CN211352042U

CN211352042U - PCB circuit for protecting switching power supply

Info

Publication number: CN211352042U
Application number: CN201922231579.3U
Authority: CN
Inventors: 袁江涛; 梁东兵
Original assignee: Advanced Electronic Zhuhai Co ltd
Current assignee: Advanced Electronic Zhuhai Co ltd
Priority date: 2019-12-12
Filing date: 2019-12-12
Publication date: 2020-08-25
Anticipated expiration: 2029-12-12

Abstract

The utility model relates to a PCB circuit for protecting switching power supply, it includes two parallel arrangement's reference ground end circuit board, input ground end circuit board, because of reference ground end circuit board and the PCB power supply circuit who is provided with above the input ground end circuit board, this circuit can reduce the influence that current time rate of change flows through reference ground end circuit board or produce loop current to the power, improves switching power supply output voltage's stability and power performance, effectively restraines the electronic components of BUCK mains interference welding on the circuit board to reach and avoid leading to high frequency sensitive device to reduce the purpose that performance or unable normal work's phenomenon takes place because of the circuit produces electromagnetic interference.

Description

PCB circuit for protecting switching power supply

[ technical field ] A method for producing a semiconductor device

The utility model relates to a PCB circuit that is used for small capacity switching power supply to supply power and uses on the veneer chip of relay is used for protection switching power supply.

[ background of the invention ]

The power supply is an essential component of various electronic products, and the performance of the power supply directly affects the performance of the electronic products. The switching power supply has the advantages of high efficiency, high frequency, high power density, high reliability and the like, so that the switching power supply has strong competitiveness and wider application fields, but along with the development of electronic technology, the requirements of electronic products on the power supply are higher and higher. Higher frequency, higher power density, higher efficiency, higher reliability and intelligence are pursued for switching power supplies. The switching power supply has the characteristics of wide voltage input range, isolated input and output power supplies, high power density and high efficiency, is widely applied to scenes such as a comprehensive automation system of a smart power grid and the like, and is particularly widely applied to relay protection devices with severe field environmental conditions, complex working electromagnetic environments and high safety and stability. With the development of semiconductor technology, a large number of component power supplies such as DSP, FPGA and the like widely adopt low-voltage power supply such as 3.3V and the like. Because the traditional main power supply of the relay protection device generally has output of +/-24V and +/-5V, in general, a BUCK switching power supply is adopted to step down the voltage of the traditional main power supply of 5V and then supply the voltage to the load of the electronic component welded on the PCB for use. During the high frequency on or off process of the BUCK switching power supply, the voltage and current ripple changes often occur in the circuit. A large amount of dither signal of the voltage current generates a varying electromagnetic field inside the switching power supply, due to the generation of an electric field between the voltage differences or the generation of a magnetic field caused by the flow of the current. These signals are conducted or radiated in the loop to generate large electromagnetic interference, which interferes the operation of the high-frequency sensitive devices, degrades the performance of some devices or causes the whole equipment to be incapable of working normally.

[ Utility model ] content

In view of this, the technical problem to be solved of the present invention is to provide a PCB circuit for protecting a switching power supply, which can avoid the phenomenon that the high frequency sensitive device reduces the performance or fails to work normally due to the electromagnetic interference generated by the circuit.

Therefore, the technical solution of the present invention is to provide a PCB circuit for protecting a switching power supply, which includes two parallel reference ground circuit boards, an input ground circuit board, a PCB power circuit disposed above the reference ground circuit board and the input ground circuit board for suppressing the interference of a BUCK power source with an electronic component soldered on the circuit board, the PCB power circuit including a load module disposed above the reference ground circuit board, a voltage output terminal, an inductor, a capacitor C1, a BUCK chip soldered on the input ground circuit board, a voltage input terminal, a capacitor C2, and a ground terminal module (GND) soldered between the reference ground circuit board and the input ground circuit board; earthing terminal module one end welding is on the input ground circuit board, and the earthing terminal module other end welding is on consulting the earthing terminal circuit board, load module one end be connected with voltage output terminal, and the voltage output terminal other end is connected with inductance L1, electric capacity C1 is connected between voltage output terminal and earthing terminal module one end, electric capacity C2 is connected between voltage input terminal and the earthing terminal module other end, the BUCK chip is connected between inductance and voltage input terminal, the BUCK chip passes through copper foil and earthing terminal module interconnect.

Further limiting, a copper foil through hole is arranged between the reference ground circuit board and the input ground circuit board to be connected; the capacitor C2 and the BUCK chip are arranged in the input ground end circuit board, and are connected with the copper foil wire through the copper foil through hole in the input ground end circuit board to form a copper foil loop.

Further limiting, the BUCK chip is an LM5117 type synchronous voltage reduction integrated control chip, the control chip is provided with 20 effective pins, the working voltage range is 5.5V-65V, and the working frequency range can be set within the range of 50 kHz-750 kHz; the control chip is internally provided with a voltage reference, the precision is 1.5%, the stable 3.3A peak value grid driving voltage is obtained, and the external high-side NMOS tube and the external low-side NMOS tube can be directly driven by using self-adaptive dead zone control time; the device is formed by adopting an analog current monitor.

Further, a switching step-down circuit is disposed inside the BUCK chip, and the switching step-down circuit includes a chip U1 with model LM5117, a pin 1 through a pin 20 disposed on a chip U1, a resistor R1 and a capacitor C3 connected to the pin 20, a capacitor C5 and a divider resistor RUV1 connected in parallel to the pin 1, an external resistor RT connected to the pin 5, a capacitor C6 and a resistor R2 connected to the pin 11, a capacitor C8 connected to the pin 4, a capacitor C9 and a capacitor C11 connected to the pin 8, a capacitor C14 connected to the pin 3, a capacitor C13 and a resistor R9 connected to the pin 10, a diode D1 connected to the pin 16, a capacitor C4 connected to an output terminal of the diode D1, a capacitor C7, a resistor R5 connected to the pin 18, a transistor Q1 connected to the other end of the resistor R5, an L2 connected to the pin 17, and a pin 12, the circuit comprises a pin 13, a capacitor C13 on a pin 14, a resistor R6 connected to a pin 15, a triode Q2 connected to the other end of the resistor R6, a resistor RS connected to a collector terminal of the triode Q2, an adjustable resistor RP1 connected to an inductor L2, a resistor R8, a capacitor C10 connected in parallel to two ends of the resistor RP1 and the resistor R8, and a capacitor C12 connected in parallel to two ends of the capacitor C10.

The utility model has the advantages of: the PCB power supply circuit arranged on the reference ground end circuit board and the input ground end circuit board can reduce the influence of the current time change rate flowing through the reference ground end circuit board or generating loop current on a power supply, improve the stability of the output voltage of the switching power supply and the performance of the power supply, effectively inhibit the BUCK power supply from interfering with electronic components welded on the circuit board, and further achieve the purpose of avoiding the phenomenon that the high-frequency sensitive device reduces the use performance or cannot normally work due to the electromagnetic interference generated by the circuit.

The technical solution of the present invention will be described in further detail with reference to the accompanying drawings and embodiments.

[ description of the drawings ]

Fig. 1 is a circuit diagram of a PCB circuit for protecting a switching power supply according to the present invention;

fig. 2 is a schematic circuit diagram of the switching voltage-reducing circuit of the present invention.

[ detailed description ] embodiments

In order to make the technical problem, technical solution and advantageous effects to be solved by the present invention clearer and more obvious, the following description of the present invention with reference to the accompanying drawings and embodiments is provided for further details. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the invention.

Referring to fig. 1 and 2, a PCB circuit for protecting a switching power supply is described below with reference to an embodiment, which includes two reference ground circuit boards disposed in parallel, and an input ground circuit board, wherein the reference ground circuit board and the input ground circuit board are provided with a PCB power circuit for suppressing interference of a BUCK power supply with electronic components soldered on the circuit boards.

PCB power supply circuit is including setting up the load module above referring to ground terminal circuit board, voltage output end, inductance, electric capacity C1, the BUCK chip of welding on the circuit board of input ground, voltage input end, electric capacity C2 to and the earthing terminal module of welding between referring to ground terminal circuit board and input ground terminal circuit board: the grounding terminal module is referred to as GND for short; earthing terminal module one end welding is on the input ground circuit board, and the earthing terminal module other end welding is on consulting the earthing terminal circuit board, load module one end be connected with voltage output terminal, and the voltage output terminal other end is connected with inductance L1, electric capacity C1 is connected between voltage output terminal and earthing terminal module one end, electric capacity C2 is connected between voltage input terminal and the earthing terminal module other end, the BUCK chip is connected between inductance and voltage input terminal, the BUCK chip passes through copper foil and earthing terminal module interconnect. A copper foil through hole is arranged between the reference ground circuit board and the input ground circuit board to be connected; the capacitor C2 and the BUCK chip are arranged in the input ground end circuit board, and are connected with the copper foil wire through the copper foil through hole in the input ground end circuit board to form a copper foil loop.

In an embodiment, the PCB layout wiring of the switching power supply is critical to suppress the ripple and the electromagnetic interference of the switching power supply. If the ripple of the switching power supply is too large or the electromagnetic interference of the switching power supply easily influences the normal work of other electronic elements on the board, therefore, the design of the power supply PCB board is reasonably carried out according to the characteristics of the power supply circuit. On-board power exchange is primarily focused on the power and ground pins of the device, which are typically directly connected to the ground plane. Therefore, the area of the ground plane is properly increased, the power chip with proper switching frequency and the output capacitor with good high-frequency characteristic and low ESR are selected as the filter capacitor, and the filter capacitor has good effects of reducing ripples of terminal voltage and reducing interference. In order to inhibit the influence of the change of the pulsating current on a system, a special current path is designed by selecting large pulsating current, the current distribution on a plane is reasonably distributed and arranged, and corresponding shielding inhibition is adopted to reduce the influence of the current distribution on the potential of an adjacent loop or a power supply reference ground plane, so that the stability of output is improved. In addition, a proper decoupling capacitor is added to a power supply end of the integrated circuit chip, and noise can be effectively reduced.

In order to inhibit the pulsating current on the ground plane from forming a transmission loop and distribute and arrange the current distribution on the plane, an input ground end circuit board and a reference ground end point are designed to be disordered, and the input ground end circuit board and the reference ground end circuit board are connected through a large-area copper foil through hole. The capacitor C2 at the voltage input end with the largest current change and the BUCK chip are connected and designed in an independent copper foil loop through a reverse power tube current circuit, do not flow through the reference ground end circuit board and the input ground end circuit board, and eliminate the influence of large current pulsation on the loop of the reference ground end circuit board. The input ground end circuit board is connected with the reference ground end circuit board through the copper foil through hole, and the impedance is relatively high, so that most of input power supply current flows back to a power supply from the independent input ground end circuit board and does not flow through the reference ground end circuit board, and the distribution of the pulsating current of the reference ground end circuit board is further reduced. The current of the load module is directly returned to the voltage output end or the grounding module GND of the voltage input capacitor by the reference grounding end circuit board, the path of the return circuit is shortest, the alternating current impedance of the load system is reduced, and the electromagnetic interference EMI can be inhibited. The BUCK reference point access point is arranged between the input ground end circuit board and the reference ground end circuit board, the BUCK reference point access point is connected with the reference ground end circuit board, and no pulse large current passes through the BUCK reference point access point. The voltage of the BUCK power supply regulation reference ground terminal is obtained nearby from the input end of the power supply output voltage, and the voltage is stable. For example, the areas of the copper foils of the input ground circuit board and the reference ground circuit board are increased to reduce high-frequency impedance and shield external electromagnetic interference, so that the influence of current flowing through the reference ground circuit board or generating loop current on a power supply in a time change rate is effectively reduced, and the stability of output voltage and the performance of the power supply are improved.

In the embodiment, the PCB layout optimization design of the BUCK power supply is carried out according to the suppression method, the size of output ripples of the BUCK power supply is effectively suppressed, the stability of output voltage under the load condition is improved, the electromagnetic interference of the power supply to a system is reduced, and the method has high practicability

The BUCK chip is an LM5117 type synchronous voltage reduction integrated control chip, the control chip is provided with 20 effective pins, the working voltage range is 5.5V-65V, and the working frequency range can be set in the range of 50 kHz-750 kHz; the control chip is internally provided with a voltage reference, the precision is 1.5%, the stable 3.3A peak value grid driving voltage is obtained, and the external high-side NMOS tube and the external low-side NMOS tube can be directly driven by using self-adaptive dead zone control time; the device is formed by adopting an analog current monitor.

The BUCK chip is internally provided with a switch voltage-reducing circuit, the switch voltage-reducing circuit comprises a chip U1 with the model of LM5117, pins 1 to 20 arranged on a chip U1, a resistor R1 and a capacitor C3 connected on the pin 20, a capacitor C5 and a divider resistor RUV1 connected on the pin 1 in parallel, an external resistor RT connected on the pin 5, a capacitor C6 and a resistor R2 connected on the pin 11, a capacitor C8 connected on the pin 4, a capacitor C9 and a capacitor C11 connected on the pin 8, a capacitor C14 connected on the pin 3, a capacitor C13 and a resistor R9 connected on the pin 10, a diode D1 connected on the pin 16, a capacitor C4 respectively connected on the output end of the diode D1, a capacitor C7, a resistor R5 connected on the pin 18, a triode Q1 connected on the other end of the resistor R5, an inductor L2 connected on the pin 17, a capacitor C13 connected on the pin 12, the pin 13 and the pin 14, the resistor R6 is connected to the pin 15, the triode Q2 is connected to the other end of the resistor R6, the resistor RS is connected to the collector terminal of the triode Q2, the adjustable resistor RP1 is connected to the inductor L2, the resistor R8, the capacitor C10 is connected to the two ends of the resistor RP1 and the resistor R8 in parallel, and the capacitor C12 is connected to the two ends of the capacitor C10 in parallel.

In this embodiment, the transistor Q2 replaces the conventional diode in the Buck circuit to achieve synchronous rectification. The capacitor C12 filters out high frequency interference. The HO terminal of the pin 18 and the LO terminal of the pin 15 of the chip U1 directly drive the high side NMOS transistor and the low side NMOS transistor, respectively. The high-side driver requires an external diode D1 in conjunction with a bootstrap capacitor C7. The output voltage is divided by the adjustable resistor RP1 and the voltage dividing resistor R8 to obtain a voltage sampling signal, and the voltage sampling signal is added to the FB terminal on the pin 8. The voltage signal on pin 8 of the FB terminal forms an error amplified signal with the high-precision 0.8 voltage reference inside the chip U1. Since the error amplifier gain is high, the voltage at the FB terminal on pin 8 is also 0.8V when stable. The input impedance at the FB terminal on pin 8 is large. The resistance ratio of the adjustable resistor RP1 and the voltage dividing resistor R8 in the feedback circuit enables the voltage division of the output voltage value on the voltage dividing resistor R8 to be 0.8V. The output was 5V. The circuit can also change the output voltage by adjusting the adjustable resistor RP 1. The COMP end on the pin 9 is an output end of the voltage feedback error amplifier, and a capacitor C9, a capacitor C11 and a resistor R7 which are connected between the COMP end and the FB end form a II-type loop compensation circuit, so that the performance of the feedback circuit is improved. The CS terminal on the pin 12 is the input terminal of the current sense amplifier and is connected to the high side of the current sense resistor RS. The CSG end of the pin 13 is connected to the low side of the current detection resistor RS. Resistor R2 and capacitor C4 between the SW terminal on pin 17, the RAMP terminal on pin 11, and the AGND terminal on pin 6 are used to set the PWM signal RAMP, the emulated inductor current RAMP signal. The VIN terminal on the pin 20 is the positive input terminal of the chip power supply, the dc power supply is connected to the VIN terminal through a small resistor R1, and the capacitor C3 filters out dc input interference signals. The DC input power is divided by a resistor RUV2 and a resistor RUV1 and then connected to a UVLO on pin 1, wherein the UVLO is an under-voltage locking programming pin. The RT terminal on the pin sets the resistance pin for the oscillation frequency. The size of a resistor RT externally connected between the RT end and the AGND end determines the working frequency of the oscillator, and the working frequency can be set from 50kHz to 750 kHz. The oscillation frequency also determines the switching frequency of the Buck circuit.

In summary, the PCB power supply circuits disposed on the reference ground circuit board and the input ground circuit board can reduce the influence of the current time change rate flowing through the reference ground circuit board or the generated loop current on the power supply, improve the stability of the output voltage of the switching power supply and the performance of the power supply, and effectively inhibit the BUCK power supply from interfering with the electronic components welded on the circuit board, thereby achieving the purpose of avoiding the phenomenon that the performance of the high-frequency sensitive device is reduced or the high-frequency sensitive device cannot work normally due to the electromagnetic interference generated by the circuits.

The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, without thereby limiting the scope of the invention. Any modification, equivalent replacement and improvement made by those skilled in the art without departing from the scope and spirit of the present invention should be within the scope of the claims of the present invention.

Claims

1. The utility model provides a PCB circuit for protecting switching power supply, its includes two parallel arrangement's reference ground circuit board, input ground circuit board which characterized in that: the PCB power supply circuit for inhibiting the BUCK power supply from interfering the electronic components welded on the circuit board is arranged on the reference ground end circuit board and the input ground end circuit board, and comprises a load module, a voltage output end, an inductor, a capacitor C1, a BUCK chip welded on the input ground circuit board, a voltage input end, a capacitor C2 and a grounding end module welded between the reference ground end circuit board and the input ground end circuit board; earthing terminal module one end welding is on the input ground circuit board, and the earthing terminal module other end welding is on consulting the earthing terminal circuit board, load module one end be connected with voltage output terminal, and the voltage output terminal other end is connected with inductance L1, electric capacity C1 is connected between voltage output terminal and earthing terminal module one end, electric capacity C2 is connected between voltage input terminal and the earthing terminal module other end, the BUCK chip is connected between inductance and voltage input terminal, the BUCK chip passes through copper foil and earthing terminal module interconnect.

2. The PCB circuit for protecting a switching power supply of claim 1, wherein: a copper foil through hole is arranged between the reference ground circuit board and the input ground circuit board to be connected; the capacitor C2 and the BUCK chip are arranged in the input ground end circuit board, and are connected with the copper foil wire through the copper foil through hole in the input ground end circuit board to form a copper foil loop.

3. The PCB circuit for protecting a switching power supply of claim 1, wherein: the BUCK chip is an LM5117 type synchronous voltage reduction integrated control chip, the control chip is provided with 20 effective pins, the working voltage range is 5.5V-65V, and the working frequency range can be set in the range of 50 kHz-750 kHz; the control chip is internally provided with a voltage reference, the precision is 1.5%, the stable 3.3A peak value grid driving voltage is obtained, and the external high-side NMOS tube and the external low-side NMOS tube can be directly driven by using self-adaptive dead zone control time; the device is formed by adopting an analog current monitor.

4. The PCB circuit for protecting a switching power supply of claim 1, wherein: the BUCK chip is internally provided with a switch voltage-reducing circuit, the switch voltage-reducing circuit comprises a chip U1 with the model of LM5117, pins 1 to 20 arranged on a chip U1, a resistor R1 and a capacitor C3 connected on the pin 20, a capacitor C5 and a divider resistor RUV1 connected on the pin 1 in parallel, an external resistor RT connected on the pin 5, a capacitor C6 and a resistor R2 connected on the pin 11, a capacitor C8 connected on the pin 4, a capacitor C9 and a capacitor C11 connected on the pin 8, a capacitor C14 connected on the pin 3, a capacitor C13 and a resistor R9 connected on the pin 10, a diode D1 connected on the pin 16, a capacitor C4 respectively connected on the output end of the diode D1, a capacitor C7, a resistor R5 connected on the pin 18, a triode Q1 connected on the other end of the resistor R5, an inductor L2 connected on the pin 17, a capacitor C13 connected on the pin 12, the pin 13 and the pin 14, the resistor R6 is connected to the pin 15, the triode Q2 is connected to the other end of the resistor R6, the resistor RS is connected to the collector terminal of the triode Q2, the adjustable resistor RP1 is connected to the inductor L2, the resistor R8, the capacitor C10 is connected to the two ends of the resistor RP1 and the resistor R8 in parallel, and the capacitor C12 is connected to the two ends of the capacitor C10 in parallel.