Power supply and protection method

Abstract

A power supply and a protection method are used for supplying power to a load, and the power supply is provided with a high-voltage side current sensing unit, a low-voltage side current sensing unit and a control circuit. The high-voltage side current sensing unit is connected to a high-voltage power supply end of a load and senses a first output current output to the load by the power supply so as to generate a high-end sensing signal. And the low-voltage side current sensing unit is connected to a low-voltage power supply end of the load and used for sensing a second output current output by the load to the power supply so as to generate a low-end sensing signal. One of the high-voltage side current sensing unit and the low-voltage side current sensing unit comprises a power switch. The control circuit receives the high-end sensing signal and the low-end sensing signal and is used for converting the high-end sensing signal and the low-end sensing signal into a high-end sensing value and a low-end sensing value respectively. When one of the high-side sensing value and the low-side sensing value exceeds an overcurrent protection value, the control circuit controls the power switch to limit one of the first output current and the second output current.

Description

Technical Field

[0001] This invention relates to a protection method for power supplies, and more particularly to a protection method and associated power supply that can provide overcurrent protection. Background Technology

[0002] Electronic information products have become indispensable tools in people's daily lives. Simultaneously, many power supplies have emerged to provide the power needed for the normal operation of these products. However, in addition to providing the required output voltage, current, or power, power supplies also need to comply with numerous safety regulations to prevent potential risks, such as IEC-62368, a safety regulation for consumer products.

[0003] IEC-62368 contains specifications for limited power sources (LPS). Furthermore, IEC-62368 specifies power limits for power supplies in the event of a single point of failure in a circuit, to prevent fires or electric shocks to personnel in the event of such a failure.

[0004] Power supplies often contain current sensing resistors to allow the power control circuit to determine the magnitude of the current flowing in the next current path and perform corresponding control. If this current sensing resistor malfunctions, such as by short-circuiting, the power control circuit may misjudge the magnitude of the current flowing through it, thus failing to meet the power supply specifications. Summary of the Invention

[0005] This invention provides a power supply for supplying power to a load, comprising a high-voltage side current sensing unit, a low-voltage side current sensing unit, and a control circuit. The high-voltage side current sensing unit is connected to a high-voltage power supply terminal of the load and senses a first output current from the power supply to the load to generate a high-side sensing signal. The low-voltage side current sensing unit is connected to a low-voltage power supply terminal of the load and senses a second output current from the load to the power supply to generate a low-side sensing signal. One of the high-voltage side current sensing unit and the low-voltage side current sensing unit includes a power switch. The control circuit receives the high-side and low-side sensing signals and converts them into a high-side sensing value and a low-side sensing value, respectively. When either the high-side or low-side sensing value exceeds an overcurrent protection value, the control circuit controls the power switch to limit either the first or second output current.

[0006] This invention provides a protection method for a power supply. The power supply supplies power to a load and is connected to a high-voltage power supply terminal and a low-voltage power supply terminal of the load. The protection method includes: detecting a first output current from the power supply to the load through the high-voltage power supply terminal to generate a high-side sensing signal; detecting a second output current from the load to the power supply through the low-voltage power supply terminal to generate a low-side sensing signal; converting the high-side sensing signal and the low-side sensing signal into a high-side sensing value and a low-side sensing value, respectively; and limiting the first or second output current when one of the high-side sensing value and the low-side sensing value exceeds an overcurrent protection value. Attached Figure Description

[0007] Figure 1 This invention shows a power supply according to an embodiment of the present invention.

[0008] Figure 2 An example is shown of a power supply according to an embodiment of the present invention.

[0009] Figure 3 Examples show Figure 2 One of the power control circuits.

[0010] Figure 4 Example 1: High-voltage side current sensing unit.

[0011] Figure 5 and 6 Examples of two power supplies according to embodiments of the present invention are shown.

[0012] [Symbol Explanation]

[0013] 100, 200, 400, 500 power supplies

[0014] 102, 202, 402, 502 loads

[0015] 104, 204, 304, 404, 504 high-voltage side current detection units

[0016] 106, 206, 406, 506 Low-voltage side current detection units

[0017] 108, 208, 408, 508 power control circuits

[0018] 214, 314 power switches

[0019] 216 and 416 detection resistors

[0020] 260 High-voltage side conversion circuit

[0021] 264 control unit

[0022] 268 Low-voltage side conversion circuit

[0023] 313 sensing resistor

[0024] 414M main power switch

[0025] 414S detection switch

[0026] CSP Current Sensing Terminal

[0027] CSPV voltage sensing terminal

[0028] GATE Gate

[0029] GND low-voltage power supply terminal

[0030] I OB I OF Output current

[0031] I OS Detecting current

[0032] S N Low-end sensing value

[0033] S P High-end sensing value

[0034] VBUS high voltage power supply terminal

[0035] VCC high voltage output power cord

[0036] V O Output voltage

[0037] V SH High-end sensing signals

[0038] CSN low-voltage output power cord

[0039] V SL Low-end sensing signal Detailed Implementation

[0040] To make the objectives, implementation methods, and advantages of the embodiments of the present invention clearer, the implementation methods in the embodiments will be clearly and completely described below with reference to the accompanying drawings. The embodiments described in this specification are merely some embodiments of the present invention, not all embodiments. Those skilled in the art can make various modifications and variations to the embodiments described in this specification without departing from the spirit and scope of the present invention.

[0041] Figure 1 This illustrates a power supply 100 according to an embodiment of the present invention, used to provide an output voltage V. OThe power supply 100 supplies power to the load 102 via the high-voltage power supply terminal VBUS and the low-voltage power supply terminal GND. The power supply 100 includes a power control circuit 108, a high-voltage side current detection unit 104, and a low-voltage side current detection unit 106. The power supply 100 provides the output current I from the high-voltage power supply terminal VBUS. OF The output current I is drawn from the low-voltage power supply terminal GND. OB According to circuit theory, under normal conditions, the output current I... OF With output current I OB They should all be the same size.

[0042] The high-voltage side current detection unit 104 is connected to the high-voltage power supply terminal VBUS to sense the output current I. OF To generate high-end sensing signal V SH Similarly, the low-voltage side current sensing unit 106 is connected to the low-voltage power supply terminal GND to sense the output current I. OB To generate a low-end sensing signal V SL .

[0043] Figure 1 In the high-voltage side current detection unit 104, there is a power switch (which will be illustrated later) connected to the gate terminal GATE of the power control circuit 108.

[0044] The power control circuit 108 respectively converts the high-side sensing signal V SH With low-end sensing signal V SL Convert to high-end sensing value S P With low-end sensing value S N And in high-end sensing value S P With low-end sensing value S N When one of them exceeds an overcurrent protection value, the power control circuit 108 controls the power switch in the high-voltage side current detection unit 104 to limit the output current I. OF Or I OB .

[0045] When either the high-voltage side current detection unit 104 or the low-voltage side current sensing unit 106 experiences a single-point fault, such as a short circuit, the power control circuit 108 can still provide appropriate protection for the power supply 100 from the one that is functioning normally. For example, when the high-side sensing value S... P With low-end sensing value S N When one of them exceeds an overcurrent protection value, the power control circuit 108 shuts off the power switch in the high-voltage side current detection unit 104, causing the output current I to... OF Or I OB Approximately 0A.

[0046] Figure 2For example, a power supply 200 according to an embodiment of the present invention is shown, and Figure 1 Similarities or resemblances can be found by referring to Figure 1 And that's all I've learned, so I won't go into detail. Figure 2 In the middle, the high-voltage side current detection unit 204 has a power switch 214, which is connected between the high-voltage output power line VCC and the high-voltage power supply terminal VBUS to provide the output current I. OF The load 202 is supplied with current. The low-voltage side current sensing unit 206 is a sensing resistor 216 connected between the low-voltage power supply terminal GND and the low-voltage output power line CSN, used to detect the output current I flowing from the load 202 to the low-voltage output power line CSN. OB For example, the high-voltage output power line VCC and the low-voltage output power line CSN are the positive and negative output power lines of a flyback power converter, respectively. When the power switch 214 is turned on, the voltage source located between the high-voltage output power line VCC and the low-voltage output power line CSN can supply power to the load 202, generating an output current I. OF With output current I OB .

[0047] When power switch 214 is turned on, the voltage difference between the high-voltage output power line VCC and the high-voltage power terminal VBUS is the drain-to-source voltage of power switch 214. DS ), can be used as a high-end sensing signal V SH This is provided to the power control circuit 208. The voltage across the sensing resistor 216 can serve as the low-side sensing signal V. SL It is provided to the power control circuit 208.

[0048] Figure 3 Examples show Figure 2 The power control circuit 208 includes a high-voltage side conversion circuit 260, a low-voltage side conversion circuit 268, and a control unit 264. The high-voltage side conversion circuit 260 converts the high-side sensing signal V. SH For high-end sensing value S P This is provided to the control unit 264. For example, the high-end sensing value S P This is a voltage signal with the low-voltage power supply terminal GND as 0 voltage. The low-voltage side conversion circuit 268 converts the low-side sensing signal V. SL Low-end sensing value S N This is provided to the control unit 264. For example, the low-voltage side conversion circuit 268 amplifies the low-side sensing signal V of the negative voltage. SL And convert it into a low-side sensing value S with a positive voltage. N In this embodiment, the high-end sensing value SP With output current I OF The ratio is equal to the low-end sensing value S. N With output current I OB The proportions are roughly equal. In other words, the high-end sensing value S P It can represent the output current I OF Low-end sensing value S N It can represent the output current I OB .

[0049] Control unit 264 can rely on high-end sensing value S P With low-end sensing value S N Controlled via the gate terminal (GATE). Figure 2 The power switch 214 provides appropriate protection. For example, the control unit 264 can provide overcurrent protection. If the high-side sensing value S... P or low-end sensing value S N When one of them exceeds a preset overcurrent protection value, the control unit 264 shuts off the power switch 214, causing the output current I to be reduced. OF It is 0A.

[0050] In another embodiment, control unit 264 can provide single-point fault protection. Control unit 264 compares the high-end sense value S. P With low-end sensing value S N If the high-end sensing value S P or low-end sensing value S N When the difference between them reaches a preset abnormal value, the output current I appears to decrease. OF It is unreasonable that the output current I is not equal to the output current. OB This means that either the high-voltage side current sensing unit 204 or the low-voltage side current sensing unit 206 is faulty, possibly short-circuited or open-circuited. In this case, the control unit 264 can turn off the power switch 214 to stop supplying power to the load 202.

[0051] Figure 4 For example, the high-voltage side current sensing unit 304, in one embodiment, can replace Figure 2 The high-voltage side current sensing unit 204 is included. In addition to the power switch 314, the high-voltage side current sensing unit 304 also has a sensing resistor 313 connected between the power switch 314 and the high-voltage output power line VCC. The voltage across the sensing resistor 313 serves as the high-side sensing signal V. SH It is provided to the power control circuit 208.

[0052] Figure 5 For example, a power supply 400 according to an embodiment of the present invention is shown, and Figure 1 , 2Similarities or resemblances can be found in previous teachings and will not be repeated here. Figure 5 In the high-voltage side current sensing unit 404, there are a main power switch 414M and a detection switch 414S. The main power switch 414M is connected between the high-voltage output power line VCC and the high-voltage power terminal VBUS to provide the output current I. OF Load 402 is supplied. A detection switch 414S is connected between the high-voltage output power line VCC and the current detection terminal CSP of the power control circuit 408. The power control circuit 408 controls both the main power switch 414M and the detection switch 414S simultaneously via the gate terminal GATE. When both the main power switch 414M and the detection switch 414S are on, the power control circuit 408 allows the output current I flowing through the main power switch 414M to... OF The detection current I flowing through the detection switch 414S OS This presents a preset proportional relationship. For example, the power control circuit 408 can use feedback control to ensure that the current sensing terminal CSP and the voltage sensing terminal CSPV (which is also the high-voltage power supply terminal VBUS) have approximately the same voltage. At this time, the output current I... OF With the detected current I OS It's roughly proportional. The power control circuit 408 can also detect the current I by sensing it. OS With low-end sensing signal V SL This achieves overcurrent protection and single-point fault protection. In one embodiment, the main power switch 414M, the detection switch 414S, and the power control circuit 408 are integrated into a single-chip integrated circuit.

[0053] Although each Figure 1 , 2 Figures 4 and 5 both show a high-voltage side current sensing unit with a power switch, but the present invention is not limited thereto. Figure 6 For example, a power supply 500 according to an embodiment of the present invention is shown, and Figure 1 Similarities or resemblances can be found in previous teachings and will not be repeated here. Figure 6 In the high-voltage side current detection unit 504, there is no power switch, but in the low-voltage side current detection unit 506, there is a power switch (not shown), controlled by the power control circuit 508. Similarly... Figure 2 , 4 Compared with the five examples, Figure 6 The low-voltage side current detection unit 506 can be simply a power switch, a combination of a power switch and a sensing resistor connected in series, or a combination of a main power switch and a detection switch. The power supply 500 can also provide overcurrent protection and single-point fault protection.

[0054] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made in accordance with the claims of the present invention shall be within the scope of the present invention.

Claims

1. A power supply for supplying power to a load, comprising: The high-voltage side current sensing unit is connected to the high-voltage power supply terminal of the load and senses the first output current output by the power supply to the load to generate a high-side sensing signal. A low-voltage side current sensing unit, connected to the low-voltage power supply terminal of the load, senses the second output current supplied by the load to the power supply to generate a low-side sensing signal. One of the high-voltage side current sensing unit and the low-voltage side current sensing unit includes a power switch. The control circuit receives the high-end sensing signal and the low-end sensing signal, and converts the high-end and the low-end sensing signals into high-end sensing values ​​and low-end sensing values ​​respectively. When one of the high-end sensing value and the low-end sensing value exceeds the overcurrent protection value, the control circuit controls the power switch to limit one of the first output current and the second output current. When the difference between the high-end sensing value and the low-end sensing value reaches a preset abnormal value, the control circuit controls the power switch to limit the output current.

2. The power supply as claimed in claim 1, wherein, The high-voltage side current sensing unit includes: The power switch is connected between the high-voltage output power line and the high-voltage power terminal to provide the first output current to the load. The high-end sensing signal is the voltage difference between the high-voltage output power line and the high-voltage power supply terminal.

3. The power supply as claimed in claim 1, wherein, The high-voltage side current sensing unit includes: The power switch is connected to the high-voltage power supply terminal to provide the first output current to the load; and A sensing resistor is connected between the power switch and the high-voltage output power line. The high-end sensing signal is the resistance voltage of the sensing resistor.

4. The power supply as claimed in claim 1, wherein, The high-voltage side current sensing unit includes: The main power switch, connected between the high-voltage output power line and the high-voltage power terminal, is used to provide the first output current to the load; and A detection switch is connected between the high-voltage output power line and the control circuit. The control circuit architecture simultaneously controls the main power switch and the detection switch, so that the first output current flowing through the main power switch and the detection current flowing through the detection switch present a preset ratio relationship.

5. The power supply according to claim 4, wherein, The main power switch, the detection switch, and the control circuit are integrated into a single-chip integrated circuit.

6. A protection method for a power supply, wherein, The power supply provides power to the load and is connected to both the high-voltage and low-voltage power supply terminals of the load. The protection method includes: The first output current supplied to the load by the power supply through the high-voltage power terminal is detected to generate a high-side sensing signal; The second output current from the load through the low-voltage power supply terminal is detected to generate a low-end sensing signal; The high-end sensing signal and the low-end sensing signal are respectively converted into high-end sensing values ​​and low-end sensing values; When either the high-end sensing value or the low-end sensing value exceeds the overcurrent protection value, the first or second output current is limited; as well as When the difference between the high-end sensing value and the low-end sensing value reaches a preset abnormal value, the first or second output current is limited.

7. The protection method according to claim 6, wherein, The power supply has a power switch connected between the high-voltage output power line and the high-voltage power terminal to provide the first output current to the load, and the high-side sensing signal is the voltage difference between the high-voltage output power line and the high-voltage power terminal.

8. The protection method according to claim 6, wherein, The power supply has a power switch and a sensing resistor connected in series between the high-voltage output power line and the high-voltage power terminal to provide the first output current to the load, and the high-side sensing signal is the resistance voltage of the sensing resistor.

9. The protection method according to claim 6, wherein, The power supply includes: The main power switch, connected between the high-voltage output power line and the high-voltage power terminal, is used to provide the first output current to the load; and A detection switch is connected between the high-voltage output power line and the current detection terminal. The protection method also includes: The first output current flowing through the main power switch and the detection current flowing through the detection switch are in a preset ratio relationship. The detected current is the high-end sensing signal.

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