Electronic package for zero-cross detection of power grid voltage and isolated power supply system
By employing alternating communication technology with electronically packaged components in isolated power supply systems, the problems of low integration and high cost in grid voltage zero-crossing detection have been solved, achieving high integration and low-delay zero-crossing signal transmission under high-temperature environments.
Patent Information
- Application Number
- CN202422813135.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-18
- Publication Date
- 2025-11-21
- Estimated Expiration
- 2034-11-18
AI Technical Summary
Existing isolated AC-CDC power supply systems have low integration and high cost of grid voltage zero-crossing detection circuits, limited optocoupler lifespan, and cannot be used in high-temperature environments.
Using electronic packaging, the system achieves isolated transmission of grid voltage zero-crossing signals through alternating electric or magnetic fields between the primary and secondary circuits. This includes an encoder and transmitter on the primary side, and a receiver and decoder on the secondary side, providing high/low level or pulse signal outputs.
It improves integration, reduces costs, is suitable for high-temperature environments, and transmits zero-crossing detection signals with a delay of less than 50μs.
Smart Images
Figure CN223584022U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to electronic field, specifically but not limited to a kind of electronic package and isolated power supply system for grid voltage zero-crossing detection. BACKGROUND
[0002] The zero-crossing detection of power frequency alternating voltage in power grid has important application value, including but not limited to the control of silicon controlled rectifier, the control of relay, the detection of power grid voltage frequency, the timing of microcomputer unit (MCU) and the like.
[0003] As shown in Figure 1 In the isolated ACDC (alternating current to direct current) power supply system, the grid voltage zero-crossing detection circuit is often matched with optocoupler, and the grid voltage zero-crossing signal is transmitted from the primary side to the MCU on the secondary side of the power supply using the optocoupler.
[0004] However, the integration of such architecture is low, and the cost of using a dedicated optocoupler system is also high. At the same time, the optocoupler is limited in life due to the problem of light attenuation, and cannot be used in high temperature environment.
[0005] Therefore, it is necessary to provide a new structure or control method to solve at least part of the above problems. SUMMARY
[0006] In order to solve at least one or more problems in the background art, the utility model provides an electronic package and isolated power supply system for grid voltage zero-crossing detection.
[0007] According to one aspect of the utility model, an electronic package for grid voltage zero-crossing detection is provided, the electronic package has a high-voltage pin for coupling to an alternating current grid and a zero-crossing detection signal output pin for providing a zero-crossing detection signal, wherein the high-voltage pin is located on the primary side of an isolated voltage conversion circuit, and the zero-crossing detection signal output pin is located on the secondary side of the isolated voltage conversion circuit. The electronic package comprises: a primary side circuit, an input end of the primary side circuit is coupled to the high-voltage pin for obtaining a grid voltage on the alternating current grid, and the primary side circuit generates a zero-crossing signal representing the zero-crossing of the grid voltage; and a secondary side circuit, which is electrically insulated from the primary side circuit, and the secondary side circuit communicates with the primary side circuit through an alternating electric field or an alternating magnetic field and obtains the zero-crossing signal, and an output end of the secondary side circuit is coupled to the zero-crossing detection signal output pin.
[0008] In one embodiment, the primary side circuit comprises an encoder and a transmitter for encoding and transmitting the zero-crossing signal; and the secondary side circuit comprises a receiver and a decoder for receiving the signal transmitted by the transmitter and providing the zero-crossing detection signal after decoding.
[0009] In one embodiment, the zero-crossing detection signal is a high-low signal, and the level of the zero-crossing detection signal jumps when the absolute value of the grid voltage is detected to be less than the zero-crossing threshold, and the level jumps again when the absolute value of the grid voltage is detected to be less than the zero-crossing threshold again.
[0010] In one embodiment, the zero-crossing detection signal is a high pulse signal or a low pulse signal, and the output pin of the zero-crossing detection signal outputs a high pulse or a low pulse when the absolute value of the grid voltage is less than the zero-crossing threshold.
[0011] In one embodiment, the time difference between the zero-crossing jump time represented by the zero-crossing detection signal and the zero-crossing time of the grid voltage is less than 50 μs.
[0012] In one embodiment, the electronic package further has a primary side reference ground pin, wherein the first port of the AC grid is coupled to the anode of the first diode, the second port of the AC grid is coupled to the anode of the second diode, the cathode of the first diode and the cathode of the second diode are coupled to the high voltage pin.
[0013] In one embodiment, the high voltage pin comprises a first grid input pin and a second grid input pin, wherein the first port of the AC grid is coupled to the first end of the first resistor, the second end of the first resistor is coupled to the first grid input pin, the second port of the AC grid is coupled to the first end of the second resistor, and the second end of the second resistor is coupled to the second grid input pin.
[0014] In one embodiment, the electronic package further has a primary side reference ground pin, a secondary side reference ground pin, a primary side power supply pin coupled to the primary side reference ground pin through a capacitor, and a secondary side power supply pin coupled to the output of the isolated voltage conversion circuit and coupled to the zero-crossing detection signal output pin through a resistor.
[0015] In one embodiment, the primary side circuit comprises an X capacitor discharge circuit for discharging the charge on the X capacitor when the isolated voltage conversion circuit is disconnected from the AC grid, wherein the X capacitor is coupled between the first port and the second port of the AC grid.
[0016] In one embodiment, the secondary side circuit comprises a field effect transistor, wherein the control terminal of the field effect transistor receives the zero-crossing detection control signal, the drain of the field effect transistor forms the zero-crossing detection signal output pin and is coupled to a voltage source through a pull-up resistor, and the source of the field effect transistor is coupled to the secondary side reference ground.
[0017] In one embodiment, the secondary side circuit comprises a transistor, wherein the control terminal of the transistor receives the zero-crossing detection control signal, the collector of the transistor forms the zero-crossing detection signal output pin and is coupled to a voltage source through a pull-up resistor, and the emitter of the transistor is coupled to the secondary side reference ground.
[0018] According to another aspect of the present application, an isolated power supply system comprises: a rectifier circuit, an input of the rectifier circuit is coupled to an AC grid power supply, an output of the rectifier circuit provides a DC bus voltage; an isolated voltage conversion circuit for converting the DC bus voltage into an output voltage; and the electronic package as claimed in any one of the embodiments, wherein a high voltage pin of the electronic package is coupled to the input of the rectifier circuit, and a zero-crossing detection signal output pin of the electronic package is located at a secondary side of the isolated voltage conversion circuit.
[0019] The electronic package for grid voltage zero-crossing detection and the isolated power supply system, BRIEF DESCRIPTION OF DRAWINGS
[0020] The accompanying drawings are included to provide a further understanding of the present application, and are incorporated in and constitute a part of this application, illustrate embodiments of the present application, and do not limit the present application. In the drawings:
[0021] Figure 1 An optical coupling-containing zero-crossing detection circuit for an isolated power supply system is shown;
[0022] Figure 2 An isolated power supply system according to an embodiment of the present application is shown;
[0023] Figure 3 An internal circuit structure diagram of an electronic package according to an embodiment of the present application is shown.
[0024] Figure 4 An isolated power supply system according to an embodiment of the present application is shown;
[0025] Figure 5 An output end architecture of an electronic package with open-drain structure according to an embodiment of the present application is shown;
[0026] Figure 6 An output end architecture of an electronic package with open-collector structure according to another embodiment of the present application is shown;
[0027] Figure 7 An isolated power supply system according to an embodiment of the present application is shown;
[0028] Figure 8 A zero-crossing detection signal waveform diagram according to an embodiment of the present application is shown;
[0029] Figure 9 A zero-crossing detection signal waveform diagram according to another embodiment of the present application is shown;
[0030] Figure 10 A zero-crossing detection signal waveform diagram according to another embodiment of the present application is shown;
[0031] Figure 11 An isolated power supply system according to an embodiment of the present application is shown.
[0032] Figure 12 An isolated power supply system according to an embodiment of the present application is shown. DETAILED DESCRIPTION
[0033] In order to further understand the present application, the preferred embodiments of the present application are described below in conjunction with the embodiments. However, it should be understood that the description is only for further illustrating the features and advantages of the present application, but not for limiting the claims of the present application.
[0034] The description of this part is only for several typical embodiments, and the present application is not limited to the scope of the embodiment description. The combination of different embodiments, the mutual replacement of some technical features in different embodiments, and the mutual replacement of some technical features in the same or similar prior art means are also within the description and protection scope of the present application.
[0035] In the specification, "coupling" or "connection" includes both direct connection and indirect connection. Indirect connection is the connection through an intermediate medium, such as the connection through an electrically conductive medium such as a conductor, wherein the electrically conductive medium can contain parasitic inductance or parasitic capacitance, or through the intermediate circuit or component described in the embodiments of the specification; indirect connection can also include the connection through other active devices or passive devices on the basis of achieving the same or similar functions, such as the connection through circuits or components such as switches, signal amplification circuits, follow-up circuits, etc. "Multiple" or "many" means two or more.
[0036] Figure 2 An isolated power supply system according to an embodiment of the present application is shown. The isolated power supply system includes a rectifier circuit 21, an isolated voltage conversion circuit 22, and an electronic package 20 with zero-crossing detection function. The rectifier circuit 21 is used to rectify the alternating current grid voltage VAC into a direct current voltage. Specifically, the rectifier circuit 21 has two input terminals, which are respectively coupled to the two ports L and N of the alternating current grid power supply, and the two output terminals of the rectifier circuit 21 respectively provide a direct current bus voltage Vbus and form a primary side reference ground GND of the isolated voltage conversion circuit 22. The isolated voltage conversion circuit 22 is used to convert the direct current bus voltage Vbus into an output voltage Vout. The isolated voltage conversion circuit 22 includes a transformer, the transformer has a primary winding and a secondary winding, the isolation of the primary side circuit and the secondary side circuit is realized through the transformer, and the energy is transmitted from the primary winding to the secondary winding through the control of the main power switch in the primary side circuit, and the stable output voltage Vout is obtained through rectification and filtering. In an embodiment, the isolated voltage conversion circuit 22 includes a flyback voltage conversion circuit.
[0037] The electronic package 20 has a zero-crossing detection function for the grid voltage VAC. The electronic package 20 is an isolated circuit, including a primary side circuit and a secondary side circuit, wherein the primary side circuit is used to obtain the grid voltage through the high voltage pin HV coupled to the electronic package 20, and accordingly generates a zero-crossing signal representing the zero-crossing of the grid voltage VAC. In Figure 2 In the embodiment shown, the first port L of the alternating current grid is coupled to the anode of the first diode D1, the second port of the alternating current grid is coupled to the anode of the second diode D2, the cathode of the first diode D1 and the cathode of the second diode D2 are coupled to the high voltage pin HV. The secondary side circuit and the primary side circuit are electrically insulated and isolated, the secondary side circuit communicates with the primary side circuit through alternating electric field or alternating magnetic field and obtains the zero-crossing signal sent by the primary side circuit, after processing, the zero-crossing detection signal is provided at the output end of the secondary side circuit through the zero-crossing detection signal output pin Zero of the electronic package, which is used to provide to the circuit on the secondary side such as MCU. The electronic package has a high voltage pin HV, a primary side reference ground pin GND, a zero-crossing detection signal output pin Zero and a secondary side reference ground pin SGND. The primary side reference ground pin GND and the secondary side reference ground pin SGND can be coupled to the primary side reference ground and the secondary side reference ground of the isolated voltage conversion circuit 22 respectively. Through such a scheme, the optical coupling with large volume and cost is eliminated, which has higher integration and reduces the cost.
[0038] Figure 3An internal circuit structure diagram of the electronic package 300 for zero-crossing detection of the isolated power supply system according to an embodiment of the present application is shown. The electronic package 300 comprises a primary side circuit 31 and a secondary side circuit 32. The primary side circuit 31 is coupled to an AC power grid through a high voltage pin HV for obtaining grid voltage. The primary side circuit 31 comprises a zero-crossing detection comparison circuit 311, an encoder 312 and a transmitter 313. A first end of the zero-crossing detection comparison circuit 311 is coupled to the high voltage pin HV, and a second end of the zero-crossing detection comparison circuit 311 is coupled to a reference signal. The zero-crossing detection comparison circuit 311 compares a signal representing the grid voltage on the high voltage pin HV with the reference signal Vref to determine when the grid voltage crosses zero. In one embodiment, the reference signal Vref is a small voltage signal close to zero, and when the voltage HV is lower than Vref, it indicates that the grid voltage crosses zero. An input end of the encoder 312 is coupled to an output end of the zero-crossing detection comparison circuit 311, and an output end of the encoder 312 is coupled to an input end of the transmitter 313. When the grid voltage crosses zero, the zero-crossing detection comparison circuit 311 outputs an active signal, such as a pulse signal or a signal with a specific waveform, which is encoded by the encoder 312 and transmitted by the transmitter 313 through an alternating magnetic field or an alternating electric field. The secondary side circuit 32 comprises a receiver 321 and a decoder 322. An input end of the decoder 322 is coupled to an output end of the receiver 321, and an output end of the decoder 322 is coupled to a zero-crossing detection signal output pin Zero. The receiver 321 receives the signal transmitted by the transmitter 313 and decodes it by the decoder 322 to provide a zero-crossing detection signal on the secondary side of the isolated voltage conversion circuit and output it through the zero-crossing detection signal output pin Zero. In one embodiment, the primary side circuit 31 and the secondary side circuit 32 are respectively fabricated on two semiconductor substrates to form two wafers, and are jointly packaged in an electronic package. In another embodiment, the transmitter 313 and the receiver 321 are independently fabricated and packaged together with other parts of the primary side circuit 31 and the secondary side circuit 32 in the same electronic package.
[0039] In one embodiment, the transmitter comprises a coil. In another embodiment, the transmitter comprises a capacitor.
[0040] Figure 4 An isolated power supply system according to an embodiment of the present application is shown. Compared with the isolated power supply system in Figure 2 , the zero-crossing detection signal output pin Zero of the electronic package 40 in Figure 4 adopts an open drain or open collector structure, and the zero-crossing detection signal output pin Zero is coupled to an external pull-up resistor R for providing high and low level signals, as shown in Figure 10 .
[0041] Figure 5The electronic package output end architecture of the open drain structure according to an embodiment of the utility model is shown. The secondary side circuit includes a field effect tube K1, the control end of the field effect tube K1 receives the zero-crossing detection control signal ZT output by the decoder 51, the drain of the field effect tube K1 forms the zero-crossing detection signal output pin Zero and is coupled to the voltage source Vcc through a pull-up resistor Rs, and the source of the field effect tube K1 is coupled to the secondary side reference ground SGND. Through such a structure, the electronic package provides the secondary side circuit with high and low level zero-crossing detection signals.
[0042] Figure 6 The electronic package output end architecture of the open collector structure according to another embodiment of the utility model is shown. The secondary side circuit includes a triode K2, wherein the control end of the triode K2 receives the zero-crossing detection control signal ZT, the collector of the triode K2 forms the zero-crossing detection signal output pin Zero and is coupled to the voltage source Vcc through a pull-up resistor Rs, and the emitter of the triode K2 is coupled to the secondary side reference ground SGND.
[0043] Figure 7 The isolation type power supply system according to an embodiment of the utility model is shown. Compared with the isolation type power supply system in Figure 2 The high voltage pin of the electronic package 70 has two, including the first grid input pin HV1 and the second grid input pin HV2, which are coupled through resistors and two ports L and N of the grid, specifically, the first port L of the alternating current grid is coupled to the first end of the first resistor R1, the second end of the first resistor R1 is coupled to the first grid input pin HV1, the second port N of the alternating current grid is coupled to the first end of the second resistor R2, and the second end of the second resistor R2 is coupled to the second grid input pin HV2.
[0044] Figure 8 The waveform diagram of the zero-crossing detection signal Vzero output by the zero-crossing detection signal output pin Zero according to an embodiment of the utility model is shown. When the grid voltage, i.e., the alternating current input voltage VAC, crosses zero, the zero-crossing detection signal Vzero presents a high level pulse. In an embodiment, when it is detected that the absolute value of the grid voltage VAC is less than the zero-crossing threshold, the zero-crossing detection signal output pin outputs a high level pulse.
[0045] Figure 9 The waveform diagram of the zero-crossing detection signal Vzero according to another embodiment of the utility model is shown. When the alternating current input voltage VAC crosses zero, the zero-crossing detection signal Vzero presents a low level pulse. In an embodiment, when it is detected that the absolute value of the grid voltage VAC is less than the zero-crossing threshold, the zero-crossing detection signal output pin outputs a low level pulse.
[0046] Figure 10The zero-crossing detection signal Vzero is a high-low level signal, and the level of the zero-crossing detection signal Vzero is switched when the zero-crossing of the grid voltage VAC is detected. In an embodiment, when the absolute value of the grid voltage VAC is detected to be less than a zero-crossing threshold, the level of the zero-crossing detection signal Vzero jumps, and the jump occurs again when the absolute value of the grid voltage is detected to be less than the zero-crossing threshold next time. Through the electronic package in the embodiment of the present application, the zero-crossing detection signal is provided to the secondary side in the isolated power supply system, has high integration, and can make the delay Tzero_delay between the zero-crossing jump moment represented by the zero-crossing detection signal Vzero and the actual zero-crossing moment of the grid voltage VAC be low. Preferably, the time difference Tzero_delay between the zero-crossing jump moment represented by the zero-crossing detection signal and the zero-crossing moment of the grid voltage is less than 50 μs.
[0047] Figure 11 An isolated power supply system according to an embodiment of the present application is shown. In the isolated power supply system, the primary side circuit 111 in the electronic package 110 further has an X capacitor discharge circuit 112 for discharging the charge on the X capacitor 115 when the isolated voltage conversion circuit 116 is disconnected from the AC grid, wherein the X capacitor 115 is coupled between the first port L and the second port N of the AC grid. The X capacitor discharge circuit 112 includes a grid disconnection detection circuit 113 and a discharge circuit 114. In an embodiment, when the grid disconnection detection circuit 113 detects that the slope change of the voltage on the high voltage pin HV is less than a preset amplitude within a preset time, it is judged that the AC grid and the isolated voltage conversion circuit 121 are disconnected. In an embodiment, the preset time is a half power frequency period. The discharge circuit 114 is coupled across the X capacitor 115, and when it is detected that the AC grid and the isolated voltage conversion circuit 116 are disconnected, the discharge circuit 114 forms a conduction path for discharging the charge on the X capacitor.
[0048] Figure 12The isolation type power supply system is shown according to a specific embodiment of the utility model. The isolation type power supply system includes a rectifier circuit, an isolation type voltage conversion circuit and an electronic package 120 for grid voltage zero-crossing detection. The input end of the rectifier circuit is coupled to the L end and N end of the AC grid power supply for receiving the AC power supply VAC, and the output end of the rectifier circuit provides a DC bus voltage Vbus. The isolation type voltage conversion circuit includes a flyback type voltage conversion circuit for converting the DC bus voltage Vbus into an output voltage Vout. The flyback type voltage conversion circuit includes a primary side control circuit 121 for controlling the main power switch tube in the primary side circuit. In the illustrated embodiment, the power switch tube is included in the primary side control circuit 121, wherein the integrated circuit 120 is integrated in a first electronic package, and the primary side control circuit 121 is integrated in a second electronic package. The secondary side circuit of the flyback type voltage conversion circuit is isolated from the primary side circuit by the transformer T and transmits energy. The secondary side circuit and the primary side circuit use an optical coupling to transmit an output voltage feedback signal representing the output voltage Vout, and control the conduction and turn-off of the main power switch tube in the primary side circuit according to the output voltage feedback signal, so as to stabilize the output voltage Vout. The isolation type power supply system includes the electronic package 120 for transmitting a zero-crossing detection signal from the primary side to the secondary side. The electronic package 120 has a high voltage pin HV, a primary side power supply pin VDD, a primary side reference ground pin GND, a secondary side power supply pin SVDD, a zero-crossing detection signal output pin Zero and a secondary side reference ground pin SGND. The high voltage pin HV is coupled to the input end of the rectifier circuit, i.e. the two ports L and N of the AC grid; the primary side power supply pin VDD and the primary side reference ground pin GND are coupled by a capacitor for supplying power to the primary side circuit in the electronic package. Preferably, the primary side power supply pin VDD of the electronic package 120 is coupled to the power supply pin of the primary side control circuit 121. The secondary side power supply pin SVDD is used to supply power to the secondary side circuit in the electronic package 120. In one embodiment, the secondary side power supply pin SVDD is coupled to the output end of the isolation type voltage conversion circuit. Furthermore, the secondary side power supply pin SVDD can be further coupled to the zero-crossing detection signal output pin Zero through a pull-up resistor Rs. The zero-crossing detection signal output pin Zero is located in the secondary side of the isolation type voltage conversion circuit. Through such a setting, the zero-crossing signal detection of the isolation type power supply can be realized by adding a high-integration integrated circuit, and the system size and cost are reduced.
[0049] As known by those skilled in the art, the "high level" and "low level", "in-phase input end" and "inverted input end" and other logic controls in the description or drawings can be interchanged or changed, and the same functions or purposes as the above embodiments can be realized by adjusting the subsequent logic controls.
[0050] The description and application of the present application are illustrative, and are not intended to limit the scope of the present application to the above-mentioned embodiments. The effects or advantages related descriptions involved in the specification may not be embodied in actual experimental examples due to the uncertainty of specific condition parameters or other factors, and the effects or advantages related descriptions are not used to limit the scope of the present application. The variations and changes of the embodiments disclosed herein are possible, and the replacements and equivalent components of the embodiments are known to those skilled in the art. It should be clear to those skilled in the art that the present application can be realized in other forms, structures, arrangements, proportions, and with other components, materials and parts without departing from the spirit or essential characteristics of the present application. Other variations and changes of the embodiments disclosed herein can be made without departing from the scope and spirit of the present application.
Claims
1. An electronic package, characterized by An electronic package has a high voltage pin and a zero-crossing detection signal output pin, the electronic package comprising: a primary side circuit, an input of the primary side circuit coupled to the high voltage pin, the primary side circuit comprising a zero-crossing detection comparison circuit, wherein a first end of the zero-crossing detection comparison circuit is coupled to the high voltage pin, and a second end of the comparison circuit is coupled to a reference signal; and a secondary side circuit, electrically isolated from the primary side circuit, the secondary side circuit communicating with the primary side circuit through an alternating electric field or an alternating magnetic field, an output of the secondary side circuit coupled to the zero-crossing detection signal output pin.
2. The electronic package of claim 1, wherein, The primary side circuit comprises an encoder and a transmitter, wherein an input of the encoder is coupled to an output of the zero-crossing detection comparison circuit, and an output of the encoder is coupled to an input of the transmitter. The secondary side circuit comprises a receiver and a decoder, an input of the decoder is coupled to an output of the receiver, and an output of the decoder is coupled to the zero-crossing detection signal output pin.
3. The electronic package of claim 1, wherein, The electronic package further has a primary side reference ground pin, wherein a first port of the AC power grid is coupled to an anode of a first diode, a second port of the AC power grid is coupled to an anode of a second diode, a cathode of the first diode and a cathode of the second diode are coupled to the high voltage pin.
4. The electronic package of claim 1, wherein, The high voltage pin comprises a first grid input pin and a second grid input pin, wherein a first port of the AC power grid is coupled to a first end of a first resistor, a second end of the first resistor is coupled to the first grid input pin, a second port of the AC power grid is coupled to a first end of a second resistor, and a second end of the second resistor is coupled to the second grid input pin.
5. The electronic package of claim 1, wherein, The electronic package further has: a primary side reference ground pin; a secondary side reference ground pin; a primary side supply pin, coupled to the primary side reference ground pin through a capacitor; and a secondary side supply pin, coupled to an output of the isolated voltage conversion circuit and coupled to the zero-crossing detection signal output pin through a resistor.
6. The electronic package of claim 1, wherein, The primary side circuit comprises an X-capacitor discharge circuit, the X-capacitor discharge circuit comprising a grid-off detection circuit and a bleeder circuit, wherein an X-capacitor is coupled between the first port and the second port of the AC power grid.
7. The electronic package of claim 1, wherein, The secondary side circuit comprises a field effect transistor, wherein a control terminal of the field effect transistor receives a zero-crossing detection control signal outputted by the decoder, a drain of the field effect transistor is coupled to the zero-crossing detection signal output pin and coupled to a voltage source through a pull-up resistor, and a source of the field effect transistor is coupled to the secondary side reference ground.
8. The electronic package of claim 1, wherein, The secondary side circuit comprises a transistor, wherein a control terminal of the transistor is coupled to an output of the decoder, a collector of the transistor is coupled to the zero-crossing detection signal output pin and coupled to a voltage source through a pull-up resistor, and an emitter of the transistor is coupled to the secondary side reference ground.
9. An isolated power supply system, comprising: a rectification circuit, an input of the rectification circuit coupled to an AC power source; an isolated voltage conversion circuit, an input of the isolated voltage conversion circuit coupled to an output of the rectification circuit, and an output of the isolated voltage conversion circuit providing an output voltage; and an electronic package as claimed in any one of claims 1-8, wherein the high voltage pin of the electronic package is coupled to the input of the rectification circuit, and the zero-crossing detection signal output pin of the electronic package is located at the secondary side of the isolated voltage conversion circuit.