Multipath output power supply

Abstract

The utility model provides a multi-path output power supply, which comprises a control chip L6565D and a high-frequency transformer T2, a starting circuit of the control chip and a winding N1 of the high-frequency transformer are both connected with a direct-current input voltage, the control chip is connected with the winding N1 of the high-frequency transformer through a driving circuit, the winding N1 can obtain a high-frequency alternating-current voltage through the driving circuit, and the high-frequency alternating-current voltage is connected with the high-frequency transformer T2. The high-frequency transformer is further provided with a feedback power supply winding N2 connected with the control chip and a plurality of windings N3-N8 with different output voltages, and the output voltages are led out through double rows of contact pins. The multi-path output power supply adopts a flyback topology circuit, adopts a soft switching control chip, adopts a transformer with a multi-pin framework model, and adopts a plugboard form to lead out multi-path output.

Description

Technical Field

[0001] The utility model relates to a multi-voltage circuit, in particular to a multi-channel output power supply. Background Art

[0002] Small and medium power high frequency switching power supply equipment (generally refers to 1KW-6KW power supply equipment) is a type of power supply equipment with a large market share. Its main features are low cost, small size, and low price, but it also requires comprehensive functions, so it has high requirements for design. The power supply equipment has drive circuits, control circuits, communication circuits, and display circuits, etc. Each unit circuit has a chip that needs to be powered, and the functions of different unit circuits are different and must be isolated. Therefore, multiple low-power power supplies are needed to meet the requirements and realize the functions of the whole power supply equipment. For example, a small and medium power supply equipment adopts a full-bridge inverter as the whole machine topology, which requires 6 low-power power supplies.

[0003] Most of the small power supplies purchased directly from the market have one output, and the voltage is usually 5V, 12V, 15V, 24V, which may not be the value required by each circuit chip inside the full bridge; if 6 power supplies are purchased according to the needs of the whole machine, the purchase cost will definitely exceed the cost control of the whole machine; and purchasing multiple small power supplies will increase the size of the whole machine and make the processability poor. Therefore, it is necessary to develop a multi-output power supply with low cost and good processability. Utility Model Content

[0004] The utility model provides a multi-channel output power supply, which solves the problem of realizing multi-channel voltage output through the chip L6565D and the high-frequency transformer. The technical solution is as follows:

[0005] A multi-channel output power supply includes a control chip L6565D and a high-frequency transformer T2. The start-up circuit of the control chip and the winding N1 of the high-frequency transformer are both connected to a DC input voltage. The control chip is connected to the winding N1 of the high-frequency transformer through a drive circuit. The winding N1 can obtain a high-frequency AC voltage through the drive circuit. The high-frequency transformer is also provided with a feedback power supply winding N2 connected to the control chip, and a plurality of windings N3 to N8 with different output voltages. The output voltage is led out through a double-row pin.

[0006] The startup circuit includes a diode D5, a resistor R86, a voltage-stabilizing diode D11 and a capacitor C60. One end of the resistor R86 is connected to the positive electrode of the DC input voltage through the diode D5, and the other end is connected to the voltage-stabilizing diode D11 and the capacitor C60 respectively. The other end of the voltage-stabilizing diode D11 is grounded. The positive and negative ends of the capacitor C60 are connected to the power supply end of the control chip and are connected to pins 8 and 1 of the control chip.

[0007] The driving circuit includes a MOSFET tube Q6, a resistor R87 and a resistor R91. Pin 7 of the control chip serves as a chip driving output, and drives the MOSFET tube Q6 high-frequency switch through the resistor R87. The resistor R91 is connected in parallel between the Q6 driving end and the ground to discharge the Q6 gate noise.

[0008] A current collection circuit is provided between the control chip and the driving circuit, and the current collection circuit includes a resistor R92, and the two ends of the resistor R92 are respectively connected to the source and ground of the MOSFET tube Q6 of the driving circuit, for collecting the current passing through the MOSFET tube Q6 and sending the collected value to pin 4 of the control chip.

[0009] A peak voltage absorption circuit is arranged between the driving circuit and the winding N1, and the peak voltage absorption circuit includes a diode D17, a diode D14, a capacitor C63, a resistor R88 and a resistor R90. After the diode D14, the capacitor C63, the resistor R88 and the resistor R90 are connected in parallel, one end of which is connected to the winding N1, and the other end of which is connected to one end of the diode D17, and the other end of the diode D17 is connected to the winding N1.

[0010] The control chip is also provided with a voltage stabilizing circuit, which includes an optocoupler PC817 and a voltage stabilizing chip TL431 connected in sequence.

[0011] The high-frequency transformer T2, wherein the winding N1 cooperates with the MOSFET tube Q6 of the driving circuit, and the Q6 high-frequency switch enables the winding N1 to obtain high-frequency alternating current, and the other windings obtain corresponding high-frequency alternating current in proportion; wherein the winding N2 is a feedback winding to power the control chip; the rectified voltage of the winding N3 is 5V, which powers the digital meter; the rectified voltages of the windings N4 and N6 are respectively used to power the two upper tube MOSFET driving chips in the full-bridge inverter; the rectified voltage of the winding N5 is used to power the two lower tube driving chips in the full-bridge inverter; the rectified voltages of the windings N7 and N8 are used to power the Hall sensor and the output control chip.

[0012] In the winding structure of the high-frequency transformer T2, the winding N1 is wound with 122 turns of 0.21 diameter enameled wire, starting from pin 1 and ending at pin 22; the winding N2 is wound with 12 turns of 0.21 diameter enameled wire, starting from pin 4 and ending at pin 3; the winding N3 is wound with 5 turns of 0.38 diameter enameled wire, starting from pin 11 and ending at pin 10; the winding N4 is wound with 17 turns of 0.38 diameter enameled wire, starting from pin 13 and ending at pin 12; the winding N5 is wound with 12 turns of 0.38 diameter enameled wire, starting from pin 14 and ending at pin 15; the winding N6 is wound with 12 turns of 0.38 diameter enameled wire, starting from pin 15 and ending at pin 16; the winding N7 is wound with 12 turns of 0.38 diameter enameled wire, starting from pin 16 and ending at pin 17; the winding N8 is wound with 12 turns of 0.38 diameter enameled wire, starting from pin 13 and ending at pin 16; the winding N9 is wound with 12 turns of 0.38 diameter enameled wire, starting from pin 14 and ending at pin 16; the winding N10 is wound with 12 turns of 0.38 diameter enameled wire, starting from pin 14 and ending at pin 16; the winding N11 is wound with 12 turns of 0.38 diameter enameled wire, starting from pin 14 and ending at pin 16; the winding N12 is wound with 12 turns of 0.21 diameter enameled wire, starting from pin 1 Winding N6 is wound 17 times with 0.38 diameter enameled wire, starting from pin 16 and ending at pin 15; Winding N7 is wound 14 times with 0.38 diameter enameled wire, starting from pin 7 and ending at pin 6; Winding N8 is wound 14 times with 0.38 diameter enameled wire, starting from pin 8 and ending at pin 7; Pins 1, 4, 7, 8, 11, 13, 16, and 20 are the same-name terminals with consistent phases.

[0013] The multi-channel voltage of the high-frequency transformer T2 is led out through a double-row solder pin, which serves as an output lead-out circuit and is finally soldered to the mainboard, wherein pins 1 and 3 of the double-row solder pin are -VCC2 and SGND lead-out terminals; pins 4 and 3 of the double-row solder pin are 5V and SGND lead-out terminals; pins 6 and 7 of the double-row solder pin are +VCC2 and SGND lead-out terminals; pins 11 and 9 of the double-row solder pin are the total DC input V+ and PGND lead-out terminals; pins 14 and 13 of the double-row solder pin are VB2 and VS2 lead-out terminals; pins 16 and 17 of the double-row solder pin are VB1 and VS1 lead-out terminals; pins 20 and 19 of the double-row solder pin are VCC1 and GND lead-out terminals.

[0014] The pins of the control chip L6565D are as follows:

[0015] Pin 1: As the inverting input terminal of the output voltage feedback, it adopts the optocoupler isolation voltage stabilization of the voltage stabilization circuit and is directly grounded;

[0016] Pin 2: As the output of the error amplifier, it is directly connected to the secondary side of the optocoupler in the voltage stabilization circuit. Its voltage change synchronously drives the drive pulse change.

[0017] Pin 3: As the input voltage feedback pin, this pin and pin 4 together set the current protection value of the MOSFET tube Q6 of the driving circuit. When the voltage of pin 3 reaches 3V, the current protection value is zero and the circuit stops working;

[0018] Pin 4: As the overcurrent protection value setting pin of the MOSFET tube Q6 of the driving circuit, the source of Q6 is connected to the ground through the resistor R92. Pin 4 sets the overcurrent protection value by collecting the pulse voltage of R92. When the voltage of pin 4 reaches 2V, the chip is overcurrent protected and the output is turned off. Pin 4 and pin 3 work together to set the overcurrent value. The value of pin 3 increases and the overcurrent protection value decreases.

[0019] Pin 5: As the soft switch control terminal, the voltage of the feedback winding N2 is collected through the resistor R94. When the voltage of N2 is zero, the control chip determines that the current of the MOSFET tube Q6 of the driving circuit is zero. After a delay time, the MOSFET tube Q6 is turned on to achieve zero voltage turn-on;

[0020] Pin 6: As the negative power supply of the chip, all pin voltages are referenced to this pin;

[0021] Pin 7: As the driving output terminal of the MOSFET tube Q6 of the driving circuit, it has a driving capability of 0.4A;

[0022] Pin 8: As the positive power supply for the chip, a 15V voltage regulator diode is connected in parallel to the ground to prevent overvoltage from damaging the chip.

[0023] The multi-channel output power supply has a simple structure and realizes 7-channel output at a very low cost. It uses a multi-pin skeleton magnetic core to ensure the isolation and insulation of each voltage, and can be widely used in the internal chip power supply and display power supply of the bridge conversion circuit; it adopts a flyback soft switch control chip to make the rectifier diode turn on at zero voltage, without spike voltage, and without adding a resistor-capacitor absorption circuit, which not only reduces the number of devices, but also reduces the area and prolongs the life of the tube. It adopts a pin-welding method to lead out the input and output, which is convenient for application to power supplies with different indicators. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a schematic diagram of a circuit framework of the multi-channel output power supply;

[0025] Figure 2 is a schematic diagram of the structure of the multi-channel output power supply;

[0026] Figure 3 is a structural schematic diagram of the high-frequency transformer;

[0027] Figure 4 It is a schematic diagram of the matching relationship curve between pin 3 and pin 4 of the chip L6565D;

[0028] Figure 5 This is a logic diagram of the relationship between pins 2, 3, 4, and 5 of the chip L6565D. DETAILED DESCRIPTION

[0029] like Figure 1 and Figure 2As shown, the multi-channel output power supply includes a control chip IC10 and a high-frequency transformer T2. The start-up circuit of the control chip and the winding N1 of the high-frequency transformer are connected to the DC input voltage. The control chip is connected to the winding N1 of the high-frequency transformer through a driving circuit. The winding N1 can obtain a high-frequency AC voltage through the driving circuit. The high-frequency transformer is also provided with a feedback power supply winding N2 connected to the control chip, and multiple windings N3 to N8 with different output voltages. The output voltage is led out through a double-row pin. Further, the control chip IC10 adopts the L6565D chip.

[0030] The DC input voltage, Figure 1 On the far left, the networks labeled V+ and PGND are the overall input to the circuit, with a range of 60-450V DC.

[0031] The startup circuit includes a diode D5, a resistor R86, a voltage-stabilizing diode D11, and a capacitor C60. One end of the resistor R86 is connected to the positive electrode of the DC input voltage through the diode D5, and the other end is connected to the voltage-stabilizing diode D11 and the capacitor C60 respectively. The other end of the voltage-stabilizing diode D11 is grounded. The positive and negative ends of the capacitor C60 are connected to the power supply end of the control chip IC10, and are connected to the pin 8 and the pin 1 of the control chip IC10. The DC input voltage charges the capacitor C60 through D5 and R86. The positive and negative ends of C60 are connected to the power supply end of the control chip IC10. When the voltage of C60 reaches 12.5V, the control chip IC10 starts to vibrate, and then the whole machine starts. The voltage-stabilizing diode D11 is connected in parallel to the two ends of C60 to protect the voltage of C60 from not exceeding 15V, so that IC10 can work reliably.

[0032] The driving circuit includes a MOSFET tube Q6, a resistor R87 and a resistor R91. Pin 7 of the control chip IC10 is a chip driving output. The MOSFET tube Q6 high-frequency switch is driven by the resistor R87. The resistor R91 is connected in parallel between the Q6 driving end and the ground to discharge the Q6 gate noise. If R91 is removed, Q6 will be mistakenly turned on due to the noise, causing the circuit control timing to be disordered and unable to work stably.

[0033] The feedback power supply winding: The transformer winding N2 is the feedback power supply winding. During the high-frequency conversion process of the circuit, the output voltage of the winding N2 is rectified by the resistor R96 and the diode D19 to produce the output voltage VC1, and the output voltage VC1 is sent to the power supply pin 8 of the chip IC10 to complete the feedback power supply of IC10, and the startup circuit is no longer used for power supply.

[0034] A current acquisition circuit is arranged between the control chip and the drive circuit, an input voltage acquisition circuit is arranged between the control chip and the DC input voltage, a peak voltage absorption circuit is arranged between the drive circuit and the winding N1, a soft switching control circuit is arranged between the control chip and the transformer winding N2, and in addition, the control chip is also provided with a voltage stabilizing circuit.

[0035] The current collection circuit includes a resistor R92, the two ends of which are respectively connected to the source and ground of the MOSFET tube Q6, and is used to collect the current passing through the MOSFET tube Q6, and send the collected value to pin 4 of the chip IC10, and the pin 4 is the CS terminal, thereby playing a role in current limiting and overcurrent protection.

[0036] The input voltage acquisition circuit includes a resistor R85 and a resistor R84 between the positive and negative electrodes of the DC input voltage. The connection end point between the resistor R85 and the resistor R84 is connected to one end of the capacitor C59 and to pin 3 of the chip IC10. The other end of the capacitor C59 is connected to the capacitor C60.

[0037] The resistors R84 and R85 divide the input voltage and collect it, and send it to the pin 3 of the chip IC10, which is used as the voltage collection terminal. The capacitor C59 is connected in parallel to the ground terminal of the pin 3, and the capacitor C59 is used to overcome the noise of the pin 3 to the ground, and can eliminate the interference of the noise to the chip.

[0038] The peak voltage absorption circuit includes a diode D17, a diode D14, a capacitor C63, a resistor R88 and a resistor R90. After the diode D14, the capacitor C63, the resistor R88 and the resistor R90 are connected in parallel, one end is connected to the winding N1, and the other end is connected to one end of the diode D17. The other end of the diode D17 is connected to the winding N1. The D17, D14, C63, R88, and R90 form a standard RDC peak voltage absorption circuit, which is used to protect Q6 from being broken down by excessive peak voltage. Because Q6 is connected to the output end of the transformer winding N1, at the moment of circuit reverse excitation, Q6 is turned off, and the energy of the winding N1 is directly added to the drain of Q6, so an absorption circuit must be added to protect Q6 from being broken down by excessive voltage.

[0039] The soft switch control circuit includes a resistor R94. The voltage of the transformer winding N2 is collected through the resistor R94 and sent to pin 5 of the chip IC10. Pin 5 is the soft switch control terminal. When the voltage of pin 5 is close to zero, the voltage of winding N2 and pin 4 is also close to zero. The chip believes that the energy of the winding has been basically released, and the conditions for opening the tube at zero voltage are met.

[0040] The voltage stabilizing circuit includes an optocoupler U9 and a voltage stabilizing chip IC13 connected in sequence, wherein the optocoupler U9 adopts a PC817 optocoupler, and the voltage stabilizing chip IC13 adopts a reference voltage source TL431, and a standard optocoupler and TL431 voltage stabilizing circuit is formed by U9 and IC13. The TL431 is connected with a feedback compensation network and a voltage stabilizing voltage divider resistor, and the feedback compensation network includes a resistor R145 and a capacitor C98 connected in sequence, one end of the capacitor C98 is connected to the reference end of the TL431, and the other end is connected to the cathode of the TL431 through the resistor R145. The voltage-stabilizing voltage-dividing resistor includes a resistor R146 and a resistor R147, the connection end between the resistor R146 and the resistor R147 is connected to the reference end of TL431, the other end of the resistor R146 is grounded, and the other end of the resistor R147 is connected to the optocoupler U9 through the optocoupler primary linear resistor R93, and the corresponding output voltage VCC1 is connected to the pin 20 of the double-row pin, and the optocoupler U9 is also provided with an optocoupler secondary compensation capacitor C62, and the C62 is connected to the pin 2 of the chip IC10, and the pin 2 is used as the error amplifier output end. The change in the VCC1 value can bring about a change in the current of the resistor R93, thereby changing the linear luminescence value of the optocoupler to change the voltage of the pin 2 of the chip IC10, thereby controlling the change in the drive pulse of the chip IC10 and achieving VCC1 voltage stabilization.

[0041] The high-frequency transformer T2 forms a transformer circuit, in which winding N1 cooperates with Q6, and Q6 is a high-frequency switch, so that winding N1 obtains high-frequency alternating current, and other windings obtain corresponding high-frequency alternating current in proportion; winding N2 is a feedback winding to power IC10; the rectified voltage of winding N3 is 5V, which powers the digital meter; the rectified voltages of winding N4 and winding N6 are respectively used to power the two upper tube MOSFET driver chips in the full-bridge inverter; the rectified voltage of winding N5 is used to power the two lower tube driver chips in the full-bridge inverter; the rectified voltages of winding N7 and winding N8 are used to power the Hall sensor and the output control chip.

[0042] Winding N3 rectifier circuit: The winding N3 rectifier current includes diode D22, filter capacitor C71 and dummy load resistor R100. The output voltage is 5V, which supplies power to the digital meter.

[0043] Winding N4 rectifier circuit: Winding N4 rectifier consists of rectifier diode D8 and filter capacitor C72. The output voltage is about 20V. The positive and negative output voltages are marked as VB1 and VS1, which power the upper tube driver chip.

[0044] Winding N5 rectifier circuit: Winding N5 rectifier consists of diode D7 and filter capacitor C30. The output voltage is about 17V. The positive and negative output voltages are marked as VCC1 and GND, which provide power to the lower tube driver chip.

[0045] Winding N6 rectifier circuit: Winding N6 rectifier consists of diode D18 and filter capacitor C29. The output voltage is about 20V. The positive and negative output voltages are marked as VB2 and VS2, which power the other upper tube driver chip.

[0046] Winding N7, winding N8 rectifier circuit: N8 rectifier consists of diode D20 and filter capacitor C69, and the output voltage is about 15V; N7 rectifier consists of diode D21 and filter capacitor C70. Since the rectifier voltage of winding N7 is negative, the direction of D21 is opposite, and the negative side of diode D21 is connected to the winding, which is different from the positive side of ordinary rectifier diodes. The output rectifier value of winding N8 is about 15V, and the output value of winding N7 rectifier is about -15V. The output voltage is expressed as +VCC2, SGND, and -VCC2, which supplies power to the voltage and current sensor.

[0047] The multi-channel voltage of the high-frequency transformer T2 is led out through a double-row solder pin, which is used as an output lead-out circuit and finally soldered to the mainboard. Pins 1 and 3 of the double-row solder pin are -VCC2 and SGND lead-out terminals; pins 4 and 3 of the double-row solder pin are 5V and SGND lead-out terminals; pins 6 and 7 of the double-row solder pin are +VCC2 and SGND lead-out terminals; pins 11 and 9 of the double-row solder pin are the total DC input V+ and PGND lead-out terminals; pins 14 and 13 of the double-row solder pin are VB2 and VS2 lead-out terminals; pins 16 and 17 of the double-row solder pin are VB1 and VS1 lead-out terminals; pins 20 and 19 of the double-row solder pin are VCC1 and GND lead-out terminals.

[0048] Figure 1 There are several groups of electrical network symbols in the , the following is a corresponding introduction:

[0049] V+, PGND, refers to the total DC input of the power supply, ranging from 60-450V;

[0050] VC1, PGND, L6565D chip supply voltage, range 12-15V;

[0051] VCC1, GND, one of the output DC voltages, about 16.7V;

[0052] VB1, VS1, one of the output DC voltages, about 20V;

[0053] VB2, VS2, one of the output DC voltages, about 20V;

[0054] +VCC2, SGND, -VCC2, output dual DC voltage of about ±15V;

[0055] 5V, SGND, output 5V voltage.

[0056] When the utility model is in use, the input voltage V+ / PGND is sent to the winding N1 of the main transformer T2;

[0057] The input voltage V+ / PGND charges the capacitor C60 through the diode D5 and the resistor R86. When the voltage of C60 reaches 12.5V, the power supply voltage of the chip L6565D reaches the starting condition, and L6565D starts to oscillate. Pin 7 of L6565D outputs a driving pulse waveform to drive the Q6 high-frequency switch. The T2 transformer winding N1 obtains a high-frequency AC voltage, and the other windings of the transformer convert the corresponding voltage in proportion. Each output voltage is led out through a welding pin and soldered to the mainboard of the whole machine to complete the connection with the corresponding load, thereby realizing the operation of the power supply equipment of the whole machine.

[0058] In a specific embodiment, the working of the high-frequency transformer T2, the main power tube Q6, the voltage stabilizing circuit and the chip IC10L6565D are described.

[0059] like Figure 3 As shown in the winding process diagram of the high-frequency transformer T2, the winding N1 is wound 122 times with a diameter of 0.21 enameled wire, starting from pin 1 and ending at pin 22;

[0060] Winding N2 is wound 12 times with 0.21 diameter enameled wire, starting from pin 4 and ending at pin 3;

[0061] Winding N3 is wound 5 times with 0.38 diameter enameled wire, starting from pin 11 and ending at pin 10;

[0062] Winding N4 is wound 17 times with 0.38 diameter enameled wire, starting from pin 13 and ending at pin 12;

[0063] Winding N5 is wound 17 times with 0.38 diameter enameled wire, starting from pin 16 and ending at pin 15;

[0064] Winding N6 is wound 17 times with 0.38 diameter enameled wire, starting from pin 20 and ending at pin 18;

[0065] Winding N7 is wound 14 turns with 0.38 diameter enameled wire, starting from pin 7 and ending at pin 6;

[0066] Winding N8 is wound 14 times with 0.38 diameter enameled wire, starting from pin 8 and ending at pin 7;

[0067] Pins 1, 4, 7, 8, 11, 13, 16, and 20 are the same-named terminals with the same phase.

[0068] Winding N5 rectifies the output voltage VCC1 through high-frequency rectifier diode D7, and then stabilizes the voltage to about 16.7V through optocoupler U9 (PC817C) and IC13 (TL431) and R93, R145, R146, R147, C93. The voltage drop of rectifier diode D7 is about 0.8V, and the voltage of winding N5 is about 17.5V. This winding is theoretically the main voltage-stabilizing winding, and the other windings are auxiliary windings.

[0069] According to the flyback power supply theory, the main winding voltage determines the voltage range of the auxiliary winding. Therefore, according to the main winding N5 is 17.5V, the theoretical voltage of other windings can be calculated according to the proportion; the theoretical voltage of winding N2 is 12.35V; the theoretical voltage of winding N3 is 5.15; the theoretical voltage of windings N4 and N6 is 17.5V; the theoretical voltage of winding N7 / winding N8 is 14.4V; the theoretical value of the flyback voltage of winding N1 is 125.6V. In the actual research and development process, it is more reasonable to modulate the flyback voltage to 135V. Therefore, the model of diode D7 is changed to change the voltage drop, to increase the single-turn voltage of winding N5 to 1.1V, and the voltage of each winding is also adjusted to a more appropriate value. Therefore, the parameters in the schematic diagram are finally determined through experiments.

[0070] In the flyback power supply theory, the larger the load on the main winding, the slightly higher the voltage on the auxiliary winding. Therefore, it is normal for the actual output voltage of each winding to deviate from the theoretical value as long as it meets the range.

[0071] The main power tube Q6 is over-voltage and over-current protected. In the circuit, Q6 is the most core main power tube, and an over-voltage and over-current protection circuit must be added to ensure that Q6 works safely and reliably. When the transformer winding N1 undergoes flyback conversion, the polarity of winding N1 changes from positive at the top and negative at the bottom to positive at the bottom and negative at the top. Under this condition, the sum of the power supply voltage V+ / PGND and the induced voltage of winding N1 is added to Q6. To protect Q6 from overvoltage breakdown, D17, C63, R88, and R89 in the schematic diagram are standard RDC absorption circuits, and D14 is a spike voltage suppressor, which can absorb high-frequency transient spike voltages in nanoseconds to ensure safe and reliable operation of MOSFET. Resistor R92 is an overcurrent protection resistor. The collected value of resistor R92 is sent to the current collection end of pin 4 of chip IC10. When the voltage of pin 4 reaches 2V, the chip forces the drive pulse to be blocked and the circuit stops working. The voltage of pin 4 of the chip is related to the voltage value of pin 3. When the voltage of pin 3 increases, the current limit value of pin 4 decreases. In other words, the current limit value increases when the input voltage decreases, and the current limit value decreases when the input voltage increases, ensuring that full power can be output in each input voltage segment, and the tube does not overcurrent. Therefore, the value of R92 is critical, and the final test determines 0.5 ohms.

[0072] The principle of the voltage stabilizing circuit is as follows: The voltage stabilizing circuit in the figure uses a standard circuit with optocoupler and TL431. The reference 2.5V input terminal of TL431 is connected between the voltage divider resistors R147 and R146. When the voltage of R146 reaches 2.5V, TL431 is turned on, the optocoupler PC817C emits light, and the circuit enters the closed-loop state of voltage stabilization control. When the closed-loop works, the optocoupler light-emitting current is usually set at about 10mA in a reasonable linear area. According to the above theoretical analysis, VCC1 voltage = 2.5*(R146+R147) / R146 = 16.625V. The actual value will be different due to the error of the resistance value and the error of the TL431 reference value, but as long as the VCC1 value is within a reasonable range, it will not affect the operation of the whole machine. The R93 current is equal to 16.625 minus the optocoupler conduction voltage drop of about 1V, and then divided by the R93 resistance value of 1.5K, which is also about 10mA, which is in the linear area of ​​the optocoupler. The secondary side of the optocoupler is connected to pin 2 of IC10. Pin 2 is the output of the error amplifier inside the chip. The voltage value of pin 2 changes linearly with the light emission of the optocoupler, driving the drive pulse to change and realizing voltage regulation control.

[0073] Working description of the chip IC10L6565D:

[0074] Pin 1: Output voltage feedback inverting input terminal. In non-isolated voltage regulation, resistor voltage division can be used to feedback the output voltage. In this circuit, optocoupler isolation voltage regulation is used, and this pin is not used and is directly grounded.

[0075] Pin 2: Error amplifier output, used for voltage and current control. In the optocoupler isolation voltage regulator circuit, it is directly connected to the secondary side of the optocoupler. The voltage change of pin 2 synchronously drives the drive pulse change.

[0076] Pin 3: Input voltage feedback pin. This pin and pin 4 together set the current protection value of the main power MOSFET. When the voltage of pin 3 reaches 3V, the current protection value is zero and the circuit stops working.

[0077] Pin 4: Main power MOSFET over-current protection value setting pin. In the circuit, the source of Q6 is grounded through resistor R92. Pin 4 sets the over-current protection value by collecting the pulse voltage of R92. When the voltage of pin 4 reaches 2V, the chip is over-current protected and the output is turned off. Pin 4 and pin 3 work together to set the over-current value. When the value of pin 3 increases, the over-current protection value decreases.

[0078] Pin 5: Soft switch control terminal. In the circuit, pin 5 collects the voltage of the feedback winding N2 through resistor R94. When the voltage of N2 is zero, the chip determines that the current of the main power MOSFET is zero. After a delay time, the MOSFET is turned on to achieve zero voltage turn-on, which greatly reduces the switching loss, improves the power supply efficiency, and reduces the voltage stress of the tube.

[0079] Pin 6: Negative power supply for the chip, all pin voltages are referenced to this pin;

[0080] Pin 7: Main power MOSFET driver output, with 0.4A driving capability;

[0081] Pin 8: Chip power supply positive, this pin is usually connected in parallel with a 15V voltage regulator diode to prevent overvoltage from damaging the chip;

[0082] In actual work, the various pins of the chip do not work independently, but are interrelated, but also perform independent functions, which are mainly reflected in the functions of pins 2, 3, 4, 5, and 7. When the voltage of pin 3 rises to 3V or above, the drive waveform is forced to be turned off regardless of the working condition of the circuit. When the voltage of pin 4 reaches 2V, the drive waveform is also forced to be turned off regardless of the working condition of the circuit. The changes in the voltage of pins 3 and 4 jointly control the current limit value, thereby controlling the pulse change of pin 7. The matching relationship curve of pins 3 and 4 is shown in the figure. Figure 4 The relationship logic of pins 2, 3, 4, and 5 follows Figure 5 .

[0083] Therefore, the resistance value of the current limiting resistor R92, 0.5 ohms, was finally determined after repeated tests in combination with the input voltage and output power.

[0084] Multi-channel output voltage lead-out method: Multi-channel output voltage uses double row pins for lead-out, which is convenient for soldering to the motherboard. Practice has proved that this lead-out method is beneficial to power supply application.

[0085] The multi-channel output power supply has a simple structure and realizes 7-channel output at a very low cost. The high-frequency transformer uses a multi-pin skeleton core to ensure the isolation and insulation of the voltages of each channel, and can be widely used in the internal chip power supply and display power supply of the bridge conversion circuit; the flyback soft switch control chip L6565D is adopted to make the rectifier diode turn on at zero voltage, without spike voltage, and without adding a resistance-capacitance absorption circuit, which not only reduces the number of devices, but also reduces the area and prolongs the life of the tube; the input and output are led out by pin soldering, which is convenient for application to power supplies with different indicators.

Claims

1. A multi-output power supply, characterized in that: It includes a control chip L6565D and a high-frequency transformer T2. The starting circuit of the control chip and the winding N1 of the high-frequency transformer are both connected to the DC input voltage. The control chip is connected to the winding N1 of the high-frequency transformer through a driving circuit. The winding N1 can obtain a high-frequency AC voltage through the driving circuit. The high-frequency transformer is also provided with a feedback power supply winding N2 connected to the control chip, and multiple windings N3 to N8 with different output voltages. The output voltage is led out through a double-row pin.

2. The multi-output power supply according to claim 1, characterized in that: The startup circuit includes a diode D5, a resistor R86, a voltage-stabilizing diode D11 and a capacitor C60. One end of the resistor R86 is connected to the positive electrode of the DC input voltage through the diode D5, and the other end is connected to the voltage-stabilizing diode D11 and the capacitor C60 respectively. The other end of the voltage-stabilizing diode D11 is grounded. The positive and negative ends of the capacitor C60 are connected to the power supply end of the control chip and are connected to pins 8 and 1 of the control chip.

3. The multi-output power supply according to claim 1, characterized in that: The driving circuit includes a MOSFET tube Q6, a resistor R87 and a resistor R91. Pin 7 of the control chip serves as a chip driving output, and drives the MOSFET tube Q6 high-frequency switch through the resistor R87. The resistor R91 is connected in parallel between the Q6 driving end and the ground to discharge the Q6 gate noise.

4. The multi-output power supply according to claim 1, characterized in that: A current collection circuit is provided between the control chip and the driving circuit, and the current collection circuit includes a resistor R92, and the two ends of the resistor R92 are respectively connected to the source and ground of the MOSFET tube Q6 of the driving circuit, for collecting the current passing through the MOSFET tube Q6 and sending the collected value to pin 4 of the control chip.

5. The multi-output power supply according to claim 1, characterized in that: A peak voltage absorption circuit is arranged between the driving circuit and the winding N1, and the peak voltage absorption circuit includes a diode D17, a diode D14, a capacitor C63, a resistor R88 and a resistor R90. After the diode D14, the capacitor C63, the resistor R88 and the resistor R90 are connected in parallel, one end of which is connected to the winding N1, and the other end of which is connected to one end of the diode D17, and the other end of the diode D17 is connected to the winding N1.

6. The multi-output power supply according to claim 1, characterized in that: The control chip is also provided with a voltage stabilizing circuit, which includes an optocoupler PC817 and a voltage stabilizing chip TL431 connected in sequence.

7. The multi-output power supply according to claim 1, characterized in that: The high-frequency transformer T2, wherein the winding N1 cooperates with the MOSFET tube Q6 of the driving circuit, and the Q6 high-frequency switch enables the winding N1 to obtain high-frequency alternating current, and the other windings obtain corresponding high-frequency alternating current in proportion; wherein the winding N2 is a feedback winding to power the control chip; the rectified voltage of the winding N3 is 5V, which powers the digital meter; the rectified voltages of the windings N4 and N6 are respectively used to power the two upper tube MOSFET driving chips in the full-bridge inverter; the rectified voltage of the winding N5 is used to power the two lower tube driving chips in the full-bridge inverter; the rectified voltages of the windings N7 and N8 are used to power the Hall sensor and the output control chip.

8. The multi-output power supply according to claim 7, characterized in that: In the winding structure of the high-frequency transformer T2, the winding N1 is wound with 122 turns of 0.21 diameter enameled wire, starting from pin 1 and ending at pin 22; the winding N2 is wound with 12 turns of 0.21 diameter enameled wire, starting from pin 4 and ending at pin 3; the winding N3 is wound with 5 turns of 0.38 diameter enameled wire, starting from pin 11 and ending at pin 10; the winding N4 is wound with 17 turns of 0.38 diameter enameled wire, starting from pin 13 and ending at pin 12; the winding N5 is wound with 12 turns of 0.38 diameter enameled wire, starting from pin 14 and ending at pin 15; the winding N6 is wound with 12 turns of 0.38 diameter enameled wire, starting from pin 15 and ending at pin 16; the winding N7 is wound with 12 turns of 0.38 diameter enameled wire, starting from pin 16 and ending at pin 17; the winding N8 is wound with 12 turns of 0.38 diameter enameled wire, starting from pin 13 and ending at pin 16; the winding N9 is wound with 12 turns of 0.38 diameter enameled wire, starting from pin 14 and ending at pin 16; the winding N10 is wound with 12 turns of 0.38 diameter enameled wire, starting from pin 14 and ending at pin 16; the winding N11 is wound with 12 turns of 0.38 diameter enameled wire, starting from pin 14 and ending at pin 16; the winding N12 is wound with 12 turns of 0.21 diameter enameled wire, starting from pin 1 Winding N6 is wound 17 times with 0.38 diameter enameled wire, starting from pin 16 and ending at pin 15; Winding N7 is wound 14 times with 0.38 diameter enameled wire, starting from pin 7 and ending at pin 6; Winding N8 is wound 14 times with 0.38 diameter enameled wire, starting from pin 8 and ending at pin 7; Pins 1, 4, 7, 8, 11, 13, 16, and 20 are the same-name terminals with consistent phases.

9. The multi-output power supply according to claim 1, characterized in that: The multi-channel voltage of the high-frequency transformer T2 is led out through a double-row solder pin, which serves as an output lead-out circuit and is finally soldered to the mainboard, wherein pins 1 and 3 of the double-row solder pin are -VCC2 and SGND lead-out terminals; pins 4 and 3 of the double-row solder pin are 5V and SGND lead-out terminals; pins 6 and 7 of the double-row solder pin are +VCC2 and SGND lead-out terminals; pins 11 and 9 of the double-row solder pin are the total DC input V+ and PGND lead-out terminals; pins 14 and 13 of the double-row solder pin are VB2 and VS2 lead-out terminals; pins 16 and 17 of the double-row solder pin are VB1 and VS1 lead-out terminals; pins 20 and 19 of the double-row solder pin are VCC1 and GND lead-out terminals.

10. The multi-output power supply according to claim 1, characterized in that: The pins of the control chip L6565D are as follows: Pin 1: As the inverting input terminal of the output voltage feedback, it adopts the optocoupler isolation voltage stabilization of the voltage stabilization circuit and is directly grounded; Pin 2: As the output of the error amplifier, it is directly connected to the secondary side of the optocoupler in the voltage stabilization circuit. Its voltage change synchronously drives the drive pulse change. Pin 3: As the input voltage feedback pin, this pin and pin 4 together set the current protection value of the MOSFET tube Q6 of the driving circuit. When the voltage of pin 3 reaches 3V, the current protection value is zero and the circuit stops working; Pin 4: As the overcurrent protection value setting pin of the MOSFET tube Q6 of the driving circuit, the source of Q6 is connected to the ground through the resistor R92. Pin 4 sets the overcurrent protection value by collecting the pulse voltage of R92. When the voltage of pin 4 reaches 2V, the chip is overcurrent protected and the output is turned off. Pin 4 and pin 3 work together to set the overcurrent value. The value of pin 3 increases and the overcurrent protection value decreases. Pin 5: As the soft switch control terminal, the voltage of the feedback winding N2 is collected through the resistor R94. When the voltage of N2 is zero, the control chip determines that the current of the MOSFET tube Q6 of the driving circuit is zero. After a delay time, the MOSFET tube Q6 is turned on to achieve zero voltage turn-on; Pin 6: As the negative power supply of the chip, all pin voltages are referenced to this pin; Pin 7: As the driving output terminal of the MOSFET tube Q6 of the driving circuit, it has a driving capability of 0.4A; Pin 8: As the positive power supply for the chip, a 15V voltage regulator diode is connected in parallel to the ground to prevent overvoltage from damaging the chip.

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