TW201138252A - Circuit and method for over-current protection - Google Patents

Abstract

An over-current protection method of DC/DC converter is provided. First, detect whether an over-current event (e.g. short circuit event) of the DC/DC converter occurred or not. If the over-current event occurs, a switch unit on a power transmission path of the DC/DC converter is turn off to cut off the power transmission path during a first period. Second, reconnect the power transmission path after the first period ended. Finally, detect whether the over-current event still exists or not.

Description

201138252 HA-2010-0002-TW 34023twf.doc/n VI. Description of the Invention: [Technical Field of the Invention] The present invention relates to a DC-DC converter (and is particularly related to a direct current) / DC converter over-current protection circuit. [Prior Art] Lutu 1 is a schematic diagram of a conventional DC/DC conversion circuit 1〇〇. The DC/DC converter 100 can adjust the input voltage Vin to the output voltage Vout. The conduction of the transistor M2 is controlled by a pulse width modulation control signal PWM. When the transistor M2 is turned on, the diode D1 exhibits a reverse bias voltage, and electric energy from the input voltage Vin is stored in the inductor L1, and the output capacitor Co is charged. When the transistor ^2 is turned off, the inductor L1 maintains the current in the same direction and the diode D1 exhibits a forward bias. In addition, the detecting unit 102 can detect the voltage drop of the output voltage V〇ut and determine the conduction state of the transistor M1. When the load 1〇4 appears in the case of #short circuit, the voltage value of the output voltage Vout will be instantaneously pulled low. At this time, the detecting unit 1〇2 outputs a trigger signal & to the latch unit 106 to The latch unit 1〇6 permanently locks the transistor M1 to a turn-off state, preventing excessive current from flowing to the load 21〇, causing the electronic component to burn. As such, the transistor M1 will be permanently worn unless the power supply of the DC/DC converter is reset (ie, the power is turned off and then re-supplied to the DC/DC converter 100). The overcurrent protection mechanism of the conventional DC/DC conversion circuit 100 can avoid component damage although the 201138252 HA-2010-0002-TW 34023twf.d〇c/n can be damaged due to the voltage drop caused by the money. The noise interference in the middle, or other temporary, sporadic, events cause the output voltage VGU1 to drop, so it is easy to cause the control unit 102 to judge and to permanently lock the transistor in the off state. In this way, the power supply must be turned back on in order to make the DC/DC conversion circuit 100 bribe the operation of the iLf, thereby making the cake more inconvenient. SUMMARY OF THE INVENTION The present invention provides an overcurrent protection circuit for a DC/DC converter that can initiate an overcurrent protection mechanism after an overcurrent event is determined to avoid a block-and-judgment situation. The present invention provides an overcurrent protection circuit of a DC/DC converter, including a -P shoulder off unit, a predicate unit, and a control module. The switch unit is disposed in the power transmission path of the DC/DC converter, and the DC/DC_transform state is used to supply power to a load through the power transmission path. During normal operation of the DC-DC converter, the switch S is in an on state. The detection unit is configured to detect whether an overcurrent event has occurred in the DC/DC converter. In addition, the control module is coupled to the detecting unit and the switching unit. If an overcurrent event occurs, the control module can cut off the switching unit to temporarily cut off the power transmission path during the first period and can be turned back on after the first period ends. The switching unit detects whether an overcurrent event still exists through the detecting unit. In an embodiment of the present invention, if the overcurrent event still exists after the end of the first period, the control module once again turns off the switching unit to temporarily transit the power transmission path in the second period, and in the second period After re-directing 201138252 HA-2010-0002-TW 34023twf.doc/n ^ Switching unit and relying on measuring the military _ overcurrent event is still stored in an embodiment, if the aforementioned re-switching unit: If the __ green event is age, the control mode J switch will reduce the permanent transmission path. ...... The circuit ί Γ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ The first-comparator's ^ two-input and zero-end knives - the reference voltage and the sub-module have an overcurrent event. (4) 1—trigger 峨 知 — — — — — — — — — — — — — — 实施 实施 实施 上述 上述 上述 上述 上述 上述 上述 上述 上述 上述 上述 上述 上述 上述 上述 上述 上述 上述 上述 上述 上述 上述 上述 上述 上述 上述 上述 上述 上述 上述 上述 上述 上述The ten-year-old element is connected to the control unit and the switch list; when: = current event, the control unit controls the counting unit to start counting two more than the input group to include the - number. The counting unit is in the first bundle 匕=,==:: ’ and the control unit is in the upper pass = early detection whether the overcurrent event still exists. In the embodiment of the flute, where the voltage of the switching signal is greater than the first, the test counting unit _ counts the first, and the voltage of the switch 201138252 HA-2010-0002-TW 34023twf.doc/n is less than the second reference voltage. At the time, the counting unit starts counting for a further period. In one embodiment of the invention, the above-described switching unit includes an electric crystal and a capacitor. Wherein, the transistor is disposed in the power transmission path, and the gate of the crystal is coupled to the control module. In addition, a capacitor is coupled between the transistor and the source. 3, 3 The present invention provides a DC/DC converter overcurrent protection method including, firstly, configuring a switching unit in the DC/DC converter - = transmission path towel's towel flow conversion conversion by the electric transmission Path = electric load. Normal operation of the DC/DC converter Single: It is in the on state. (4) Whether the flow/DC converter has undergone a temporary cutoff of the power transmission path and obtains the "period conduction switch unit to detect _$. After the end of the month, it is determined whether the overcurrent event still exists. The protection method further includes, if 25 In the middle, the overcurrent protection of the DC 7 straight (four) shop is again - the overcurrent event still exists after the end of the switch unit is called, and the round path is followed. Then, in the second phase, the interception can be transmitted after the 'detection of the current event depends on =Save ^.^通开关单兀. However, in one of the implementations of the present invention, it is judged that the above-mentioned re-conducting open-current protection method is more packaged. If the arrow is merging, the number of times before the sever is up to a critical value The current counts. The number of times the switch unit reaches a critical number, and the call is called u 'Cai coffee off unit permanent Lin f can transmit 201138252 HA-20l〇O〇〇2-TW 34〇23twf.doc/n in this In an embodiment of the invention, the overcurrent event includes a short circuit event. Based on the above-mentioned invention, the control module is used to switch the conduction state of the switching unit disposed on the DC/DC H-well Wei cage to determine the overcurrent. The event is a twin The hearing error is added to activate the overcurrent protection mechanism, causing inconvenience to the user.

The above described features and advantages of the present invention will become more apparent from the description of the appended claims. [Embodiment] FIG. 2 is not a block diagram of an overcurrent protection circuit 2GG of the DC/DC converter 208 of the present invention. Referring to FIG. 2, the overcurrent protection circuit 200 includes a switching unit 2〇2, a control module, and a debt measurement unit 206. The switch unit 2〇2 is disposed in the power transmission path of the DC/DC converter, and the power transmission path is a DC/DC converter=input (for the Weiren voltage Vin) and the output (for providing the output) The path between 2 V〇Ut). The DC/DC converter 208 transmits this electrical energy, and the wheel path converts the input voltage Vin into an output voltage VGut to provide an appropriate voltage for the load 210. The detecting unit 206 is lightly connected to the DC/DC "stolen" to make an overcurrent event of the DC/DC converter; 〇::: ^^ 3=ι, the switching unit 202 is turned on: state; occurs; The control of the provincial control module 204, the switch unit 2〇2 can be turned off by 201138252 HA-2010-0002-TW 34〇23twf.doc/n and the DC/DC converter 208 power transmission wheel grip is cut off. A flow chart of an overcurrent protection method for a DC/DC converter according to an embodiment of the present invention is described below. An overcurrent protection method for a direct/direct/melon converter will be described below with reference to FIG. 2 and FIG. 3. 2 and FIG. 3 First, step S3〇2 is to detect whether an overcurrent event occurs in the DC/DC converter by using the preamble unit 2〇6 of FIG. 2 (for example, a short circuit event in this embodiment). 〇6 can measure the output voltage V〇Ut of the DC/DC converter to determine whether a short circuit event occurs at the load terminal of the DC/DC converter 208. If the voltage value of the output voltage v〇ut drops suddenly, it represents the load 2H. a situation in which a short circuit occurs. Conversely, if the output voltage is biased In the case of no dip, the switching unit is kept in the on state to keep the DC/DC converter 208 in a normal operation (step S3〇4). After the 2%_miscell event occurs, the detecting unit 206 outputs - trigger signal su to control mode (4) 4 to inform the control group 204 of the occurrence of a short circuit event. The skin neck is in the 丨, the dream sti is in the middle ^ ί 04, according to the trigger signal s 11 round a switching signal si to the switch The unit 2 〇2 is used to close the switching unit 2〇2 to temporarily cut off the power transmission path of the DC/DC conversion boundary 208 (step S3〇6), and then to the end of the first period = re-open the switching unit 202, in order to enable the power transmission path to recover the power, and through the _ unit hire to detect the short circuit event, the road event does not exist, then to step s marriage = step changer to maintain normal operation. Conversely, if short circuit Event;; If yes, return to step S306 to turn off the switching unit 2〇2 and cut off the power transmission path, and then perform the step s times, and so on: $201138252 HA-2010-0002-TW 34023twf.doc/n = ::Sc.S times until the short circuit event is released, making DC/straight The transition state 208 returns to normal operation. = In other words, if the short circuit event occurs for the component in the load 21(), the component in the load 210 can be cooled and returned to the normal state after the power transmission path is cut off. Therefore, the short-circuit event is released. Therefore, when the electric M of the voltage VGut is recovered, it represents the short-circuited W... bundle 'this day's DC/DC converter is as described above, through the actual figure of FIG. 2 and FIG. 3 = = Destroy the circuit components, and it is not necessary to cut off the power transmission path permanently as in the case of the conventional technology. Because the short-circuit situation occurs, the conventional protection circuit is permanently cut off. _ The power supply must be restarted to restore the normal operation of the DC I: Benefit 208, causing many inconveniences. 4 In addition, it is worth noting that each time a single "_" is long, it needs to be set as =::= in the case of injury, when the first step S3 is performed, such as when the 4 is closed for a long time (called The first period) mast ^ early 兀 202 ==, the time of the second period of time 0 - noon J wood % Figure 4 Α ~ Figure 4 Β + Guan Yuming - the waveform diagram of the switching signal of the example. Please like A 曰 not this hair. I assume that when the switching signal S1 is high voltage? Figure 4B » Off state (ie, cut off DC/DC converter J; 9 201138252 HA-2010-0002-TW 34023twf.doc/n path), and the switch unit on state when the switching signal S1 is at the low voltage level ( It also restores power supply capacity compared with Wei. In Fig. 4A, the length of the switching signal 31 (the first period) is, for example, 5 〇m. The length of time (second period) is, for example, 5 〇ms. Between = is the retest period. The switching unit 2〇2 is then turned on by the value == L (for example, 3ms), that is, the DC/DC conversion power = the transmission path is secretly restored for Wei Li. Therefore, during the retesting period, the detecting unit 206 performs short-circuiting while avoiding the power transmission path of the DC/DC converter, and excessive current flows to (4) (10), causing the electronic components to burn out. In Fig. 4Β, when the control module 2〇4 first controls the switch unit 2〇2 ^power transmission face (phase-period), the second time when the power transmission path is cut off is 5Gms, and when the control module 2G4 is again When the control switch unit is disassembled and the transmission path is enabled (second period), the time of the _ energy transmission path becomes two 〇ms. According to this, the time of the power transmission path can be gradually changed = 'The frequency of the end of the over-current protection circuit 2GCM 贞聪路 event is higher, so that the DC/New Zealand H is as fast as possible to the normal operation. . It should be noted that the length of time of the above-mentioned period - the second period and the second period is only an exemplary embodiment of the present invention, and the actual amount should not be limited thereto. Length of time. FIG. 5 is a flow chart showing an overcurrent protection method of a DC/DC converter according to another embodiment of the present invention. Please refer to FIG. 2 and FIG. 5 at the same time. In the embodiment of 201138252 HA-2010-0002-TW 34023 twf.doc/n, there may also be a situation in which the power transmission path of the DC/DC converter 208 is required to be permanently broken. Since the reason for the sudden drop of the turn-off voltage v〇ut may be only the voltage drift caused by the components in the load 210 being dry, the present embodiment will teach an overcurrent protection method for the DC/DC converter to avoid the output. The voltage drift of the voltage v〇ut is erroneously judged as a short circuit. The current protection method of this embodiment is as follows: First, the detection unit 2〇6 of FIG. 2 detects whether a short-circuit event occurs in the DC/DC converter 208 (step S502). If the detecting unit 206 does not detect the short-circuit event, the switching unit is kept in the ON state to maintain the DC/DC converter 208 in a normal operation (step S5〇4). Conversely, if the detecting unit 206 detects the short circuit event, the control module 2〇4 turns off the switching unit 202 during a first period to temporarily cut off the power transmission path of the DC/DC conversion benefit 208 (step S506). ). Then, after the end of the first period, the control module 204 turns on the switch unit 2〇2 again, so that the power transmission path of the DC/DC converter is restored to the power supply capability, and the detection unit 206 detects whether the short circuit event remains. Present (step S5〇g). φ „The right short circuit event does not exist, then to step %〇4, the DC/DC converter 208 maintains normal operation. Conversely, if the short circuit event still exists, turning off the re-turning of the opening element 2G2 is a money-critical The number of times (step SMG). If the number of times of re-switching the switching unit does not reach the critical number of times, for example, three times, the process returns to step S5〇6. Conversely, if the number of times of re-directing the L-switch unit 202 has reached the critical value The number of times (for example, 3 times) is controlled, and her 204 controls the switching unit 2〇2 to be permanently turned off to permanently cut off the power transmission path of the interchanger period (step S5i2), entering 201138252 HA-2010-0002-TW 34023twf.doc/n avoids the load 210 from continuously drawing a large current to the DC/DC converter 208 to burn out the circuit components. After the control module 204 permanently turns off the switch unit 2 0 2 , the user can only control by The power supply of the unit 102 is reset (ie, the power is turned off and then re-supplied to the control unit 102) to re-energize the switch unit 202.

As described above, by repeatedly turning off and turning on the switching unit 202 to detect whether or not the short-circuit event actually occurs, the function of the protection circuit/element can be instantaneously achieved while avoiding erroneously permanently closing the switching unit 2〇2 due to misjudgment. 6 is a schematic diagram of an overcurrent protection circuit 200 of a DC/DC converter 208 according to another embodiment of the present invention. Referring to FIG. 6 , in the embodiment, the detecting unit 206 includes a voltage dividing circuit 602 (implemented by the resistors R1 and R2 in this embodiment) and the comparator a control module 204 includes a control unit 604 and a counting unit 606. And comparator A2. The switching unit 202 then includes a transistor Q1 (in this embodiment, a PM 〇 S transistor) and a capacitor ci. In addition, in this embodiment, the DC/DC converter 2〇8 is a boost power conversion circuit (boost convei.ter), which includes an inductor L1 and a transistor.

Q2, the driving unit Dr, the diode D1, and the output capacitor c〇. . . In the detecting unit 206, the resistor is connected to the grounding voltage v〇ut of the DC/DC converter 208 and the ground Gn〇, and the two input ends of the comparator are connected to the common side of the sister and the R2. Contact and reference. The output of the test Vrl 'Comparative A1' is then taken up to the control unit 604. In the module 2〇4, the control unit 604 is connected to the gate of the fish battery Q1 of the counting unit 606, and the two input terminals of the whistle A2 respectively touch the control unit 604 and the reference voltage Vr2, and the output of the comparator ^ is _ 12 201138252 HA-2010-0002-TW 34023twf.doc/n 疋 606. In the switch unit 202, the transistor φ is lightly connected between the input dust Vm and the inductor L1. The capacitor C1 is between the source and the gate of the transistor. In addition, the inductor u and the diode Di in the DC/DC converter 2 (10) are connected in series between the transistor Q1 and the load 21〇, and the transistor Q2 is connected to the common contact and ground of the inductor L1 and the diode m. $'Transistor Q2's gate_connected unit is added. In some embodiments, the 'drive early' can also be set to the control module 2〇4 t. In addition, the output capacitor Co _ is connected between the diode m and the ground. Switching - by means of resistors R1 and R2, the DC/DC converter is divided, and the output voltage V〇Ut ' is obtained to obtain a divided voltage Vs. Compare the generated U voltage US with the reference voltage Vrl to determine whether to generate a voltage ί event. When the voltage dividing voltage VS is less than the reference power 604M, the output trigger signal St1 tells the control unit that the path event has occurred. The reference w can be, for example, = ttr 2, but not limited to this. The user can design according to the design: No production = value in the element is over the current event, the voltage divider circuit 602 may Press Vrl. Comparator A1 directly compares the output electrical waste V〇ut with the reference ^, and the unit 6〇4 receives the trigger signal called Mai, then § S1 to the transistor Q1 to switch the electricity day ηι μ, the stomach is exhausted, the unit _ start count: The exchange of the second is as shown in Figure 4. The voltage level of the switch signal is not changed. The switch signal 81 is first controlled in the postal code at the low battery 201138252 HA-2010-0002- TW 34023twf.doc / n level (in this case, the transistor Q is turned on), after waiting for 3ms of the counting unit, then switch the switching signal S1 to the high voltage level. In the first period, the transistor is turned off, and the DC/DC power transmission path is off. After the counting unit has finished the first period (for example, 5 〇ms), the control unit 6〇4 is connected; the coffee is turned to the low voltage level and enters the retesting period. The switch = is turned on briefly (for example, 3ms), and the power transmission path of the converter 208 is also briefly during this retest, so that the control material 6G4 can be used for this retest. Test. By analogy, the control unit 6^^ repeatedly switches the transistor Q1 until the short-circuit event is released/the DC converter 208 returns to normal operation. In the foregoing embodiment, the control unit 6〇4 knows that the short-circuit event occurs. ^ is that the switching signal S1 is first kept at the low voltage level within 3ms, and the second post-switching signal S1 is switched to the high voltage level. In some embodiments, when 6 G 4 knows that a short circuit event occurs, the voltage level of the control signal S1 can also be immediately changed to a high voltage level. In addition, if the power transmission of the DC/DC converter is permanently cut off, the control unit 604 can also permanently turn off the transistor after repeating the switching of the transistor Q1 for a few times (for example, 10 times). The power transmission path of the DC/DC converter period is cut off by Yong. This can be = short, whether the event really happened, avoiding misjudgment and starting the current protection makeup, resulting in the need to re-open the power supply.知知/主思的疋'The above transistor Φ and capacitor C1 can be used in system opening 14 201138252 HA-2010-0002-TW 34023twf.d〇c/n machine to avoid inrush current leading to electronic components damage. However, when the capacitance C1 is too large, the voltage change on the gate of the transistor Q1 will be affected by the capacitance C1 #charge-discharge effect, and the transistor Q1 cannot be completely turned on during the re-measurement (for example, 3 ms). Therefore, in the other two examples, the counting period during the above retesting period is such that the counting unit 6〇6 starts counting after the transistor QJ is completely turned on.

For example, FIG. 7 is a waveform diagram illustrating the threshold voltage of the transistor Q1 of FIG. 6 (ie, the switching signal S1) in accordance with an embodiment of the present invention. Please refer to Figure 6 and Figure 7, assuming that the gate voltage of transistor Q1 is less than or equal to the reference voltage Vr2 % aa body Q1 will be fully turned on. The comparator A2 compares the gate voltage of the transistor qi, that is, the switching signal S1) with the reference voltage, and outputs according to the comparison result, sending the signal St2 to the counting unit. When the short circuit event occurs, the control unit 604 pulls the switching signal S1 to a high voltage level (for example, the gate voltage of the transistor Q1 is greater than the reference voltage Vr2), and the counting unit 6〇6=counts according to the trigger signal St2. Period (for example, counting ah). At the end of the period - the control unit 6〇4 will turn the switching signal voltage level. However, when the switching signal S1 is switched from the high voltage level to the low voltage=bit, the charge of the capacitor α is controlled to be discharged, so that the transistor Q1_ pole voltage will drop to a low voltage level after a period of time. Bit. # Gate Q1's gate power [When falling below the reference voltage Vl.2, the comparator A2 can trigger the retest by triggering the ^2 trigger count unit _ _ counting and retesting period (for example, counting: =-) The period_time length is sufficient for the protection circuit 200 to detect whether an overcurrent event still exists. Motor 201138252 HA-2010-0002-TW 34023twf.doc/n This embodiment uses a boost power conversion circuit (b〇〇st c〇 Nverter) is an example of the overcurrent protection circuit 200 of the DC/DC converter 208. However, the type of the DC/DC converter 208 is not limited thereto. For example, the DC/DC converter 208 can also be as shown in FIG. The buck converter shown in Fig. 9 or the buck-boost converter shown in Fig. 9 has an operation principle of overcurrent protection similar to that of Fig. 6. In addition, in the embodiment shown in FIG. 6, the switching unit 202 is disposed between the input voltage Vin and the inductor L1, but not limited thereto. The user can switch the unit 2〇2 according to the actual situation. Set in other locations on the power transfer path to intercept Or a conductive energy transmission path, a mechanism for performing overcurrent protection. For example, in some embodiments, the switching unit 202 may be disposed between the diode 〇1 and the load 21A of FIG. 6. In summary, the above The embodiments use the control module 204 to switch the conduction state of the switching unit 202 on the power transmission path of the DC/DC converter 2〇8 multiple times to determine whether an overcurrent event actually occurs. When determining an overcurrent event After the occurrence (for example, the re-conduction of the switching unit 202 reaches the critical-number of people), the control module 204 controls the switching unit 202 to permanently _ cut off the power transmission path of the DC/DC converter 2〇8, so that The DC/DC converter output 可 can be avoided, and the voltage odor misinterpretation is caused by an overcurrent event and the power transmission path is cut off, which causes inconvenience to the user. Although the present invention has been disclosed by way of example, it is not To define the general knowledge of any technical field in X month, you can make some changes and retouch without leaving 16 201138252 I»-〇〇〇2-TW34〇23twf.doc/n BRIEF DESCRIPTION OF THE DRAWINGS The following is a schematic diagram of a conventional DC/DC converter. Figure 2 illustrates an overcurrent of a DC/DC converter according to an embodiment of the present invention. Block diagram of the protection circuit.

3 is a flow chart showing a method of over/under protection of a DC/DC converter according to an embodiment of the invention. 4A-4B are waveform diagrams of a switching signal according to an embodiment of the present invention. FIG. 5 is a flow chart showing a method for protecting an overcurrent of a DC/DC converter according to another embodiment of the present invention. Fig. 6 is a schematic view showing an overcurrent protection circuit of a DC/DC converter according to another embodiment of the present invention. Fig. 7 is a waveform diagram showing the gate voltage of the transistor Q1 according to an embodiment of the present invention.

In the spirit and scope of the present invention, the scope of protection of the present invention is shown in FIG. 8 as a schematic diagram of an overcurrent protection circuit of a DC/DC converter according to another embodiment of the present invention. FIG. 9 is a schematic diagram of an overcurrent protection circuit of a DC/DC converter according to another embodiment of the present invention. [Description of main component symbols] 100, 208 · DC/DC conversion circuit 104, 210: Load 17; u02-TW 34023twf.doc/n 106: Latch unit 200. Overcurrent protection circuit 202: Switch unit 204: Control mode Group 102, 206: detection unit 602: voltage dividing circuit 604: control unit 606: counting unit

St, Stl, St2: trigger signal

Vrl, Vr2: reference voltage

Rl, R2: resistance

Al, A2: Comparator S1: Switching signal C1: Capacitor

Drl: drive unit

Vs : voltage divider

Vin : input voltage

Vout : Output voltage D1 : Diode , M2 , Q Bu Q2 : Transistor L1 : Inductance

Co : Output capacitor GND : Ground PWM: Pulse width modulation control signal S302-S308, S502~512 : Process steps of overcurrent protection method

Claims (2)

201138252 *...w ιΌ-0002-TW 34Q23twf_doc/n VII. Patent application scope: 1. An overcurrent protection circuit for a DC/DC converter, comprising: a switching unit, a power transmission arranged in the DC/DC converter In the path, where the DC/DC converter supplies power to the load through the power transmission path, the switch unit is in a conducting state during normal operation of the DC/DC converter; a detecting unit is configured to detect the Whether an overcurrent event occurs in the DC/DC converter; and a control module coupled to the detection unit and the switch unit. If the overcurrent event occurs, the control module can be used to cut off the switch unit for a first During the period, the power transmission path is temporarily cut off, and is used to re-turn on the switch unit after the end of the first period and to detect whether the overcurrent event still exists through the detection unit. 2. The overcurrent protection circuit of the DC/DC converter according to claim 1 wherein the overcurrent event still exists after the end of the first period, the control module is used to cut off the switch unit again The power transmission path is temporarily cut off during a second period, and is used to re-turn on the switch unit after the second period ends and to detect whether the overcurrent event still exists through the detecting unit. 3. The overcurrent protection circuit of the DC/DC converter according to claim 2, wherein if the number of times of re-switching the switch unit reaches a critical number and the overcurrent event still exists, the control module uses The switch unit is controlled to permanently cut off the power transfer path. 4. The overcurrent of the DC/DC converter as described in the scope of claim 2 201138252 ^002-TW 34023twf.doc/n The flow protection circuit, wherein the overcurrent event comprises a short circuit event. 5. The overcurrent protection circuit of the DC/DC converter according to Item 1 of the patent scope, the detection unit comprises: a knife circuit for receiving and dividing the output of the DC/DC converter Voltage: to output a calendar electric calendar, and a first comparator, wherein the two input ends are respectively coupled to a first reference voltage and the sub-fourth road, when the read f ship is in the first reference power (four), The first comparison H can output a -first trigger signal to inform the control that the overcurrent event has been touched. w 1 · The over-current protection circuit of the DC/DC converter according to Item 1 of the claim 5, wherein the control module comprises: - a control unit lacking the detection unit and the off unit, For controlling the output of the detecting unit, the rim _ Η 0 occupies the conduction state of the L; the money switching signal switches the switching unit - the counting _ the control unit is the closed unit, and when the event occurs, the control unit The counting unit can be controlled to start counting the first period of the brother. 7. The flow protection circuit according to item 6 of claim 2, wherein the control module further comprises: 4 for the benefit of the over-current-second= comparator, the two-wheeled person is divided into the switch signal; Brother-reference power two ratio S: : After the end of the first period, according to the second retest period (four) through the _ unit 20 201138252 ------J-0002-TW 34023twf.doc/n. 8. If the voltage of the switching signal is: in the first conversion: two ^, the number of the Wei unit is as described in item 7 of the patent application scope. The first--, the voltage of the number is less than the second reference voltage ° ° the re-measurement _. The number of feeds 70 can start counting the over-current protection circuit of the DC/DC converter mentioned in the first paragraph, wherein The switch unit includes: a transistor disposed in the power transmission path, the complex gate is coupled to the control module; and, the T-electrode is coupled to the gate and the source of the transistor An overcurrent protection method for a DC/DC converter, comprising: a configuration-switch unit in a power transmission path of the DC/DC converter, wherein the DC/DC converter uses the power transmission path Power is supplied to a load' and the conduction state is during positive f operation of the DC/DC converter; κ detects whether the DC/DC converter is generated - an overcurrent event. If the overcurrent event occurs, the switch unit is worn Temporary truncation in a first period a power transmission path; and 'returning the switching unit after the end of the first period to detect whether the overcurrent event still exists. 11. Overcurrent protection of the DC/DC converter according to claim 10 The method further includes: if the overcurrent event still exists after the end of the first period, then again 02-TW 34023twf.doc/n 201138252 Guan Xiaoyi temporarily cuts off the current section of the power transmission path in a second period - the number of over-current converters is measured; ΓΓ μ the number of times the switch unit is re-guided Whether it is up to - critical: the number of times the unit is undermined, and can be mixed. The gift of (4) unit permanently reduces the power. The overcurrent event of one of the DC/DC converters described in the second step of the second method includes a short circuit event. twenty two