CN203827185U - Switching power supply circuit being compatible with various communication command and supporting multistage buck-boost - Google Patents

Abstract

The utility model discloses a switching power supply circuit being compatible with various communication commands and supporting multistage buck-boost. The switching power supply circuit comprises an AC input rectifying and EMI filtering circuit, a flyback switching circuit, a control circuit, a power supply circuit, an output rectifying and filtering circuit, a feedback sampling circuit, an overshoot absorption circuit, a command protocol receiving and coding circuit and a command transmission circuit, wherein an input end of the AC input rectifying and EMI filtering circuit is connected with an AC power supply, and an output end is connected with an input end of the power supply circuit; an input end of the flyback switching circuit is connected with an output end of the control circuit and an output end of the overshoot absorption circuit, and an output end is connected with an input end of the output rectifying and filtering circuit; and an input end of the control circuit is connected with an output end of the power supply circuit and an input end of the feedback sampling circuit, and the output end is connected with the input end of the flyback switching circuit, an input end of the command protocol receiving and coding circuit and an input end of the command transmission circuit.

Description

Compatible with a variety of communication commands and a switching power supply circuit that supports multi-level buck-boost

technical field

The utility model relates to the field of circuits, in particular to a switching power supply circuit with the characteristics of supporting reception of various communication commands and adjustable output voltage.

Background technique

Currently, conventionally designed switching power supply chargers on the market are only compatible with one communication protocol, so they can only charge one type of portable device. As an example, FIG. 1 shows an exemplary block diagram of a switching power supply system supporting only one protocol solution in the prior art. As shown in FIG. 1 , in a switching power supply system that supports only one protocol scheme (for example, a Class A communication command such as a current signal), the Class A portable device 100 sends a Class A communication command to the switching power supply 200 through its main control chip 101 The decoding chip 201 in the switching power supply 200 decodes the instruction and controls the output power through the power control module 202, so as to provide adjustable electric energy to the load module 102 of the portable device. However, due to the incompatibility of the commands, the switching power supply 200 cannot provide the function of output regulation to other portable devices other than Class A portable devices.

As another example, FIG. 2 shows an exemplary diagram of a secondary-side controlled switching power supply fast charging circuit that supports only one protocol scheme in the prior art. As shown in Figure 2, Class B portable devices only support one protocol scheme (such as Class B communication commands such as voltage signals), and provide commands to the control circuit of the switching power supply through receivers that only support Class B communication commands, thereby controlling power supply A circuit charges the portable device. Likewise, this switching power supply cannot provide the function of output regulation to other portable devices other than Class B portable devices.

And when charging different portable devices, because the communication commands sent by the portable devices are different, it is often necessary to replace different power chargers to charge them. Obviously, this has brought great trouble to the operation of the operator.

Therefore, there is an urgent need for a switching power supply circuit that is compatible with different communication protocols (commands) and has a flexible and adjustable output voltage.

Utility model content

At least to solve the above technical difficulties, the utility model provides a switching power supply circuit with low design and manufacturing costs, simple circuit structure, good compatibility and adjustable output voltage and current.

The switching power supply circuit according to the utility model includes AC input rectification, EMI filter circuit, flyback switch circuit, control circuit, power supply circuit, output rectification filter circuit, feedback sampling circuit, overshoot absorption circuit, instruction protocol receiving encoding circuit and instruction Transmission circuit, wherein: the input end of the AC input rectification and EMI filter circuit is connected to the AC power supply, the output end is connected to the input end of the power supply circuit; the input end of the flyback switch circuit is connected to the output end of the control circuit and the overshoot absorption circuit The output terminal is connected, the output terminal is connected with the input terminal of the output rectification filter circuit; the input terminal of the control circuit is connected with the output terminal of the power supply circuit, the input terminal of the feedback sampling circuit, and the output terminal is connected with the input terminal of the flyback switching circuit 1. The input end of the instruction protocol receiving encoding circuit is connected with the input end of the instruction transmission circuit; the input end of the power supply circuit is connected with the output end of the AC input rectification and EMI filter circuit, and the output end is connected with the input end of the feedback sampling circuit and the control circuit The input end of the output rectification filter circuit is connected with the output end of the flyback switch circuit, and the output end is connected with the load and the input end of the command protocol receiving encoding circuit; the input end of the feedback sampling circuit is connected with the power supply circuit The output terminal is connected to the input terminal of the control circuit, and the output terminal is connected to the input terminal of the overshoot absorption circuit; the input terminal of the overshoot absorption circuit is connected to the output terminal of the feedback sampling circuit, and the output terminal is connected to the input terminal of the flyback switch circuit The input end of the instruction protocol receiving encoding circuit is connected with the output end of the control circuit, the output end of the output rectification filter circuit and the output end of the instruction transmission circuit, and the output end is connected with the load; and the input end of the instruction transmission circuit It is connected with the output end of the control circuit, and the output end is connected with the input end of the output rectification filter circuit and the input end of the instruction protocol receiving encoding circuit.

The charging circuit of the switching power supply of the utility model contains decoding circuits of various mainstream communication protocols on the market, and the communication commands sent by different types of portable devices can be well identified, so as to distinguish whether it is a type A device or a type B device , or Class C equipment, the switching power supply charger designed by the switching power supply circuit of the utility model can charge different types of equipment on the market with only one charger, and output voltages of different levels according to different communication commands. While greatly improving the charging efficiency of the system, it also greatly improves the compatibility with various types of portable devices.

For example, when a manufacturer is producing a charger for a portable device, it only needs to manufacture a charging device for the decoding circuit, which can be well compatible with almost all portable devices on the market, which greatly saves system manufacturing costs and safety certification. cost. And in the future, the number of chargers on the market may be greatly reduced, thereby greatly reducing the environmental pollution caused by the discarding of a large number of waste chargers in the past.

The switching power supply provided by the utility model is applied in the field of battery charging of portable devices, and can be applied to charging occasions of various types of portable devices, which can greatly save system cost.

Description of drawings

Can understand the utility model better from the following in conjunction with accompanying drawing to the description of the specific embodiment of the utility model, wherein:

Fig. 1 shows an exemplary block diagram of a switching power supply system that only supports one protocol scheme in the prior art;

FIG. 2 shows an exemplary diagram of a secondary-side controlled switching power supply fast charging circuit that only supports another protocol scheme in the prior art;

FIG. 3 shows a schematic block diagram of a multi-communication protocol compatible solution according to an embodiment of the present invention;

Fig. 4 shows an exemplary connection method of a switching power supply circuit according to an embodiment of the present invention;

Fig. 5 shows another exemplary connection method of a switching power supply circuit according to an embodiment of the present invention;

Fig. 6 shows a detailed illustration of a connection method of a switching power supply circuit according to an embodiment of the present invention;

FIG. 7 shows an exemplary method of controlling the fall time when the voltage is dropped by an external resistor;

FIG. 8 shows another exemplary method of controlling the fall time when the voltage is dropped by an external resistor;

Fig. 9 shows an exemplary connection of the power supply circuit of the switching power supply circuit according to the embodiment of the present invention;

Fig. 10 shows another exemplary connection of the power supply circuit of the switching power supply circuit according to the embodiment of the present invention; and

FIG. 11 shows various exemplary connection methods of the overshoot absorbing circuit of the switching power supply circuit according to the embodiment of the present invention.

Detailed ways

Features and exemplary embodiments of various aspects of the present invention will be described in detail below. The following description covers numerous specific details in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without some of these specific details. The following description of the embodiments is only to provide a clearer understanding of the present invention by showing examples of the present invention. The utility model is by no means limited to any specific configuration proposed below, but covers any modification, substitution and improvement of related elements or components without departing from the spirit of the utility model.

The switching power supply circuit according to the embodiment of the utility model is composed of two parts, one part is the primary side feedback PWM control main control chip, and the other part is the communication protocol receiving and encoding chip.

According to an embodiment, FIG. 3 shows a schematic block diagram of a multi-communication protocol compatibility solution according to an embodiment of the present invention. As shown in FIG. 3 , a switching power supply 300 includes a power device 301 connected to a power supply input 310, command protocol receiving encoding circuits (command receivers) 302 and 305, a control chip 304, and optionally includes isolation components between the above components 303. The power device 301 outputs power to the connected portable device 302 , and different types of portable devices send different output voltage adjustment instructions (such as instruction A, instruction B) to the switching power supply.

In Figure 3, the power supply part is suitable for various power supply methods such as AC or DC power supply. Different types of portable devices send different output voltage adjustment instructions to the switching power supply, and the transmission method can include current transmission or voltage transmission, including multiple encoding methods such as single-wire or multi-wire. Command types include current pulse, voltage pulse, digital pulse signal, PWM pulse voltage and other commands. Switching power supply types include various circuit structures such as isolated and non-isolated types. In the isolated circuit structure, the feedback method is suitable for the primary side feedback method. In addition, the switching power supply power conversion topology includes buck Buck, boost Boost, buck-boost Various circuit topologies such as Buck-Boost, Flyback, and Forward.

For the convenience of explaining the content of the present utility model, according to an embodiment, a flyback switching power supply for an external charger of a mobile phone is used as an example for illustration. However, those skilled in the art should understand that the scope of coverage of the present utility model It is not limited to the following example applications, but has a wider range of applications.

Fig. 4 shows an exemplary connection method of a switching power supply according to an embodiment of the present invention. In Fig. 4, the circuit adopts AC input, and the circuit structure is an isolated flyback switching power supply circuit. The type A command issued by the secondary side load device is to control the change of the output voltage by transmitting the change to the primary chip U1 through the flyback transformer T1-A through the way that the output load current changes according to a specific rule. And if the load device sends a B-type command (for example, the voltage pulse or voltage level changes according to a specific pattern), the B-type command can enter the chip U3 through the data receiving terminal D- and/or D+, and the chip U3 recognizes the B-type After the instruction, it is encoded, so that the encoded signal is transmitted to the primary chip U1 through the photocoupler U2-A, and is used to control the change of the output voltage.

Fig. 5 shows another exemplary connection method of the switching power supply circuit according to the embodiment of the present invention. As shown in Figure 5, according to the different ways of starting the line and power supply, the circuit can also derive another form of circuit connection. For example, the control chip U1 of the control circuit may have 8 pins. And the resistor R2 between the input rectification filter circuit and the power supply circuit can be connected between the input rectification filter circuit and the GATE pin of the control chip U1 of the control circuit to provide different controllable power supply modes.

FIG. 6 shows a detailed illustration of a connection method of a switching power supply circuit according to an embodiment of the present invention. As shown in Figure 6, the adjustable flyback switch circuit according to the embodiment of the utility model mainly includes the following components: AC input rectification, EMI filter circuit (1), flyback switch circuit (2), control circuit (3), Power supply circuit (4), output rectification and filtering circuit (5), feedback sampling circuit (6), overshoot absorbing circuit (7), instruction protocol receiving encoding circuit (8), and instruction transmission circuit (9).

The AC input rectification and EMI filter circuit (1) may include a fuse FUSE, a bridge rectifier, and an X capacitor. The AC input rectification and EMI filter circuit (1) may also include other common connections in the field between the two points AB.

The flyback switch circuit (2) may include a flyback transformer T1-A, a switch MOSFET or BJT transistor Q2, and a primary side current sampling resistor part R7.

The main device of the control circuit (3) is a PWM control chip and necessary peripheral auxiliary components. In this embodiment, it is a control chip with six function pins (pin) or eight function pins, wherein (not according to the pin position order):

VDD: power supply input pin, used for chip power supply startup, connected to the power supply circuit (4),

FB: Feedback sampling pin, used to detect the output voltage, connected to the feedback sampling circuit (6),

GND: chip ground, the reference ground of the chip,

GATE: Gate drive pin, used to control the switch of power MOSFET or BJT triode, connected with the flyback switch circuit (2),

CS: Current sampling pin, used to detect the primary current of the transformer, collect voltage information on the sampling resistor R7, and connect to the flyback switch circuit (2),

DATA: communication command pin, used to receive the command information for adjusting the output voltage and current transmitted by the load device, and connected to the command protocol transmission circuit (8),

SOURCE: source level pin, with this pin in the circuit using an eight-pin chip, connected to the MOSFET source level or the emitter of the BJT triode in the flyback switch circuit (2), and

CMP: loop compensation pin, with this pin in the circuit using eight-pin chip, external loop compensation capacitor, used to improve the loop response and stability of the negative feedback system.

The instruction protocol receiving encoding circuit (8) is a decoding encoding chip with 6 functional pins, which can receive but not limited to the following signals: voltage level signal, current level signal, PWM pulse modulation signal, digital encoding signal, etc. And in the present embodiment, the pin of instruction protocol receiving encoding circuit (8) is as follows (not in pin order):

VDD: power supply pin, which is used to start the chip power supply and connect to the output part (5) of the main control circuit,

GND: chip ground, the reference ground of the chip,

D+: Data is receiving terminal pin,

D-: data negative receiving terminal pin,

VD: signal transmission pin, the encoded pulse of this pin is transmitted to the PWM control chip (3) through the optocoupler transmission circuit (9), and

VP: Connect the PWM main control chip (3) to output Vbus through R8, and control the time when the output voltage drops. As an example, FIG. 7 shows an exemplary method in which an external resistor is used to control the falling time of the output voltage.

According to another embodiment, FIG. 8 shows another exemplary method of output voltage drop control without an external resistor.

In addition, in addition to the connection shown in Figure 6, there are other connections between points A and B of the power supply circuit (4). For example, according to one embodiment, Fig. 9 shows an exemplary connection of the power supply circuit of the switching power supply circuit according to the embodiment of the present utility model; Fig. 10 shows the power supply of the switching power supply circuit according to the embodiment of the present utility model Another exemplary connection of the circuit. As shown in FIG. 9 , point A can be connected to point B through a switch Q1 through a resistor R3 ; or, as shown in FIG. 10 , point A can be directly connected to point B through a resistor R3 .

As shown in Figure 6, the output rectification filter circuit (5) can include three main parts: an output rectification diode D8, a filter capacitor C6, and an input dummy load. According to the needs of EMI, the output rectification diode D8 can be connected in parallel with an RC snubber circuit. For different output ripple requirements, the output filter circuit can add a π-type filter circuit or a common-mode filter circuit. Other common connections in the field may also be included between the two points AB of the output rectification filter circuit (5).

The feedback sampling circuit (6) may include a transformer auxiliary winding T1-B, and a voltage dividing resistor network composed of one or more resistors R4, R5, so as to detect output voltage information.

The overshoot absorbing circuit (7) may include three parts: a absorbing resistor R6, a absorbing capacitor C5 and a one-way diode D7. According to an embodiment, FIG. 11 shows various exemplary connection methods of the overshoot absorbing circuit of the switching power supply circuit according to the embodiment of the present invention. In addition, the connection between points A and B in the overshoot absorbing circuit (7) may also include but not limited to the connection method as shown in FIG. 11 .

The command transmission circuit (9) may include one or more current limiting resistors R9, optocouplers U2-BA, U2-B. The command transmission circuit (9) is connected between the primary side feedback PWM controller (3), the output circuit (5) and the command protocol receiving and encoding circuit (8). When the instruction protocol receiving encoding circuit (8) receives the boost or buck signal provided by the portable mobile device, it will give different types of signals through internal conversion, including but not limited to: voltage level signal, PWM pulse modulation signal, digital code signal etc. The signal is transmitted to the primary measurement of the PWM controller (3) through the optocoupler to realize the multi-stage output of the output voltage of the secondary side.

The switching power supply circuit provided by the utility model has the following advantages: low manufacturing cost, simple circuit structure, good compatibility and adjustable output voltage and current.

The utility model has been described above with reference to the specific embodiments of the utility model, but those skilled in the art will understand that various modifications, combinations and changes can be made to these specific embodiments without departing from the requirements set by the appended claims or Its equivalents define the spirit and scope of the present invention. Furthermore, any signal arrows in the figures should be considered as illustrative only, and not restrictive, unless specifically indicated otherwise. Combinations of components or steps are also considered to have been recited when terms are foreseen to obscure the ability to separate or combine.

Claims (11)

1. A switching power supply circuit, including AC input rectification, EMI filter circuit, flyback switch circuit, control circuit, power supply circuit, output rectification filter circuit, feedback sampling circuit, overshoot absorption circuit, command protocol receiving encoding circuit and command transmission circuit, where: The input end of the AC input rectification and EMI filter circuit is connected to the AC power supply, and the output end is connected to the input end of the power supply circuit; The input end of the flyback switch circuit is connected to the output end of the control circuit and the output end of the overshoot absorption circuit, and the output end is connected to the input end of the output rectification filter circuit; The input end of the control circuit is connected to the output end of the power supply circuit and the input end of the feedback sampling circuit, and the output end is connected to the input end of the flyback switch circuit and the input end of the instruction protocol receiving encoding circuit And the input terminal of the instruction transmission circuit is connected; The input end of the power supply circuit is connected to the output end of the AC input rectification and EMI filter circuit, and the output end is connected to the input end of the feedback sampling circuit and the input end of the control circuit; The input end of the output rectification filter circuit is connected to the output end of the flyback switch circuit, and the output end is connected to the load and the input end of the instruction protocol receiving encoding circuit; The input end of the feedback sampling circuit is connected to the output end of the power supply circuit and the input end of the control circuit, and the output end is connected to the input end of the overshoot absorption circuit; The input end of the overshoot absorbing circuit is connected to the output end of the feedback sampling circuit, and the output end is connected to the input end of the flyback switch circuit; The input end of the instruction protocol receiving encoding circuit is connected to the output end of the control circuit, the output end of the output rectification filter circuit and the output end of the instruction transmission circuit, and the output end is connected to the load; and The input end of the instruction transmission circuit is connected to the output end of the control circuit, and the output end is connected to the input end of the output rectification filter circuit and the input end of the instruction protocol receiving and encoding circuit. the 2. The switching power supply circuit according to claim 1, wherein the control circuit includes a pulse width modulation PWM control chip, and the PWM control chip includes: The power supply input pin is used to supply power to the control chip and is connected to the output terminal of the power supply circuit; The feedback sampling pin is used to detect the output voltage of the switching power supply circuit and is connected to the input terminal of the feedback sampling circuit; The chip ground pin is used as the reference ground of the control chip; The driving pin is used to drive the switching tube in the flyback switching circuit, and is connected to the input terminal of the flyback switching circuit; The current sampling pin is used to sample the primary current of the transformer in the flyback switch circuit, and is connected to the output terminal of the flyback switch circuit; and The communication instruction pin is used to receive instruction information for adjusting the output voltage and current transmitted by the load, and is connected to the input end of the instruction transmission circuit. the 3. The switching power supply circuit according to claim 2, characterized in that, in the circuit using an eight-pin chip, the PWM control chip also includes: a loop compensation pin, an external loop compensation capacitor, for improving the negative feedback system Loop response and stability. the 4. The switching power supply circuit according to claim 2, characterized in that, in the circuit using an eight-pin chip, the PWM control chip also includes: a source level pin for connecting with the MOSFET source in the flyback switching circuit level or the emitter of a BJT transistor. the 5. The switching power supply circuit according to claim 2, wherein the instruction protocol receiving and encoding circuit includes a decoding and encoding chip, and the decoding and encoding chip includes: The power supply pin is used to start the power supply of the chip and is connected to the output terminal of the control circuit; The chip ground pin is used as the reference ground of the control chip; C: D+ pin, used as the positive receiving end of data; D: D-pin, used as the data negative receiving end; and E: VD pin, the pin used for signal transmission, the E: code pulse of VD pin is transmitted to the PWM control chip. the 6. The switching power supply circuit according to claim 5, characterized in that, the decoding and encoding chip further comprises: F: VP pin, connected to the PWM control chip through a resistor, or directly connected to the PWM control chip, with In the output voltage signal to control the length of time when the output voltage drops. the 7. The switching power supply circuit according to claim 1, characterized in that the switching power supply circuit further comprises an optocoupler transmission circuit connected between the control circuit and the instruction protocol receiving encoding circuit for transmitting encoded pulses. the 8. The switching power supply circuit according to claim 1, wherein the output rectification filter circuit comprises an output rectification diode and a filter capacitor. the 9. The switching power supply circuit according to claim 8, wherein the output rectification filter circuit further comprises a π-type filter circuit and/or a common-mode filter circuit. the 10. The switching power supply circuit according to claim 1, wherein the feedback circuit is composed of a sampling resistor. the 11. The switching power supply circuit according to claim 1, characterized in that, the output voltage is controlled through the regular change of the output load current and through the coupling of the transformer. the