Power adapter

Abstract

A power adapter includes: a flyback circuit; a transformer; a synchronous rectification circuit; a protection switch; a current detection resistor; and a control unit. When the control unit calculates that an output current of the power adapter is larger than a first critical value, an output voltage of the flyback circuit is controlled to be reduced, so that the output power of the power adapter is kept at a second critical value, and when the output current is larger than a third critical value for a critical time, the control unit turns off a power supply path, so that the output power of the power adapter is kept at the second critical value. Wherein the control unit calculates an output current of the power adapter based on a voltage difference of the current detection resistor and a resistance value of the current detection resistor, measures an output voltage of the power adapter based on the output end of the protection switch, and controls the output of the power adapter based on the output current of the power adapter and the output voltage of the power adapter. And obtaining the output power of the power adapter.

Description

Technical Field

[0001] This application relates to power adapters, and more particularly to power adapters with overcurrent protection detection mechanisms. Background Technology

[0002] For 100W power adapters that need to comply with Limit Power Supply (LPS) safety standards, if their rated capacity is 20V / 5A but the overcurrent protection trip point is often set above 5A, the output power may exceed 100W, thus failing to meet LPS safety standards. The current approach is a dedicated process design that uses communication between the power adapter and the device to identify whether the device's identification ID matches a specific customer ID. If the device identification ID matches a specific customer ID, the power adapter is allowed to output more than 100W of power. If the system device identification ID does not match a specific customer ID, the power adapter enters LPS-96W mode: limiting the output power to 96W or the rated 96W. In this mode, the overcurrent protection trip point is set at 4.95A; if the system output current exceeds 4.95A, overcurrent protection will be activated after 30ms. The drawback of the current practice is that it requires communication to identify whether the device's identification ID is a specific customer ID, and for non-specific customer products, the output power is limited to 96W. The current practice also suffers from incompatibility with various products and necessitates a reduction in output power to 96W. Utility Model Content

[0003] To address the shortcomings of current practices, this application provides a power adapter for receiving AC power at an input terminal and outputting power at an output terminal. The power adapter comprises: a flyback circuit coupled to the input terminal; a transformer coupled to the flyback circuit; a synchronous rectification circuit coupled to the transformer; a protection switch coupled to the synchronous rectification circuit and the output terminal; a current sensing resistor coupled to the output terminal; and a control unit coupled to the current sensing resistor, the flyback circuit, and the protection switch; wherein, when the control unit calculates that the output current of the power adapter is greater than a first... At a critical value, the control unit reduces the output voltage of the flyback circuit to maintain the output power of the power adapter at a second critical value. When the output current exceeds a third critical value for a critical time, the control unit shuts off a power supply path. The control unit calculates the output current of the power adapter based on the voltage difference and resistance value of the current sensing resistor, measures the output voltage of the power adapter based on the output terminal of the protection switch, and determines the output power of the power adapter based on the output current and the output voltage of the power adapter.

[0004] In one embodiment, the control unit controls the protection switch to de-energize in order to shut off the power supply path.

[0005] In one embodiment, the first threshold value is 5 amperes.

[0006] In one embodiment, the second threshold value is 100 watts.

[0007] In one embodiment, the third threshold value is 5.2 amperes.

[0008] In one embodiment, the critical time is 30 milliseconds.

[0009] In one embodiment, the power adapter further includes: a bridge rectifier circuit coupled to the input terminal for receiving the AC power; an energy storage capacitor coupled to the bridge rectifier circuit; a power factor correction circuit coupled to the energy storage capacitor and the flyback circuit; an optocoupler coupled to the control unit for converting a control signal of the control unit into an optical signal; a flyback control unit coupled to the optocoupler and the flyback circuit for controlling the flyback circuit; and a power factor correction control unit coupled to the flyback control unit and the power factor correction circuit for controlling the power factor correction circuit. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of a power adapter circuit architecture according to an embodiment of this application.

[0011] Figure 2 An example of the dynamic output voltage adjustment process of a power adapter according to an embodiment of this application.

[0012] Figure label 10… power adapter,

[0013] 101…flyback circuit

[0014] 102…Transformer

[0015] 103…Synchronous rectifier circuit,

[0016] 104… Protection switch

[0017] 105… Current sensing resistor,

[0018] 106… control unit

[0019] 111… Input terminal

[0020] 112…output terminal

[0021] 113… AC power supply,

[0022] 121…bridge rectifier circuit,

[0023] 122… Energy storage capacitor,

[0024] 123…PFC circuit,

[0025] 124… Optical Coupler

[0026] 125… Flightback control unit,

[0027] 126…PFC control unit,

[0028] 130… power supply path,

[0029] I o …output current value,

[0030] P o …output power,

[0031] V1… Output voltage of flyback circuit, V o …power adapter output voltage, t1, t2, t3…time points,

[0032] θ1…first critical value

[0033] θ2…second critical value

[0034] θ3…Third critical value

[0035] θ t …critical time. Detailed Implementation

[0036] Some typical embodiments embodying the features and advantages of this application will be described in detail in the following description. It should be understood that this application can have various variations in different ways, all of which do not depart from the scope of this application, and the descriptions and drawings herein are for illustrative purposes only and not for limiting this application.

[0037] Please see Figure 1The diagram illustrates a power adapter circuit architecture according to an embodiment of this application. The power adapter 10 receives an AC power supply 113 at an input terminal 111 and outputs power at an output terminal 112 to supply power to a power-consuming device (not shown). The power adapter 10 includes: a flyback stage 101 coupled to the input terminal 111; a transformer 102 coupled to the flyback stage 101; a synchronous rectifier switch 103 coupled to the transformer 102; a blocking MOS switch 104 coupled to the synchronous rectifier switch 103 and the output terminal 112; a current sensing resistor 105 coupled to the output terminal 112; and a control unit (MCU) 106 coupled to the current sensing resistor 105, the flyback stage 101, and the blocking MOS switch 104.

[0038] According to another embodiment of this application, the power adapter 10 further includes: a bridge rectifier circuit 121, a bulk capacitor 122, a power factor correction stage (PFC) circuit 123, an optocoupler 124, a flyback control unit 125, and a PFC control unit 126. The bridge rectifier circuit 121 is coupled to the input terminal 111 and is used to convert alternating current (AC) to direct current (DC). The bulk capacitor 122 is coupled to the bridge rectifier circuit 121 and is used to smooth the pulsating DC voltage after rectification, making the output closer to a stable DC voltage. The PFC circuit 123 is a power factor correction circuit, coupled between the bulk capacitor 122 and the flyback circuit 101, and is used to provide efficient and stable power input for subsequent circuits. Control messages from the control unit 106 are transmitted as optical signals to the flyback control unit 125 via the optocoupler 124 to control the flyback circuit 101. PFC control unit 126 is coupled between flyback control unit 125 and PFC circuit 123, and is used to control PFC circuit 123. Power supply path 130 is a circuit path that allows current to flow from input terminal 111 through internal circuitry, including: bridge rectifier circuit 121, energy storage capacitor 122, PFC circuit 123, flyback circuit 101, transformer 102, synchronous rectifier circuit 103, protection switch 104, to output terminal 112.

[0039] The core control component of this application is the control unit 106. This control unit 106 can measure the output voltage of the protection switch 104, which is the output voltage value V of the power adapter 10. o Meanwhile, the control unit 106 can calculate the output current value I of the power adapter 10 based on a voltage difference across the current sensing resistor 105 and the resistance value thereon. oBased on the output voltage value V o With output current value I o The output power P of power adapter 10 can then be calculated. o =V o ×I o Through these detection capabilities, the control unit 106 can accurately grasp the real-time output status of the power adapter 10, including output voltage, output current, and output power.

[0040] One of the key technologies of this application lies in dynamically adjusting the output voltage to limit the output power. Based on the detection results, when the control unit 106 calculates the output current I... o The output power P is greater than a first critical value θ1 (e.g., 5 amperes) and the calculated output power P o =V o ×I o When the voltage exceeds a second threshold value θ2 (e.g., 100 watts), the control unit 106 immediately controls the reduction of the output voltage V1 of the flyback circuit 101. The purpose of this voltage adjustment is to reduce the output power P of the power adapter 10. o Maintaining the power supply at a level not exceeding the second critical value θ2 ensures that the power adapter 10 can still meet the power limit requirements of LPS even when current demand is high.

[0041] In addition to dynamic power limiting, this application also integrates a delayed-triggered overcurrent protection mechanism. Even if the output voltage V o It has been reduced due to power limitations (e.g., output voltage V). o (Adjusted to 19.23V), if the output current I o When the output current I continues to increase and exceeds a third critical value θ3 (e.g., 5.2 amperes), the control unit 106 will detect when the output current I... o The value is greater than the third critical value θ3 and remains above the critical value for a period of time θ. t After (for example, 30 milliseconds), the protection switch 104 is controlled to not conduct, so as to turn off the power supply path 130 and achieve the overcurrent protection effect.

[0042] Please see Figure 2 This illustrates an example of the dynamic output voltage adjustment process of the power adapter in this application. Taking LPS100 watts as an example, the second critical value θ2 is set to 100W, the first critical value θ1 is set to 5A, the third critical value θ3 is set to 5.2A, and the critical time θ... t Set to 30 milliseconds. Therefore, the normal and stable output voltage V at output terminal 112 is... o 20V, output current I o The current is 5A. However, in one embodiment, the output current I after time point t1 may be higher due to the power demand of the electrical device or other reasons such as a short circuit. oAs the current begins to rise, when the control unit 106 detects the increase in output current, it immediately controls the reduction of the output voltage V1 of the flyback circuit 101, so that the output voltage V... o Lower it so that the output power P o Maintain at 100W. As the output current continues to rise after time point t1, the control unit 106 adjusts the output voltage V to maintain 100W. o The voltage continues to decrease. At time point t2, the output voltage V... o To reduce the voltage to 19.23V, the output current I o It has risen to 5.2A, exceeding the third critical value θ3. When the output current I... o A sustained value above 5.2A exceeds the critical time θ t At time t3, 30 milliseconds later, control unit 106 turns off protection switch 104, shuts off power supply path 130, and outputs current I. o Output voltage V o All values ​​are reduced to 0, achieving the overcurrent protection function.

[0043] In summary, this application provides a power adapter solution that eliminates the need to identify whether the device ID is a specific customer ID. By accurately detecting voltage and current through the control unit 106, this application can dynamically reduce the output voltage to maintain the output power at the second critical value θ2 when the system output current exceeds a first critical value θ1 and the output power exceeds a second critical value θ2. This application is compatible with various products and does not require reducing the output power to a predetermined power (e.g., 96W) to maintain the output power at the second critical value θ2, thus improving the product's versatility and efficiency.

[0044] It should be noted that the above are merely preferred embodiments for illustrating this application, and this application is not limited to the described embodiments. The scope of this application is determined by the appended claims. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. Furthermore, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A power adapter for receiving AC power at an input terminal and outputting power at an output terminal, characterized in that, This power adapter includes: A flyback circuit is coupled to this input terminal; A transformer is coupled to the flyback circuit; A synchronous rectifier circuit is coupled to the transformer; A protective switch is connected to the synchronous rectifier circuit and the output terminal; A current sensing resistor is coupled to this output terminal; as well as A control unit is coupled to the current sensing resistor, the flyback circuit, and the protection switch; Specifically, when the control unit calculates that the output current of the power adapter is greater than a first threshold value, it controls the reduction of the output voltage of the flyback circuit so that the output power of the power adapter is maintained at a second threshold value. When the output current is higher than a third threshold value for more than a critical time, the control unit shuts off a power supply path. The control unit calculates the output current of the power adapter based on the voltage difference and the resistance value of the current sensing resistor, measures the output voltage of the power adapter based on the output terminal of the protection switch, and obtains the output power of the power adapter based on the output current and the output voltage of the power adapter.

2. The power adapter according to claim 1, characterized in that, The control unit controls the protective switch to deactivate, thereby shutting off the power supply path.

3. The power adapter according to claim 1, characterized in that, The first critical value is 5 amperes.

4. The power adapter according to claim 1, characterized in that, The second critical value is 100 watts.

5. The power adapter according to claim 1, characterized in that, The third critical value is 5.2 amperes.

6. The power adapter according to claim 1, characterized in that, The critical time is 30 milliseconds.

7. The power adapter according to claim 1, characterized in that, The power adapter further includes: A bridge rectifier circuit, coupled to the input terminal, is used to receive the AC power supply; A storage capacitor is coupled to the bridge rectifier circuit; and A power factor correction circuit is coupled to the energy storage capacitor and the flyback circuit; An optical coupler, coupled to the control unit, is used to convert a control signal of the control unit into an optical signal; A flyback control unit, coupled to the optocoupler and the flyback circuit, is used to control the flyback circuit; A power factor correction control unit is coupled to the flyback control unit and the power factor correction circuit, and is used to control the power factor correction circuit.

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