Switching power supply self-adaptive to specific LED low-voltage lamp strip (including small load) voltage

Abstract

The invention discloses a switching power supply self-adaptive to specific voltage of a light-emitting diode (LED) low-voltage lamp strip (including a small load), which comprises a high-voltage rectification and control circuit (W1), an isolation transformer and low-voltage rectification circuit (W2) and an LED lamp strip voltage identification and self-adaptive circuit (W3), and is characterized in that the high-voltage rectification and control circuit (W1) is connected to a main line of an alternating-current power supply; the isolation transformer and low-voltage rectification circuit (W2) is connected to the high-voltage rectification and control circuit (W1), the LED lamp strip voltage identification and self-adaptive circuit (W3) is connected to the isolation transformer and low-voltage rectification circuit (W2), and the LED lamp strip voltage identification and self-adaptive circuit (W3) is connected with the high-voltage rectification and control circuit (W1). The invention relates to the field of switching power supply design and LED application, in particular to a switching power supply self-adaptive to the voltage of a specific LED low-voltage lamp strip (including a small load).

Description

Technical Field

[0001] The present invention relates to the technical fields of switching power supply design and LED application technology, and particularly relates to a switching power supply that adapts to the voltage of a specific LED low-voltage light strip (including small loads). Background Art

[0002] LED low-voltage light strips are increasingly used in the fields of home decoration and industrial decoration due to their diverse types, flexible cutting, and low-voltage safety characteristics. The switching power supplies that supply power to the LED low-voltage light strips have also developed vigorously. In different usage scenarios, the series and parallel numbers of LED lamp beads are often different. The commonly used supply voltages for LED low-voltage light strips in the market are DC12V, DC24V, and DC48V. Therefore, it is necessary to match the switching power supplies with corresponding voltages for LED light strips with different supply voltages. This undoubtedly increases the product categories for power supply manufacturers, requires dealers to prepare inventories of multiple voltage specifications, and for end-users, multiple voltage specifications increase the probability of errors. When we go to the site to handle customer complaints, we often find situations where the voltage of the switching power supply does not match the voltage of the LED low-voltage light strip: an LED low-voltage light strip with a high voltage is wrongly paired with a switching power supply with a low voltage - the lamp cannot be lit; an LED light strip with a low voltage is paired with a switching power supply with a high output voltage, damaging the light strip. The first situation is easy to detect and can be solved during the construction process; the second situation is not easy to detect. The light strip with too high a voltage can also light up for a period of time, but this situation is very dangerous: the lamp beads will eventually be damaged due to excessive temperature, and there is a risk of fire, causing economic losses to the customers.

[0003] In existing solutions, some manufacturers add LED digital tubes or liquid crystal screens to the switching power supply to indicate its output voltage, and some manufacturers add buttons on top of the display to allow customers to switch different output voltages through the buttons. These practices all require manual identification and intervention, increasing the workload of users and cannot fundamentally solve the problem of wrongly connecting voltages. Even new risks may be introduced: if a customer connects a 12V light strip and accidentally adjusts the output voltage to 48V with the button, the light strip even has the risk of being instantly burned out. Customers often mention that they hope to make a switching power supply that adapts to the voltage of a specific LED low-voltage light strip. Summary of the Invention

[0004] In view of the above technical problems, the present invention provides a switching power supply that adapts to the voltage of a specific LED low-voltage light strip (including small loads).

[0005] The technical solution of the present invention is as follows: The present invention is a switching power supply that adapts to the voltage of a specific LED low-voltage light strip (including small loads), including a high-voltage rectification and control circuit (W1), an isolation transformer and a low-voltage rectification circuit (W2), and an LED light strip voltage identification and adaptation circuit (W3). The high-voltage rectification and control circuit (W1) is connected to the AC power supply main line. The isolation transformer and the low-voltage rectification circuit (W2) are connected to the high-voltage rectification and control circuit (W1). The LED light strip voltage identification and adaptation circuit (W3) is connected to the isolation transformer and the low-voltage rectification circuit (W2), and the LED light strip voltage identification and adaptation circuit (W3) is connected to the high-voltage rectification and control circuit (W1).

[0006] The LED light strip voltage identification and adaptation circuit (W3) includes an input positive pole Vinput, a power supply negative pole GND, a power supply and system voltage sampling circuit (W301), an MCU control unit (W302), a low-side wire change, overload detection, short-circuit detection and current sampling circuit (W303), a programmed opto-isolation feedback circuit (W304), a high-side wire change and light strip voltage sampling circuit (W305), a display part circuit (W306), an FB signal, a high-voltage GND, a light strip interface LED+ and a light strip interface LED-.

[0007] The MCU control unit (W302) is sequentially connected to the power supply and system voltage sampling circuit (W301), the low-side wire change, overload detection, short-circuit detection and current sampling circuit (W303), the programmed opto-isolation feedback circuit (W304), the high-side wire change and light strip voltage sampling circuit (W305), and the display part circuit (W306). The low-side wire change, overload detection, short-circuit detection and current sampling circuit (W303) is connected to the light strip interface LED-. The programmed opto-isolation feedback circuit (W304) is connected to the high-voltage rectification and control circuit (W1). The high-side wire change and light strip voltage sampling circuit (W305) is connected to the light strip interface LED+. The power supply and system voltage sampling circuit (W301), the programmed opto-isolation feedback circuit (W304), and the high-side wire change and light strip voltage sampling circuit (W305) are commonly connected to the positive pole Vinput. The power supply and system voltage sampling circuit (W301), the MCU control unit (W302), the low-side wire change, overload detection, short-circuit detection and current sampling circuit (W303), the programmed opto-isolation feedback circuit (W304), the high-side wire change and light strip voltage sampling circuit (W305), and the display part circuit (W306) are commonly connected to the power supply negative pole GND.

[0008] Further, the power supply and system voltage sampling circuit (W301) includes a positive electrode Vinput, a power supply negative electrode GND, a positive electrode VCC of the single-chip microcomputer power supply, a system voltage sampling port ADC1, a DCDC step-down power supply circuit (W30101), and a voltage dividing circuit (W30102). The positive electrode VCC of the single-chip microcomputer power supply is connected to the DCDC step-down power supply circuit (W30101), the system voltage sampling port ADC1 is connected to the voltage dividing circuit (W30102), the DCDC step-down power supply circuit (W30101) and the voltage dividing circuit (W30102) are commonly connected to the positive electrode Vinput, and the DCDC step-down power supply circuit (W30101) and the voltage dividing circuit (W30102) are commonly connected to the power supply negative electrode GND.

[0009] Further, the low-side wire change, over-load detection, short-circuit detection, and current sampling circuit (W303) includes a light bar interface LED-, a power supply negative electrode GND, a low-side small current channel (W30301), a low-side small current dual-threshold detection circuit (W30302), a low-side large current short-circuit detection circuit (W30303), a low-side large current channel (W30304), a low-side large current sampling and amplification circuit (W30305), a low-side small current channel control terminal LG1, a low-side large current channel control terminal LG2, a low-side small current low-threshold feedback terminal CMP1, a low-side small current high-threshold feedback terminal CMP2, a low-side large current short-circuit feedback terminal CMP3, a low-side voltage signal VRCS, and a low-side large current sampling signal ADC3. The low-side small current channel (W30301) is connected to the low-side small current dual-threshold detection circuit (W30302), the low-side large current channel (W30304) is connected to the low-side large current sampling and amplification circuit (W30305), the low-side large current short-circuit detection circuit (W30303) is connected to the low-side large current sampling and amplification circuit (W30305) through the low-side voltage signal VRCS, the low-side small current channel control terminal LG1 is connected to the low-side small current channel (W30301), the low-side large current channel control terminal LG2 is connected to the low-side large current channel (W30304), the low-side small current low-threshold feedback terminal CMP1 is connected to the low-side small current dual-threshold detection circuit (W30302), the low-side small current high-threshold feedback terminal CMP2 is connected to the low-side small current dual-threshold detection circuit (W30302), the low-side large current short-circuit feedback terminal CMP3 is connected to the low-side large current short-circuit detection circuit (W30303), the low-side large current sampling signal ADC3 is connected to the low-side large current sampling and amplification circuit (W30305), the low-side small current channel (W30301) and the low-side large current channel (W30304) are commonly connected to the light bar interface LED-, and the low-side small current dual-threshold detection circuit (W30302), the low-side large current short-circuit detection circuit (W30303), and the low-side large current sampling and amplification circuit (W30305) are commonly connected to the power supply negative electrode GND.

[0010] Further, the programmed opto - electrical isolation feedback circuit (W304) includes a positive electrode Vinput, a power supply negative electrode GND, an FB signal, a high - voltage GND, a single - chip microcomputer port PWM, an opto - coupler isolator (W30401), a reference source circuit (W30402), and a voltage - controlled constant - current source circuit (W30403). The FB signal and the high - voltage GND are respectively connected to the opto - coupler isolator (W30401). The opto - coupler isolator (W30401) is connected to the reference source circuit (W30402). The reference source circuit (W30402) is connected to the voltage - controlled constant - current source circuit (W30403). The positive electrode Vinput is connected to the reference source circuit (W30402). The single - chip microcomputer port PWM is connected to the voltage - controlled constant - current source circuit (W30403). The reference source circuit (W30402) and the voltage - controlled constant - current source circuit (W30403) are commonly connected to the power supply negative electrode GND.

[0011] Further, the high - side line - change and strip - voltage sampling circuit (W305) includes a positive electrode Vinput, a power supply negative electrode GND, a strip interface LED+, a high - side large - current channel control terminal HG1, a high - side small - current channel control terminal HG2, a high - side strip - voltage sampling signal ADC2, a current - limiting resistor Rx, a high - side large - current channel (W30501), a high - side small - current channel (W30502), and a voltage - dividing circuit (W30503). The high - side large - current channel control terminal HG1 is connected to the high - side large - current channel (W30501). The high - side small - current channel control terminal HG2 is connected to the high - side small - current channel (W30502). The first end of the current - limiting resistor Rx is connected to the high - side small - current channel (W30502). The high - side strip - voltage sampling signal ADC2 is connected to the voltage - dividing circuit (W30503). The high - side large - current channel (W30501) and the high - side small - current channel (W30502) are commonly connected to the positive electrode Vinput. The high - side large - current channel (W30501), the high - side small - current channel (W30502), and the voltage - dividing circuit (W30503) are commonly connected to the power supply negative electrode GND. The high - side large - current channel (W30501), the second end of the current - limiting resistor Rx, and the voltage - dividing circuit (W30503) are commonly connected to the strip interface LED+.

[0012] The implementation process of the present invention adopting the above structure is as follows: The loads of the LED strip can be divided into two categories: small loads and large loads. Relatively speaking, large loads are easier to detect and identify. The present invention has improved the circuit and can also identify small-load LED strips and their voltages. According to the user's usage habits, the connection method between the LED strip and the switching power supply can be divided into two types: pre-connection type (connect the strip first and then power on the switching power supply) and post-connection type (power on the switching power supply first and then connect the LED strip without turning off the power). According to the actual usage situation, the present invention designs the following two identification processes: the voltage identification process of the pre-connected type LED low-voltage strip (see Figure 2 ), and the voltage identification process of the post-connected type LED low-voltage strip (see Figure 3 ).

[0013] The voltage identification process of the pre-connected LED low-voltage light strip is as follows: After the power is turned on, the voltage of the positive electrode Vinput at the initial power-on is relatively low. The power supply and system voltage sampling circuit (W301) starts to work first and activates the MCU control unit (W302). The MCU control unit (302) turns on the high-side large-current channel (W30501) through the high-side large-current channel control terminal HG1, and turns on the low-side large-current channel (W30304) through the low-side large-current channel control terminal LG2, connecting the low-side large-current sampling and amplification circuit (W30305). The programmable optoelectronic feedback circuit (W304) is controlled through the PWM port to raise the voltage of the positive electrode Vinput to the first voltage value. If there is an output at the low-side large-current short-circuit feedback terminal CMP3, it is determined that the load is short-circuited, and all current channels are closed and then reopened after a delay. If there is no output at the low-side large-current short-circuit feedback terminal CMP3, it is further determined whether there is an output of the low-side large-current sampling signal ADC3. If there is an output of the low-side large-current sampling signal ADC3, it is determined that a large-load LED light strip is connected, and the current channel opening state and the first voltage output at this time can be maintained. If there is no output of the low-side large-current sampling signal ADC3, it may be a small load, no load, or the voltage is not high enough. The MCU control unit (302) closes the low-side large-current channel (W30304) through the low-side large-current channel control terminal LG2, turns on the low-side small-current channel (W30301) through the low-side small-current channel control terminal LG1, and connects the low-side small-current dual-threshold detection circuit (W30302). If there is an output at the low-side small-current low-threshold feedback terminal CMP1, it is determined that a small-load LED light strip is connected, and the current channel opening state and the first voltage output at this time can be maintained. If there is no output at the low-side small-current low-threshold feedback terminal CMP1, it may be no load or the voltage is not high enough. At this time, the MCU control unit (302) closes the low-side small-current channel (W30301) through the low-side small-current channel control terminal LG1, turns on the low-side large-current channel (W30304) through the low-side large-current channel control terminal LG2, and controls the programmable optoelectronic feedback circuit (W304) through the PWM port to raise the voltage of the positive electrode Vinput to the Nth voltage value, and continue the above judgment process. When the voltage rises to the set maximum voltage, if the MCU control unit (302) still cannot detect the output of the low-side small-current low-threshold feedback terminal CMP1 of the low-side small-current channel (W30301), it is determined that there is no load, and thus the voltage identification process of the pre-connected LED low-voltage light strip ends.

[0014] The voltage identification process of the rear-connected LED low-voltage light strip is as follows: In the no-load state, the voltage of the positive electrode Vinput has risen to the set Nth voltage value. The MCU control unit (302) turns on the high-side large-current channel (W30501) through the high-side large-current channel control terminal HG1, and turns on the low-side small-current channel (W30301) through the low-side small-current channel control terminal LG1, connecting the low-side small-current dual-threshold detection circuit (W30302). If there is no output at the low-side small-current low-threshold feedback terminal CMP1 at this time, it indicates that it is still in the no-load state; if there is an output at the low-side small-current low-threshold feedback terminal CMP1 at this time, immediately detect the low-side small-current high-threshold feedback terminal CMP2. If there is no output at the low-side small-current high-threshold feedback terminal CMP2, it is determined that a small-load LED light strip is connected. At this time, the MCU control unit (302) closes the high-side large-current channel (W30501) through the high-side large-current channel control terminal HG1, turns on the high-side small-current channel (W30502) through the high-side small-current channel control terminal HG2, detects the high-side light strip voltage sampling signal ADC2, and can calculate the voltage of the small-load LED low-voltage light strip. Then, the MCU control unit (302) adjusts the voltage of the positive electrode Vinput to the voltage of the small-load LED light strip through the PWM port to control the programmable optoelectronic feedback circuit (W304), closes the high-side small-current channel (W30502) through the high-side small-current channel control terminal HG2, turns on the high-side large-current channel (W30501) through the high-side large-current channel control terminal HG1, and keeps the low-side small-current channel (W30301) turned on. At this time, the system enters the normal working state of the small light strip load; if there is an output at the low-side small-current high-threshold feedback terminal CMP2, it indicates that a large-load LED or a short-circuit abnormality may occur at this time. The MCU control unit (W302) closes the low-side small-current channel (W30301) through the low-side small-current channel control terminal LG1, turns on the low-side large-current channel (W30304) through the low-side large-current channel control terminal LG2, and connects the low-side large-current sampling and amplification circuit (W30305).At this time, if the low-side large current short-circuit feedback terminal CMP3 has an output, it is determined that the load is short-circuited, and all current channels are closed and reopened after a delay; if the low-side large current short-circuit feedback terminal CMP3 has no output, it is determined that the LED large load light bar is connected. At this time, the MCU control unit (302) closes the high-side large current channel (W30501) through the high-side large current channel control terminal HG1, opens the high-side small current channel (W30502) through the high-side small current channel control terminal HG2, detects the high-side light bar voltage sampling signal ADC2, and can calculate The voltage of the heavy-load LED low-voltage light strip is calculated, and then the MCU control unit (302) controls the programmable photoelectric feedback circuit (W304) through the PWM port to adjust the positive electrode Vinput voltage to the heavy-load LED light strip voltage, closes the high-side small current channel (W30502) through the high-side small current channel control terminal HG2, opens the high-side large current channel (W30501) through the high-side large current channel control terminal HG1, and the low-side large current channel (W30304) remains open. At this point, the system enters the normal working state of the heavy-load LED light strip. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the overall structure of a switching power supply capable of adaptively adjusting the voltage of a specific LED low-voltage light strip (including a small load) according to the present invention;

[0016] Figure 2 It is a schematic diagram of a voltage identification process of a pre-connected LED low-voltage light strip of a switching power supply that is adaptive to a specific LED low-voltage light strip (including a small load) voltage of the present invention;

[0017] Figure 3 It is a schematic diagram of the voltage identification process of a rear-accessible LED low-voltage light strip of a switching power supply that is adaptive to the voltage of a specific LED low-voltage light strip (including a small load) of the present invention;

[0018] Figure 4 It is a structural schematic diagram of a power supply and system voltage sampling circuit (W301) of a switching power supply that is adaptive to a specific LED low-voltage light strip (including a small load) voltage of the present invention;

[0019] Figure 5 It is a structural schematic diagram of a low-side line switching, overload detection, short-circuit detection and current sampling circuit (W303) of a switching power supply that is adaptive to a specific LED low-voltage light strip (including a small load) voltage of the present invention;

[0020] Figure 6 It is a structural schematic diagram of a program-controlled photoelectric isolation feedback circuit (W304) of a switching power supply that is adaptive to a specific LED low-voltage light strip (including a small load) voltage of the present invention;

[0021] Figure 7It is a schematic diagram of the high-side switching circuit and the strip voltage sampling circuit (W305) of a switching power supply that can adapt to the voltage of a specific LED low-voltage strip (including small loads) according to the present invention. Specific embodiments

[0022] In order to make the technical problems, technical solutions, and beneficial effects to be solved by the present application clearer and more understandable, the following further details the present application in conjunction with the accompanying drawings and embodiments. It should be understood that the embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0023] The present invention is a switching power supply that can adapt to the voltage of a specific LED low-voltage strip (including small loads). Its implementation principle is: with a single-chip microcomputer as the core, controllable high-side and low-side large-current and small-current channels are built. Utilizing the programmable characteristics of the single-chip microcomputer, the high-side large-current and small-current channels and the low-side large-current and small-current channels are flexibly paired and switched, thereby realizing the identification and adaptation of the voltage of the LED low-voltage strip (including small loads). According to the order of connecting the LED strip and powering on the switching power supply, it can be divided into two situations: pre-connection type (connect the LED strip first and then power on the switching power supply) and post-connection type (power on the switching power supply first and then connect the LED strip).

[0024] Voltage identification method for pre-connected LED low-voltage strips: After the power supply is started, the MCU control unit gradually increases the Vinput voltage from low to high through the PWM port, and detects the low-side large-current sampling signal ADC3, the low-side small-current low-threshold feedback terminal CMP1, the low-side small-current high-threshold feedback terminal CMP2, and the low-side large-current short-circuit feedback terminal CMP3 at each predetermined voltage node to determine whether an LED strip is connected. When an LED load is found after the voltage is increased to a certain voltage node, the voltage at this node is the voltage of the LED strip.

[0025] Voltage identification method for post-connected LED low-voltage strips: When the positive pole Vinput is increased to a fixed high voltage, the MCU control unit (W302) turns on the high-side small-current channel (W30502) through the high-side small-current channel control terminal HG2. The high-side small-current channel (W30502) supplies power to the LED strip after being connected in series with the current-limiting resistor Rx. On the premise that the Vinput voltage is known, by sampling the high-side strip voltage sampling signal ADC2, the MCU control unit (W302) can calculate the voltage of this unknown LED strip according to the voltage division circuit (W30503) and the resistance value of the Rx resistor.

[0026] Such as Figures 1-7As shown in the figure, the present invention is a switching power supply that can adapt to the voltage of a specific LED low-voltage light strip (including small loads), which includes a high-voltage rectification and control circuit (W1), an isolation transformer and a low-voltage rectification circuit (W2), and an LED light strip voltage identification and adaptation circuit (W3). The high-voltage rectification and control circuit (W1) is connected to the main line of the AC input power supply. The isolation transformer and the low-voltage rectification circuit (W2) are connected to the high-voltage rectification and control circuit (W1). The LED light strip voltage identification and adaptation circuit (W3) is connected to the isolation transformer and the low-voltage rectification circuit (W2). The LED light strip voltage identification and adaptation circuit (W3) is connected to the high-voltage rectification and control circuit (W1) through its internal programmed opto-isolation feedback circuit (W304). The LED light strip voltage identification and adaptation circuit (W3) internally includes a power supply and system voltage sampling circuit (W301), an MCU control unit (W302), a low-side wire change, overload detection, short-circuit detection, and current sampling circuit (W303), a programmed opto-isolation feedback circuit (W304), a high-side wire change and light strip voltage sampling circuit (W305), and a display part circuit (W306).

[0027] Further, the power supply and system voltage sampling circuit (W301) includes a positive electrode Vinput, a power supply negative electrode GND, a single-chip microcomputer power supply positive electrode VCC, a system voltage sampling port ADC1, a DCDC buck power supply circuit (W30101), and a voltage division circuit (W30102). In this circuit, the voltage change range of the positive electrode Vinput is large. Therefore, the selected DCDC buck power supply circuit (W30101) needs to be able to provide a stable VCC output within this wide voltage range to supply power to the MCU control unit (W302). The selected voltage division circuit (W30102) also needs to be compatible with the voltage change range of this positive electrode Vinput.

[0028] Further, the low-side line change, overload detection, short-circuit detection, and current sampling circuit (W303) includes a light bar interface LED-, a power supply negative electrode GND, a low-side small current channel (W30301), a low-side small current dual-threshold detection circuit (W30302), a low-side large current short-circuit detection circuit (W30303), a low-side large current channel (W30304), a low-side large current sampling and amplification circuit (W30305), a low-side small current channel control terminal LG1, a low-side large current channel control terminal LG2, a low-side small current low-threshold feedback terminal CMP1, a low-side small current high-threshold feedback terminal CMP2, a low-side large current short-circuit feedback terminal CMP3, a low-side voltage signal VRCS, and a low-side large current sampling signal ADC3. In this circuit, the MCU control unit (W302) can select to turn on the low-side small current channel (W30301) or the low-side large current channel (W30304) through the low-side small current channel control terminal LG1 and the low-side large current channel control terminal LG2, so as to match LED light bar loads of different sizes. By adjusting the detection threshold of the low-side small current dual-threshold detection circuit (W30302), the insertion detection of small-load LED light bars at the mA level can be achieved, thus solving the problem of difficult detection of small-load LED light bars. In this circuit, the key point for setting the action threshold of the low-side small current high-threshold feedback terminal CMP2 is that loads exceeding this threshold must be detectable by the low-side large current sampling and amplification circuit (W30305).

[0029] Further, the programmed opto-isolation feedback circuit (W304) includes a positive electrode Vinput, a power supply negative electrode GND, an FB signal, a high-voltage GND, a single-chip microcomputer port PWM, an opto-coupler isolator (W30401), a reference source circuit (W30402), and a voltage-controlled constant current source circuit (W30403). This circuit can realize the adjustment of the voltage of the positive electrode Vinput by the MCU control unit (W302). The specific working process is as follows: The PWM control signal from the MCU control unit is sequentially conducted to the high-voltage rectification and control circuit (W1) through circuits such as the voltage-controlled constant current source circuit (W30403), the reference source circuit (W30402), the opto-coupler isolator (W30401), the FB signal, and the high-voltage GND. After receiving this signal, the high-voltage rectification and control circuit (W1) will respond to this signal, and finally this response is conducted to the positive electrode Vinput through the isolation transformer and the low-voltage rectification circuit (W2), thereby changing the voltage value of the positive electrode Vinput.

[0030] Furthermore, the high-side line change and strip voltage sampling circuit (W305) includes a positive electrode Vinput, a power supply negative electrode GND, a strip interface LED+, a high-side large current channel control terminal HG1, a high-side small current channel control terminal HG2, a high-side strip voltage sampling signal ADC2, a current limiting resistor Rx, a high-side large current channel (W30501), a high-side small current channel (W30502), and a voltage dividing circuit (W30503). Among them, the high-side small current channel (W30502) is mainly used for voltage identification of the LED strip: when an LED strip with an unknown voltage is inserted, the MCU control unit (W302) turns on the high-side small current channel (W30502) through the high-side small current channel control terminal HG2. This high-side small current channel is connected to the LED strip after being connected in series with a current limiting resistor Rx, so that even if the voltage of the LED strip is low, it will not be damaged. On the premise that the Vinput voltage is known, the MCU control unit (W302) samples the high-side strip voltage sampling signal ADC2, and can calculate the voltage of this unknown LED strip according to the resistance values of the voltage dividing circuit (W30503) and the current limiting resistor Rx. Then, the MCU control unit can adjust the Vinput voltage to the working voltage of this LED strip through the PWM port.

[0031] It should be noted that the current limiting resistor Rx mainly plays a protective role. The principle for selecting its resistance value is: it is necessary to ensure that even if the current limiting resistor Rx is connected in parallel between Vinput and LED-, the heat generated will not cause any damage to the current limiting resistor Rx itself; in addition, the current value flowing through the current limiting resistor Rx cannot exceed the maximum current value that the small-load LED strip can withstand.

[0032] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A switching power supply that is adaptive to the voltage of a specific LED low-voltage light strip (including a small load), characterized by: The invention comprises a high-voltage rectification and control circuit (W1), an isolation transformer and a low-voltage rectification circuit (W2), and an LED light strip voltage identification and adaptive circuit (W3); the high-voltage rectification and control circuit (W1) is connected to an AC power main line; the isolation transformer and the low-voltage rectification circuit (W2) are connected to the high-voltage rectification and control circuit (W1); the LED light strip voltage identification and adaptive circuit (W3) is connected to the isolation transformer and the low-voltage rectification circuit (W2); and the LED light strip voltage identification and adaptive circuit (W3) is connected to the high-voltage rectification and control circuit (W1).

2. A switching power supply capable of self-adapting to a specific LED low-voltage light strip (including a small load) voltage according to claim 1, characterized in that: The LED light strip voltage identification and adaptive circuit (W3) includes a positive electrode Vinput, a negative power supply GND, a power supply and system voltage sampling circuit (W301), an MCU control unit (W302), a low-side line switching, overload detection, short circuit detection and current sampling circuit (W303), a programmable photoelectric isolation feedback circuit (W304), a high-side line switching and light strip voltage sampling circuit (W305), a display circuit (W306), an FB signal, a high-voltage GND, a light strip interface LED+ and a light strip interface LED-; The MCU control unit (W302) is connected to the power supply and system voltage sampling circuit (W301), the low-side line switching, overload detection, short-circuit detection and current sampling circuit (W303), the program-controlled photoelectric isolation feedback circuit (W304), the high-side line switching and light strip voltage sampling circuit (W305) and the display circuit (W306) in sequence. The low-side line switching, overload detection, short-circuit detection and current sampling circuit (W303) is connected to the light bar interface LED-, the program-controlled photoelectric isolation feedback circuit (W304) is connected to the high-voltage rectification and control circuit (W1), and the high-side line switching and light strip voltage sampling circuit (W305) is connected to the display circuit (W306). The light bar interface LED+ is connected, the power supply and system voltage sampling circuit (W301), the programmable photoelectric isolation feedback circuit (W304) and the high-side line switching and light strip voltage sampling circuit (W305) are commonly connected to the positive electrode Vinput, and the power supply and system voltage sampling circuit (W301), the MCU control unit (W302), the low-side line switching, overload detection, short-circuit detection and current sampling circuit (W303), the programmable photoelectric isolation feedback circuit (W304), the high-side line switching and light strip voltage sampling circuit (W305) and the display part circuit (W306) are commonly connected to the negative power supply GND.

3. A switching power supply capable of self-adapting to a specific LED low-voltage light strip (including a small load) voltage according to claim 2, characterized in that: The low-side line-changing, overload detection, short-circuit detection and current sampling circuit (W303) includes a light bar interface LED-, a negative power supply GND, a low-side small current channel (W30301), a low-side small current dual-threshold detection circuit (W30302), a low-side large current short-circuit detection circuit (W30303), a low-side large current channel (W30304), a low-side large current sampling and amplification circuit (W30305), a low-side small current channel control terminal LG1, a low-side large current channel control terminal LG2, a low-side small current low threshold feedback terminal CMP1, a low-side small current high threshold feedback terminal CMP2, a low-side large current short-circuit feedback terminal CMP3, a low-side voltage signal VRCS and a low-side large current sampling signal ADC3; The low-side small current channel (W30301) is connected to the low-side small current dual threshold detection circuit (W30302), the low-side large current channel (W30304) is connected to the low-side large current sampling and amplification circuit (W30305), the low-side large current short-circuit detection circuit (W30303) is connected to the low-side large current sampling and amplification circuit (W30305) through the low-side voltage signal VRCS, the low-side small current channel control terminal LG1 is connected to the low-side small current channel (W30301), the low-side large current channel control terminal LG2 is connected to the low-side large current channel (W30304), the low-side small current low threshold feedback terminal CMP1 is connected to the low-side small current dual threshold detection circuit (W30302) The low-side small current high threshold feedback terminal CMP2 is connected to the low-side small current dual threshold detection circuit (W30302), the low-side large current short-circuit feedback terminal CMP3 is connected to the low-side large current short-circuit detection circuit (W30303), the low-side large current sampling signal ADC3 is connected to the low-side large current sampling and amplification circuit (W30305), the low-side small current channel (W30301) and the low-side large current channel (W30304) are commonly connected to the light bar interface LED-, and the low-side small current dual threshold detection circuit (W30302), the low-side large current short-circuit detection circuit (W30303) and the low-side large current sampling and amplification circuit (W30305) are commonly connected to the power supply negative electrode GND.

4. A switching power supply capable of self-adapting to a specific LED low-voltage light strip (including a small load) voltage according to claim 2, characterized in that: The program-controlled photoelectric isolation feedback circuit (W304) includes a positive electrode Vinput, a negative power supply GND, an FB signal, a high-voltage GND, a single-chip microcomputer port PWM, a photoelectric coupling isolator (W30401), a reference source circuit (W30402) and a voltage-controlled constant current source circuit (W30403); The FB signal and the high voltage GND are respectively connected to the photoelectric coupling isolator (W30401), the photoelectric coupling isolator (W30401) is connected to the reference source circuit (W30402), the reference source circuit (W30402) is connected to the voltage-controlled constant current source circuit (W30403), the positive electrode Vinput is connected to the reference source circuit (W30402), the single-chip microcomputer port PWM is connected to the voltage-controlled constant current source circuit (W30403), and the reference source circuit (W30402) and the voltage-controlled constant current source circuit (W30403) are commonly connected to the negative electrode of the power supply GND.

5. A switching power supply capable of self-adapting to a specific LED low-voltage light strip (including a small load) voltage according to claim 2, characterized in that: The high-side line switching and light strip voltage sampling circuit (W305) includes a positive electrode Vinput, a negative power supply electrode GND, a light strip interface LED+, a high-side large current channel control terminal HG1, a high-side small current channel control terminal HG2, a high-side light strip voltage sampling signal ADC2, a current limiting resistor Rx, a high-side large current channel (W30501), a high-side small current channel (W30502) and a voltage divider circuit (W30503); The high-side large current channel control terminal HG1 is connected to the high-side large current channel (W30501), the high-side small current channel control terminal HG2 is connected to the high-side small current channel (W30502), the first end of the current limiting resistor Rx is connected to the high-side small current channel (W30502), the high-side light bar voltage sampling signal ADC2 is connected to the voltage divider circuit (W30503), the high-side large current channel (W30501) and the high-side small current channel (W30502) are commonly connected to the positive electrode Vinput, the high-side large current channel (W30501), the high-side small current channel (W30502) and the voltage divider circuit (W30503) are commonly connected to the negative power supply GND, and the high-side large current channel (W30501), the second end of the current limiting resistor Rx and the voltage divider circuit (W30503) are commonly connected to the light bar interface LED+.

6. A switching power supply capable of self-adapting to a specific LED low-voltage light strip (including a small load) voltage according to claim 2, characterized in that: With the single-chip microcomputer as the core, controllable high-side and low-side high-current and low-current channels are built. By utilizing the programmable characteristics of the single-chip microcomputer, the high-side large and small current channels and the low-side large and small current channels are flexibly paired and switched, thereby realizing the recognition and adaptation of the voltage of the LED low-voltage light strip (including small load). According to the order of LED light strip access and switching power supply power-on, it can be divided into two situations: pre-access (first connect the LED light strip, then power on the switching power supply) and post-access (first power on the switching power supply, then connect the LED light strip).

7. A switching power supply capable of self-adapting to a specific LED low-voltage light strip (including a small load) voltage according to claim 6, characterized in that: The voltage identification method of the pre-connected LED low-voltage light strip is as follows: after the power is started, the MCU control unit increases the Vinput voltage from low to high step by step through the PWM port, and detects the low-side large current sampling signal ADC3, the low-side small current low threshold feedback terminal CMP1, the low-side small current high threshold feedback terminal CMP2 and the low-side large current short-circuit feedback terminal CMP3 at each predetermined voltage node to determine whether an LED light strip is connected. When the voltage is increased to a certain voltage node and an LED load is found, the voltage at this node is the LED light strip voltage.

8. The switching power supply capable of self-adapting to the voltage of a specific LED low-voltage light strip (including a small load) according to claim 6, characterized in that: The voltage identification method of the rear-accessible LED low-voltage light strip is as follows: when the positive electrode Vinput is increased to a fixed high-end voltage, the MCU control unit (W302) turns on the high-side small current channel (W30502) through the high-side small current channel control terminal HG2, and the high-side small current channel (W30502) is connected in series with the current limiting resistor Rx to supply power to the LED light strip. Under the premise that the Vinput voltage is known, by sampling the high-side light strip voltage sampling signal ADC2, the MCU control unit (W302) can calculate the voltage of the unknown LED light strip according to the voltage divider circuit (W30503) and the resistance value of the Rx resistor.

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