A low voltage driving power supply and power supply box

Abstract

The utility model discloses a low-voltage driving power supply and a power supply box. The low-voltage driving power supply includes a rectifier filter circuit, a power switch tube, a transformer, a driving chip, an output circuit, an auxiliary power supply and a starting circuit. The power switch tube, the transformer and the driving chip constitute a flyback circuit, which converts the high-voltage direct current output by the rectifier filter circuit into a low-voltage alternating current. The output circuit rectifies the low-voltage alternating current and supplies power to external electrical equipment. The starting circuit provides a starting voltage for the driving chip when the low-voltage driving power supply is started. The starting circuit is provided with a starting capacitor, which is used to filter out the AC component in the starting voltage, improve the stability of the starting voltage, and improve the working stability of the driving chip.

Description

Technical Field

[0001] The utility model relates to power supply technology, in particular to a low-voltage driving power supply and a power supply box. Background Art

[0002] Many electrical appliances in our daily lives are powered by low-voltage DC power, while the mains power is usually high-voltage AC. Therefore, a low-voltage power supply module is needed to convert the mains power into low-voltage DC power.

[0003] Currently, isolated switching power supplies are commonly used to achieve high-voltage to low-voltage conversion. These power supplies consist of a transformer and power switches. A driver chip controls the on / off switching of the power switches, modulating the input voltage to achieve high-voltage to low-voltage conversion.

[0004] Driver chips often require a startup circuit to provide startup current, and after normal operation, they are powered by an auxiliary power supply. In practical applications, there is often a problem that the driver chip cannot start, resulting in the low-voltage driver power supply not being able to work properly. Utility Model Content

[0005] The utility model provides a low-voltage driving power supply and a power supply box, so as to improve the stability of the starting voltage and the working stability of the driving chip.

[0006] In a first aspect, the utility model provides a low-voltage driving power supply, including a rectifier filter circuit, a power switch tube, a transformer, a driving chip, an output circuit, an auxiliary power supply and a starting circuit;

[0007] The input end of the rectifier and filter circuit is connected to the mains, the output end of the rectifier and filter circuit is connected to the first end of the primary side of the transformer, the second end of the primary side of the transformer is connected to the first end of the power switch tube, the second end of the power switch tube is grounded, and the control end of the power switch tube is connected to the drive signal output pin of the driver chip;

[0008] The secondary side of the transformer is connected to the input end of the output circuit, and the output end of the output circuit supplies power to the outside;

[0009] The power pins of the driver chip are respectively connected to the output end of the auxiliary power supply and the output end of the startup circuit;

[0010] The startup circuit includes a startup resistor and a startup capacitor, wherein a first end of the startup resistor is connected to an input end of the rectifier and filter circuit, a second end of the startup resistor is respectively connected to a first end of the startup capacitor and a power pin of the driver chip, and a second end of the startup capacitor is grounded. The startup circuit provides a startup voltage for the driver chip when the low-voltage driver power supply is started, and the auxiliary power supply provides an operating voltage for the driver chip after the low-voltage driver power supply is started.

[0011] Optionally, the output circuit includes a rectifier control chip, a rectifier switch tube and a first capacitor;

[0012] A first end of the first capacitor is connected to a first end of the secondary side of the transformer, a second end of the first capacitor is grounded, and the first end of the first capacitor serves as an output end of the output circuit;

[0013] The first end of the rectifier switch tube is connected to the second end of the secondary side of the transformer, the second end of the rectifier switch tube is grounded, and the control end of the rectifier switch tube is connected to the drive signal output pin of the rectifier control chip.

[0014] Optionally, the auxiliary power supply includes an auxiliary coil, a first diode and a first resistor;

[0015] The auxiliary coil is coupled to the primary side of the transformer, a first end of the auxiliary coil is connected to the voltage detection pin of the driver chip and the anode of the first diode respectively, and a second end of the auxiliary coil is grounded;

[0016] The cathode of the first diode is connected to the first end of the first resistor, and the second end of the first resistor is connected to the first end of the startup capacitor.

[0017] Optionally, the low-voltage driving power supply further includes a primary current feedback unit and an output voltage feedback unit;

[0018] The input end of the primary current feedback unit is connected to the second end of the power switch tube, and the output end of the primary current feedback unit is connected to the current feedback pin of the driver chip. The driver chip adjusts the duty cycle of the pulse width modulation signal output to the control end of the power switch tube based on the feedback signal fed back by the primary current feedback unit;

[0019] The input end of the output voltage feedback unit is connected to the output end of the output circuit, and the output end of the output voltage feedback unit is connected to the voltage feedback pin of the driver chip. The driver chip adjusts the duty cycle of the pulse width modulation signal output to the control end of the power switch tube based on the feedback signal fed back by the output voltage feedback unit.

[0020] Optionally, the primary current feedback unit includes a second resistor and a second capacitor;

[0021] The first end of the second resistor is connected to the second end of the power switch tube, and the second end of the second resistor is connected to the current feedback pin of the driver chip;

[0022] A first end of the second capacitor is connected to a second end of the second resistor, and a second end of the second capacitor is grounded.

[0023] Optionally, the output voltage feedback unit includes an optocoupler, a reference voltage chip, a third resistor and a fourth resistor;

[0024] The first end of the primary side of the optical coupler is connected to the output end of the output circuit, and the second end of the primary side of the optical coupler is connected to the cathode of the reference voltage chip;

[0025] A first end of the third resistor is connected to the output end of the output circuit, a second end of the third resistor is connected to the first end of the fourth resistor, and a second end of the fourth resistor is grounded;

[0026] The anode of the reference voltage chip is grounded, and the reference electrode of the reference voltage chip is connected to the first end of the fourth resistor;

[0027] A first end of the secondary side of the optocoupler is connected to a voltage feedback pin of the driver chip, and a second end of the secondary side of the optocoupler is grounded.

[0028] Optionally, the low-voltage driving power supply further includes at least one protocol communication interface circuit and a power distribution chip, wherein the protocol communication interface circuit includes a protocol chip, a step-down circuit and a power supply interface;

[0029] The power distribution chip is communicatively connected to the protocol chip, the input end of the step-down circuit is connected to the output end of the output circuit, the output end of the step-down circuit is connected to the power supply interface, the control end of the step-down circuit is connected to the protocol chip, and the detection pin of the power supply interface is connected to the protocol chip.

[0030] Optionally, the step-down circuit includes a first switching tube, a second switching tube, an inductor and a third capacitor;

[0031] A first end of the first switch tube is connected to the output end of the output circuit, a second end of the first switch tube is connected to the first end of the second switch tube, a second end of the second switch tube is grounded, and a control end of the first switch tube and a control end of the second switch tube are both connected to the protocol chip;

[0032] The first end of the inductor is connected to the second end of the first switch tube, the second end of the inductor is connected to the power supply interface and the first end of the third capacitor respectively, and the second end of the third capacitor is grounded.

[0033] Optionally, the protocol communication interface circuit includes a TYPE_A protocol communication interface circuit and / or a TYPE_C protocol communication interface circuit.

[0034] In a second aspect, the present invention further provides a power supply box, comprising the low-voltage driving power supply provided in the first aspect of the present invention, and further comprising a box body, wherein the power supply module is placed in the box body.

[0035] The utility model provides a low-voltage driving power supply, including a rectifier and filter circuit, a power switch tube, a transformer, a driving chip, an output circuit, an auxiliary power supply, and a startup circuit. The input end of the rectifier and filter circuit is connected to the mains electricity, the output end of the rectifier and filter circuit is connected to the first end of the primary side of the transformer, the second end of the primary side of the transformer is connected to the first end of the power switch tube, the second end of the power switch tube is grounded, the control end of the power switch tube is connected to the driving signal output pin of the driving chip, the secondary side of the transformer is connected to the input end of the output circuit, the output end of the output circuit supplies power to the outside, the power pin of the driving chip is respectively connected to the output end of the auxiliary power supply and the output end of the startup circuit, the startup circuit includes a startup resistor and a startup capacitor, the first end of the startup resistor is connected to the input end of the rectifier and filter circuit, the second end of the startup resistor is respectively connected to the first end of the startup capacitor and the power pin of the driving chip, the second end of the startup capacitor is grounded, the startup circuit provides a startup voltage for the driving chip when the low-voltage driving power supply is started, and provides a discharge channel for the charge at the input end of the rectifier and filter circuit when the low-voltage driving power supply is powered off. The auxiliary power supply provides an operating voltage for the driving chip after the low-voltage driving power supply is started. The starting circuit is provided with a starting capacitor for filtering out the AC component in the starting voltage, improving the stability of the starting voltage, and improving the working stability of the driver chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

[0037] Figure 1 A schematic structural diagram of a low-voltage drive power supply provided by an embodiment of the utility model;

[0038] Figure 2 A circuit diagram of a low-voltage driving power supply provided by an embodiment of the utility model;

[0039] Figure 3 A circuit diagram of a protocol communication interface circuit provided by an embodiment of the present utility model;

[0040] Figure 4A circuit diagram of another protocol communication interface circuit provided in an embodiment of the present utility model. DETAILED DESCRIPTION

[0041] To make the technical problems solved by the present invention, the technical solutions adopted, and the technical effects achieved more clearly, the technical solutions of the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work shall fall within the scope of protection of the present invention.

[0042] In the description of this utility model, unless otherwise specified or limited, the terms "connected," "connect," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on the specific circumstances.

[0043] In the present invention, unless otherwise expressly specified and limited, the first feature being "above" or "below" the second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Moreover, the first feature being "above", "above" and "above" the second feature includes the first feature being directly above and obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature includes the first feature being directly below and obliquely below the second feature, or simply means that the first feature is lower in level than the second feature. In addition, the terms "first" and "second" are only used to distinguish in description and have no special meaning.

[0044] Figure 1 A schematic diagram of the structure of a low-voltage driving power supply provided by an embodiment of the present utility model is shown as follows: Figure 1 As shown, the low-voltage driving power supply includes a rectifier and filter circuit 110 , a power switch tube Q11 , a transformer T1 , a driving chip U7 , an output circuit 120 , an auxiliary power supply 130 and a starting circuit 140 .

[0045] The input of the rectifier and filter circuit 110 is connected to the mains electricity supply, the output of the rectifier and filter circuit 110 is connected to the first end of the primary side of the transformer T1, the second end of the primary side of the transformer T1 is connected to the first end of the power switch Q11, the second end of the power switch Q11 is grounded, and the control end of the power switch Q11 is connected to the drive signal output pin GATE of the driver chip U7. The secondary side of the transformer T1 is connected to the input of the output circuit 120, and the output end of the output circuit 120 provides external power. The rectifier and filter circuit 110 is used to rectify and filter the mains electricity supply, converting AC power into DC power. The power switch Q11, transformer T1, and driver chip U7 form a flyback circuit that converts high-voltage DC power into low-voltage AC power and also isolates the high-voltage and low-voltage circuits. Specifically, driver chip U7 controls the periodic on and off switching of power switch Q11. When power switch Q11 is on, the current in the primary inductor of transformer T1 begins to rise. Due to the relationship between the secondary terminals, transformer T1 stores energy, and the capacitor in output circuit 120 supplies power to the output circuit. When power switch Q11 is off, the voltage induced by the primary inductor of transformer T1 reverses, and transformer T1 supplies power to the output circuit while simultaneously charging the capacitor in output circuit 120, replenishing the energy previously lost in the capacitor.

[0046] The power pin VCC of the driver chip U7 is connected to the output end of the auxiliary power supply 130 and the output end of the startup circuit 140 respectively. Figure 1 As shown, the startup circuit 140 includes a startup resistor R24 ​​and a startup capacitor EC1. The first end of the startup resistor R24 ​​is connected to the input end of the rectifier and filter circuit 110, and the second end of the startup resistor R24 ​​is connected to the first end of the startup capacitor EC1 and the power pin VCC of the driver chip U7, respectively. The second end of the startup capacitor EC1 is grounded. The startup circuit 140 provides a startup voltage for the driver chip when the low-voltage driver power supply is started. The auxiliary power supply 130 provides an operating voltage for the driver chip U7 after the low-voltage driver power supply is started. For example, when the low-voltage driver power supply is just started, the voltage at the input end of the rectifier and filter circuit 110 charges the startup capacitor EC1 through the startup resistor R24. The voltage of the startup capacitor EC1 gradually rises. When the voltage of the startup capacitor EC1 reaches the startup voltage of the driver chip U7, the driver chip U7 starts to operate, controls the on and off of the power switch Q11, activates the flyback circuit, and supplies power to the external through the output circuit 120. When the flyback circuit is operating stably, the auxiliary power supply 130 begins to supply power to the driver chip U7 to maintain its operation. The starting capacitor EC1 filters out the AC component in the starting voltage, improves the stability of the starting voltage, and improves the working stability of the driver chip.

[0047] The low-voltage driving power supply provided by the present invention includes a rectifier and filter circuit, a power switch tube, a transformer, a driver chip, an output circuit, an auxiliary power supply, and a startup circuit. The input end of the rectifier and filter circuit is connected to the mains electricity supply, the output end of the rectifier and filter circuit is connected to the first end of the primary side of the transformer, the second end of the primary side of the transformer is connected to the first end of the power switch tube, the second end of the power switch tube is grounded, the control end of the power switch tube is connected to the drive signal output pin of the driver chip, the secondary side of the transformer is connected to the input end of the output circuit, the output end of the output circuit supplies power to the outside, the power pin of the driver chip is respectively connected to the output end of the auxiliary power supply and the output end of the startup circuit, the startup circuit includes a startup resistor and a startup capacitor, the first end of the startup resistor is connected to the input end of the rectifier and filter circuit, the second end of the startup resistor is respectively connected to the first end of the startup capacitor and the power pin of the driver chip, and the startup circuit provides a startup voltage to the driver chip when the low-voltage driving power supply is started. The startup circuit is provided with a startup capacitor for filtering out the AC component in the startup voltage, improving the stability of the startup voltage, and improving the operating stability of the driver chip.

[0048] In some embodiments of the present invention, Figure 1 As shown, the input front end of the rectifier and filter circuit 110 is also provided with an electromagnetic compatibility circuit 150. The input end of the electromagnetic compatibility circuit 150 is connected to the mains power supply, and the output end of the electromagnetic compatibility circuit 150 is connected to the input end of the rectifier and filter circuit 110. The electromagnetic compatibility circuit 150 is used to filter out electromagnetic interference from the mains power grid, thereby preventing the power module from being affected by electromagnetic interference from the grid during operation. At the same time, the electromagnetic compatibility circuit 150 can also isolate the electromagnetic interference generated during the operation of the power module to prevent it from affecting other devices in the grid.

[0049] Figure 2 A circuit diagram of a low-voltage driving power supply provided by an embodiment of the present utility model is shown as follows: Figure 2 As shown, the electromagnetic compatibility circuit 150 includes a first common mode inductor LF1 , a second common mode inductor LF2 and a filtering unit 151 .

[0050] The first end (1) of the first winding of the first common-mode inductor LF1 is connected to the neutral line N, the first end (4) of the first winding of the first common-mode inductor LF1 is connected to the first end (1) of the first winding of the second common-mode inductor LF2, and the second end (4) of the first winding of the second common-mode inductor LF2 is connected to the first input end of the rectifier filter circuit 110. The fuse F1 and the thermistor NTC1 are connected in series between the first end (2) of the second winding of the first common-mode inductor LF1 and the live line L, the second end (3) of the second winding of the first common-mode inductor LF1 is connected to the first end (2) of the second winding of the second common-mode inductor LF2, and the second end (3) of the second winding of the second common-mode inductor LF2 is connected to the second input end of the rectifier filter circuit 110. The thermistor NTC1 is used to suppress inrush current, and its main function is to limit the instantaneous current when the circuit is turned on.

[0051] The series connection of two common-mode inductors can effectively suppress common-mode interference signals. When common-mode current flows through, the magnetic fluxes in the magnetic rings are superimposed on each other, resulting in a considerable inductance. The coils then exhibit high impedance, producing a strong damping effect, thereby suppressing the common-mode current. When differential-mode current flows through the two coils, two mutually canceling magnetic fields H1 and H2 are generated. At this time, the operating current is mainly damped by the coil's ohmic resistance and the negligible small leakage inductance at the operating frequency, so the differential-mode signal can pass through without attenuation.

[0052] The filter unit 151 can be used to filter out clutter outside the preset frequency range, such as Figure 2 As shown, the filtering unit 151 includes a filtering capacitor CX1 and a discharge resistor composed of resistors R1-R4.

[0053] The first end of the filter capacitor CX1 is connected to the second end (2) of the first winding of the first common-mode inductor LF1, and the second end of the filter capacitor CX1 is connected to the second end (3) of the second winding of the first common-mode inductor LF1. The first end of the resistor R2 is connected to the second end (4) of the first winding of the first common-mode inductor LF1, the second end of the resistor R2 is connected to the first end of the resistor R3, the second end of the resistor R3 is connected to the second end (3) of the second winding of the first common-mode inductor LF1, the first end of the resistor R4 is connected to the second end (4) of the first winding of the first common-mode inductor LF1, the second end of the resistor R4 is connected to the first end of the resistor R1, the second end of the resistor R1 is connected to the second end (3) of the second winding of the first common-mode inductor LF1, and the second end of the resistor R4 is connected to the second end of the resistor R2. During the operation of the low-voltage drive power supply, the filter capacitor CX1 is fully charged. When the low-voltage drive power supply stops working, the energy of the filter capacitor CX1 is discharged through the discharge resistor, reducing the voltage of the input port and preventing the residual charge of the capacitor from causing electric shock damage to the human body.

[0054] like Figure 2As shown, the rectifier filter circuit 110 includes a rectifier DB1 and a CLC filter unit, a first input terminal (1) of the rectifier DB1 connected to the second terminal (4) of the first winding of the second common-mode inductor LF2, a second input terminal (2) of the rectifier DB1 connected to the second terminal (3) of the second winding of the second common-mode inductor LF2, a ground terminal (4) of the rectifier DB1 connected to the ground, an output terminal (3) of the rectifier DB1 connected to the input terminal of the CLC filter unit, and an output terminal of the CLC filter unit connected to the first terminal of the primary winding of the transformer T1. The rectifier DB1 is used to rectify the AC power output by the electromagnetic compatibility circuit 150 into DC power, and the CLC filter unit is used to filter the DC power output by the rectifier DB1 to remove high-frequency interference components, thereby reducing EMI.

[0055] like Figure 2 As shown, the CLC filter unit includes a capacitor EC2, a capacitor EC6, and an inductor L1, wherein a first end of the inductor L1 is connected to the output end (3) of the rectifier DB1, and a second end of the inductor L1 is connected to the first end of the primary winding of the transformer T1. A first end of the capacitor EC2 is connected to the output end (3) of the rectifier DB1, a second end of the capacitor EC2 is grounded, a first end of the capacitor EC6 is connected to the second end of the inductor L1, and a second end of the capacitor EC6 is grounded.

[0056] For example, Figure 2 As shown, a bleeder resistor R5 is connected in parallel at both ends of the inductor L1. After the low-voltage driving power supply is powered off, the bleeder resistor R5 forms a bleeder circuit with the inductor L1 to consume the reverse electromotive force generated by the inductor L1.

[0057] For example, Figure 2 As shown, the rectifier and filter circuit 110 also includes a capacitor EC5, a capacitor C27, and a capacitor C31. The first ends of the capacitor EC5, the capacitor C27, and the capacitor C31 are all connected to the second end of the inductor L1, and the second ends of the capacitor EC5, the capacitor C27, and the capacitor C31 are all grounded. The capacitor EC5, the capacitor C27, and the capacitor C31 play the role of voltage stabilization and filtering.

[0058] In some embodiments of the present invention, Figure 2As shown, the primary side of transformer T1 is also provided with an absorption unit 161, which includes a resistor R41, a resistor R48, a resistor R35, a resistor R36, a capacitor C29, and a diode D4. The first end of resistor R41 is connected to the first end of the primary side of transformer T1, the second end of resistor R41 is connected to the first ends of resistors R35 and R36, the second ends of resistors R35 and R36 are connected to the cathode of diode D4, and the anode of diode D4 is connected to the second end of the primary side of transformer T1 via resistor FB100. The first end of resistor R48 is connected to the first end of the primary side of transformer T1, the second end of resistor R48 is connected to the first ends of resistors R35 and R36. The first end of capacitor C29 is connected to the first end of the primary side of transformer T1, and the second end of capacitor C29 is connected to the first end of resistor R35.

[0059] Absorption unit 161 absorbs spike voltages, preventing damage to power switch Q11. For example, when power switch Q11 is turned off, the leakage inductance energy in the primary side of transformer T1 charges the parasitic capacitance of power switch Q11 and capacitor C30, causing the voltage at the first terminal of power switch Q11 to rise. When this voltage reaches the voltage of capacitor C29, diode D4 turns on, and resistor R41, resistor R48, and capacitor C29 absorb the spike voltage generated by the leakage inductance of the primary side of transformer T1 when power switch Q11 is turned off.

[0060] like Figure 2 As shown, the first end of the power switch Q11 is connected to the second end of the primary side of the transformer T1, the second end of the power switch Q11 is grounded via a resistor R42, and the control end of the power switch Q11 is connected to the drive signal output pin GATE of the driver chip U7 via a resistor R45. A diode D2 and a resistor R44 are connected in parallel across resistor R45. The first end of resistor R44 is connected to the control end of the power switch Q11, the second end of resistor R44 is connected to the anode of diode D2, and the cathode of diode D2 is connected to the drive signal output pin GATE of the driver chip U7. Due to the unidirectional conductivity of the diode, the driving resistor of the power switch Q11 is resistor R45. The off resistance is the resistance of resistors R45 and R44 in parallel. A relatively large on resistance slows down the turn-on speed, which helps reduce EMI. A relatively small off resistance reduces EMI while also taking into account the transistor's turn-off losses.

[0061] For example, Figure 2As shown, a protection unit is also provided for the power switch Q11. The protection unit includes a voltage regulator ZD1 and a resistor R16. The anode of the voltage regulator ZD1 is connected to the second terminal of the power switch Q11, and the cathode of the voltage regulator ZD1 is connected to the control terminal of the power switch Q11. The first terminal of the resistor R16 is connected to the control terminal of the power switch Q11, and the second terminal of the resistor R16 is connected to the second terminal of the power switch Q11. The voltage regulator ZD1 acts as a clamp to prevent the control terminal of the power switch Q11 from breakdown.

[0062] In some embodiments of the present invention, Figure 2 As shown, the low-voltage drive power supply also includes a primary current feedback unit, the input end of the primary current feedback unit is connected to the second end of the power switch tube Q11, and the output end of the primary current feedback unit is connected to the current feedback pin CS of the driver chip U7. The driver chip U7 adjusts the duty cycle of the pulse width modulation signal output to the control end of the power switch tube Q11 based on the feedback signal fed back by the primary current feedback unit, thereby realizing the regulation of the output voltage of the flyback circuit.

[0063] For example, Figure 2 As shown, the primary current feedback unit includes a second resistor R51 and a second capacitor C35. The first end of the second resistor R51 is connected to the second end of the power switch Q11, and the second end of the second resistor R51 is connected to the current feedback pin CS of the driver chip U7. The first end of the second capacitor C35 is connected to the second end of the second resistor R51, and the second end of the second capacitor C35 is grounded. The second resistor R51 and the second capacitor C35 form an RC current filter, which filters out high-frequency noise.

[0064] In some embodiments of the present invention, Figure 2 As shown, the low-voltage driving power supply also includes an output voltage feedback unit 162, the input end of the output voltage feedback unit 162 is connected to the output end V+ of the output circuit 120, and the output end of the output voltage feedback unit 162 is connected to the voltage feedback pin COME of the driving chip U7. The driving chip U7 adjusts the duty cycle of the pulse width modulation signal output to the control end of the power switch tube Q11 based on the feedback signal fed back by the output voltage feedback unit 162, thereby realizing the regulation of the output voltage of the flyback circuit.

[0065] For example, Figure 2As shown, the output voltage feedback unit 162 includes an optocoupler U6, a reference voltage chip U4, a third resistor R30, and a fourth resistor R29. The first end (1) of the primary side of the optocoupler U6 is connected to the output terminal V+ of the output circuit 120, and the second end (2) of the primary side of the optocoupler U6 is connected to the cathode (2) of the reference voltage chip U4. The first end of the third resistor R30 is connected to the output terminal V+ of the output circuit 120, the second end of the third resistor R30 is connected to the first end of the fourth resistor R29, and the second end of the fourth resistor R29 is grounded. The anode (3) of the reference voltage chip U4 is grounded, and the reference electrode (1) of the reference voltage chip U4 is connected to the first end of the fourth resistor R29. The third resistor R30 plays a role in voltage division, and the voltage of the reference electrode (1) of the reference voltage chip U4 is the voltage of the fourth resistor R29. The first end (4) of the secondary side of the optocoupler U6 is connected to the voltage feedback pin COME of the driver chip U7, and the second end (3) of the secondary side of the optocoupler U6 is grounded. For example, in order to prevent the primary side current of the optocoupler U6 from being damaged due to excessive current, a current limiting resistor R46 is connected in series between the first terminal (1) of the primary side of the optocoupler U6 and the output terminal V+ of the output circuit 120 .

[0066] For example, when the voltage at the output end of the output circuit 120 is higher than the rated voltage, the voltage of the fourth resistor R29 increases, that is, the potential of the reference electrode (1) of the reference voltage chip U4 increases, making it higher than the reference voltage, the impedance of the reference voltage chip U4 decreases, the current flowing through the primary side of the optocoupler U6 increases, the luminous brightness of the primary side of the optocoupler U6 increases, the impedance of the secondary side of the optocoupler U6 decreases, and the voltage of the capacitor C28 connected in parallel with the secondary side of the optocoupler U6 decreases. The driver chip U7 detects the voltage drop and adjusts the duty cycle of the pulse width modulation signal transmitted to the power switch tube Q11 to reduce the output voltage. Similarly, when the voltage at the output end of the output circuit 120 is lower than the rated voltage, the voltage of the fourth resistor R29 decreases, that is, the potential of the reference electrode (1) of the reference voltage chip U4 decreases, making it lower than the reference voltage, the impedance of the reference voltage chip U4 increases, the current flowing through the primary side of the optocoupler U6 decreases, the luminous brightness of the primary side of the optocoupler U6 decreases, the impedance of the secondary side of the optocoupler U6 increases, and the voltage of the capacitor C28 connected in parallel with the secondary side of the optocoupler U6 increases. The driver chip U7 detects the voltage increase and adjusts the duty cycle of the pulse width modulation signal transmitted to the power switch tube Q11 to increase the output voltage.

[0067] In some embodiments of the present invention, Figure 2As shown, the output circuit 120 includes a rectifier control chip U8, a rectifier switch tube Q9, and a first capacitor EC4. The first end of the first capacitor EC4 is connected to the first end of the secondary side of the transformer T1, and the second end of the first capacitor EC4 is grounded. The first end of the first capacitor EC4 serves as the output terminal V+ of the output circuit 120. The first end of the rectifier switch tube Q9 is connected to the second end of the secondary side of the transformer T1, and the second end of the rectifier switch tube Q9 is grounded. The control terminal of the rectifier switch tube Q9 is connected to the drive signal output pin VG of the rectifier control chip U8. For example, the output terminal of the output circuit 120 is also connected in parallel with capacitors EC3 and C25 to provide voltage stabilization and filtering.

[0068] Exemplarily, the rectifier control chip U8 collects the voltage across the rectifier switch Q9 and controls the rectifier switch Q9 to conduct when a voltage difference exists between the first voltage detection pin VD and the second voltage detection pin VSS. The rectifier control chip U8 controls the rectifier switch Q9 to periodically conduct and shut down. When the rectifier switch Q9 is on, the primary inductor current of the transformer T1 begins to rise. At this time, due to the relationship between the secondary same-name terminals, the transformer T1 stores energy and does not discharge it externally. When there is no voltage difference between the first voltage detection pin VD and the second voltage detection pin VSS of the rectifier control chip U8, the rectifier control chip U8 controls the rectifier switch Q9 to be turned off, and the load is supplied with energy by the first capacitor EC4 in the output circuit. When the rectifier switch Q9 is turned off, the induced voltage on the primary inductor of transformer T1 reverses, causing transformer T1 to discharge. A voltage difference exists between the first voltage detection pin VD and the second voltage detection pin VSS of the rectifier control chip U8. The rectifier control chip U8 then turns on the rectifier switch Q9, allowing the energy in transformer T1 to be supplied to the load while simultaneously charging the first capacitor EC4, replenishing the energy previously lost in EC4. In this embodiment, the rectifier control chip U8 and the rectifier switch Q9 replace the diode to achieve synchronous rectification, reducing the voltage drop across the rectifier on-state voltage and improving energy efficiency.

[0069] For example, Figure 2 As shown, a protection circuit can also be connected in parallel at both ends of the rectifier switch tube Q9. The protection circuit includes resistors R31, R32 and a capacitor C24. The resistors R31 and R32 are connected in parallel, and the first end of the equivalent resistor after the parallel connection is connected to the second end of the rectifier switch tube Q9, the second end of the equivalent resistor after the parallel connection is connected to the first end of the capacitor C24, and the second end of the capacitor C24 is connected to the first end of the second switching transistor Q2. The rapid change of current causes the parasitic inductance to generate a spike voltage. The resistors R31, R32 and the capacitor C24 are used to absorb the spike voltage when the rectifier switch tube Q9 is turned off, thereby achieving the purpose of absorbing high-frequency interference signals, playing a role in protecting the rectifier switch tube Q9, and helping to reduce EMI.

[0070] In some embodiments of the present invention, Figure 2 As shown, the auxiliary power supply 130 includes an auxiliary coil Np, a first diode D3, and a first resistor R26. The auxiliary coil Np is coupled to the primary side of the transformer T1. The first end of the auxiliary coil Np is connected to the voltage detection pin FB of the driver chip U7 and the anode of the first diode D3, respectively. The second end of the auxiliary coil Np is grounded. Exemplarily, the first end of the auxiliary coil Np is connected to the voltage detection pin FB of the driver chip U7 via series resistors R49 and R37. The cathode of the first diode D3 is connected to the first end of the first resistor R26, and the second end of the first resistor R26 is connected to the first end of the start capacitor EC1. Exemplarily, after the low-voltage drive power supply is connected to the mains and the transformer T1 begins to operate stably, the auxiliary coil Np is coupled to the primary side of the transformer T1 to generate an auxiliary voltage. The auxiliary voltage is rectified by the first diode D3 and the first resistor R26 to charge the start capacitor EC1. After the start capacitor EC1 is fully charged, power is supplied to the power pin VCC of the driver chip U7 to maintain the operation of the driver chip U7.

[0071] In some embodiments of the present invention, the low-voltage driving power supply also includes at least one protocol communication interface circuit and a power distribution chip. The protocol communication interface circuit includes a TYPE_A protocol communication interface circuit and / or a TYPE_C protocol communication interface circuit, which supports electrical equipment with multiple different power supply protocols. When it is detected that two or more protocol communication interface circuits are connected to electrical equipment, the power distribution chip controls the protocol communication interface circuit and intelligently distributes power. Figure 3 This is a circuit diagram of a protocol communication interface circuit provided by an embodiment of the present utility model. The protocol communication interface circuit includes a TYPE_C power supply interface, Figure 4 This is a circuit diagram of another protocol communication interface circuit provided by an embodiment of the present utility model. The protocol communication interface circuit includes a TYPE_C power supply interface and a TYPE_A power supply interface.

[0072] like Figure 3 As shown, the protocol communication interface circuit includes a protocol chip U5, a step-down circuit 171, and a power supply interface TYPE_C1. The power distribution chip U9 is in communication with the protocol chip U5. The input end of the step-down circuit 171 is connected to the output end V+ of the output circuit 120. The output end of the step-down circuit 171 is connected to the power supply interface TYPE_C1. The control end of the step-down circuit 171 is connected to the protocol chip U5. The detection pin B4 / A9 of the power supply interface TYPE_C1 is connected to the TYPE_C load access pin VBUSC of the protocol chip U5.

[0073] For example, Figure 3As shown, the step-down circuit 171 includes a first switch Q3, a second switch Q5, an inductor L2, and a third capacitor C22. The first end of the first switch Q3 is connected to the output terminal V+ of the output circuit 120, the second end of the first switch Q3 is connected to the first end of the second switch Q5, and the second end of the second switch Q5 is grounded. The control end of the first switch Q3 is connected to the HGATE pin of the protocol chip U5, and the control end of the second switch Q5 is connected to the LGATE pin of the protocol chip U5. The first end of the inductor L2 is connected to the second end of the first switch Q3, the second end of the inductor L2 is connected to the power supply interface TYPE_C1 and the first end of the third capacitor C22, respectively, and the second end of the third capacitor C22 is grounded. The first switch Q3, the second switch Q5, the inductor L2, and the third capacitor C22 form a buck circuit. The protocol chip U5 controls whether the first switch Q3 or the second switch Q5 is turned on, thereby reducing the voltage at the output terminal V+ of the output circuit 120 to the voltage required by the power device.

[0074] For example, Figure 3 As shown, capacitor C23 and capacitor EC6 are also connected in parallel at both ends of the third capacitor C22, which play the role of voltage stabilization and filtering. A detection resistor RC26 and a switch tube Q4 are also connected in series between the step-down circuit 171 and the power supply interface TYPE_C1, and the control end of the switch tube Q4 is connected to the GATEC pin of the protocol chip U5. The two ends of the detection resistor RC26 are respectively connected to the CSPC pin and the CSNC pin of the protocol chip U5, which are used to detect the output current of the power supply interface TYPE_C1. The switch tube Q4 is used to control whether the power supply interface TYPE_C1 supplies power to the outside. For example, if it is detected that the output current of the power supply interface TYPE_C1 is zero or lower than the preset value, the switch tube Q4 can be controlled to turn off. In addition, during the power supply process, the temperature of the power supply interface TYPE_C1 is detected by the thermistor RT1. When the temperature exceeds the threshold, the protocol chip U5 detects that the voltage of the NTC pin reaches the set voltage value, reduces the output current, and derates the use to avoid damage to the power supply.

[0075] Figure 4 The protocol communication interface circuit in the embodiment also includes a protocol chip and a step-down circuit. The difference is that the protocol communication interface circuit includes two power supply interfaces, namely the power supply interface USB_TYPE_C1 and the power supply interface TYPE_A1. The connection relationship of the protocol communication interface circuit can be referred to the above embodiment, and the embodiment of the utility model will not be repeated here.

[0076] The embodiment of the present utility model also provides a power supply box, which includes a box body and a low-voltage driving power supply provided by any of the aforementioned embodiments, the box body is formed with a receiving cavity, and the low-voltage driving power supply is placed in the receiving cavity. A socket panel is provided on one side of the box body, and the socket panel is provided with a jack corresponding to the power supply interface of the low-voltage driving power supply. The power supply interface can be a TYPE_A power supply interface and / or a TYPE_C power supply interface for supplying power to external electrical equipment. The box body can be embedded in a standard-sized junction box (for example, an 86-type junction box, a 118-type junction box, and a 120-type junction box, etc.). Therefore, during construction, a more number of standard-sized junction boxes can be reserved for standard-sized installation positions to provide an installation position for the subsequent setting of the power supply box, and in the subsequent process, it is only necessary to install the power box on the standard-sized junction box located at the installation position to achieve the installation of the low-voltage driving power supply as a whole on the standard-sized junction box. The installation and construction process is convenient and has a low error rate, which can reduce the installation and construction cost of the power module.

[0077] In the description of this article, it should be understood that the terms "up", "down", "left", "right", and other orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of description and simplification of operation, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0078] Throughout this specification, references to terms such as "one embodiment" and "example" indicate that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example.

[0079] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0080] The technical principles of the present invention have been described above with reference to specific embodiments. These descriptions are intended solely to illustrate the principles of the present invention and should not be construed in any way as limiting the scope of protection of the present invention. Based on the explanations herein, those skilled in the art will be able to devise other specific implementations of the present invention without inventive effort, and such implementations will fall within the scope of protection of the present invention.

Claims

1. A low voltage driving power supply, characterized in that: Including rectifier filter circuit, power switch tube, transformer, driver chip, output circuit, auxiliary power supply and start-up circuit; The input end of the rectifier and filter circuit is connected to the mains, the output end of the rectifier and filter circuit is connected to the first end of the primary side of the transformer, the second end of the primary side of the transformer is connected to the first end of the power switch tube, the second end of the power switch tube is grounded, and the control end of the power switch tube is connected to the drive signal output pin of the drive chip; The secondary side of the transformer is connected to the input end of the output circuit, and the output end of the output circuit supplies power to the outside; The power pins of the driving chip are respectively connected to the output end of the auxiliary power supply and the output end of the starting circuit; The startup circuit includes a startup resistor and a startup capacitor, wherein a first end of the startup resistor is connected to an input end of the rectifier and filter circuit, a second end of the startup resistor is respectively connected to a first end of the startup capacitor and a power pin of the driver chip, a second end of the startup capacitor is grounded, and the startup circuit provides a startup voltage for the driver chip when a low-voltage driver power supply is started, and the auxiliary power supply provides a working voltage for the driver chip after the low-voltage driver power supply is started.

2. The low voltage driving power supply according to claim 1, characterized in that: The output circuit includes a rectifier control chip, a rectifier switch tube and a first capacitor; The first end of the first capacitor is connected to the first end of the secondary side of the transformer, the second end of the first capacitor is grounded, and the first end of the first capacitor serves as the output end of the output circuit; The first end of the rectifier switch tube is connected to the second end of the secondary side of the transformer, the second end of the rectifier switch tube is grounded, and the control end of the rectifier switch tube is connected to the drive signal output pin of the rectifier control chip.

3. The low voltage driving power supply according to claim 1, characterized in that: The auxiliary power supply includes an auxiliary coil, a first diode and a first resistor; The auxiliary coil is coupled to the primary side of the transformer, a first end of the auxiliary coil is connected to a voltage detection pin of the driving chip and an anode of the first diode respectively, and a second end of the auxiliary coil is grounded; The cathode of the first diode is connected to the first end of the first resistor, and the second end of the first resistor is connected to the first end of the startup capacitor.

4. The low-voltage driving power supply according to any one of claims 1 to 3, characterized in that: It also includes a primary current feedback unit and an output voltage feedback unit; The input end of the primary current feedback unit is connected to the second end of the power switch tube, the output end of the primary current feedback unit is connected to the current feedback pin of the driver chip, and the driver chip adjusts the duty cycle of the pulse width modulation signal output to the control end of the power switch tube based on the feedback signal fed back by the primary current feedback unit; The input end of the output voltage feedback unit is connected to the output end of the output circuit, and the output end of the output voltage feedback unit is connected to the voltage feedback pin of the driver chip. The driver chip adjusts the duty cycle of the pulse width modulation signal output to the control end of the power switch tube based on the feedback signal fed back by the output voltage feedback unit.

5. The low voltage driving power supply according to claim 4, characterized in that: The primary current feedback unit includes a second resistor and a second capacitor; The first end of the second resistor is connected to the second end of the power switch tube, and the second end of the second resistor is connected to the current feedback pin of the driving chip; A first end of the second capacitor is connected to a second end of the second resistor, and a second end of the second capacitor is grounded.

6. The low voltage driving power supply according to claim 4, characterized in that: The output voltage feedback unit includes an optical coupler, a reference voltage chip, a third resistor and a fourth resistor; The first end of the primary side of the optical coupler is connected to the output end of the output circuit, and the second end of the primary side of the optical coupler is connected to the cathode of the reference voltage chip; The first end of the third resistor is connected to the output end of the output circuit, the second end of the third resistor is connected to the first end of the fourth resistor, and the second end of the fourth resistor is grounded; The anode of the reference voltage chip is grounded, and the reference electrode of the reference voltage chip is connected to the first end of the fourth resistor; A first end of the secondary side of the optocoupler is connected to a voltage feedback pin of the driving chip, and a second end of the secondary side of the optocoupler is grounded.

7. The low voltage driving power supply according to any one of claims 1-3, 5 and 6, characterized in that: It also includes at least one protocol communication interface circuit and a power distribution chip, wherein the protocol communication interface circuit includes a protocol chip, a step-down circuit and a power supply interface; The power distribution chip is communicatively connected to the protocol chip, the input end of the step-down circuit is connected to the output end of the output circuit, the output end of the step-down circuit is connected to the power supply interface, the control end of the step-down circuit is connected to the protocol chip, and the detection pin of the power supply interface is connected to the protocol chip.

8. The low voltage driving power supply according to claim 7, characterized in that: The step-down circuit includes a first switch tube, a second switch tube, an inductor and a third capacitor; The first end of the first switch tube is connected to the output end of the output circuit, the second end of the first switch tube is connected to the first end of the second switch tube, the second end of the second switch tube is grounded, and the control end of the first switch tube and the control end of the second switch tube are both connected to the protocol chip; The first end of the inductor is connected to the second end of the first switch tube, the second end of the inductor is respectively connected to the power supply interface and the first end of the third capacitor, and the second end of the third capacitor is grounded.

9. The low voltage driving power supply according to claim 7, characterized in that: The protocol communication interface circuit includes a TYPE_A protocol communication interface circuit and / or a TYPE_C protocol communication interface circuit.

10. A power supply box, characterized in that: It comprises the low-voltage driving power supply as described in any one of claims 1-9, and also comprises a box body, and the power supply module is placed in the box body.

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