Flyback switching power supply structure based on ESOP8 packaging form

Abstract

The utility model provides a flyback switching power supply structure based on an ESOP8 packaging form. The flyback switching power supply structure comprises a slide holder, terminal pins, a connecting lead, chip bonding glue, a control chip, a high-voltage power switch, and a plastic package body for sealing the slide holder, the terminal pins, the connecting lead, the chip bonding glue, the control chip and the high-voltage power switch. The terminal pins comprise a first pin, a second pin, a third pin, a fourth pin and a fifth pin which are uniformly distributed on one side of the plastic package body, and a sixth pin, a seventh pin and an eighth pin which are non-uniformly distributed on the other side of the plastic package body; the sixth pin, the seventh pin and a metal sheet on the back surface of the plastic package body are led out from the slide holder; the connecting wire is used for electrically connecting the control chip, the high-voltage power switch and the terminal pin; the chip bonding glue is used for fixing the control chip, the high-voltage power switch is arranged on the 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 ESOP8 packaging form. Background Art

[0002] In the application of small power switching power supply below 100W, the flyback power supply architecture is often used. This architecture can be divided into primary side feedback PSR and secondary side feedback SSR. PSR has the advantages of simple periphery, simple transformer structure, single output rectifier diode, no need for output energy storage inductor, wide output input voltage range, etc.; SSR adds optocoupler to feed back the output voltage to the control chip in real time. The control chip adjusts or stabilizes the output voltage in time, so the output is more accurate; both architectures are widely used in adapter 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 chip, 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 interference and is difficult to operate stably, the present application provides a flyback switching power supply structure based on the ESOP8 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 ESOP8 package form, which adopts the following technical solutions:

[0007] A flyback switching power supply structure based on the ESOP8 packaging form, comprising a wafer carrier, lead pins, connecting wires, chip adhesive, a control chip and a high-voltage power switch, and a plastic package body that seals the wafer carrier, the lead pins, the connecting wires, the chip adhesive, the control chip and the high-voltage power switch; the lead pins comprise a first pin, a second pin, a third pin, a fourth pin and a fifth pin that are evenly distributed on one side of the plastic package body, and a sixth pin, a seventh pin and an eighth pin that are unevenly distributed on the other side of the plastic package body; the wafer carrier leads out the sixth pin, the seventh pin and a metal sheet on the back of the plastic package body; the connecting wires are used for electrical connection of the control chip, the high-voltage power switch and the lead pins; the chip adhesive is used for fixing the control chip and the high-voltage power switch on the wafer carrier.

[0008] Preferably, the high-voltage power switch is a gallium nitride device, and the control chip has a built-in high-voltage startup function and a self-power supply function.

[0009] Preferably, the insulation gap between the eighth pin and adjacent pins is larger than the insulation gap between other lead pins.

[0010] Preferably, 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.

[0011] Preferably, the pin width of the sixth pin and the seventh pin is greater than the width of other pins, and the sixth pin and the seventh pin are both set to be ground pins GND, which is conducive to heat dissipation and enhancing the heat dissipation of the structure, and the insulation gap between the sixth pin and the seventh pin is smaller than the insulation gap between other pins.

[0012] Preferably, the fifth 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 first pin is set as a free pin; the second pin is set as a power supply pin VCC; the third pin is set as a remote switch pin EN; and the fourth pin is set as a waveform sampling and signal feedback pin VS.

[0014] Preferably, the first pin is set as a waveform sampling pin DEM; the second pin is set as a remote switch pin EN; the third pin is set as a signal feedback pin FB; and the fourth pin is set as a power supply pin VCC.

[0015] Preferably, the first pin is set as a free pin; the second pin is set as a waveform sampling pin DEM; the third pin is set as a signal feedback pin FB; and the fourth pin is set as a power supply pin VCC.

[0016] Preferably, it also includes a diode, which is fixed on the wafer carrier by the adhesive glue, and the diode has an anode and a cathode, the cathode is electrically connected to the high-voltage pin D, and the anode is electrically connected to the ground pin GND by conductive glue.

[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 flyback switching power supply system diagram of the primary side feedback control of the present application is shown;

[0019] Figure 2 A flyback switching power supply system diagram of the secondary side feedback control of the present application is shown;

[0020] Figure 3 Shown applied to Figure 1 ESOP8 package pinout of the system;

[0021] Figure 4 Shown applied to Figure 2 The first embodiment diagram of the ESOP8 package pinout of the system;

[0022] Figure 5 Shown applied to Figure 2 The second embodiment diagram of the ESOP8 package pinout of the system;

[0023] Figure 6 A schematic diagram of the internal structure of the ESOP8 packaging frame of the present application is shown. DETAILED DESCRIPTION

[0024] refer to Figure 1 , Figure 2 , which is a flyback switching power supply system diagram of this application, includes a power control IC, a storage transformer, an output rectifier diode and necessary peripheral devices. The power control IC is a control chip and a high-voltage power switch sealed together to form a single integrated control chip, making the system simpler, reducing one packaging cost and lowering the cost.

[0025] Figure 1This is the primary side feedback PSR switching power supply system diagram. VIN is the input AC voltage. After bridge rectification and input filter capacitor E1, a positive power supply voltage of up to 450V or even higher is usually obtained. IC is a power control IC in ESOP8 package, which contains a control chip and a high-voltage power switch. The control chip has built-in high-voltage startup and self-power supply functions. C2 is a self-powered external energy storage capacitor that provides the power control IC with a working voltage after startup. R1, R2, C1, and D1 are leakage inductance absorption and buffer networks. R2 provides damping to reduce the interference of leakage inductance oscillation on R3 and R4 waveform sampling. R3, R4 It is a waveform sampling and output voltage feedback network. It senses the waveforms of the primary winding and the secondary winding through the auxiliary winding, and feeds them back to the power control IC. Based on this, it controls the circuit to complete the system's voltage regulation, constant current and protection control. EN is a remote switch, which can conveniently control the on or off of the power system by connecting a single-chip microcomputer or other equipment. R5 is a switch current limiting and detection resistor. When the current of the primary winding reaches the maximum value, the high-voltage power switch is disconnected. D2 and E2 are output rectifier and filter networks. R7 is an output dummy load.

[0026] The control chip in the PSR system 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 feedback and control of the system only on the high-voltage side, thereby reducing the external feedback network-related settings, making the system simpler and effectively reducing system costs.

[0027] Figure 2This is the secondary side optocoupler feedback SSR switching power supply system diagram. An external optocoupler is required to feed back the output voltage to the control chip in real time. The control chip receives the feedback signal FB and adjusts and stabilizes the output voltage in time. The secondary side optocoupler feedback system has higher voltage regulation accuracy than the primary side feedback system and is suitable for occasions with higher voltage requirements. 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 power control IC in ESOP8 package, which contains a control chip and a high-voltage power switch. The control chip has built-in high-voltage startup and self-power supply functions. C2 is a self-powered external energy storage capacitor, which provides the power control IC with the working voltage after startup; R1, R2, C1, and D1 are leakage inductance absorption and buffer networks, and R2 provides damping to reduce the interference of leakage inductance oscillation on R3 and 4 waveform sampling; R3 and R4 are waveform sampling, and the auxiliary winding senses the waveform of the primary winding or the secondary winding to complete the protection functions such as valley opening, input undervoltage or overvoltage, and output undervoltage or overvoltage; EN remote switch function, which can conveniently control the power system on or off by connecting a single-chip microcomputer or other equipment; FB signal feedback, using the optocoupler to feedback the output voltage to the control chip in real time, and the control chip receives the feedback signal FB to adjust and stabilize the output voltage in time; R5 is the switch current limiting and detection resistor. When the current of the primary winding reaches the designed value, the high-voltage power switch is disconnected. D2 and E2 are the output rectifier filter network. R7 is the output dummy load.

[0028] The above-mentioned control chips all have built-in high-voltage starting function and self-power supply function, which reduces the setting of external starting circuit and power supply circuit, and can effectively improve the starting speed by increasing the high-voltage starting charging current; by turning off the high-voltage starting circuit after starting, the standby power consumption is effectively reduced.

[0029] 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 switch generates a large amount of heat, which causes the temperature of the power control IC to rise. At the same time, the transformer also forms a corresponding large magnetic field change, which will cause the system to 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 the device parameters in the control chip and the impact of electromagnetic interference on the control chip, so as to ensure the reliable and stable operation of the system control function.

[0030] As system power continues to increase, the packaging of the power control IC must also have certain heat dissipation requirements, which also requires that the layout and lead-out positions of the power control IC 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.

[0031] Therefore, the present application proposes a flyback switching power supply structure based on the ESOP8 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.

[0032] Reference Figure 6 A flyback switching power supply structure based on the ESOP8 packaging form includes a wafer stage 9, lead pins, connecting wires, adhesive glue, a control chip, a high-voltage power switch and a plastic package 10. The control chip and the high-voltage power switch are both arranged on the wafer stage 9 (not shown in the figure), and the plastic package seals the wafer stage, connecting wires, adhesive glue, the control chip and the high-voltage 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 ESOP8 packaging form, which has 8 external pins, and its overall dimensions are not greater than 6.4mm*6.1mm*1.25mm, of which the length is 6.4mm, the width including the overall span of the pins is 6.1mm, and the height is 1.25mm.

[0033] In the embodiment of the present application, a gallium nitride GaN device is used as a high-voltage power switch, and the control chip has built-in high-voltage startup and self-power supply functions. The first pin 1 to the fifth pin 5 are located on the same side of the plastic package 10 in sequence, and the sixth pin 6 to the eighth pin 8 are located on the other side of the plastic package 10; the pin width of the first pin to the fifth pin is preferably 0.4mm, and the insulation gap between the first pin to the fifth pin is 0.9mm, the pin width of the sixth pin and the seventh pin is preferably 1.4mm, and the insulation gap between the sixth pin and the seventh pin is 0.35mm, and the pin width of the eighth pin is preferably 0.65mm; and the insulation gap between the eighth pin and the seventh pin is the largest, preferably not less than 1.6mm; the eight functional pins include A high-voltage pin D: the drain of the internal high-voltage power switch; a power supply pin VCC: provides working power for the control chip; two ground pins GND: are the reference ground terminals of the control chip; a waveform sampling pin DEM: is the auxiliary winding waveform input terminal, which senses the waveform of the primary winding or the secondary winding through the auxiliary winding to complete valley opening, input undervoltage or overvoltage, output undervoltage or overvoltage and other protection functions; a feedback signal pin FB or waveform sampling and signal feedback pin VS: is the control chip to feedback the power supply output signal to achieve the purpose of voltage regulation; a current and sampling pin CS: is the switch current limiting and detection resistor terminal; a remote switch pin EN: conveniently controls the power system on or off by connecting a microcontroller or other equipment.

[0034] The wafer stage 9 leads out the sixth pin 6, the seventh pin 7, and the metal sheet on the back of the plastic package 10. Preferably, the metal sheet is a copper sheet, and the area of ​​the copper sheet is not less than half of the area of ​​the back of the plastic package 10. The control chip and the high-voltage power switch are both arranged on the wafer stage 9, and the package has only one wafer stage. The copper sheet on the back of the plastic package 10 is a heat dissipation channel between the control chip and the high-voltage power switch tube and the external environment, so that the control chip and the high-voltage power switch tube can quickly dissipate heat and cool down. It should be noted that the pin widths of the sixth pin 6 and the seventh pin 7 are much larger than the widths of other pins. The heat of the high-voltage power switch is derived through the sixth pin 6 and the seventh pin 7 and the copper sheet on the back of the plastic package. The heat dissipation effect of the structure is enhanced by widening the pins. In the PCB, the metal area can be maximized to the ground to dissipate heat for the high-voltage power switch, thereby better balancing heat dissipation and electrical connection.

[0035] The substrate of the control chip and the high-voltage power switch is connected to the wafer carrier 9 through an adhesive (not shown in the figure), wherein the adhesive is preferably a conductive adhesive. The sixth pin 6 and the seventh pin 7 led out from the wafer carrier 9 are both set to a low potential, and their voltage level is generally 0V, which is an electrostatic potential in an electric field. Setting the sixth pin 6 and the seventh pin 7 to ground GND can further make the substrate of the gallium nitride switch 0 potential, thereby obtaining a good electrostatic potential without increasing EMI radiation.

[0036] like Figure 3 , Figure 4 , Figure 5 The package pins are shown as follows: the fifth pin 5 is set to CS, the sixth pin 6 and the seventh pin 7 are set to GND, and the eighth pin is set to D. Both are applicable to PSR systems or SSR systems. The first pin 1 to the fourth pin 4 can be reasonably arranged according to different system applications.

[0037] The details are as follows:

[0038] The fifth pin 5 is the current and sampling pin CS, which is located on the opposite side of the high-voltage pin to reduce interference and facilitate PCB wiring.

[0039] The sixth pin 6 and the seventh pin 7 are both ground pins GND. The sixth pin 6 and the seventh pin 7 are connected to the large copper sheet on the back of the plastic package through the wafer carrier 9, forming a heat dissipation channel between the control chip, the high-voltage power switch and the external environment, so that the control chip and the high-voltage 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 1.4mm. The gap between the sixth pin 6 and the seventh pin 7 is preferably 0.35mm. By widening the pins to enhance the heat dissipation effect of the structure, it is beneficial to extract heat. The high-voltage power switch preferably has a structure in which the gallium nitride device is substrate-grounded, which better takes into account heat dissipation and electrical connection.

[0040] The eighth pin 8 is the high-voltage pin D, and the distance between the eighth pin 8 and the adjacent pin is the largest, so that the high-voltage pin and other low-voltage pins have a larger insulation gap, which is not less than 1.6mm, wherein the insulation gap is preferably 1.6mm, and the width of the eighth pin 8 is preferably 0.65mm. Setting the high-voltage terminal on the first pin 1 can meet the high-voltage isolation requirements, comply with safety regulations and improve safety performance.

[0041] like Figure 1 and Figure 3 As shown, the pinout of the PSR system and ESOP8 package:

[0042] The first pin 1 is an empty pin;

[0043] The second pin 2 is the power supply pin VCC: the control chip has built-in high-voltage startup function and self-power supply function, and stores energy through the external capacitor C2 to provide working power for the control chip;

[0044] The third pin 3 is the remote switch pin EN: it can conveniently control the on or off of the power system by connecting a single-chip microcomputer or other equipment. Other equipment 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 third pin 3;

[0045] The fourth pin 4 is the waveform sampling and signal feedback pin VS: the auxiliary winding senses the waveform of the primary winding or the secondary winding to complete valley start, input undervoltage or overvoltage, output undervoltage or overvoltage and other protection functions. At the same time, when the secondary winding is working, the sensed output voltage is used to control the chip to feedback the power supply output voltage, thereby controlling the chip to adjust and stabilize the output voltage to achieve the purpose of voltage stabilization.

[0046] like Figure 2 and Figure 4 As shown, the first embodiment of the SSR system and ESOP8 package pinout is shown in the figure:

[0047] The first pin 1 is the waveform sampling pin DEM: the auxiliary winding senses the waveform of the primary winding or the secondary winding to complete the valley bottom opening, input undervoltage or overvoltage, output undervoltage or overvoltage and other protection functions;

[0048] The second pin 2 is the remote switch pin EN: it can conveniently control the on or off of the power system by connecting a single-chip microcomputer or other devices. Other devices can be Bluetooth control, wireless control, infrared control, photoelectric control, etc. There is no restriction here, as long as they can output high and low level control signals to the second pin 2;

[0049] The third pin 3 is the signal feedback pin FB: the optocoupler is used to feed back the output voltage to the control chip in real time. The control chip receives the feedback signal FB and adjusts and stabilizes the output voltage in time to achieve the purpose of high-precision voltage regulation.

[0050] The fourth pin 4 is the power supply pin VCC: the control chip has built-in high-voltage startup function and self-power supply function, and stores energy through the external capacitor C2 to provide working power for the control chip and the optocoupler;

[0051] like Figure 2 and Figure 5 As shown, the second embodiment of the SSR system and ESOP8 package pinout is shown in the figure:

[0052] The remote switch function is an optional function. If the system does not have the remote switch control function, this pin EN may not be brought out. Compared with the first embodiment of the ESOP8 package pins shown above, the first pin 1 is designed as an empty pin, the second pin is designed as a waveform sampling pin DEM, and the remaining pins are the same as the first ESOP8 package pins shown above.

[0053] 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 wafer stage 9 in the package, so that its cathode is electrically connected to the high voltage pin D, and its anode is electrically connected to the ground pin. 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 avalanches and breaks down, thereby clamping the voltage amplitude to protect the gallium nitride power device, and the system control function can operate stably.

[0054] 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.

[0055] The implementation principle of a flyback switching power supply structure based on the ESOP8 packaging form in an embodiment of the present application is as follows: based on the ESOP8 packaging form, the waveform sampling pin DEM, the remote switch pin EN, the power supply pin VCC, the signal feedback pin FB or the waveform sampling and signal feedback pin VS, and the current and sampling pin CS are connected in sequence on the same side of the frame, and a high-voltage pin D and a widened ground pin GND are set on the other side. These 8 functional pins achieve minimized interference characteristics and maximized heat dissipation function through a reasonable pin function layout, making the system function more reasonable and more reliable.

[0056] 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.

[0057] The above-mentioned embodiments only express several implementation methods of the utility model, and the description is relatively specific and detailed, but it 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, which 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 ESOP8 packaging, characterized in that: It comprises a wafer carrier (9), lead pins, connecting wires, wafer adhesive, a control chip and a high-voltage power switch, and a plastic package (10) for sealing the wafer carrier (9), the lead pins, the connecting wires, the wafer adhesive, the control chip and the high-voltage 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) uniformly distributed on one side of the plastic package (10), and a sixth pin (6), a seventh pin (7) and an eighth pin (8) unevenly distributed on the other side of the plastic package (10); The chip carrier (9) leads out the sixth pin (6), the seventh pin (7) and the metal sheet on the back of the plastic package (10); The connecting wire is used for electrical connection between the control chip, the high-voltage power switch and the lead pin; The chip adhesive is used to fix the control chip and the high-voltage power switch on the chip carrier (9).

2. A flyback switching power supply structure based on ESOP8 packaging form according to claim 1, characterized in that: The high-voltage power switch is a gallium nitride device, and the control chip has built-in high-voltage startup function and self-power supply function.

3. A flyback switching power supply structure based on ESOP8 packaging form according to claim 2, characterized in that: The insulation gap between the eighth pin (8) and adjacent pins is greater than the insulation gap between other lead pins.

4. A flyback switching power supply structure based on ESOP8 packaging form according to claim 3, characterized in that: The eighth pin (8) is set as a high-voltage pin D, which meets the high-voltage isolation requirements and ensures the reliable and stable operation of the system control function.

5. A flyback switching power supply structure based on ESOP8 packaging form according to claim 4, characterized in that: The pin widths of the sixth pin (6) and the seventh pin (7) are greater than the widths of the other pins. The sixth pin (6) and the seventh pin (7) are both configured as ground pins GND, which is beneficial for heat dissipation and enhances the heat dissipation of the structure. The insulation gap between the sixth pin (6) and the seventh pin (7) is smaller than the insulation gap between the other pins.

6. A flyback switching power supply structure based on ESOP8 packaging form according to claim 5, characterized in that: The fifth pin (5) 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. A flyback switching power supply structure based on ESOP8 packaging according to claim 6, characterized in that: The first pin (1) is set as a free pin; the second pin (2) is set as a power supply pin VCC; the third pin (3) is set as a remote switch pin EN; and the fourth pin (4) is set as a waveform sampling and signal feedback pin VS.

8. The flyback switching power supply structure based on ESOP8 packaging form according to claim 6, characterized in that: The first pin (1) is set as a waveform sampling pin DEM; the second pin (2) is set as a remote switch pin EN; the third pin (3) is set as a signal feedback pin FB; and the fourth pin (4) is set as a power supply pin VCC.

9. The flyback switching power supply structure based on ESOP8 packaging form according to claim 6, characterized in that: The first pin (1) is set as a free pin; the second pin (2) is set as a waveform sampling pin DEM; the third pin (3) is set as a signal feedback pin FB; and the fourth pin (4) is set as a power supply pin VCC.

10. The flyback switching power supply structure based on ESOP8 packaging form according to claim 6, characterized in that: It also includes a diode, which is fixed on the wafer carrier (9) by the wafer adhesive, and has an anode and a cathode, the cathode is electrically connected to the high-voltage pin D, and the anode is electrically connected to the ground pin GND by the conductive glue.

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