connected to a signal corresponding to the load (i.e., a determination result) according to the magnitude of the signal corresponding to the ripple signal output by the ripple detecting circuit 10; if the signal output by the ripple detection circuit 10 is a dc signal converted by the rectifier circuit, the determination circuit 20 may output a low level signal of the load to the output port of the switching power supply to the control circuit 30 when the voltage value of the dc signal is greater than or equal to the threshold value; when the voltage value of the dc signal is smaller than the threshold, a high level signal that the output port of the switching power supply is not connected to the load may be output to the control circuit 30. For example, the judging circuit may include a first resistor and a first switching tube, a control end of the first switching tube is connected to a first output end of the rectifying circuit as a first input end of the judging circuit 20, a first end of the first switching tube and a first end of the first resistor are connected, and a common end thereof is connected to an output end of the judging circuit 20 and an input end of the control circuit 30 as an output end thereof, a second end of the first resistor is used for being connected to a preset voltage output end, and a second end of the first switching tube is connected to a second output end of the rectifying circuit as a second input end of the judging circuit 10 and a common end thereof is grounded; therefore, the first switch tube is turned on or off correspondingly according to the comparison between the voltage value of the direct current signal input by the control end and the threshold value, and a signal whether the output port of the switch power supply is connected with the load or not is output to the control circuit 30. As long as the determining circuit 20 can output a signal corresponding to whether the output port of the switching power supply is connected to the load to the control circuit 30 according to the magnitude of the signal output by the ripple detecting circuit 10, this embodiment does not limit this.

Specifically, the control circuit 30 in this embodiment may control the output of the switching power supply according to the determination result output by the determination circuit 20 through the arrangement of the circuit structure. As for the specific circuit structure of the control circuit 30 in this embodiment, that is, the specific control content of the control circuit 30 on the output of the switching power supply, which can be set by a designer according to a practical scenario and a user requirement, as shown in fig. 3, when the multi-port charger includes an output port (i.e., the second power supply port) of the switching power supply in this embodiment and another output port (i.e., the first power supply port) of another switching power supply, the control circuit 30 may include: the second switching tube, the processor and the switch control circuit; the VBUS end of the output port of the switching power supply and the VBUS end of another output port of another switching power supply are connected through a second switching tube, and the processor can control the second switching tube to be turned on and off through the switch control circuit 30 according to the judgment result output by the judgment circuit 20, so that the output of the switching power supply is controlled. The present embodiment is not limited to this, as long as the control circuit 30 can correspondingly control the output of the switching power supply according to the judgment result output by the judgment circuit 20.

In this embodiment, the ripple signal of the output port is detected by the ripple detection circuit 10, and because whether the output port is connected to the load affects the ripple signal, the judgment circuit 20 can judge whether the output port is connected to the load according to the detected magnitude of the ripple signal, and output the judgment result to the control circuit 30, so that the control circuit 30 can recognize the load connection state of the output port and correspondingly control the output of the switching power supply; the embodiment of the invention avoids the use of a current sampling resistor, can avoid the increase of heating points and system power loss, and improves the system efficiency; and the identification blind area of the output current is reduced, and the identification accuracy of load connection is improved.

Referring to fig. 3, fig. 3 is a schematic structural diagram of a load connection identification circuit of a multi-port charger according to an embodiment of the present invention. The load connection identification circuit at least comprises a first power supply port 40 and a second power supply port 50, wherein the first power supply port 40 and the second power supply port 50 are connected through a second switch tube 60 (Q1); the method can also comprise the following steps: the ripple detection circuit 10, the judgment circuit 20 and the control circuit 30;

the ripple detection circuit 10 is coupled to the second power supply port 50 and configured to detect a ripple signal of the second power supply port 50, where the ripple detection circuit 10 at least includes an amplification circuit and is configured to amplify the ripple signal and generate an amplified signal;

the judging circuit 20 judges whether the second power supply port 50 is connected to a load or not according to the amplified signal;

and the control circuit 30 controls the conduction and the cut-off of the second switching tube according to the judgment result of the judgment circuit so as to control the output of the second power supply port.

It is understood that the first power supply port 40 and the second power supply port 50 in the present embodiment may be output ports of a switching power supply in a multi-port charger, respectively, that is, the multi-port charger in the present embodiment may include two switching power supplies. That is, the first power supply port 40 and the second power supply port 50 in the present embodiment may be output ports of a switching power supply that supplies power to the USB interfaces connected thereto, respectively, so as to supply power to loads connected to the USB interfaces. As shown in fig. 3, the first power supply Port 40 may supply power to the load 1 through the connected first USB interface (Port1) and USB cable (USB cable), and the second power supply Port 50 may supply power to the load 2 through the connected second USB interface (Port2) and USB cable (USB cable).

Specifically, since the ripple signal (e.g., ripple voltage and/or ripple current) in the output of the second power supply port 50 may be changed when the second power supply port 50 is connected to the load, and the ripple voltage output by the second power supply port 50 may become larger when the second power supply port 50 is connected to the load, the load connection identification circuit of the multi-port charger provided in this embodiment may couple the detected ripple signal (e.g., ripple voltage and/or ripple current) of the second power supply port 50 by using the ripple detection circuit 10 disposed in the second power supply port 50, so as to determine whether the second power supply port 50 is connected to the load.

Correspondingly, the ripple detection circuit 10 in the present embodiment may include an amplification circuit for amplifying the detected ripple signal. For the specific circuit structure of the amplifying circuit, the specific circuit structure can be set by a designer according to a practical scene and a user requirement, for example, the specific circuit structure can be set according to the type of the ripple signal that needs to be detected by the ripple detecting circuit 10, for example, when the ripple signal detected by the ripple detecting circuit 10 is a voltage signal (i.e., a ripple voltage), as shown in fig. 3, the amplifying circuit can be a transformer 11(T1), so that the transformer 11 is used for coupling and detecting the ripple voltage of the second power supply port 50, and the detected ripple voltage is amplified to output an amplified signal; that is, the first end and the second end of the primary winding of the transformer 11 may be respectively used as the first input end and the second input end of the ripple detection circuit 10, that is, the first end of the primary winding of the transformer 11 is connected to the VBUS end or the GND end of the second power supply port 50, and the second end of the primary winding of the transformer 11 is used for being connected to a load; the first end and the second end of the secondary winding of the transformer 11 can output amplified signals, that is, the first end of the secondary winding of the transformer 11 is connected with the first input end of the judging circuit 20, and the second end of the secondary winding of the transformer 11 is connected with the second input end of the judging circuit 20.

Specifically, as shown in fig. 3, in the present embodiment, a transformer 11 is connected in series in an output bus (VBUS line or GND line, i.e., power line or ground line) of the second power supply port 50 of the multi-port charger, and a ripple voltage in an output voltage of the second power supply port 50 is coupled out by using a characteristic that the transformer 11 can only couple an alternating current signal, so as to identify whether the second power supply port 50 is connected to a load through a USB interface by using the coupled ripple voltage.

Correspondingly, the specific setting position of the transformer 11 is not limited in this embodiment, as shown in fig. 3, the transformer 11 may be connected in series to the VBUS line of the second power supply port 50 of the multi-port charger, that is, the first end of the primary winding of the transformer 11 is connected to the VBUS end of the second power supply port 50, and the second end of the primary winding of the transformer 11 is connected to the VBUS end of the second USB interface; the transformer 11 may also be connected in series to the GND line of the second power supply port 50 of the multi-port charger, that is, the first end of the primary winding of the transformer 11 is connected to the GND end of the second power supply port 50, and the second end of the primary winding of the transformer 11 is connected to the GND end of the second USB interface.

Likewise, the present embodiment does not limit the specific structure type of the transformer 11, and the coupled ripple voltage may be amplified to an ac voltage (such as Vac _ signal in fig. 3) with a higher amplitude by using the turns setting of the primary winding and the secondary winding in the transformer 11, i.e. the number of turns of the secondary winding in the transformer 11 is greater than that of the primary winding.

It should be noted that, in this embodiment, when the ripple signal detected by the ripple detection circuit 10 is a voltage signal, that is, when the amplified signal generated by the amplification circuit is an ac voltage signal, as shown in fig. 3, the ripple detection circuit 10 may further include a rectification circuit 12 for converting the amplified signal into a corresponding dc signal; the first output end and the second output end of the amplifying circuit are respectively connected with the first input end and the second input end of the rectifying circuit 12 in a one-to-one correspondence manner, and the first output end and the second output end of the rectifying circuit 12 are respectively connected with the first input end and the second input end of the judging circuit 20 in a one-to-one correspondence manner. As shown in fig. 3, the rectifying circuit 12 connected to the two ends of the secondary winding of the transformer 11 in this embodiment can convert the ripple voltage coupled by the transformer 11 into corresponding direct current, so that it can be distinguished whether the USB interface connected to the second power supply port 50 of the multi-port charger is connected to a load by using the change of the direct current corresponding to the ripple voltage. That is, in this embodiment, the first input end of the rectifying circuit 12 is connected to the first end of the secondary winding of the transformer 11, the second input end of the rectifying circuit 12 is connected to the second end of the secondary winding of the transformer 11, the first output end of the rectifying circuit 12 is connected to the first input end of the judging circuit 20, and the second output end of the rectifying circuit 12 is connected to the second input end of the judging circuit 20, so that the ripple voltage coupled out of the transformer 11 at the secondary winding of the transformer 11 is converted into a corresponding dc voltage (e.g., Vdc _ signal in fig. 2) and output to the judging circuit 20.

Specifically, for the specific circuit structure of the rectifier circuit 12 in this embodiment, the specific circuit structure can be set by a designer according to a practical scene and a user requirement, for example, the rectifier circuit 12 may specifically be a rectifier filter circuit, as shown in fig. 3, the rectifier circuit 12 may include: a first diode (D1), a first capacitor (C3), and a second resistor (R3); an anode of the first diode is used as a first input end of the rectifying circuit 12 and connected with a first end of a secondary winding of the transformer 11(T1), a cathode of the first diode is respectively connected with a first end of the first capacitor and a first end of the second resistor, a common end of the cathode of the first diode, the first end of the first capacitor and the first end of the second resistor is used as a first output end of the rectifying circuit 12, a second end of the first capacitor is connected with a second end of the second resistor, and a common end of the second end of the first capacitor and the second end of the second resistor is used as a second input end and a second output end of the rectifying circuit 12. The present embodiment does not limit the ripple voltage at the secondary winding of the transformer 11 to a corresponding ac voltage as long as the rectifying circuit 12 can convert the ac voltage into a corresponding dc voltage.

Correspondingly, the present embodiment does not limit specific circuit element parameters in the rectifying circuit 12, as shown in fig. 3, the rectifying circuit 12 may convert the ac voltage (Vac _ signal) amplified by the ripple voltage at the secondary winding of the transformer 11 into the dc voltage (Vdc _ signal), and after the parameters of the transformer 11(T1), the first capacitor (C3) and the second resistor (R3) are reasonably adjusted, the difference between the dc voltage after the load (load 2) is connected to the USB interface (Port2) connected to the second power supply Port 50 through the USB cable (USB cable) and the dc voltage after the load is not connected to the load is relatively large, such as about 1V, so that whether the load is connected to the Port2 can be effectively distinguished by using the voltage difference.

It can be understood that, by setting the circuit structure, the determining circuit 20 in this embodiment outputs, to the control circuit 30, whether the second power supply port 50 is connected to a signal corresponding to a load (i.e., a determination result) according to the magnitude of the signal corresponding to the ripple signal output by the ripple detecting circuit 10; if the signal output by the ripple detection circuit 10 is a dc signal converted by the rectifier circuit 12, as shown in fig. 3, the determination circuit 20 in this embodiment may convert the voltage value of the dc power output by the rectifier circuit 12 into a corresponding first level signal (determination result), that is, whether the USB interface connected to the second power supply port 50 is connected to a high-low level signal corresponding to the load, so that the control circuit 30 may determine whether the USB interface connected to the second power supply port 50 is connected to the load according to the first level signal output by the determination circuit 20. That is, when the USB interface connected to the second power supply port 50 is connected to a load, the ripple voltage coupled by the transformer 11 will be increased, so that the dc voltage output by the rectifying circuit 12 will be increased, and therefore the determining circuit 20 may determine that the USB interface connected to the second power supply port 50 is connected to the load when the dc voltage output by the rectifying circuit 12 is greater than or equal to the threshold, and output a corresponding first level signal, such as a low level signal, to the control circuit 30; when the dc voltage output from the rectifying circuit 12 is less than the threshold value, it is determined that the load is not connected to the USB interface to which the second power supply port 50 is connected, and a corresponding first level signal, such as a high level signal, is output to the control circuit 30.

Specifically, the specific circuit structure of the determination circuit 20 may be set by a designer, as long as the determination circuit 20 can output a determination result of whether the USB interface connected to the second power supply port 50 is connected to the load to the control circuit 30 according to the magnitude of the voltage value of the direct current output by the rectification circuit 12, which is not limited in this embodiment. As shown in fig. 3, the determination circuit 20 may include: a first resistor (R4) and a first switch tube (Q3); when the Port2 is connected to the load 2, the voltage value (Vdc _ signal) of the direct current output from the rectifying circuit 12 is greater than or equal to the conduction threshold value (i.e., the threshold value) of the first switching tube, the first switching tube is conducted, and the first level signal output from the judging circuit 20 to the control circuit 30 is a low level signal pulled down to be close to 0V; when the Port2 is not connected to the load 2, Vdc _ signal is smaller than the turn-on threshold of the first switch tube, so that the first switch tube is turned off, and the first level signal output from the determination circuit 20 to the control circuit 30 is a high level signal pulled up to VCC voltage. The control end of the first switch tube is connected with the first output end of the rectifying circuit 12 as the first input end of the judging circuit 20, the first end of the first switch tube is connected with the first end of the first resistor, the common end of the first switch tube connected with the first end of the first resistor is connected with the input end of the control circuit 30 as the output end of the judging circuit 20, the second end of the first resistor is used for being connected with the preset voltage output end, the second end of the first switch tube is connected with the second output end of the rectifying circuit 12 as the second input end of the judging circuit 20, and the common end of the second end of the first switch tube connected with the second output end of the rectifying circuit 12 is grounded.

Correspondingly, the determination circuit 20 may output a high level signal to the input terminal of the control circuit 30 when the voltage value of the dc power output by the rectification circuit 12 is greater than or equal to the threshold value; when the voltage value of the direct current output from the rectifier circuit 12 is smaller than the threshold value, a low level signal is output to the input terminal of the control circuit 30. The present embodiment does not set any limit to this.

Specifically, the present embodiment does not limit the specific circuit element types and parameters in the determination circuit 20, as shown in fig. 3, a first switching tube such as an NPN-type triode may be adopted in the determination circuit 20, that is, a base of the NPN-type triode is connected to the first output end of the rectification circuit 12, a collector of the NPN-type triode is connected to the first end of the first resistor, and an emitter of the NPN-type triode is grounded; other types of first switching tubes may be adopted, or an operational amplifier or a comparator may be adopted instead of the first switching tube, as long as it is ensured that the determining circuit 20 can output, according to the magnitude of the voltage value of the direct current output by the rectifying circuit 12, the first level signal corresponding to whether the USB interface connected to the second power supply port 50 is connected to the load or not to the input end of the control circuit 30, which is not limited in this embodiment.

It should be noted that, for the specific circuit structure of the control circuit 30 in this embodiment, that is, the specific way in which the control circuit 30 controls the output of the second power supply port 50 according to the determination result of the determination circuit 20, may be set by a designer according to the use scenario and the user requirement, as shown in fig. 3, the control circuit 30 may include a processor 31 (protocol chip) and a switch control circuit 32; a first GPIO terminal (GPIO3) of the processor 31 is used as an input terminal of the control circuit 30, connected to the output terminal of the judging circuit 20, and configured to receive a first level signal corresponding to the judgment result output by the judging circuit 20; a second GPIO terminal (GPIO2) of the processor 31 is connected to the control terminal of the second switch tube 60 through the switch control circuit 32, and is configured to output a second level signal corresponding to the first level signal to the switch control circuit 32 to control the second switch tube 60 to be turned on and off; thereby adjusting the output of the second power supply port 50 by controlling the on and off of the second switching tube 60. That is, the processor 31 may determine whether the USB interface connected to the second power supply port 50 is connected to the load according to the high-low level of the first level signal received by the first GPIO terminal, so as to output a corresponding second level signal (a high-level signal or a low-level signal) through the second GPIO terminal, and control the switch control circuit 32 to turn on or turn off the second switching tube 60.

Correspondingly, as shown in fig. 3, the VBUS terminals of the first power supply port 40 and the second power supply port 50 of the multi-port charger in the embodiment may be connected through the second switch tube 60(Q1), and the VBUS terminal of the processor 31 may be connected with the VBUS terminal of the first power supply port 40. The present embodiment does not limit the specific circuit structure of the switch control circuit 32 connected to the second GPIO terminal of the processor 31, as long as the switch control circuit 32 can send a corresponding signal to the control terminal of the second switch tube 60 according to the second level signal output by the second GPIO terminal of the processor 31, so as to control the second switch tube 60 to be turned on and off, which is not limited in this embodiment. As shown in fig. 3, the switch control circuit 32 may include: a third resistor (R1), a fourth resistor (R2) and a third switching tube (Q2); the first end of the third resistor is connected with the first end of the third switching tube, the common end of the first end of the third resistor, which is connected with the first end of the third switching tube, is connected with the control end of the second switching tube 60(Q1), the second end of the third resistor is connected with the first end of the second switching tube 60, the control end of the third switching tube is connected with the first end of the fourth resistor, the common end of the control end of the third switching tube, which is connected with the first end of the fourth resistor, is connected with the second GPIO (GPIO2) of the processor 31, the second end of the third switching tube is connected with the second end of the fourth resistor, and the second end of the third switching tube and the common end of the second end of the fourth resistor are grounded; a first terminal of the second switching tube 60 is connected to the VBUS terminal of the first power supply port 40, and a second terminal of the second switching tube 60 is connected to the VBUS terminal of the second power supply port 50.

Specifically, as shown in fig. 3, the load connection identification circuit provided in this embodiment may further include a second capacitor (C1) and a third capacitor (C2), wherein a first end of the second capacitor is connected to the VBUS terminal of the first power supply port 40, a common end of the first end of the second capacitor connected to the VBUS terminal of the first power supply port 40 is connected to the first end of the second switch tube 60, a second end of the second capacitor is connected to the GND terminal of the first power supply port 40, and a second end of the second capacitor connected to the common end of the GND terminal of the first power supply port 40 is grounded; the first end of the third capacitor is connected to the VBUS end of the second power supply port 50, the common end of the first end of the third capacitor connected to the VBUS end of the second power supply port 50 is connected to the second end of the second switch tube 60, the second end of the third capacitor is connected to the GND end of the second power supply port 50, and the common end of the second end of the third capacitor connected to the GND end of the second power supply port 50 is grounded. That is, one capacitor connected in series across each supply port filters the output of the supply port.

It can be understood that, as shown in fig. 1, the load connection identification circuit in the prior art mainly has the following core components: a power LDO (U2, low dropout regulator), a high-precision comparator (U3), a reference voltage source (Vref) with mV level and a current detection resistor (R3); the switching tube Q1 between the USB interface (Port1) connected to the upper power supply Port (i.e., the first power supply Port) and the USB interface (Port2) connected to the lower power supply Port (the second power supply Port) is turned on or off in only two cases. When the switching tube Q1 of the ports 1 to 2 is in an off state, the output of the Port2 is powered by the U2 and waits for the load (load 1) to be connected; if a load is connected to Port2, U2 begins to charge the load, and the output current (Iout) flows through resistor R3, and the voltage across resistor R3 has only two results: a, if Iout × R3< Vset (set threshold), the processor 31 (protocol chip) considers that Port2 has no load connected, and the switch Q1 remains off; b, if Iout R3 is larger than or equal to Vset, the output voltage of the comparator (U3) is inverted, the protocol chip considers that the Port2 has load connection, then the output voltage of the Port1 is reduced to a safe voltage, and then the switch tube Q1 is turned on. When the switch Q1 of Port1 to Port2 is in the on state, i.e. Port1 and Port2 are connected together, the output voltage of U2 is bypassed by Port1, i.e. U2 is inactive, Port2 is powered by the output Port (first power supply Port) connected to Port1, and the method for determining whether Port2 is connected to the load is the same as that when the switch Q1 is turned off.

In the embodiment of the present invention, in order to further reduce circuit elements in the load connection identification circuit, the power LDO may not be provided in the circuit, but the third GPIO terminal (GPIO1) of the processor 31 is connected to the VBUS terminal of the second power supply port 50 as shown in fig. 3, so that when the second switching tube 60 is turned off, the processor 31 may determine whether the load is connected to the USB interface connected to the second power supply port 50 through the high-level voltage change output by default at the third GPIO terminal. As shown in fig. 3, when the second switch transistor 60(Q1) of the Port1 to the Port2 is in an off state, the third GPIO terminal of the processor 31 (protocol chip) is connected to the output of the Port2, the default output of the third GPIO terminal is high level, once the Port2 is connected with a load (load 2), the GPIO1 terminal has insufficient current capability to cause the voltage drop of the terminal itself, when the voltage output by the third GPIO terminal drops to a threshold value, the protocol chip considers that the Port2 is connected with the load, and then the protocol chip can reduce the output voltage of the Port1 to a safe voltage and then turn on the Q1. When the second switch 60(Q1) of Port1 to Port2 is in the conducting state, the output voltage at the output Port of the charger is composed of two voltage signals, i.e. a direct current voltage and an alternating current voltage: 1) the switching power supply outputs expected useful direct-current voltage signals; 2) ripple voltage, which is an undesirable alternating voltage signal output by the switching power supply but inevitably exists; by utilizing the characteristic that the transformer 11(T1) can only couple alternating current signals, ripple voltage in the output voltage of the USB interface (Port2) connected with the third GPIO terminal can be coupled out and amplified into alternating current voltage (Vac _ signal) with higher amplitude; the rectifying circuit 12 can convert the amplified alternating current voltage (Vac _ signal) into a direct current voltage (Vdc _ signal), so that after the parameters of the transformer 11, the first capacitor (C3) and the second resistor (R3) are reasonably adjusted, the difference between the Vdc _ signal voltage of the Port2 connected with the load and the Vdc _ signal voltage of the Port2 not connected with the load is large (about 1V), and whether the Port2 is connected with the load or not can be effectively distinguished by utilizing the voltage difference; in the judgment circuit 20, the first switch tube (Q3) can be controlled to be turned on or off by the Vdc _ signal to obtain a voltage signal (first level signal) with logic high or logic low, for example, when the Vdc _ signal is greater than or equal to Vbe (threshold), the Q3 is turned on, the voltage of the first GPIO terminal (GPIO3) of the processor 31 (protocol chip) is pulled down to be close to 0V, that is, the first level signal is logic low (low level signal), at this time, the protocol chip considers that the Port2 is connected with a load, and the switch control circuit 32 can control the Q1 to keep a conducting state; when Vdc _ signal < Vbe, Q3 is turned off, the voltage at the first GPIO terminal (GPIO3) of the processor 31 (protocol chip) is pulled up to VCC voltage, that is, the first level signal is logic high (high level signal), at this time, the protocol chip considers that Port2 is not connected to a load, that is, the load 2 is pulled out from the Port2, Q1 can be controlled to be turned off through the switch control circuit 32, and subsequently, Port1 can be controlled to start the fast charging protocol.

That is to say, the load connection identification circuit provided by this embodiment can avoid the sacrifice of system efficiency because no current detection resistor is used, and can reduce the output current identification blind area from about 400mA in the prior art to below 30mA, thereby improving the identification accuracy of load connection; and the number and cost of elements in the circuit can be reduced, and the layout area of the circuit board can be reduced.

Correspondingly, in order to further ensure the use safety of the circuit, as shown in fig. 3, the load connection identification circuit provided in this embodiment may further include: a second diode (D2); the third GPIO terminal (GPIO1) of the processor 31 is connected to the anode of the second diode, and the cathode of the second diode is connected to the VBUS terminal of the second power supply port 50, that is, the third GPIO terminal of the processor 31 is connected to the VBUS terminal of the second power supply port 50 through the second diode, so as to prevent the current from reversely flowing into the third GPIO terminal of the processor 31.

It can be understood that, in this embodiment, the output ports (i.e., power supply ports) of two switching power supplies in 2 multi-port chargers are taken as an example for illustration, and for a multi-port charger with 3 or more power supply ports, i.e., a multi-port charger with 3 or more switching power supplies, the load connection identification circuit provided in this embodiment may be correspondingly configured in the same or similar manner, as long as it can determine whether the USB interface connected to the output port is connected to the load by using the ripple signal in the output of the power supply port, which is not limited in this embodiment.

Specifically, the embodiment does not limit the specific Type of the USB interface connected between the first power supply port 40 and the second power supply port 50, for example, the USB interface connected to the second power supply port 50 may be a USB-a interface or a Type-C interface.

In this embodiment, the ripple signal of the second power supply port 50 is detected by the arrangement and coupling of the ripple detection circuit 10, and since whether the second power supply port 50 is connected to the load or not affects the ripple signal, the determination circuit 20 can determine whether the second power supply port 50 is connected to the load or not according to the detected magnitude of the ripple signal, and output the determination result to the control circuit 30, so that the control circuit 30 can identify the load connection state of the second power supply port 50 and correspondingly control the output of the second power supply port 50; the embodiment of the invention avoids the use of a current sampling resistor, can avoid the increase of heating points and system power loss, and improves the system efficiency; and the identification blind area of the output current is reduced, and the identification accuracy of load connection is improved.

The embodiments are described in a progressive manner in the specification, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.

It is further noted that, in the present specification, relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

The load connection identification circuit of the switching power supply and the multi-port charger provided by the invention is described in detail above. The principles and embodiments of the present invention are explained herein using specific examples, which are presented only to assist in understanding the method and its core concepts. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.

Claims

1. A load connection identification circuit of a switching power supply, comprising:

2. The load connection identification circuit of the switching power supply according to claim 1, wherein the amplifying circuit is a transformer;

3. The load connection identification circuit of the switching power supply according to claim 1, wherein when the amplified signal is an ac voltage signal, the ripple detection circuit further comprises a rectifier circuit for converting the amplified signal into a corresponding dc signal;

4. The load connection identification circuit of the switching power supply according to claim 3, wherein the judgment circuit comprises: a first resistor and a first switch tube;

5. The load connection identification circuit of a switching power supply according to claim 2, wherein the first end of the primary winding of the transformer is connected to the VBUS terminal of the outlet.

6. A load connection identification circuit of a multi-port charger at least comprises a first power supply port and a second power supply port, wherein the first power supply port and the second power supply port are connected through a second switch tube; it is characterized by also comprising: the ripple detection circuit, the judgment circuit and the control circuit;

7. The load connection identification circuit of a multi-port charger according to claim 6, wherein the amplifying circuit is a transformer;

8. The load connection identification circuit of claim 6, wherein when the amplified signal is an ac voltage signal, the ripple detection circuit further comprises a rectifying circuit for converting the amplified signal into a corresponding dc signal;

9. The load connection identification circuit of a multi-port charger according to claim 8, wherein the judgment circuit comprises: a first resistor and a first switch tube;

10. The load connection identification circuit of the multi-port charger according to claim 9, wherein the first switching tube is an NPN-type triode;

11. The load connection identification circuit of a multi-port charger according to claim 8, wherein said rectifying circuit comprises: the circuit comprises a first diode, a first capacitor and a second resistor;

12. The load connection identification circuit of claim 6, wherein the VBUS terminal of the first power port and the VBUS terminal of the second power port are connected through the second switch tube.

13. The load connection identification circuit of a multi-port charger according to any one of claims 6 to 12, wherein the judgment circuit comprises: a processor and a switch control circuit;

14. The load connection identification circuit of claim 13, wherein the third GPIO terminal of the processor is connected to the VBUS terminal of the second power port.

15. The load connection identification circuit of a multi-port charger of claim 14, wherein the control circuit further comprises: a second diode;

16. The load connection identification circuit of claim 13, wherein the switch control circuit comprises: a third resistor, a fourth resistor and a third switching tube;