TW201417432A - Protection apparatus for a DC-DC converter - Google Patents

Abstract

A protection apparatus applied for a DC-DC converter and a system board is provided. It comprises a first switch, and a power control circuit. The first switch is coupled between a DC voltage and the system board. The first switch has a first end for receiving a power control signal and switches the DC voltage to the system board according to the power control signal. The power control circuit is coupled to the first end of the first switch and outputs the power control signal according to a control signal.

Description

Protection device for DC-DC converter

The present invention relates to a protection device for a DC-DC converter, and more particularly to a protection device for a DC-DC converter applied to a system board.

There is a power supply in the computer system that can supply a stable DC voltage (such as 12V or 5V) to make it work properly. Since the electronic components in the computer system, such as the central processing unit, the control chip, or the memory, the operating voltage is not the same as the DC voltage provided by the power supply, the motherboard in the computer system must have DC-DC. The buck function of the converter and the ability to convert a higher DC voltage (eg 12V) into a lower operating voltage (eg 1.3V) required for the electronics.

Figure 1 is a circuit diagram showing the protection of a conventional DC-DC converter. The DC-DC converter 21 converts the DC voltage Vcc into an output voltage Vout for supplying an electronic component load action in the computer system. The DC-DC converter 21 includes a high-end transistor Q1, a low-end transistor Q2, and an inductor L1. The capacitor C1 and the pulse width modulation circuit PWM that controls the high side transistor Q1 and the low side transistor Q2. When the high-end transistor Q1 is damaged, the DC voltage Vcc is directly input to the electronic component load, thereby causing damage to other originally normal electronic components. Although in the conventional protection device, a protection circuit 10 is disposed between the DC voltage Vcc and the motherboard 20, when the motherboard 20 reaches the required protection point, the protection device will enter the protection mode, thereby cutting off the DC voltage Vcc to Motherboard 20.

In a typical protection circuit 10, the protection method employed is usually The disadvantage of the dangerous wire or the slow disconnect circuit is that the protection speed is very slow, usually it takes about several ms to several hundred ms or more, and there is a way to achieve the protection effect. Therefore, when the high-end transistor Q1 is damaged, The normal components of the motherboard 20 may be damaged or the copper foil may be broken, resulting in an additional cost to replace the damaged components with the motherboard. Therefore, it is an important subject in the technical field to find a voltage that can quickly cut off the voltage supplied from the DC voltage Vcc to the motherboard 20 when the high-end transistor Q1 is damaged, thereby achieving an effective and rapid protection function.

In view of the above problems, the object of the present invention is to provide a protection device for a DC-DC converter, which uses a first switch, a second switch, and a power control circuit to control the voltage of the DC voltage source input system board, when components on the system board When protection is required (for example, when the high-end transistor in the DC-DC converter is damaged), the second switch receives the control signal to quickly cut off the DC voltage input to the system board. The cut-off speed is about 60μs. Left and right, to avoid damage to the normal components on the motherboard or copper foil breakage, to achieve effective protection.

In addition, the power control circuit of the present invention uses different paths to control the switching of the first switch, that is, the conduction path is used to turn on the first switch, so that the first switch can be controlled to be turned on at a slow speed to prevent an excessive current (Inrush Current). ) The resulting component is destroyed. And use the cutoff path to quickly cut off the first switch to quickly cut off the voltage of the DC voltage input to the system board.

Furthermore, the present invention measures the inductance of a DC-to-DC converter. The voltage value of the middle end point, and the overvoltage protection circuit is used to output the control signal according to the measured voltage value and the first reference voltage. And when the system board reaches the overvoltage protection point, the output control signal can control the protection device of the DC-DC converter, and quickly cut off the voltage of the DC voltage input to the system board to achieve the function of overvoltage protection, wherein the overvoltage The protection point can be adjusted via a voltage value of the first reference voltage or the second reference voltage.

In addition, the present invention utilizes a current detecting circuit to convert a current flowing into a system board into a voltage difference, input an overcurrent protection circuit, and an overcurrent protection circuit to generate a control signal accordingly. When the current input to the system board reaches the overcurrent protection point, the output control signal can control the protection device of the DC-DC converter, and quickly cut off the voltage of the DC voltage input to the system board to achieve the function of overcurrent protection, wherein The overcurrent protection point can be adjusted via the voltage value of the third reference voltage.

To achieve the above object, the present invention provides a protection device for a DC-DC converter, which is applied to a system board. The system board includes an inductor, and the inductor has a first end coupled to one of the second ends of the DC voltage. The protection device of the DC-DC converter comprises a first switch and a power control circuit. The first switch is coupled between the DC voltage and the system board, and the first switch has a first end for receiving a power control signal and switching the voltage of the DC voltage input system board according to the power control signal. The power control circuit is coupled to the first end of the first switch and generates a power control signal according to a control signal.

According to the above invention, the present invention further provides a protection device for a DC-DC converter, wherein when the power control circuit receives the control signal, the first switch then cuts off the voltage of the DC voltage input to the system board.

According to the above invention, the present invention further provides a protection device for a DC-DC converter, wherein the power control circuit has a conduction path and a cut-off path, and the conduction path and the cut-off path are coupled to the first switch.

According to the above invention, the present invention further provides a protection device for a DC-DC converter, further comprising a second switch having a first end and a second end, the first end of the second switch being configured to receive The control signal, the second end of the second switch is coupled to the power control circuit, and the second switch outputs a switching signal according to the control signal, and is transmitted to the power control circuit to enable the power control circuit to generate a power control signal.

According to the above invention, the present invention further provides a protection device for a DC-DC converter, wherein the power control circuit has a push-pull circuit coupled to the first switch and a DC voltage.

According to the above invention, the present invention further provides a protection device for a DC-DC converter, further comprising an overvoltage protection circuit coupled between the system board and the power control circuit, and according to the voltage value of the first end of the inductor , output control signal.

According to the above invention, the present invention further provides a protection device for a DC-DC converter, further comprising an overvoltage protection circuit coupled between the system board and the power control circuit, and based on the voltage value of the second end of the inductor , output control signal.

According to the above invention, the present invention further provides a protection device for a DC-DC converter, wherein the overvoltage protection circuit includes a first comparator. The first comparator compares the voltage value of the first end of the inductor with a first reference voltage and outputs a control signal.

According to the above invention, the present invention further provides a DC-DC conversion The protection device of the converter, wherein the overvoltage protection circuit comprises a second comparator and an integration unit, and the integration unit integrates the signal of the detection point of the second end of the inductor, and outputs an integrated voltage signal, and the second comparison The controller outputs a control signal according to the integrated voltage signal and a second reference voltage.

According to the above invention, the present invention further provides a protection device for a DC-DC converter, further comprising a current detecting circuit and an overcurrent protection circuit. The current detecting circuit is coupled between the system board and the DC voltage, and generates a voltage difference according to the current flowing into the system board. The overcurrent protection circuit is coupled to the current detecting circuit, and outputs a control signal according to the voltage difference.

According to the above invention, the present invention further provides a protection device for a DC-DC converter, wherein the overcurrent protection circuit includes a determination unit and a signal generation unit. The judging unit outputs a judgment signal according to the voltage difference signal. The signal generating unit outputs a control signal according to the determination signal.

According to the above invention, the present invention further provides a protection device for a DC-DC converter, wherein the overcurrent protection circuit further includes a delay unit coupled between the determination unit and the signal generation unit, and according to a set The delay time delays the off signal input signal generating unit.

The advantages and spirit of the present invention will be further understood from the following detailed description of the invention.

Fig. 2 is a circuit diagram showing an embodiment of a protection device for a DC-DC converter of the present invention. As shown in FIG. 2, the protection device 210 of the DC-DC converter is applied to a system board 120, and the system board 120 can be A computer motherboard or a circuit board requiring a protection device is a scope of application of the present invention. The system board 120 includes a converter 121 that continuously flows DC and a load (electronic component). The above-mentioned load load is a plurality of electronic components on the motherboard. In this embodiment, only one set of DC-to-DC converters 121 is taken as an example. However, in practical applications, the protection circuit of the present invention can be applied to multiple sets of motherboards. DC to DC converter. The DC-to-DC converter 121 converts the DC voltage VCC into an output voltage Vo to supply the voltage required for the load load. In FIG. 2, the DC-DC converter protection device 210 is provided separately from the system board 120. However, in practical applications, the DC-DC converter protection device 210 can be integrated on the system board 120.

The DC-to-DC converter 121 of the present embodiment includes a high-end transistor Q3, a low-end transistor Q4, an inductor L2, a capacitor C2, and a pulse width modulation circuit PWM. The first end of the inductor L2 is coupled to the capacitor C2, and generates an output voltage Vo. The second end of the inductor L2 is coupled to the DC voltage VCC, and the high-end transistor Q3 is coupled between the DC voltage VCC and the second end of the inductor L2. The low-end transistor Q4 is coupled between the second end of the inductor L2 and the ground. The pulse width modulation circuit PWM is coupled to the high-end transistor Q3 and the low-end transistor Q4, and controls the high-end transistor Q3 and the low-end transistor. The conduction period of the crystal Q4. The DC-to-DC converter 121 of the present embodiment is exemplified by a buck circuit, but the invention is not limited thereto, and can be applied to a boost circuit or a buck-boost circuit (buck- Boost) and so on.

The DC-DC converter protection device 210 includes a first switch Q5, a power control circuit 211, and a second switch Q6. The second end of the first switch Q5 is coupled to the DC voltage VCC, the third end of the first switch Q5 is coupled to the system board 120, and the first end of the first switch Q5 is coupled to the power control circuit 211. After receiving the power control signal PS, the first terminal of the first switch Q5 switches the voltage of the DC voltage VCC input to the system board 120 according to the power control signal PS. The first end of the power control circuit 211 is coupled to the first end of the first switch Q5, and generates the power control signal PS according to a switching signal SS. The second end of the power control circuit 211 is coupled to the DC voltage VCC, and the third end of the power control circuit 211 is configured to receive the switching signal SS. The first end of the second switch Q6 receives a control signal CS, the second end is coupled to the third end of the power control circuit 211, and outputs a switching signal SS according to the control signal CS.

In addition, in this embodiment, only one first switch Q5 is taken as an example, and the present invention can increase the number of the first switches Q5 in parallel according to the increase of the load. In addition, in the present invention, the second switch Q6 is configured according to the level of the control signal CS. Therefore, if the control signal CS is at the opposite level, the second switch Q6 can also be omitted. The CS directly controls the power supply control circuit 211 to generate a power supply control signal PS.

Fig. 2A is a circuit diagram showing an embodiment of the power supply control circuit 211 in Fig. 2 of the present invention. Please refer to both Figure 2A and Figure 2. The power control circuit 211 includes a switch control module 2110, a diode Z1, and a resistor R1. The switch control module 2110 is coupled to the DC voltage VCC, the first end of the first switch Q5 and the second end of the second switch Q6. The switch control module 2110 of the embodiment is composed of bipolar transistors (BJT) B1 and B2. A push-pull circuit is constructed, but the invention is not limited thereto, and may be composed of a pair of switching elements having complementary characteristics. The resistor R1 is coupled between the switch control module 2110 and the first end of the first switch Q5, and the diode Z1 is connected in parallel with the resistor R1.

When the control signal CS is at a high level, the second switch Q6 is turned on. And outputting the low-level switching signal SS, the switch control module 2110 receives the low-level switching signal SS, and turns on the first switch Q5. At this time, the voltage of the DC voltage VCC can be transmitted to the DC on the system board 120. A DC converter 121. In this process, the power supply control circuit 211 provides a conduction path a, that is, the first terminal voltage of the first switch Q5, is pulled down to the low voltage level via the resistor R1 and the bipolar transistor B2 to turn on the first switch Q5. Since the resistor R1 is located in the conduction path a, when the control signal CS is turned to the high level, the first switch Q5 can be controlled to be turned on at a slow speed, thereby preventing an instantaneous excessive current (Inrush Current) from being generated. destruction.

When the control signal CS is at a low level, the second switch Q6 is turned off and outputs a high level switching signal SS. After the switch control module 2110 receives the high level switching signal SS, the first switch Q5 is turned off. At this time, the voltage of the DC voltage VCC is stopped from being transmitted to the DC-to-DC converter 121 on the system board 120, that is, the DC voltage VCC no longer supplies voltage to the system board 120. In this process, the power control circuit 211 provides a cutoff path b, that is, the first terminal voltage of the first switch Q5, is pulled up to a high voltage level via the diode Z1 and the bipolar transistor B1 to cut off the first The switch Q5, since the diode Z1 is located in the cutoff path b, when the control signal CS is turned to the low level, the first switch Q5 can be quickly turned off to immediately cut off the voltage of the DC voltage VCC input to the system board 120.

Fig. 3A is a circuit diagram showing another embodiment of the protection device of the DC-DC converter of the present invention. Please refer to FIG. 2 and FIG. 3A simultaneously. An over-voltage protection circuit 314 is coupled between the system board 120 and the power control circuit 211, and is controlled according to the voltage value V1 of the first end of the inductor L2. Signal CS. The overvoltage protection circuit 314 has a first comparator 3141. The non-inverting input terminal of the first comparator 3141 receives a first reference voltage Vr1. The inverting input terminal of the first comparator 3141 receives the voltage value V1. When the first comparator 3141 compares the voltage value V1 with the first reference voltage Vr1, the control signal CS is output. When the voltage value V1 is greater than the first reference voltage Vr1, that is, the high-end transistor Q3 is damaged, the comparator 3141 outputs a low-level control signal CS to quickly cut off the voltage of the DC voltage VCC input system board 120, thus avoiding DC The voltage VCC is directly input to the system board 120, causing damage to other normal components or copper foil breakage. The setting of the first reference voltage Vr1 is a voltage setting value to be protected by the circuit designer.

In addition, in this embodiment, a latch circuit 315 can be disposed between the overvoltage protection circuit 314 and the protection device 210 of the DC-DC converter. When the protection device 210 of the DC-DC converter cuts off the DC voltage VCC input system board. After the voltage of 120, the latch circuit 315 maintains the output of the overvoltage protection circuit 314 at a fixed level to maintain the DC voltage VCC and the system board 120 in an off state, and prevents the voltage of the DC voltage VCC from being input to the system board 120 again. The components on the system board 120 are damaged.

Fig. 3B is a circuit diagram showing another embodiment of the protection device of the DC-DC converter of the present invention. Please refer to FIG. 2 and FIG. 3B simultaneously. An over-voltage protection circuit 314' is coupled between the power supply control circuit 211 of the system board 120, and outputs a control signal CS according to the signal of the second end detection point T1 of the inductor L2. . The overvoltage protection circuit 314' has a second comparator 3141' and an integration unit 314a. The integration unit 314a is coupled to the second end of the inductor L2, and integrates the signal of the detection point T1 to output an integrated voltage signal MS. . The second comparator 3141' is coupled to the integration unit 314a, the second comparison One of the non-inverting inputs of the converter 3141' receives a second reference voltage Vr2, and one of the inverting inputs of the second comparator 3141' receives the integrated voltage signal MS, and when the second comparator 3141' compares the integrated voltage signal MS with After the second reference voltage Vr2, the control signal CS is output.

When the integrated voltage signal MS is greater than the second reference voltage Vr2, that is, the high-end transistor Q3 is damaged or overloaded, the second comparator 3141' outputs a low-level control signal CS to quickly cut off the DC voltage VCC. Enter the voltage of system board 120. In addition, in this embodiment, a latch circuit 315 can be disposed between the overvoltage protection circuit 314' and the protection device 210 of the DC-DC converter. The function of the latch circuit 315 is the same as that of the embodiment of FIG. 3A, and details are not described herein.

The integrating unit 314a includes a diode Z2, a resistor R4, and a capacitor C5. The resistor R4 is coupled between the second end of the inductor L2 and the second comparator 3141'. One end of the capacitor C5 is coupled to the connection point of the resistor R4 and the second comparator 3141', and the diode Z2 is connected in parallel with the resistor R4. 3C shows the signal waveform of the second end detection point T1 of the inductor L2 in FIG. 3B, which is a duty cycle of the DC-to-DC converter 121, as shown in FIG. 3C, The edge bands 321 and 323 are charged to the capacitor C5 via the resistor R4. At this time, the voltage of the capacitor C5 starts to rise until the negative edge bands 322 and 324, and the voltage of the capacitor C5 is discharged via the diode Z2.

When the system board 120 is in normal operation, as shown in (A) of FIG. 3C, the positive edge band 321 is smaller than the width of the negative edge band 322, that is, the charge and discharge time of the capacitor C5 is less than the discharge time, and therefore, when the voltage of the capacitor C5 is Once it is raised, it will be returned to the original voltage value. When the system board 120 is in abnormal operation (for example, the high-end transistor Q3 is damaged or overloaded), such as As shown in (B) of Figure 3C, the width of the positive edge band 323 will be much larger than the negative edge band 324. At this time, the voltage of the capacitor C5 will continue to increase until the voltage of the capacitor C5 (ie, the integrated voltage signal MS) is greater than the second reference. After the voltage Vr2, the second comparator 3141' outputs the control signal CS to quickly cut off the voltage of the DC voltage VCC input to the system board 120 to achieve a protection effect.

Figure 4 is a circuit diagram showing another embodiment of a protection device for a DC-DC converter according to the present invention. Referring to FIG. 2 and FIG. 4 simultaneously, a current detecting circuit 411 is coupled between the system board 120 and the DC voltage VCC, and generates a voltage difference V3 according to the current I1 flowing into the system board 120. An overcurrent protection circuit 412 is coupled between the current detection circuit 411 and the second switch Q6, and outputs the control signal CS according to the voltage difference V3. The current detecting circuit 411 of the present embodiment takes an inductor as an example, but the present invention is not limited thereto, and it is within the scope of the invention as long as the current passing through can be converted into a voltage difference output component (for example, a high current resistor).

The overcurrent protection circuit 412 includes a determination unit 4121, a delay unit 4122, and a signal generation unit 4123. The determining unit 4121 outputs a determining signal S1 according to the voltage difference signal V3. The delay unit 4122 is coupled to the determining unit 4121, and outputs a delay signal S2 according to the determining signal S1. The delay signal S2 is delayed after the determining signal S1 is delayed. The output signal. The signal generating unit 4123 is coupled to the delay unit 4122, and after receiving the delay signal S2, outputs the control signal CS. The delay time can be adjusted according to the design requirements. When the designer does not need the delay time, the delay unit 4122 can be removed, that is, the signal generating unit 4123 is coupled to the determining unit 4121, and is controlled according to the determining signal S1. Signal CS.

Figure 4A shows one of the overcurrent protection circuits 412 in Figure 4 Schematic diagram of the circuit of the embodiment. Referring to FIG. 4 and FIG. 4A simultaneously, the determining unit 4121 includes an amplifier 4121a and a comparator 4121b. The output end of the amplifier 4121a is coupled to the first end of the switch Q7, and the reverse input end is coupled to the second switch Q7. end. The third end of the switch Q7 is coupled to a non-inverting input terminal of the RC circuit and the comparator 4121b, and the RC circuit is composed of a resistor R3 and a capacitor C3 in parallel. After receiving the voltage difference V3 between the inverting input terminal and the non-inverting input terminal of the amplifier 4121a, and amplifying the voltage difference V3, an amplified voltage signal V4 is output through the third terminal of the switch Q7. The non-inverting input terminal of the comparator 4121b receives the amplified voltage signal V4 and compares it with a third reference voltage Vr3.

The delay unit 4122 includes a latch reset circuit 4122a, a comparator 4122b and a current source 4122c. The inverting input terminal of the comparator 4122b inputs a fourth reference voltage Vr4, the non-inverting input terminal is coupled to the output end of the current source 4122c and a capacitor C4, and the output end is coupled to the latch reset circuit 4122a, the comparator 4122b The delay signal S2 is output according to the output value of the current source 4122c and the fourth reference voltage Vr4. The latch reset circuit 4122a is coupled to the current source 4122c, and the latch reset circuit 4122a controls the current source 4122c according to the determination signal S1.

The signal generating unit 4123 includes a switch Q8 and a resistor R5. The resistor R5 is coupled between the second end of the switch Q8 and a voltage source VDD. When the first end of the switch Q8 receives the determination signal S1 or the delay signal S2, the control signal CS is output.

When the voltage value of the amplified voltage signal V4 is greater than the third reference voltage Vr3, the comparator 4121b outputs a high level determination signal S1, and the latch reset circuit 4122a receives the high level determination signal S1, that is, controls the current source. 4122c outputs current I2 and charges capacitor C4. When the voltage value of the non-inverting input terminal of comparator 4122b is greater than the fourth reference voltage Vr4, comparator 4122b outputs high-level delay signal S2, when switch Q8 receives high level. The delay signal S2 is a control signal CS that outputs a low level. At this time, the voltage of the DC voltage VCC is stopped from being transmitted to the DC-to-DC converter 121 on the system board 120, that is, the DC voltage VCC no longer supplies voltage to the system board 120.

In this embodiment, the overcurrent protection point can be set by changing the voltage value of the third reference voltage Vr3. When the overcurrent protection point to be protected is larger, the voltage value of the third reference voltage Vr3 can be increased. The above capacitance value C4 can be used to set the delay time required by the delay unit 4122. When the required delay time is longer, the larger capacitance value C4 can be selected. If the overcurrent protection circuit 412 does not require a delay time, the delay unit 4122 can also be removed, that is, when the overcurrent protection point is reached, the high level determination signal S1 can also be immediately input to the switch Q8, and the control signal is The CS is turned to a low level output to cut off the voltage input to the system board 120 by the DC voltage VCC.

In addition, in the above embodiments, the reference to the high and low levels, the comparator and the reverse and non-inverting input of the amplifier are illustrative of the present invention and are not intended to limit the present invention. It can be changed by various circuits of the same principle.

The present invention has been described above by way of examples, and the scope of the invention is not limited thereto, and various modifications and changes can be made by those skilled in the art without departing from the scope of the invention.

10‧‧‧Protection circuit

120‧‧‧System Board

121‧‧‧DC to DC converter

20‧‧‧ motherboard

21‧‧‧DC-DC Converter

210‧‧‧DC-DC converter protection device

211‧‧‧Power Control Circuit

2110‧‧‧Switch Control Module

314,314'‧‧‧Overvoltage protection circuit

315‧‧‧Latch circuit

3141,3141'‧‧‧ Comparator

314a‧‧Integral unit

411‧‧‧ Current detection circuit

412‧‧‧Overcurrent protection circuit

4121‧‧‧Judgement unit

4121a‧‧Amplifier

4121b‧‧‧ comparator

4122‧‧‧Delay unit

4122a‧‧‧Latch reset circuit

4122b‧‧‧ Comparator

4122c‧‧‧current source

4123‧‧‧Signal generating unit

PWM‧‧‧ pulse width modulation circuit

Vcc‧‧‧ DC voltage

VDD‧‧‧voltage source

I1, I2‧‧‧ current

Vout, Vo‧‧‧ output voltage

Load‧‧‧electronic components

Q1, Q3‧‧‧ high-end transistor

Q2, Q4‧‧‧ low-end transistor

B1, B2‧‧‧ bipolar transistor

L1, L2‧‧‧ inductance

C1, C2, C3, C4, C5‧‧‧ capacitors

R1, R2, R3, R4, R5‧‧‧ resistance

Z1, Z2‧‧‧ diode

Q5‧‧‧First switch

Q6‧‧‧Second switch

Q7, Q8‧‧‧ switch

PS‧‧‧Power control signal

SS‧‧‧Switching signal

CS‧‧‧Control signal

MS‧‧·Integral voltage signal

A‧‧‧ conduction path

B‧‧‧ cut-off path

V1‧‧‧ voltage value

T1‧‧‧Detection point

V3‧‧‧ voltage difference

V4‧‧‧Amplified voltage signal

S1‧‧‧judgment signal

S2‧‧‧ delayed signal

Vr1, Vr2, Vr3, Vr4‧‧‧ reference voltage

321,323‧‧‧Positive band

322,324‧‧‧native band

Figure 1 shows a schematic circuit diagram of a conventional DC-DC converter protection device.

Fig. 2 is a circuit diagram showing an embodiment of a protection device for a DC-DC converter of the present invention.

Fig. 2A is a circuit diagram showing an embodiment of the power supply control circuit 211 in Fig. 2.

Fig. 3A is a circuit diagram showing another embodiment of the protection device of the DC-DC converter of the present invention.

Fig. 3B is a circuit diagram showing another embodiment of the protection device of the DC-DC converter of the present invention.

Fig. 3C shows the signal waveform of the second end detection point T1 of the inductor L2 in Fig. 3B.

Fig. 4 is a circuit diagram showing another embodiment of the protection device for the DC-DC converter of the present invention.

Figure 4A shows a circuit schematic of one embodiment of the overcurrent protection circuit 412 of Figure 4.

Vcc‧‧‧ DC voltage

CS‧‧‧Control signal

SS‧‧‧Switching signal

PS‧‧‧Power control signal

Q5‧‧‧First switch

Q6‧‧‧Second switch

Q3‧‧‧High-end transistor

Q4‧‧‧Low-end transistor

211‧‧‧Power Control Circuit

210‧‧‧DC-DC converter protection device

120‧‧‧System Board

121‧‧‧DC to DC converter

L2‧‧‧Inductance

C2‧‧‧ capacitor

Vo‧‧‧ output voltage

Load‧‧‧electronic components

PWM‧‧‧ pulse width modulation circuit

Claims (12)

A protection device for a DC-DC converter is applied to a system board, the system board includes an inductor having a first end coupled to a second end of a DC voltage, the DC-DC converter The protection device includes: a first switch coupled between the DC voltage and the system board, the first switch having a first end for receiving a power control signal, and switching the DC according to the power control signal The voltage is input to the voltage of the system board; and a power control circuit is coupled to the first end of the first switch, and generates the power control signal according to a control signal. The protection device of the DC-DC converter according to claim 1, wherein when the power control circuit receives the control signal, the first switch then cuts off the voltage of the DC voltage input to the system board. The protection device of the DC-DC converter of claim 1, wherein the power control circuit has a conduction path and a cut-off path, and the conduction path and the cut-off path are coupled to the first switch. The protection device of the DC-DC converter according to claim 1, further comprising a second switch having a first end and a second end, wherein the first end of the second switch is used Receiving the control signal, the second end of the second switch is coupled to the power control circuit, and the second switch outputs a switching signal according to the control signal, and transmits the signal to the power control circuit to enable the power control circuit This power control signal is generated. The protection device of the DC-DC converter of claim 3, wherein the power control circuit has a push-pull circuit coupled to the first switch and the DC voltage. The protection device of the DC-DC converter according to claim 1, further comprising an overvoltage protection circuit coupled between the system board and the power control circuit, and according to the first end of the inductor The voltage value outputs the control signal. The protection device of the DC-DC converter according to claim 1, further comprising an overvoltage protection circuit coupled between the system board and the power control circuit, and according to the second end of the inductor The voltage value outputs the control signal. The protection device of the DC-DC converter according to claim 6, wherein the overvoltage protection circuit comprises a first comparator, wherein the first comparator compares the voltage of the first end of the inductor After the value and a first reference voltage, the control signal is output. The protection device for a DC-DC converter according to claim 7, wherein the overvoltage protection circuit comprises a second comparator and an integrating unit, the integrating unit of the second end of the inductor After integrating the signal of the detection point, an integrated voltage signal is output, and the second comparator outputs the control signal according to the integrated voltage signal and a second reference voltage. The protection device of the DC-DC converter according to claim 1, further comprising a current detecting circuit and an overcurrent protection circuit, the current detecting circuit being coupled between the system board and the DC voltage And generating a voltage difference according to the current flowing into the system board, the overcurrent protection circuit is coupled to the current detecting circuit, and outputs the control signal according to the voltage difference. The protection device for a DC-DC converter according to claim 10, wherein the overcurrent protection circuit comprises: a determination unit that outputs a determination signal according to the voltage difference signal; and a signal generation unit that outputs the control signal according to the determination signal. The protection device of the DC-DC converter of claim 11, wherein the overcurrent protection circuit further includes a delay unit coupled between the determination unit and the signal generation unit, and The decision signal is delayed from being input to the signal generating unit according to a set delay time.