Flyback switching power supply structure based on ASOP8 packaging form

Abstract

The utility model provides a flyback switching power supply structure based on an ASOP8 packaging form, which comprises a first slide holder, a second slide holder, a third slide holder, terminal pins, connecting leads, chip bonding glue, a chip and a power switch, the plastic package body is used for sealing the first slide holder, the second slide holder, the third slide holder, the terminal pins, the connecting wires, the chip bonding glue, the chip and the power switch; the terminal pins comprise a first pin, a second pin, a third pin, a fourth pin and a fifth pin which are positioned on one side of the plastic package body, and a sixth pin, a seventh pin and an eighth pin which are positioned on the other side of the plastic package body; the lead is used for electrically connecting the chip, the power switch and the terminal pin; the chip bonding glue is used for fixing the chip, the power switch is connected with the first chip carrying table or the second chip carrying table or the third chip carrying table, the maximum heat dissipation requirement and the minimum interference characteristic are achieved through reasonable pin function layout, and the system function is more reasonable and more reliable.

Description

Technical Field

[0001] The present invention relates to the technical field of power supply, and in particular to a flyback switching power supply structure based on an ASOP8 packaging form. Background Art

[0002] In low-power switching power supply applications below 100W, a flyback power supply architecture is often used. This architecture has the advantages of simple periphery, simple transformer structure, single output rectifier diode, no need for output energy storage inductor, and wide output and input voltage range. Therefore, it is widely used in adapters and charger power supplies.

[0003] At present, in the relevant technology, when the power supply system is working, the high-voltage power switch will continuously turn on and off between 0 and 600V. The heat generated by the high-voltage power tube and the large magnetic field fluctuations formed by the transformer will cause the system to produce large electric and magnetic field interferences, the chip temperature will rise, and the parameter changes of the electronic components will affect the control circuit, making it difficult for the system control function to operate reliably and stably.

[0004] The above-mentioned related technologies have the defect that the control function is easily disturbed by temperature and magnetic field and is difficult to operate stably. Summary of the invention

[0005] In order to improve the problem that the control function is easily affected by temperature and magnetic field and is difficult to operate stably, the present application provides a flyback switching power supply structure based on the ASOP8 package form, which achieves minimized interference characteristics and maximized heat dissipation function through reasonable pin function layout, making the system function more stable and reliable.

[0006] The present application provides a flyback switching power supply structure based on the ASOP8 package form, which adopts the following technical solutions:

[0007] A flyback switching power supply structure based on the ASOP8 packaging form comprises a first wafer stage, a second wafer stage, a third wafer stage, lead pins, connecting wires, chip adhesive, a chip and a power switch, and a plastic package body for sealing the first wafer stage, the second wafer stage, the third wafer stage, the lead pins, the connecting wires, the chip adhesive, the chip and the power switch; the lead pins comprise a first pin, a second pin, a third pin, a fourth pin and a fifth pin located on one side of the plastic package body and a sixth pin, a seventh pin and an eighth pin located on the other side of the plastic package body; the wires are used for electrical connection of the chip, the power switch and the lead pins; the chip adhesive is used for fixing the chip and the power switch on the first wafer stage, the second wafer stage or the third wafer stage.

[0008] Preferably, the first wafer stage, the second wafer stage and the third wafer stage are all made of metal, which can be metal copper or metal copper with a silver-plated layer; the first wafer stage leads out the first pin, the second wafer stage leads out the sixth pin and the seventh pin, and the third wafer stage leads out the fifth pin, wherein the area of ​​the second wafer stage is larger than the area of ​​the first wafer stage and the area of ​​the third wafer stage, and the chip and the power switch are both arranged on the second wafer stage.

[0009] Preferably, the power switch is a gallium nitride device, and the chip is a switching power supply chip.

[0010] Preferably, the insulation gap between the first pin and the eighth pin and the adjacent lead pins is larger than the insulation gap between other adjacent lead pins, and is preferably not less than 1.5 mm.

[0011] Preferably, the first pin or the eighth pin is set as a high-voltage pin D to meet high-voltage isolation requirements and ensure reliable and stable operation of the system control function.

[0012] Preferably, the eighth pin or the first pin is set as a current and sampling pin CS, which is located on the opposite side of the high-voltage pin to facilitate system PCB layout.

[0013] Preferably, the sixth pin and the seventh pin are both configured as ground pins GND, and the pin widths of the sixth pin and the seventh pin are greater than the widths of other pins, so as to facilitate heat dissipation and enhance the heat dissipation capacity of the structure.

[0014] Preferably, the third pin is set as a power supply pin VCC, and the power supply pin VCC provides working power for the chip. The fourth pin is set as another GND as an independent ground terminal for signal reference, which is conducive to reducing the influence of noise. The fifth pin is set as a waveform sampling pin VS.

[0015] Preferably, it also includes a diode, which is placed on the first wafer carrier, and has an anode and a cathode, the cathode is electrically connected to the first pin, and the anode is electrically connected to the eighth pin or the sixth pin and the seventh pin.

[0016] Preferably, the withstand voltage of the power switch is not less than the maximum value of the normal input voltage, and the withstand voltage of the diode is not greater than the withstand voltage of the power switch. When the input instantaneous high voltage is greater than the withstand voltage of the diode, the diode is used to protect the power switch to ensure stable operation of the system control function.

[0017] By adopting the above technical solutions, reasonable pin function layout can achieve minimized interference characteristics and maximized heat dissipation function, making the system function more stable and more reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A power system diagram of the present application with high voltage startup and primary side feedback control is shown;

[0019] Figure 2 A schematic diagram showing the appearance of the packaging frame of the present application is shown;

[0020] Figure 3 A schematic diagram of the internal structure of the packaging frame of the present application is shown. DETAILED DESCRIPTION

[0021] In low-power switching power supply applications below 100W, the flyback power supply architecture is often used. This architecture has the advantages of simple periphery, simple transformer structure, single output rectifier diode, no output energy storage inductor, and wide output and input voltage range. Therefore, it is widely used in adapters and charger power supplies. Figure 1 As shown in the figure, a typical flyback power supply circuit structure in the related technology is shown. The traditional flyback power supply is generally composed of a PWM control IC, a high-voltage power switch, a storage transformer, an output rectifier diode and necessary peripheral devices. When the power is small, the control IC can also be packaged together with the high-voltage power switch through a co-sealing method to form a single integrated control chip, making the system simpler, reducing one packaging cost and lowering the cost.

[0022] VIN is the input AC voltage, which is usually as high as 450V or even higher positive power supply voltage after bridge rectification and input filter capacitor E1; IC is a PWM control chip in ASOP8 package, which contains power control circuit and high-voltage power switch; R1, R2, C1, D1 are leakage inductance absorption and buffer network, R2 provides damping to reduce the interference of leakage inductance oscillation on R4 and R5 waveform sampling; C2 is the power supply decoupling and energy storage capacitor of the switching power supply chip; R3 and D3 are auxiliary power supply rectification circuit, which provide the chip with the working voltage after startup from the auxiliary winding of the transformer; R4 and R5 are the output voltage feedback network, which senses the output voltage through the auxiliary coil and feeds it back to the switching power supply chip for analysis of the sampling waveform and controls the circuit accordingly to complete the system's voltage stabilization, constant current and protection control; R6 is the switch current limiting and detection resistor, which disconnects the high-voltage power switch when the current of the primary coil reaches the design value; D2 and E2 are the output rectification and filtering network; R7 is the output dummy load.

[0023] The power control circuit includes a high-voltage startup function, which reduces the external startup circuit settings and can effectively increase the startup speed by increasing the high-voltage startup charging current; and effectively reduce the standby power consumption by shutting down the high-voltage startup circuit after startup.

[0024] The system control circuit detects the waveform of the auxiliary winding and, based on the in-phase induction relationship between the output winding and the auxiliary winding, completes the system feedback and control only on the high-voltage side, thereby reducing the external feedback network-related settings, making the system simpler and effectively reducing system costs.

[0025] During normal operation, the system operates in a typical pulse switching state with a relatively high operating voltage. In a typical charger application with an operating voltage range of 85~265Vac, the high-voltage power switch will continuously switch on and off between 0~600V. The high-voltage power tube generates a large amount of heat, and the transformer also forms a corresponding large magnetic field change. The system will therefore generate large electric and magnetic field interference. Therefore, it is necessary to reasonably layout the pins of the control chip to minimize the impact of temperature on device parameters and the impact of electromagnetic interference on the control circuit, so as to ensure the reliable and stable operation of the system control function.

[0026] As system power continues to increase, the packaging of control chips must also have certain heat dissipation requirements, which also requires that the arrangement and lead-out positions of the control chip functional pins and high-voltage power switch tubes be relatively reasonable, so as to increase the heat dissipation area and reduce signal interference, while meeting relevant safety requirements.

[0027] Therefore, the present application proposes a flyback switching power supply structure based on the ASOP8 package form, and realizes the maximum heat dissipation requirements and minimized interference characteristics through a reasonable pin function layout, making the system function more reasonable and more reliable.

[0028] Reference Figure 2 and Figure 3 A flyback switching power supply structure based on the ASOP8 packaging form includes a first wafer stage 91, a second wafer stage 92, a third wafer stage 93, lead pins, connecting wires, adhesive glue, a chip, a power switch and a plastic package, wherein the plastic package seals the first wafer stage 91, the second wafer stage 92, the third wafer stage 93, lead pins, connecting wires, adhesive glue, a chip and a power switch tube; the connecting wires can be gold wires, silver wires, alloy wires, copper wires, gold palladium copper wires and other metal wires with conductive properties, which are not limited here. The flyback switching power supply structure adopts the ASOP8 packaging form, which has 8 external pins, and its overall dimensions are not greater than 6.2mm*6.1mm*1.25mm, wherein the length is 6.2mm, the width including the overall span of the pins is 6.1mm, and the height is 1.25mm.

[0029] In the embodiment of the present application, a gallium nitride GaN device is used as a power switch, and the chip is preferably a switching power supply chip. The first pin 1 to the fifth pin 5 are located on the same side of the plastic package 9 in sequence, and the sixth pin 6 to the eighth pin 8 are located on the other side of the plastic package 9; the eight functional pins include a high-voltage pin D: the drain of the internal power switch; a power supply pin VCC: providing working power for the control circuit; a ground pin GND: a reference terminal for the control circuit; two heat dissipation lead-out pins GND: conducive to heat dissipation; a waveform sampling pin VS: an auxiliary winding waveform input terminal; a current and sampling pin CS: a switch current limiting and detection resistor terminal; an empty pin NC, or an optional remote switch pin EN: conveniently controlling the power system on or off by connecting a single-chip microcomputer or other device.

[0030] The first wafer stage 91, the second wafer stage 92 and the third wafer stage 93 are all made of metal, preferably copper or copper with a silver coating; the first wafer stage 91 leads to the first pin 1, the second wafer stage 92 leads to the sixth pin 6 and the seventh pin 7 and has the largest wafer area, the third wafer stage 93 leads to the fifth pin 5, the chip and the power switch tube are both arranged on the largest second wafer stage 92 (not shown in the figure), forming a heat dissipation channel between the chip, the power switch tube and the external environment, so that the chip and the power switch tube can quickly dissipate heat. It should be noted that the pin width of the sixth pin 6 and the seventh pin 7 is greater than the width of other pins, and the heat dissipation effect of the structure is enhanced by widening the pins, so as to better balance heat dissipation and electrical connection.

[0031] The substrate of the chip and the power switch tube is connected to the sixth pin 6 and the seventh pin 7 through adhesive (not shown in the figure), wherein the adhesive is preferably conductive adhesive, the sixth pin 6 and the seventh pin 7 are both at low potential, and their voltage level is generally 0V, which is electrostatic potential in the electric field, and the heat of the power switch tube is extracted through the sixth pin 6 and the seventh pin 7. The sixth pin 6 and the seventh pin 7 are grounded GND, which can further make the substrate of the gallium nitride switch at 0 potential, thereby obtaining a good electrostatic potential, so that the metal area laid to GND in the PCB can be maximized to dissipate heat for the power switch without increasing EMI radiation.

[0032] The first pin 1 or the eighth pin 8 is set as a high-voltage pin D. The first pin 1, the eighth pin 8 and the adjacent pins have a large spacing, so that the high-voltage pin and other low-voltage pins have an insulation gap, and the insulation gap is not less than 2mm, wherein the insulation gap 10 is preferably 2mm, and the width of the first pin 1 is preferably 0.35mm. Setting the high-voltage terminal on a pin away from other pins can improve safety performance.

[0033] The eighth pin 8 or the first pin 1 is set as the current and sampling pin CS, which is located on one side of the ground pin and on the opposite side of the high-voltage pin, which is beneficial to the system PCB layout design as a current limiting resistor connection pin, to achieve the closest connection to the ground pin GND, reduce interference and facilitate PCB wiring. Structurally, the eighth pin 8 has the largest spacing with the adjacent pins, so that the current and sampling pin CS and other pins have an insulating gap 11, which is not less than 2mm, wherein the insulating gap 11 is preferably 2.05mm, which is beneficial to reducing signal interference and enhancing the stability of the system, and the width of the eighth pin 8 is not less than 0.4mm, preferably 0.6mm.

[0034] The second pin 2 is an empty pin NC, or a remote switch pin EN can be optionally set: by connecting a microcontroller or other device to conveniently control the on or off of the power system, other devices can be Bluetooth control, wireless control, infrared control, photoelectric control, etc., there is no restriction here, as long as it can output high and low level control signals to the second pin.

[0035] The third pin 3 is a power supply pin VCC, which can decouple the third pin 2 through an external capacitor, thereby effectively filtering and isolating the electric field interference signal generated by the high-voltage pin, and providing a working voltage for the switching power supply chip.

[0036] The fourth pin 4, the sixth pin 6, and the seventh pin 7 are all ground pins GND. By connecting the ground pin GND to the large-area second wafer stage 92 inside the package, a heat dissipation channel between the chip, the power switch and the external environment is formed, so that the chip and the power switch can quickly dissipate heat. It should be noted that the pin width of the sixth pin 6 and the seventh pin 7 is greater than the width of other pins, and the width is preferably 1.27mm or greater. The gap between the sixth pin 6 and the seventh pin 7 is preferably 0.4mm, and is located on the other side of the fourth pin. By widening the pin, the heat dissipation effect of the structure is enhanced, which is conducive to heat extraction. The power switch preferably has a structure in which the gallium nitride device is grounded to the substrate. Therefore, the sixth pin 6 and the seventh pin 7 are most suitable as ground pins, and the sixth pin 6 and the seventh pin 7 are connected to the largest second wafer stage 92 inside, and the chip and the power switch are set on the second wafer stage 92, which better takes into account heat dissipation and electrical connection. The fourth pin 4 is set to another GND as an independent grounding terminal for signal reference, which is conducive to reducing the influence of noise.

[0037] The fifth pin 5 is the waveform sampling pin VS. This pin is close to the power supply pin VCC, which can effectively avoid external space interference level. At the same time, because its input voltage divider resistor network and the power supply pin VCC power supply circuit also come from the auxiliary winding, it is easier to carry out PCB wiring processing.

[0038] The pin widths of the second pin 2 , the third pin 3 , the fourth pin 4 and the fifth pin 5 are in the range of 0.3-0.4 mm; the pin gaps between the second pin 2 , the third pin 3 , the fourth pin 4 and the fifth pin 5 are preferably 0.65 mm.

[0039] Another embodiment of the present application, on the basis of the above embodiment, adds a protection function for the power switch. It is well known that the grid voltage has a certain fluctuation range, and it is inevitable that lightning will generate instantaneous high voltage. If the input instantaneous high voltage is greater than the withstand voltage of the power switch, the power switch will be damaged and the system will be unable to operate. In the present invention, a gallium nitride power device is selected as the power switch, and its operating voltage is between 0 and 600V. Therefore, a gallium nitride power device with a withstand voltage of not less than 600V is required, preferably 800V. A diode is arranged on the first wafer stage 91 in the package, so that its cathode is electrically connected to the first pin 1, and its anode is electrically connected to the eighth pin 8 or the sixth pin 6 and the seventh pin 7. The breakdown voltage of the diode is selected to be no greater than the breakdown voltage of the gallium nitride power device. When the input instantaneous high voltage is greater than the breakdown voltage of the gallium nitride power device, for example, 800V, the diode preferentially avalanche breaks down, thereby clamping the voltage amplitude to protect the gallium nitride power device, and the system control function can operate stably.

[0040] It should be noted that during the production process, the pins are connected by connecting ribs, and the connecting ribs are eventually cut off to form separate pins.

[0041] The implementation principle of a flyback switching power supply structure based on the ASOP8 packaging form in the embodiment of the present application is as follows: based on the ASOP8 packaging form, the high-voltage pin D, the power supply pin VCC, the ground pin GND and the waveform sampling pin VS are connected in sequence on the same side of the frame, and the current and sampling pin CS and the widened ground pin GND are set on the other side. These five functional pins achieve minimized interference characteristics and maximized heat dissipation function through reasonable pin function layout, making the system function more reasonable and more reliable.

[0042] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0043] The above-mentioned embodiments only express several implementation methods of the utility model, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the utility model patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the utility model, and these all belong to the protection scope of the utility model. Therefore, the protection scope of the utility model patent shall be based on the attached claims.

Claims

1. A flyback switching power supply structure based on ASOP8 packaging, characterized in that: It comprises a first chip carrier (91), a second chip carrier (92), a third chip carrier (93), lead pins, connecting wires, chip adhesive, a chip and a power switch, and a plastic package (9) for sealing the first chip carrier (91), the second chip carrier (92), the third chip carrier (93), the lead pins, the connecting wires, the chip adhesive, the chip and the power switch; The lead pins include a first pin (1), a second pin (2), a third pin (3), a fourth pin (4) and a fifth pin (5) located on one side of the plastic package (9) and a sixth pin (6), a seventh pin (7) and an eighth pin (8) located on the other side of the plastic package (9); The wire is used for electrical connection between the chip, the power switch and the lead pin; The adhesive is used to fix the chip and the power switch on the first chip carrier (91) or the second chip carrier (92) or the third chip carrier (93).

2. A flyback switching power supply structure based on ASOP8 packaging according to claim 1, characterized in that: The first wafer stage (91), the second wafer stage (92) and the third wafer stage (93) are all made of metal, which may be copper or copper with a silver-plated layer; the first wafer stage (91) leads out the first pin (1), the second wafer stage (92) leads out the sixth pin (6) and the seventh pin (7), and the third wafer stage (93) leads out the fifth pin (5), wherein the area of ​​the second wafer stage (92) is larger than the area of ​​the first wafer stage (91) and the area of ​​the third wafer stage (93), and the chip and the power switch are both arranged on the second wafer stage (92).

3. The flyback switching power supply structure based on the ASOP8 packaging form according to claim 1, characterized in that: The power switch is a gallium nitride device, and the chip is a switching power supply chip.

4. The flyback switching power supply structure based on the ASOP8 packaging form according to claim 1, characterized in that: The insulation gap between the first pin (1) and the eighth pin (8) and the adjacent lead pins is greater than the insulation gap between other adjacent lead pins, and the insulation gap between the first pin (1) and the eighth pin (8) and the adjacent lead pins is not less than 1.5 mm.

5. The flyback switching power supply structure based on the ASOP8 packaging form according to claim 3, characterized in that: The first pin (1) or the eighth pin (8) is set as a high-voltage pin D, which meets the high-voltage isolation requirement and ensures the reliable and stable operation of the system control function.

6. The flyback switching power supply structure based on the ASOP8 packaging form according to claim 5, characterized in that: The eighth pin (8) or the first pin (1) is configured as a current and sampling pin CS and is located on the opposite side of the high voltage pin, which facilitates the system PCB layout.

7. The flyback switching power supply structure based on the ASOP8 packaging form according to claim 6, characterized in that: The sixth pin (6) and the seventh pin (7) are both configured as ground pins GND, and the pin widths of the sixth pin (6) and the seventh pin (7) are greater than the widths of other pins, so as to facilitate heat dissipation and enhance the heat dissipation capability of the structure.

8. The flyback switching power supply structure based on the ASOP8 packaging form according to claim 7, characterized in that: The third pin (3) is set as a power supply pin VCC, and the power supply pin VCC provides working power for the chip. The fourth pin (4) is set as another GND, which serves as an independent ground terminal for signal reference, which is conducive to reducing the influence of noise. The fifth pin (5) is set as a waveform sampling pin VS.

9. The flyback switching power supply structure based on the ASOP8 packaging form according to claim 3, characterized in that: It also includes a diode, which is placed on the first wafer carrier (91), and has an anode and a cathode, the cathode is electrically connected to the first pin (1), and the anode is electrically connected to the eighth pin (8) or the sixth pin (6) and the seventh pin (7).

10. The flyback switching power supply structure based on the ASOP8 packaging form according to claim 9, characterized in that: The withstand voltage of the power switch is not less than the maximum value of the normal input voltage, and the withstand voltage of the diode is not greater than the withstand voltage of the power switch. When the input instantaneous high voltage is greater than the withstand voltage of the diode, the diode is used to protect the power switch to ensure stable operation of the system control function.

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