Power conversion device and function trigger circuit and function triggering method thereof

Abstract

The present application discloses a power conversion device and a function trigger circuit, function trigger method thereof. The power conversion device includes a transformer and a control module coupled to a primary side of the transformer. The function trigger circuit is coupled between a secondary side of the transformer and the control module, and includes a current detection circuit, a delay circuit and a switching circuit. The current detection circuit senses the secondary side of the transformer to generate a delayed detection signal. The delay circuit makes an initial level higher than an internal level before the transformer is in a steady state, and after the transformer is in the steady state, the switching circuit selectively generates a function trigger signal based on the detection signal. The function trigger signal is used to make the control module perform an overcurrent protection operation. In this way, the accuracy and stability are improved, and the power conversion device has the characteristics of accurate overcurrent protection and low standby power consumption.

Description

Technical Field

[0001] This invention relates to a functional triggering circuit, and more particularly to a functional triggering circuit for a power conversion device, a functional triggering method thereof, and the power conversion device. Background Technology

[0002] Electronic products typically use power conversion devices to provide the power they need. With increasingly stringent safety regulations, compliance with safety standards (such as IEC 60950) has become a key focus in the design of power conversion devices for electronic products.

[0003] For example, the safety standard IEC 60950 requires electronic products to have fire-resistant enclosures. However, when an electronic product uses a power converter that conforms to the Limited Power Source (LPS) specification, the fire resistance standard becomes more lenient. Regarding the LPS specification, since voltage, current, and energy are all limited to a specified value, the scale of damage caused by an electronic product malfunction can be limited. Therefore, when other conditions in the IEC 60950 safety standard are met (e.g., using circuit boards with a fire rating of V-1 or higher), and a power converter conforming to the LPS specification is used, the fire resistance standard for the electronic product enclosure can be lowered. Lower fire resistance requirements not only save on enclosure costs but also allow for the use of more environmentally friendly materials.

[0004] Under power-limited conditions (e.g., output must be less than 60V / 8A / 100W), if the output power exceeds the power limit under these conditions, the protection function must be activated in real time to effectively prevent undesirable conditions such as overvoltage or overcurrent. However, when the rated output power of the power converter is very close to the power-limited boundary conditions (e.g., the rated full-load output is very close to 100W), the relevant voltage value used to trigger the protection function must be precise to avoid the protection function failing to activate when the output power exceeds the power limit.

[0005] However, generating precise voltage often results in power loss, which makes it difficult to meet the requirements of low standby power consumption of power conversion devices. Summary of the Invention

[0006] One objective of this invention is to enable power conversion devices to have low power consumption.

[0007] Another objective of this invention is to improve the stability of the functional triggering circuit applied to power conversion devices.

[0008] Another object of the present invention is to enable the function triggering action of the power conversion device to be correctly enabled in real time based on accurate voltage detection.

[0009] To achieve the above and other objectives, the present invention provides a functional trigger circuit for a power conversion device. The power conversion device includes a transformer and a control module coupled to the primary side of the transformer. The functional trigger circuit is configured to be coupled between the secondary side of the transformer and the control module. The functional trigger circuit includes a current detection circuit, a delay circuit, and a switching circuit. The current detection circuit generates a detection signal based on a comparison between a current sampling level signal from the secondary side of the transformer and a reference level signal. The delay circuit is coupled to the current detection circuit and includes a delay unit, an isolation capacitor, and a first comparator. The delay unit delays the timing of the detection signal input to the negative terminal of the first comparator. The positive terminal of the first comparator has a fixed internal level. The isolation capacitor is coupled between the secondary side of the transformer and the negative terminal of the first comparator. Before the transformer reaches steady-state operation, the isolation capacitor causes the negative terminal of the first comparator to generate an initial level higher than the internal level. The switching circuit is coupled to the control module. When the first comparison signal output by the output terminal of the first comparator is at a high level, the switching circuit generates a function trigger signal, which is used to cause the control module to perform an overcurrent protection operation.

[0010] According to one embodiment of the present invention, the switching circuit may include a hysteresis module coupled between the negative terminal of the first comparator and ground, the hysteresis module responding to the high-level first comparison signal to ground the negative terminal of the first comparator.

[0011] According to one embodiment of the present invention, the hysteresis module may have a field-effect transistor, the gate of which is coupled to the output of the first comparator, the drain of which is coupled to the negative terminal of the first comparator, and the source of which is coupled to ground. When the first comparison signal is at a high level, the field-effect transistor is turned on.

[0012] According to one embodiment of the present invention, the switching circuit may include an isolation communication module and a clamping module. The isolation communication module is coupled to the control module, and the clamping module is coupled between the output of the first comparator and the isolation communication module. When the level of the first comparison signal is higher than a clamping level, the clamping module is turned on.

[0013] According to one embodiment of the present invention, the clamping level may be set to a higher level than the internal level of the first comparator.

[0014] According to one embodiment of the present invention, the switching circuit may include a hysteresis module, a clamping module, and an isolation communication module. The isolation communication module is coupled to the control module. The clamping module is coupled between the output terminal of the first comparator and the isolation communication module. The hysteresis module is coupled between the negative terminal of the first comparator and ground. A control terminal of the hysteresis module is coupled between the output terminal of the first comparator and the clamping module. The hysteresis module responds to a high-level first comparison signal by grounding the negative terminal of the first comparator. When the level of the first comparison signal is higher than a clamping level of the clamping module, the clamping module is turned on.

[0015] According to one embodiment of the present invention, the hysteresis module may have a field-effect transistor, the gate of which serves as the control terminal of the hysteresis module. The gate is coupled to the output terminal of the first comparator, the drain is coupled to the negative terminal of the first comparator, and the source is coupled to ground. When the first comparison signal is at a high level, the field-effect transistor is turned on.

[0016] To achieve the above and other objectives, the present invention further provides a power conversion device, comprising: a transformer, a control module, and a functional trigger circuit. The transformer includes a primary side and a secondary side. The control module is coupled to the primary side of the transformer. The functional trigger circuit is coupled between the secondary side of the transformer and the control module. The functional trigger circuit senses the secondary side of the transformer to generate a delayed detection signal, and before the transformer reaches steady-state operation, sets an initial level higher than an internal level. After the transformer reaches steady-state operation, it selectively generates a functional trigger signal based on the detection signal, the functional trigger signal being used to cause the control module to perform an overcurrent protection operation.

[0017] According to one embodiment of the present invention, the function triggering circuit may include: a delay unit, a capacitor and a first comparator, wherein the capacitor is coupled between the secondary side of the transformer and the negative terminal of the first comparator, and the capacitor causes the negative terminal of the first comparator to generate the initial level before the transformer is in steady-state operation.

[0018] According to one embodiment of the present invention, the detection signal is input to the negative terminal of the first comparator, and the positive terminal of the first comparator has the internal level.

[0019] According to one embodiment of the present invention, the delayer is used to delay the detection signal within a peak load time period, which is the peak load time required for the load connected to the power conversion device.

[0020] According to one embodiment of the present invention, the function triggering circuit may include: a second comparator coupled between the secondary side of the transformer and the delay unit to generate the detection signal, the positive terminal of the second comparator receiving a reference level signal divided by voltage, and the negative terminal of the second comparator receiving a current sampling level signal from the secondary side of the transformer.

[0021] To achieve the above and other objectives, the present invention further proposes a method for triggering a function of a power conversion device, comprising: sensing the secondary side of a transformer of the power conversion device to generate a detection signal; delaying the detection signal; during a startup period before the power conversion device has entered steady-state operation, causing the negative terminal of a first comparator to generate an initial level, wherein the initial level is higher than an internal level of the positive terminal of the first comparator; and during an operation period after the power conversion device has entered steady-state operation, selectively generating a function trigger signal based on the detection signal to cause the power conversion device to perform a protection operation.

[0022] According to one embodiment of the present invention, the positive terminal of the first comparator may have a fixed internal level, and the initial level is higher than the internal level.

[0023] According to one embodiment of the present invention, the delay time of the detection signal may be the peak load time required to connect to one of the loads of the power conversion device.

[0024] According to one embodiment of the present invention, during the startup period or during the operation period, a hysteresis phenomenon may be generated between the output terminal and the negative terminal of the first comparator.

[0025] According to one embodiment of the present invention, during the startup or operation period, the level of the first comparison signal may be transmitted only when it is greater than or equal to a clamp level, so as to generate the function trigger signal accordingly.

[0026] According to one embodiment of the present invention, the clamping level may be higher than the internal level of the first comparator.

[0027] Accordingly, the function triggering circuit uses the secondary side of the transformer as the basis for current detection, and with the first comparator having high accuracy of internal level and low loss characteristics, and in conjunction with the isolation capacitor, not only is the accuracy of the first comparison signal improved, but the stability of the function triggering is also improved. Attached Figure Description

[0028] Figure 1 This is a circuit block diagram of a power conversion device according to an embodiment of the present invention.

[0029] Figure 2 This is a circuit block diagram of a current detection circuit according to an embodiment of the present invention.

[0030] Figure 3 This is a circuit block diagram of a power conversion device according to another embodiment of the present invention.

[0031] Figure 4 This is a partial circuit block diagram of the switching circuit and the control module according to an embodiment of the present invention.

[0032] [Symbol Explanation]

[0033] 100 Function Trigger Circuit

[0034] 110 Current Detection Circuit

[0035] 111 voltage divider circuit

[0036] 112 Second comparator

[0037] 120 Delay Circuit

[0038] 121 First Comparator

[0039] 122 Delay Unit

[0040] 123 Isolation capacitor

[0041] 130 Switching Circuit

[0042] 131 Hysteresis Module

[0043] 132 clamping module

[0044] 133 Isolation Communication Module

[0045] 200 control module

[0046] 210 Controller

[0047] 220 detector

[0048] 300 load

[0049] 400 Transformer

[0050] EN function trigger signal

[0051] Ifb current sampling level signal

[0052] Iref reference level signal

[0053] L1 isolation communication module grounding path

[0054] The primary side of the Np transformer

[0055] Ns transformer secondary side

[0056] SC1 First Comparison Signal

[0057] SD detection signal

[0058] SNS pin

[0059] Vcc internal circuit voltage

[0060] VS Input Power

[0061] Vout output voltage

[0062] Vref internal level Detailed Implementation

[0063] To fully understand the purpose, features, and effects of this invention, the invention will be described in detail below with reference to the specific embodiments and accompanying drawings, as follows:

[0064] In this document, the terms "a" or "an" are used to describe units, components, devices, modules, instruments, circuits, or signals. This is used for ease of explanation and to provide a general meaning for the scope of this invention. Therefore, unless it is clearly indicated otherwise, this description should be understood to include one or at least one, and the singular also includes the plural.

[0065] In this document, the terms “comprising,” “including,” “having,” or any other similar terms are not limited to the elements listed herein, but may include other elements not expressly listed but which are generally inherent in the unit, component, device, module, instrument, circuit, or signal.

[0066] In this document, the terms "first" or "second" and similar ordinal numbers are used to distinguish or refer to units, components, devices, modules, components, circuits, or signals that are related to the same or similar entities, and do not necessarily imply a spatial or temporal order of these units, components, devices, modules, components, circuits, or signals. It should be understood that in certain situations or configurations, ordinal numbers can be used interchangeably without affecting the implementation of the invention.

[0067] Please refer to Figure 1 This is a circuit block diagram of a power conversion device according to an embodiment of the present invention. The power conversion device includes: a functional trigger circuit 100, a control module 200, and a transformer 400.

[0068] The control module 200 is coupled to the primary side Np of the transformer 400, and the load 300 is coupled to the secondary side Ns of the transformer 400. Based on the control of the control module 200, the transformer 400 can convert the input power supply VS to the power specifications required by the load 300 and provide it to the load 300. The function trigger circuit 100 is configured between the secondary side Ns of the transformer 400 and the control module 200.

[0069] The function trigger circuit 100 is coupled to the secondary side Ns and the control module 200. The function trigger circuit 100 can feed back the detection result to the control module 200 based on the power supply status of the secondary side Ns, so that the control module 200 can execute the corresponding functional action. In the embodiment disclosed in this invention, the function trigger circuit 100 senses the secondary side Ns of the transformer 400 to generate a detection signal SD, and selectively generates a function trigger signal EN based on the detection signal SD, so that the control module 200 performs an overcurrent protection operation.

[0070] The control module 200 inherently provides overcurrent detection and protection on the primary side Np of the transformer 400. However, due to its limited accuracy, this is insufficient for power conversion devices operating under power-limited source conditions. In particular, the reliability of overcurrent detection and protection on the primary side Np decreases significantly when the rated output power is very close to the power-limited source boundary conditions. In embodiments of the present invention, this can be improved by configuring the functional trigger circuit 100.

[0071] The function triggering circuit 100 includes a current detection circuit 110, a delay circuit 120, and a switching circuit 130. The delay circuit 120 is coupled between the current detection circuit 110 and the switching circuit 130.

[0072] The current detection circuit 110 is based on a current sampling level signal I from the secondary side Ns of the transformer 400. fb With a reference level signal I ref (can be referenced simultaneously) Figure 2 The detection signal SD is generated by comparing the values ​​of 120 and 120. The delay circuit 120 delays the detection signal SD and determines it according to an internal level V. ref A first comparison signal SC1 is generated. The switching circuit 130 generates a corresponding output based on the level of the first comparison signal SC1, and generates the function trigger signal EN when the first comparison signal SC1 is at a high level.

[0073] The first comparison signal SC1 is the output of the delay circuit 120, and the level of the first comparison signal SC1 is used as the basis for determining whether the subsequent function trigger signal EN is generated. Therefore, whether the first comparison signal SC1 can be generated correctly is the key to the design of the delay circuit 120.

[0074] The delay circuit 120 includes a first comparator 121, a delay circuit 122, and an isolation capacitor 123. The positive terminal of the first comparator 121 has a fixed internal level V. refFor example, an integrated circuit controller (IC controller) composed of operational amplifiers can be used to provide an accurate reference signal for comparison to the delay circuit 120 based on its internal fixed level, such as 2.5V. Furthermore, this reference level signal I... ref It is also due to the internal level V ref It is obtained by voltage division; therefore, if there is a precise internal level V... ref This will yield the same precise reference level signal I. ref In an embodiment of the present invention, the signal received by the negative terminal of the first comparator 121 is compared with the internal level V. ref Compare them.

[0075] Due to the configuration of the function trigger circuit 100, overcurrent protection becomes more sensitive. The delay unit 122 is used to delay the timing of the detection signal SD input to the negative terminal of the first comparator 121, so as to eliminate the large fluctuation of the detection signal SD in a short period of time by means of the time delay between input and output. For example, when the power conversion device consumes power instantaneously during initial operation or when the load 300 consumes power instantaneously under a specific function operation, the overcurrent protection function does not expect to be triggered at this time. Therefore, the delay unit 122 can handle the large instantaneous power consumption at this time, so that the input detection signal SD does not have this fluctuation segment after processing, and thus the negative terminal of the first comparator 121 can receive the processed detection signal SD. The delay unit 122 can, for example, use an RC circuit to perform a slow charge and fast discharge delay function, and the length of the delay period is defined by the combination of its internal resistors and capacitors.

[0076] For another example, the delay defined by the delay unit 122 can delay the detection signal SD within a peak load time period. This peak load time period is the peak load time required by the load 300. For example, this peak load time is the period during which the power conversion device must generate a large instantaneous voltage or current on the secondary side Ns when the load 300 performs a specific function. Setting this peak load time allows the function trigger circuit 100 to avoid generating the function trigger signal EN during this time period, thus preventing false triggering.

[0077] For this function trigger circuit 100, although at the internal level V ref Using this technology can make voltage comparison results more accurate; however, it also affects the accuracy of the internal level V. ref This refers to the internal voltage of the integrated circuit controller. During the initial circuit startup, this internal level V... refThe generation time is shorter than that of the level from outside the integrated circuit controller (the detection signal SD), especially compared to the delayed detection signal SD. Under normal conditions (no overvoltage or overcurrent) or steady state, the voltage level of the detection signal SD will be higher than the internal level V. ref So that the level received by the negative terminal of the first comparator 121 can be higher than the internal level V received by the positive terminal. ref The first comparison signal SC1 output by the first comparator 121 is at a low level, which will not cause the switching circuit 130 to generate the function trigger signal EN.

[0078] However, as mentioned above, this internal level V ref It is established relatively quickly, once the internal level V is reached. ref If the detection signal SD is not yet established after the circuit is started (in the initial stage of circuit startup), the first comparator 121 will output a high-level first comparison signal SC1 because the level received at the positive terminal is higher than the level received at the negative terminal, leading to a false triggering of the function trigger signal EN. Accordingly, the function trigger circuit 120 disclosed in this embodiment further establishes a voltage level quickly through the setting of the isolation capacitor 123, so that the negative terminal of the first comparator 121 can have a higher level than the internal level V at the initial stage of circuit startup. ref The position.

[0079] The isolation capacitor 123 can be a general capacitor component. At power-on (before steady-state operation), the output voltage V... out Since the voltage rises from zero (there is a noticeable change), the impedance of the isolation capacitor 123 is not infinite. It forms a voltage divider with the internal resistance of the negative terminal of the first comparator 121. This quickly establishes a level for the negative terminal of the first comparator 121, preventing the positive terminal level from being higher than the negative terminal level during power-on (before steady-state operation). A higher positive terminal level would cause the first comparator 121 to output a high-level first comparison signal SC1, leading to a false triggering of the function's trigger signal EN. After steady-state operation, the isolation capacitor 123 is connected to the output voltage V, which has no frequency change. out The output voltage V out All of it will cross over the isolation capacitor 123, and because the isolation capacitor 123 is unaffected by the changing output voltage V out Its impedance is infinite, thus not affecting the negative terminal level of the first comparator 121. In other words, this invention utilizes the impedance characteristics of the isolation capacitor 123 to quickly establish the level of the negative terminal of the first comparator 121 during power-on, thereby avoiding malfunctions. After steady-state operation, the output voltage V... outAll of these are connected across the isolation capacitor 123, so they will not affect the level of the negative terminal of the first comparator 121, and thus will not affect the detection behavior under steady state.

[0080] Please refer to Figure 2 This is a circuit block diagram of a current detection circuit according to an embodiment of the present invention. The current detection circuit 110 includes: a voltage divider unit 111 and a second comparator 112. The negative terminal of the second comparator 112 receives voltage from the secondary side Ns of the transformer 400 (see reference). Figure 1 The current sampling level signal I obtained fb The positive terminal of the second comparator 112 receives the internal level V. ref The reference level signal I is formed after voltage division by the voltage divider unit 111. ref .

[0081] Based on this configuration, under normal load conditions, the level received by the positive terminal of the second comparator 112 is set to be higher than the level received by the negative terminal. The second comparator 112 enables the detection signal SD, as output, to have a high level, and the level of the detection signal SD is higher than the internal level V. ref This allows the output of the first comparator 121 to be at a low level, preventing the function trigger signal EN from being generated. The low-level reference level signal I... ref It utilizes the precise internal positioning V ref This is generated by voltage division. Conversely, in abnormal situations (such as overcurrent) that require the generation of the function trigger signal EN, the current sampling level signal I... fb It will have a higher level signal I than the reference level. ref This causes the output of the second comparator 112 to switch to a low level and be provided to the negative terminal of the first comparator 121, thus causing the output of the first comparator 121 to switch to a high level, and the function trigger signal EN is generated.

[0082] Please refer to Figure 3 This is a circuit block diagram of a power conversion device according to another embodiment of the present invention. Figure 3 In one example, the switching circuit 130 may include a hysteresis module 131, a clamping module 132, and an isolation communication module 133. In other embodiments, the hysteresis module 131 and the clamping module 132 may both be omitted or only one of them may be used.

[0083] The isolation communication module 133 is coupled to the control module 200 and switches based on the level of the output of the first comparator 121. The isolation communication module 133 uses, for example, an optocoupler as a switching device. One end of the optocoupler is controlled by the output level of the first comparator 121, and the other end of the optocoupler serves as a switch to determine whether a ground path is connected or not.

[0084] For example, when the output level of the first comparator 121 is high (indicating an abnormality), the optocoupler is turned on, thus creating a closed ground path; conversely, when the output level of the first comparator 121 is low (indicating no abnormality), the optocoupler is turned off, thus creating an open ground path. The ground path formed by the closed state of the ground path (which can be considered as the generation of a function trigger signal EN) can affect the internal circuitry of the control module 200 (which can be considered as the reception of the function trigger signal EN), thereby causing the control module 200 to perform overcurrent protection operations (such as interrupting the power supply), achieving the purpose of protection.

[0085] The clamping module 132 is coupled between the output of the first comparator 121 and the isolation communication module 133. The clamping module 132 is turned on when the level of the first comparison signal SC1 is higher than a clamping level of the clamping module 132. This clamping level can be further set to be higher than the internal level V of the first comparator 121. ref For example, the clamping level can be set to 4.3V. However, the clamping level setting is not necessarily related to the internal level V. ref There is a direct correlation. Therefore, the threshold for triggering the function trigger signal EN can be established by setting the clamping level. On the other hand, since the rated high level of the first comparison signal SC1 is actually higher than the clamping level, when a real abnormal condition occurs, the function trigger signal EN can be issued normally and will not be blocked by the clamping module 132.

[0086] The clamping module 132 can be, for example, a series connection of a Zener diode and a resistor unit. Accordingly, the clamping module 132 provides a second layer of protection when the voltage across the isolation capacitor 123 builds up too quickly or fails, preventing false triggering of the function trigger signal EN, and further ensuring that the level of the first comparison signal SC1 can be correctly determined. Specifically, if the voltage across the isolation capacitor 123 builds up too quickly, when the voltage across the isolation capacitor 123 is already equal to the output voltage V... out Therefore, the negative terminal of the first comparator 121 will not receive voltage V from the output voltage. outDue to the voltage drop across the circuit, the negative level of the first comparator 121 will not be able to be quickly raised to a high point during the power-on instant. On the other hand, when the isolation capacitor 123 fails, although the level of the first comparison signal SC1 at the output of the first comparator 121 will start to rise, it will be cut off by the clamping module 132 before it reaches the rated high level, thus preventing the isolation communication module 133 from being triggered and causing malfunction.

[0087] The hysteresis module 131 is coupled between the negative terminal of the first comparator 121 and ground. The hysteresis module 131 is used to connect the negative terminal of the first comparator 121 to ground in response to a high-level first comparison signal SC1. For example, the hysteresis module 131 may have a field-effect transistor (FET) with its gate coupled to the output of the first comparator 121, its drain coupled to the negative terminal of the first comparator 121, and its source coupled to ground. Accordingly, when the first comparison signal SC1 is at a high level, the FET can be turned on, thereby connecting the negative terminal of the first comparator 121 to ground. Therefore, when the first comparison signal SC1 is at a high level, it indicates that an abnormal condition (such as overcurrent) has occurred, and the corresponding functional action (such as overcurrent protection operation) should be activated as soon as possible. By setting the hysteresis module 131, the potential of the negative terminal of the first comparator 121 can be quickly pulled down and maintained, so that the high-level first comparison signal SC1 can be output stably, avoiding the unstable situation of bouncing back and forth.

[0088] Accordingly, the function triggering method of the power conversion device is performed in the following manner: (1) sensing the secondary side of one of the transformers of the power conversion device to generate a detection signal; (2) delaying the detection signal; (3) during the startup period when the power conversion device has not yet entered steady-state operation, causing the negative terminal of a first comparator to generate an initial level, and the initial level is higher than an internal level of the positive terminal of the first comparator; and (4) during the operation period when the power conversion device enters steady-state operation, selectively generating a function triggering signal based on the detection signal to cause the power conversion device to perform a protection operation.

[0089] The aforementioned hysteresis module 131 enables hysteresis to occur between the output and negative terminals of the first comparator 121 during the startup or operation of the power conversion device. Furthermore, during startup or operation of the power conversion device, the level of the first comparison signal SC1 is only transmitted when it is greater than or equal to the clamping level of the clamping module 132, thereby generating the function trigger signal EN and preventing false triggering.

[0090] Please refer to Figure 4The diagram below is a partial circuit block diagram of the switching circuit and control module according to an embodiment of the present invention. The control module 200 may include a controller 210 and a detector 220. The controller 210 may, for example, be a TEA2016 controller manufactured by NXP Semiconductors, which has a pin SNS for detecting the current status of the primary side Np of the transformer. This pin SNS is coupled to a complex array of parallel capacitors or resistors, and a detection voltage is formed by drawing current from the primary side Np, allowing the controller 210 to detect whether an overcurrent condition has occurred.

[0091] Because the detector 220 has low accuracy in detecting overcurrent on the primary side Np, it cannot meet the requirements of power conversion devices under power-limited source (LPS) conditions. Figure 4 In the example, through special control of the detector 220 of the control module 200, the detection of overcurrent and the activation of overcurrent protection can be enhanced. The aforementioned function trigger circuit 100 not only has low power consumption (e.g., meeting the condition that standby power consumption must be less than 0.15W), but also can accurately detect overcurrent conditions and quickly generate the function trigger signal EN, thereby causing the detector 220 to produce a corresponding detection result, and enabling the controller 210 to perform overcurrent protection operation.

[0092] Based on one of the capacitor paths in the detector 220 being switched by a switching element based on an internal circuit voltage V cc To control this, the internal circuit voltage V is changed. cc The control state of this switching element can adjust the configuration state of the capacitors connected in parallel in the detector 220. For example... Figure 4 As shown, when the isolation communication module 133 is turned on (indicating an overcurrent phenomenon), the grounding path L1 is completed. At this time, the gate (or control signal) of the switching element is grounded, and the switching element is turned off, thereby changing the configuration state of the parallel capacitor in the detector 220. Accordingly, this adjustment function, for example, can make... Figure 4 The two sets of capacitors that were originally connected in parallel are adjusted to only one set. The detection voltage value formed on the SNS pin will be different between the single set of capacitors and the double set of capacitors. This allows the controller 210 to detect the occurrence of overcurrent and perform overcurrent protection operation accordingly.

[0093] In summary, the functional triggering circuit disclosed in the embodiments of the present invention can improve the accuracy and stability of the power conversion device in terms of the triggering mechanism for functional operation, so that the power conversion device can meet the power supply specifications of the power limited source (LPS) under the safety standard IEC 60950, and at the same time has the characteristics of accurate overcurrent protection and low standby power consumption.

[0094] The present invention has been disclosed above with reference to preferred embodiments. However, those skilled in the art should understand that these embodiments are merely illustrative of the invention and should not be construed as limiting its scope. It should be noted that all variations and substitutions equivalent to these embodiments should be considered within the scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A functional trigger circuit for a power conversion device, characterized in that, The power conversion device includes a transformer and a control module coupled to the primary side of the transformer. The control module includes a controller and a detector. The controller has a pin for detecting the current status of the primary side of the transformer. The pin is coupled to the detector, which consists of a series of capacitors or resistors connected in parallel. The function trigger circuit is configured to be coupled between the secondary side of the transformer and the detector of the control module, and the function trigger circuit includes: A current detection circuit generates a detection signal based on the comparison between a current sampling level signal and a reference level signal on the secondary side of the transformer. A delay circuit, coupled to the current detection circuit, includes: a delay unit, an isolation capacitor, and a first comparator. The delay unit delays the timing of the detection signal input to the negative terminal of the first comparator. The positive terminal of the first comparator has a fixed internal level. The isolation capacitor is coupled between the secondary side of the transformer and the negative terminal of the first comparator. Before the transformer reaches steady-state operation, the isolation capacitor causes the negative terminal of the first comparator to generate an initial level higher than the internal level. A switching circuit is coupled to the detector of the control module. When the first comparison signal output by the output terminal of the first comparator is at a high level, the switching circuit generates a function trigger signal. The function trigger signal is used to change the configuration state of the capacitor connected in parallel in the detector, thereby making the detection voltage value formed on the pin different, so that the controller detects the overcurrent condition and performs an overcurrent protection operation.

2. The functional trigger circuit of claim 1, wherein, The switching circuit includes a hysteresis module coupled between the negative terminal of the first comparator and ground. The hysteresis module responds to the high-level first comparison signal by grounding the negative terminal of the first comparator.

3. The functional trigger circuit of claim 2, wherein, The hysteresis module has a field-effect transistor whose gate is coupled to the output of the first comparator, its drain is coupled to the negative terminal of the first comparator, and its source is coupled to ground. When the first comparison signal is high level, the field-effect transistor is turned on.

4. The functional trigger circuit of claim 1, wherein, The switching circuit includes an isolation communication module and a clamping module. The isolation communication module is coupled to the control module, and the clamping module is coupled between the output of the first comparator and the isolation communication module. When the level of the first comparison signal is higher than a clamping level, the clamping module is turned on.

5. The functional trigger circuit of claim 4, wherein, The clamping level is higher than the internal level of the first comparator.

6. The functional trigger circuit of claim 1, wherein, The switching circuit includes a hysteresis module, a clamping module, and an isolation communication module. The isolation communication module is coupled to the control module. The clamping module is coupled between the output of the first comparator and the isolation communication module. The hysteresis module is coupled between the negative terminal of the first comparator and ground. A control terminal of the hysteresis module is coupled between the output of the first comparator and the clamping module. The hysteresis module responds to a high-level first comparison signal by grounding the negative terminal of the first comparator. When the level of the first comparison signal is higher than a clamping level of the clamping module, the clamping module is turned on.

7. The function trigger circuit of claim 6, wherein, The hysteresis module has a field-effect transistor, whose gate terminal serves as the control terminal of the hysteresis module. The gate terminal is coupled to the output terminal of the first comparator, the drain terminal is coupled to the negative terminal of the first comparator, and the source terminal is coupled to ground. When the first comparison signal is high level, the field-effect transistor is turned on.

8. The functional triggering circuit as described in claim 6, characterized in that, The clamping level is higher than the internal level of the first comparator.

9. A power conversion device, characterized by, include: A transformer, comprising a primary side and a secondary side; A control module, coupled to the primary side of the transformer, includes a controller and a detector. The controller has a pin for detecting the current condition of the primary side of the transformer, the pin being coupled to the detector, which consists of a complex array of capacitors or resistors connected in parallel. A functional trigger circuit is coupled between the secondary side of the transformer and the detector of the control module. The functional trigger circuit is used to sense the secondary side of the transformer to generate a delayed detection signal, and before the transformer is in steady-state operation, to set an initial level higher than an internal level, and after the transformer is in steady-state operation, to selectively generate a functional trigger signal based on the detection signal. The functional trigger signal is used to change the configuration state of the capacitors connected in parallel in the detector, thereby making the detection voltage value formed on the pin different, thereby causing the controller to detect an overcurrent condition and perform an overcurrent protection operation.

10. The power conversion device of claim 9, wherein, The function triggering circuit includes: a delay unit, a capacitor and a first comparator. The capacitor is coupled between the secondary side of the transformer and the negative terminal of the first comparator. Before the transformer is in steady-state operation, the capacitor causes the negative terminal of the first comparator to generate the initial level.

11. The power conversion device of claim 10, wherein, The detection signal is input to the negative terminal of the first comparator, the positive terminal of which has the internal level.

12. The power conversion device of claim 10, wherein, The delay device is used to delay the detection signal within a peak load time period, which is the peak load time required for the load connected to the power conversion device.

13. The power conversion device of claim 10, wherein, The function triggering circuit includes a second comparator coupled between the secondary side of the transformer and the delay unit to generate the detection signal. The positive terminal of the second comparator receives a reference level signal after voltage division, and the negative terminal of the second comparator receives a current sampling level signal from the secondary side of the transformer.

14. A function triggering method of a power conversion device, wherein, The power conversion device includes a transformer and a control module coupled to the primary side of the transformer. The control module includes a controller and a detector. The controller has a pin for detecting the current status of the primary side of the transformer, and the pin is coupled to the detector, which consists of a complex array of capacitors or resistors connected in parallel. The device is characterized by including: The secondary side of one of the transformers in the power conversion device is sensed to generate a detection signal; Delay the detection signal; During the startup phase before the power conversion device reaches steady-state operation, an initial level is generated at the negative terminal of a first comparator, and this initial level is higher than an internal level at the positive terminal of the first comparator; and During a period of operation when the power conversion device enters steady-state operation, a function trigger signal is selectively generated based on the detection signal to cause the power conversion device to perform a protection operation. The function trigger signal is used to change the configuration state of the capacitors connected in parallel in the detector, thereby causing the detection voltage value formed on the pin to be different, thereby causing the controller to detect the overcurrent condition and perform an overcurrent protection operation.

15. The function triggering method of claim 14, wherein, The positive terminal of the first comparator has a fixed internal level, and the initial level is higher than the internal level.

16. The function triggering method of claim 14, wherein, The delay time of the detection signal is the peak load time required to connect to one of the loads of the power conversion device.

17. The function triggering method as described in claim 14, characterized in that, During the startup or operation period, a hysteresis phenomenon is caused between the output and negative terminals of the first comparator.

18. The function triggering method of claim 14, wherein, During the startup or operation period, the level of the first comparison signal output by the first comparator is transmitted only when it is greater than or equal to a clamp level, so as to generate the function trigger signal accordingly.

19. The function triggering method of claim 18, wherein, The clamping level is higher than the internal level of the first comparator.

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