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TW202030960A - Output overvoltage detection system and method - Google Patents

Output overvoltage detection system and method Download PDF

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TW202030960A
TW202030960A TW108109140A TW108109140A TW202030960A TW 202030960 A TW202030960 A TW 202030960A TW 108109140 A TW108109140 A TW 108109140A TW 108109140 A TW108109140 A TW 108109140A TW 202030960 A TW202030960 A TW 202030960A
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control chip
voltage
switch
control
overvoltage
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TW108109140A
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TWI711249B (en
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劉拓夫
周俊
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大陸商昂寶電子(上海)有限公司
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Abstract

The invention provides an output overvoltage detection system and method. The output overvoltage detection system comprises a control chip and a resistor located outside the control chip and coupled with the control chip. The control chip comprises a current source, a control capacitor, a comparator and an overvoltage detection circuit. The current of the current source is set by a resistor coupled outside the control chip. The control capacitor performs discharge zero clearing after a control chip driver is switched on for a period of time, and is charged by a current source of the control chip within the demagnetization time of the output inductor after the control chip driver is switched off. The comparator compares the voltage at the two ends of the control capacitor with the peak voltage of the current switching period on the sampling resistor. The overvoltage detection circuit responds to a demagnetization ending signal indicating that the inductor is completely demagnetized after the control chip drive is switched off, and determines whether an overvoltage state is detected based on a comparison result of the comparator.

Description

輸出過壓感測系統和感測方法 Output overvoltage sensing system and sensing method

本發明總體涉及晶片領域,更具體地,涉及一種輸出過壓感測系統和感測方法。 The present invention generally relates to the field of wafers, and more specifically, to an output overvoltage sensing system and sensing method.

輸出過壓保護可以在系統異常時,防止輸出電壓過高引起系統損壞。輸出電壓感測於是成為輸出過壓保護中的關鍵。傳統地,電壓感測一般通過直接感測系統的輸出電壓或者通過感測系統中輸出電感兩端的電壓來實現。然而,在某些系統應用條件下,無法直接對系統的輸出電壓或系統中輸出電感兩端的電壓進行感測,常常需要通過增加額外的元件來輔助實施電壓感測。 The output over-voltage protection can prevent the system from being damaged when the output voltage is too high when the system is abnormal. Output voltage sensing then becomes the key to output overvoltage protection. Traditionally, voltage sensing is generally achieved by directly sensing the output voltage of the system or by sensing the voltage across the output inductor in the system. However, under certain system application conditions, it is impossible to directly sense the output voltage of the system or the voltage across the output inductor in the system, and it is often necessary to add additional components to assist in implementing voltage sensing.

根據本發明的一方面,提供了一種輸出過壓感測系統,包括控制晶片和電阻,該電阻位於控制晶片外部並與控制晶片耦合。控制晶片包括電流源、控制電容、比較器、過壓感測電路。電流源的電流大小由控制晶片外部耦合的電阻設定。控制電容在控制晶片驅動開通延遲一段時間後進行放電清零,並在控制晶片驅動關斷後輸出電感的退磁時間內由控制晶片的電流源充電,其中比較器對控制電容兩端的電壓與取樣電阻上的當前開關週期的峰值電壓進行對比;並且過壓感測電路回應於指示控制晶片驅動關斷後輸出電感完全退磁的退磁結束信號,基於比較器的比較結果來確定是否感測到過壓狀態。 According to an aspect of the present invention, there is provided an output overvoltage sensing system, including a control chip and a resistor, the resistor being located outside the control chip and coupled with the control chip. The control chip includes a current source, a control capacitor, a comparator, and an overvoltage sensing circuit. The current size of the current source is set by the externally coupled resistance of the control chip. The control capacitor is discharged and cleared after a period of delay after the drive of the control chip is turned on, and is charged by the current source of the control chip during the demagnetization time of the output inductor after the drive of the control chip is turned off. The comparator controls the voltage across the control capacitor and the sampling resistor. Compare the peak voltage of the current switching cycle on the above; and the overvoltage sensing circuit responds to the demagnetization end signal indicating that the inductance is completely demagnetized after the control chip is driven off, and determines whether the overvoltage state is sensed based on the comparison result of the comparator .

根據本發明的另一方面,提供了一種輸出過壓感測方法,包括:採集控制晶片中控制電容兩端的電壓,其中控制電容在控制晶片驅動開通延遲一段時間後進行放電清零,並在控制晶片驅動關斷後輸出電感 的退磁時間內由控制晶片的電流源充電,其中,控制晶片的電流源的電流大小由控制晶片外部耦合的電阻設定;採集取樣電阻上的當前開關週期的峰值電壓;將控制電容兩端的電壓與所述峰值電壓進行對比;以及回應於指示控制晶片驅動關斷後輸出電感完全退磁的退磁結束信號,基於比較器的比較結果來確定是否感測到過壓狀態。 According to another aspect of the present invention, there is provided an output overvoltage sensing method, including: collecting the voltage across a control capacitor in a control chip, wherein the control capacitor is discharged and cleared after a delay in driving the control chip on for a period of time, and the control chip Output inductance after chip drive is turned off During the demagnetization time, the current source of the control chip is charged by the current source of the control chip. The current size of the current source of the control chip is set by the resistor externally coupled to the control chip; the peak voltage of the current switching cycle on the sampling resistor is collected; The peak voltage is compared; and in response to a demagnetization end signal indicating that the output inductor is completely demagnetized after the control chip is driven off, it is determined whether an overvoltage state is sensed based on the comparison result of the comparator.

根據本發明的輸出過壓感測系統和感測方法,可以便於在控制晶片的基準地無法直接感測輸出電壓或輸出電感兩端的電壓時實現電壓感測並進而實現輸出過壓保護功能,而無需額外的輔助電路,因此能夠有助於減小系統體積並進而降低成本。 According to the output overvoltage sensing system and sensing method of the present invention, it is convenient to realize voltage sensing and thereby realize the output overvoltage protection function when the reference ground of the control chip cannot directly sense the output voltage or the voltage across the output inductor, and No additional auxiliary circuit is needed, so it can help reduce the system volume and thereby reduce the cost.

1、3、4‧‧‧框 1, 3, 4‧‧‧Frame

3013、4016‧‧‧比較器 3013, 4016‧‧‧Comparator

2、303‧‧‧負載 2, 303‧‧‧Load

3014、4017‧‧‧過壓感測電路 3014, 4017‧‧‧Overvoltage sensing circuit

13‧‧‧電流感測模組 13‧‧‧Current Sensing Module

4011‧‧‧轉換器 4011‧‧‧Converter

14‧‧‧退磁感測模組 14‧‧‧Demagnetization Sensing Module

FB‧‧‧信號 FB‧‧‧Signal

16‧‧‧驅動器 16‧‧‧Drive

IL‧‧‧輸出電感電流 I L ‧‧‧Output inductor current

301、401‧‧‧控制晶片 301, 401‧‧‧control chip

ISET‧‧‧電流 I SET ‧‧‧Current

3011、4012‧‧‧電流源 3011、4012‧‧‧Current source

S1、S1 4013‧‧‧第一開關 S 1S 1 4013‧‧‧First switch

3012、C 4014‧‧‧控制電容 3012, C 4014‧‧‧Control capacitor

S2、S2 4015‧‧‧第二開關 S 2S 2 4015‧‧‧Second switch

C‧‧‧控制電容的電容值 C‧‧‧Control the capacitance of the capacitor

S701-S705、S801-S808‧‧‧步驟 S701-S705, S801-S808‧‧‧Step

ICS_PEAK‧‧‧流過取樣電阻的電流 I CS_PEAK ‧‧‧The current flowing through the sampling resistor

T‧‧‧時間 T‧‧‧Time

L‧‧‧輸出電感的電感值 L‧‧‧Inductance value of output inductor

TDMG‧‧‧退磁時間 T DMG ‧‧‧Demagnetization time

RCS‧‧‧取樣電阻的電阻值 R CS ‧‧‧Resistance value of sampling resistor

TON_DELAY‧‧‧延遲時間 T ON_DELAY ‧‧‧Delay time

VC‧‧‧控制電容兩端的電壓 V C ‧‧‧Control the voltage across the capacitor

VDD‧‧‧電源電壓 V DD ‧‧‧Power supply voltage

VCS_PEAK‧‧‧取樣電阻的峰值電壓 V CS_PEAK ‧‧‧Peak voltage of sampling resistor

VOUT‧‧‧輸出電壓 V OUT ‧‧‧Output voltage

302、RSET、RSET 402‧‧‧電阻 302, RSET, RSET 402‧‧‧Resistor

11‧‧‧欠壓保護(UVLO)模組 11‧‧‧Undervoltage protection (UVLO) module

12‧‧‧恒流(CC)/恒壓(CV)調節模組 12‧‧‧Constant current (CC)/constant voltage (CV) adjustment module

15‧‧‧脈衝寬度調變(PWM)控制模組 15‧‧‧Pulse width modulation (PWM) control module

17‧‧‧過壓保護(OVP)模組 17‧‧‧Over Voltage Protection (OVP) Module

GATE‧‧‧控制晶片驅動的開通與關斷的信號 GATE‧‧‧The signal that controls the turn-on and turn-off of the chip drive

OVP‧‧‧過壓感測電路的感測結果信號 OVP‧‧‧Sensing result signal of over-voltage sensing circuit

從下面結合圖式對本發明的具體實施方式的描述中可以更好地理解本發明,其中:第1圖示出了一種通過光耦實現輸出電壓感測的示例性系統的示意圖;第2圖示出了一種通過輔助繞組實現輸出電壓感測的示例性系統的示意圖;第3圖示出了根據本發明實施例的一種輸出過壓感測系統的示意框圖;第4圖示出了根據本發明實施例的一種輸出過壓感測系統的電路示意圖;第5圖示出了根據本發明實施例的一種輸出過壓感測系統在感測到過壓狀態時的控制波形的示意圖;第6圖示出了示出了根據本發明實施例的一種輸出過壓感測系統在未感測到過壓狀態時的控制波形的示意圖。 The present invention can be better understood from the following description of the specific embodiments of the present invention in conjunction with the drawings, in which: Figure 1 shows a schematic diagram of an exemplary system for output voltage sensing through an optocoupler; Figure 2 A schematic diagram of an exemplary system for output voltage sensing through an auxiliary winding is shown; Figure 3 shows a schematic block diagram of an output overvoltage sensing system according to an embodiment of the present invention; A schematic circuit diagram of an output overvoltage sensing system according to an embodiment of the present invention; Figure 5 shows a schematic diagram of a control waveform of an output overvoltage sensing system according to an embodiment of the present invention when an overvoltage state is sensed; sixth The figure shows a schematic diagram showing a control waveform of an output overvoltage sensing system according to an embodiment of the present invention when the overvoltage state is not sensed.

第7圖示出了根據本發明實施例的一種輸出過壓感測方法的流程圖。 Figure 7 shows a flowchart of an output overvoltage sensing method according to an embodiment of the present invention.

第8圖示出了根據本發明實施例的一種輸出過壓感測方法的具體示例的流程圖。 Fig. 8 shows a flowchart of a specific example of a method for output overvoltage sensing according to an embodiment of the present invention.

下面將詳細描述本發明的各個方面的特徵和示例性實施例。在下面的詳細描述中,提出了許多具體細節,以便提供對本發明的全面理解。但是,對於本領域技術人員來說很明顯的是,本發明可以在不需要這些具體細節中的一些細節的情況下實施。下面對實施例的描述僅僅是為了通過示出本發明的示例來提供對本發明的更好的理解。本發明決不限於下面所提出的任何具體配置,而是在不脫離本發明的精神的前提下覆蓋了元素、部件和演算法的任何修改、替換和改進。在圖式和下面的描述中,沒有示出公知的結構和技術,以便避免對本發明造成不必要的模糊。 The features and exemplary embodiments of various aspects of the present invention will be described in detail below. In the following detailed description, many specific details are proposed in order to provide a comprehensive understanding of the present invention. However, it is obvious to those skilled in the art that the present invention can be implemented without some of these specific details. The following description of the embodiments is only to provide a better understanding of the present invention by showing examples of the present invention. The present invention is by no means limited to any specific configuration proposed below, but covers any modification, replacement and improvement of elements, components and algorithms without departing from the spirit of the present invention. In the drawings and the following description, well-known structures and technologies are not shown in order to avoid unnecessary obscurity of the present invention.

第1圖示出了一種通過光耦實現輸出電壓感測的示例性系統的示意圖。如第1圖所述,該示例性系統應用高壓交流電(AC,Alternate Current)為控制系統供電,進而為負載提供電力。更具體地,輸入高壓AC被施加到由四個二極體構成的整流橋的兩個輸入端,通過整流橋整流之後再經濾波電容濾波,然後由虛線框1指示的控制晶片控制整個系統為負載2提供電力。 Figure 1 shows a schematic diagram of an exemplary system for output voltage sensing through an optocoupler. As described in Figure 1, this exemplary system uses high-voltage alternating current (AC, Alternate Current) to supply power to the control system, thereby providing power to the load. More specifically, the input high-voltage AC is applied to the two input ends of a rectifier bridge composed of four diodes, and then rectified by the rectifier bridge and then filtered by a filter capacitor, and then the entire system is controlled by the control chip indicated by the dashed box 1 Load 2 provides power.

如第1圖所示,控制晶片包括欠壓保護(UVLO,Under Voltage Lock Out)模組11、恒流(CC,Constant-current)/恒壓(CV,Constant-voltage)調節模組12、電流感測模組13、退磁感測模組14、脈衝寬度調變(PWM,Pulse Width Modulation)控制模組15、驅動器16、以及過壓保護(OVP,Over Voltage Protection)模組17。 As shown in Figure 1, the control chip includes UVLO (Under Voltage Lock Out) module 11, constant-current (CC, Constant-current)/constant-voltage (CV, Constant-voltage) adjustment module 12, and current The sensing module 13, the demagnetization sensing module 14, the Pulse Width Modulation (PWM, Pulse Width Modulation) control module 15, the driver 16, and the Over Voltage Protection (OVP) module 17.

欠壓保護(UVLO)模組)11感測電源電壓VDD是否低於欠壓保護閾值時,並且當電源電壓VDD低於欠壓保護閾值時控制晶片處於保護狀態。恒流(CC)/恒壓(CV)調節模組12根據負載情況實現CC和CV模式的調節。脈衝寬度調變(PWM)控制模組15對電壓波形執行脈衝寬度調變。驅動器16通過信號GATE驅動開關電晶體開通或關斷。電 流感測(CS,Current Sensor)模組13通過取樣信號CS感測流過取樣電阻的電流。退磁感測模組14感測開關電晶體關斷(即控制晶片驅動關斷)後輸出電感完全退磁的時間。過壓保護(OVP)模組17通過信號FB感測輸出電壓是否高於輸出過壓保護閾值,並且當感測到的電壓高於輸出過壓保護閾值時啟動過壓保護。 The under-voltage protection (UVLO) module) 11 senses whether the power supply voltage V DD is lower than the under-voltage protection threshold, and when the power supply voltage V DD is lower than the under-voltage protection threshold, the control chip is in a protection state. The constant current (CC)/constant voltage (CV) adjustment module 12 realizes the adjustment of the CC and CV modes according to the load condition. The pulse width modulation (PWM) control module 15 performs pulse width modulation on the voltage waveform. The driver 16 drives the switching transistor to be turned on or off through the signal GATE. The current sensor (CS, Current Sensor) module 13 senses the current flowing through the sampling resistor through the sampling signal CS. The demagnetization sensing module 14 senses the time when the output inductor is completely demagnetized after the switching transistor is turned off (that is, the control chip is driven to turn off). The overvoltage protection (OVP) module 17 senses whether the output voltage is higher than the output overvoltage protection threshold through the signal FB, and activates the overvoltage protection when the sensed voltage is higher than the output overvoltage protection threshold.

如第1圖所述,示例性系統通過光耦元件和相關電路(圖中虛線框3和框4所示)來輔助實現電壓感測。 As described in Figure 1, the exemplary system uses optocoupler elements and related circuits (shown in dashed boxes 3 and 4 in the figure) to assist in implementing voltage sensing.

第2圖示出了一種通過輔助繞組實現輸出電壓感測的示例性系統的示意圖。第2圖中與第1圖相同的元件以及功能在此不再贅述,所不同的是在第2圖中在輸出電感左側位置增加了輔助繞組,借助於這些繞組來實現輸出電壓感測。 Figure 2 shows a schematic diagram of an exemplary system for output voltage sensing through an auxiliary winding. The components and functions in Figure 2 that are the same as those in Figure 1 will not be repeated here. The difference is that in Figure 2, auxiliary windings are added to the left of the output inductor, and output voltage sensing is realized by these windings.

然而,在第1圖和第2圖所示的示例性系統中,控制晶片都需要增加額外的輔助電路來輔助實現輸出電壓感測,這增大了系統體積並進而增加了成本。 However, in the exemplary systems shown in FIG. 1 and FIG. 2, the control chip needs to add additional auxiliary circuits to assist in realizing output voltage sensing, which increases the volume of the system and further increases the cost.

根據本發明的實施例提供了一種新型的輸出過壓感測技術,這種新型的輸出過壓感測技術可以便於在控制晶片的基準地無法直接感測輸出電壓或輸出電感兩端的電壓時實現電壓感測並進而實現輸出過壓保護功能,而無需額外的輔助電路,因此能夠有助於減小系統體積並進而降低成本。 According to the embodiment of the present invention, a new type of output overvoltage sensing technology is provided. This new type of output overvoltage sensing technology can be easily implemented when the reference ground of the control chip cannot directly sense the output voltage or the voltage across the output inductor Voltage sensing and then realize the output overvoltage protection function without additional auxiliary circuit, so it can help reduce the system volume and thereby reduce the cost.

第3圖示出了根據本發明實施例的一種輸出過壓感測系統的示意框圖。請注意,為不模糊本發明,第3圖中僅圖示了有助於理解本發明的部分,實際上系統還可以包括其他的元件,例如,退磁感測模組、電流感測模組、驅動器、開關電晶體、取樣電阻、輸出電感等等,並且這些其他元件具有與第1圖和第2圖中所示那樣相同的功能和操作。 Figure 3 shows a schematic block diagram of an output overvoltage sensing system according to an embodiment of the present invention. Please note that in order not to obscure the present invention, Figure 3 only illustrates the parts that are helpful for understanding the present invention. In fact, the system can also include other components, such as demagnetization sensing modules, current sensing modules, Drivers, switching transistors, sampling resistors, output inductors, etc., and these other components have the same functions and operations as shown in Figures 1 and 2.

如第3圖所示,該系統包括控制晶片301以及位於控制晶片外部並與控制晶片耦合的電阻302。控制晶片301控制對負載303的供電。 As shown in Figure 3, the system includes a control chip 301 and a resistor 302 located outside the control chip and coupled with the control chip. The control chip 301 controls the power supply to the load 303.

控制晶片301包括電流源3011、控制電容3012、比較器3013、過壓感測電路3014。 The control chip 301 includes a current source 3011, a control capacitor 3012, a comparator 3013, and an overvoltage sensing circuit 3014.

電流源3011的電流大小由控制晶片301外部耦合的電阻302設定。 The magnitude of the current of the current source 3011 is set by the resistor 302 externally coupled to the control chip 301.

控制電容3012在控制晶片301驅動開通延遲一段時間後進行放電清零,並在控制晶片301驅動關斷後輸出電感的退磁時間由控制晶片301的電流源3011充電。 The control capacitor 3012 is discharged and cleared after the control chip 301 is driven and turned on for a period of time, and the demagnetization time of the output inductor is charged by the current source 3011 of the control chip 301 after the control chip 301 is driven and turned off.

比較器3013對控制電容3012兩端的電壓與取樣電阻上的當前開關週期的峰值電壓進行對比。 The comparator 3013 compares the voltage across the control capacitor 3012 with the peak voltage of the current switching cycle on the sampling resistor.

過壓感測電路3014回應於指示控制晶片301驅動關斷後輸出電感完全退磁的退磁結束信號,基於比較器3013的比較結果來確定是否感測到過壓狀態。 The overvoltage sensing circuit 3014 responds to a demagnetization end signal indicating that the inductance is completely demagnetized after the control chip 301 is turned off, and determines whether an overvoltage state is sensed based on the comparison result of the comparator 3013.

在一些實施例中,回應於退磁結束時比較器3013的比較結果指示控制電容3012兩端的電壓低於取樣電阻上的當前開關週期的峰值電壓時,過壓感測電路3014感測到過壓狀態。回應於退磁結束時比較器3013的比較結果指示控制電容3012兩端的電壓高於取樣電阻上的當前開關週期的峰值電壓時,過壓感測電路3014未感測到過壓狀態。 In some embodiments, in response to the comparison result of the comparator 3013 at the end of the demagnetization indicating that the voltage across the control capacitor 3012 is lower than the peak voltage of the current switching cycle on the sampling resistor, the overvoltage sensing circuit 3014 senses the overvoltage state . In response to the comparison result of the comparator 3013 at the end of the demagnetization indicating that the voltage across the control capacitor 3012 is higher than the peak voltage of the current switching cycle on the sampling resistor, the overvoltage sensing circuit 3014 does not sense the overvoltage state.

在一些實施例中,控制晶片301還包括第一開關S1和第二開關S2,第一開關S1跨接在控制電容3012兩端,並且第二開關S2串聯在控制電容3012與電流源3011之間,並且其中,在控制晶片301驅動開通時,第二開關S2被關斷,延遲一段時間後,第一開關S1被開通,並且在控制晶片301的驅動關斷後輸出電感的退磁時,第一開關S1被關斷,而第二開關S2被開通。 In some embodiments, the control chip 301 further includes a first switch S 1 and a second switch S 2. The first switch S 1 is connected across the control capacitor 3012, and the second switch S 2 is connected in series with the control capacitor 3012 and the current between the source 3011, and wherein, when the control wafer 301 drives the opening of the second switch S 2 is turned off, after a delay, the first switch S 1 is opened, the driving and shutdown of the output inductor 301 of the control chip During the demagnetization, the first switch S 1 is turned off, and the second switch S 2 is turned on.

第4圖示出了根據本發明實施例的一種輸出過壓感測系統的感測電路示意圖。 Figure 4 shows a schematic diagram of a sensing circuit of an output overvoltage sensing system according to an embodiment of the present invention.

如第4圖所示,系統包括控制晶片401(如虛線框所示)以及位於控制晶片401外部並與控制晶片401耦合的電阻RSET 402。晶片 電源電壓被載入到控制晶片401,在電阻RSET 402的設定下經由轉換器4011被轉換為電流源電流ISET以作為施加到控制晶片401的內部電流。 As shown in FIG. 4, the system includes a control chip 401 (shown as a dashed frame) and a resistor R SET 402 located outside the control chip 401 and coupled with the control chip 401. The chip power supply voltage is loaded into the control chip 401, and is converted into a current source current I SET via the converter 4011 under the setting of the resistance R SET 402 as the internal current applied to the control chip 401.

控制晶片還包括電流源4012、第一開關S1 4013、控制電容C 4014、第二開關S2 4015、比較器4016和過壓感測電路4017。 The control chip also includes a current source 4012, a first switch S 1 4013, a control capacitor C 4014, a second switch S 2 4015, a comparator 4016, and an overvoltage sensing circuit 4017.

電流源4012為控制晶片401提供內部電流ISETThe current source 4012 provides the internal current I SET for the control chip 401.

第一開關S1 4013跨接在控制電容C 4014兩端,回應於控制晶片驅動開通延遲一段時間TON_DELAY後而被開通,並回應於控制晶片驅動關斷而被關斷。 The first switch S 1 4013 is connected across the control capacitor C 4014 and is turned on in response to a delay of T ON_DELAY of the control chip driving on, and is turned off in response to the control chip driving being turned off.

控制電容C 4014在控制晶片401驅動開通延遲一段時間TON_DELAY後進行放電清零,並在控制晶片驅動關斷後輸出電感的退磁時間(TDMG)內由控制晶片401的內部電流ISET充電。 The control capacitor C 4014 is discharged and cleared after the control chip 401 is driven on and delayed for a period of time T ON_DELAY , and is charged by the internal current I SET of the control chip 401 during the demagnetization time (T DMG ) of the output inductor after the control chip is driven off.

第二開關S2 4015串聯在控制電容C 4014與電流源4012之間,回應於控制晶片401的驅動關斷而被開通,並回應於控制晶片感測到輸出電感退磁結束而被關斷(退磁結束後,控制晶片可以進入下一開關週期,進而進入新迴圈)。 The second switch S 2 4015 is connected in series between the control capacitor C 4014 and the current source 4012, and is turned on in response to the driving of the control chip 401 being turned off, and is turned off in response to the control chip sensing that the demagnetization of the output inductor ends (demagnetization) After the end, the control chip can enter the next switching cycle, and then enter a new loop).

比較器4016對控制電容C 4014兩端的電壓與取樣電阻上的當前開關週期的峰值電壓(VCS_PEAK)進行對比。 The comparator 4016 compares the voltage across the control capacitor C 4014 with the peak voltage (V CS_PEAK ) of the current switching cycle on the sampling resistor.

過壓感測電路4017回應於指示控制晶片401驅動關斷後輸出電感完全退磁的退磁結束信號(DMG,Demagnetization),基於比較器4016的比較結果來確定是否感測到過壓狀態。在一些實施例中,在退磁結束後比較器4016的比較結果指示控制電容C 4014兩端的電壓低於取樣電阻上的當前開關週期的峰值電壓時,過壓感測電路4017感測到過壓狀態,進而過壓保護被啟動。在退磁結束後比較器4016的比較結果指示控制電容C 4014兩端的電壓高於取樣電阻上的當前開關週期的峰值電壓時,過壓感測電路4017未感測到過壓狀態,控制晶片照常工作。 The overvoltage sensing circuit 4017 responds to a demagnetization end signal (DMG, Demagnetization) indicating that the inductance is completely demagnetized after the control chip 401 is turned off, and determines whether an overvoltage state is sensed based on the comparison result of the comparator 4016. In some embodiments, the comparison result of the comparator 4016 after the end of demagnetization indicates that the voltage across the control capacitor C 4014 is lower than the peak voltage of the current switching period on the sampling resistor, the overvoltage sensing circuit 4017 senses the overvoltage state , And the overvoltage protection is activated. After the demagnetization is over, the comparison result of the comparator 4016 indicates that the voltage across the control capacitor C 4014 is higher than the peak voltage of the current switching cycle on the sampling resistor, the overvoltage sensing circuit 4017 does not sense the overvoltage state, and the control chip works as usual .

第5圖示出了根據本發明實施例的一種輸出過壓感測系統在感測到過壓狀態時的控制波形的示意圖;第6圖示出了根據本發明實 施例的一種輸出過壓感測系統未感測到過壓狀態時的控制波形的示意圖。 Figure 5 shows a schematic diagram of the control waveform of an output overvoltage sensing system when an overvoltage state is sensed according to an embodiment of the present invention; Figure 6 shows an implementation according to the present invention A schematic diagram of outputting the control waveform when the overvoltage sensing system does not sense the overvoltage state of the embodiment.

如第5圖和第6圖所示,圖中都圖示了四個物理量(即GATE、IL、VC、OVP)隨時間T的變化曲線圖,其中,GATE表示控制晶片驅動的開通與關斷的信號,IL表示輸出電感電流,VC表示控制電容兩端的電壓,OVP表示過壓感測電路的感測結果信號。在第5圖和第6圖中,作為示例,僅圖示出兩個開關週期,本領域技術人員能夠理解這些波形曲線可以包含更多或更少的開關週期。 As shown in Figure 5 and Figure 6, the figures both illustrate the four physical quantities (ie GATE, I L , V C , OVP) over time T, where GATE represents the turn-on and control chip drive Turn-off signal, IL represents the output inductor current, V C represents the voltage across the control capacitor, and OVP represents the sensing result signal of the overvoltage sensing circuit. In Figures 5 and 6, as an example, only two switching periods are shown. Those skilled in the art can understand that these waveform curves may include more or fewer switching periods.

首先參見第5圖,在GATE曲線中,高位準表示控制晶片驅動開通時間,低位準表示控制晶片驅動關斷時間。如圖所示,可以看出每個開關週期內控制晶片先開通,經過一段時間後(如圖中虛線所示),進入TON_DELAY(在此時間期間,第一開關S1開通)。請注意,第二開關S2在控制晶片驅動的整個開通時間都是關斷的。接著,控制晶片關斷,輸出電感進入退磁時間TDMG(在此時間期間,第二開關S2開通,第一開關S1關斷)。 First, referring to Figure 5, in the GATE curve, the high level represents the turn-on time of the control chip drive, and the low level represents the turn-off time of the control chip drive. As shown in the figure, it can be seen that the control chip is turned on first in each switching cycle, and after a period of time (shown by the dotted line in the figure), it enters T ON_DELAY (during this time, the first switch S 1 is turned on). Please note that the second switch S 2 is turned off during the entire turn-on time of the control chip drive. Then, the control chip is turned off, and the output inductor enters the demagnetization time T DMG (during this time, the second switch S 2 is turned on, and the first switch S 1 is turned off).

接下來是輸出電感電流IL曲線,從其中可見在控制晶片的驅動開通時間內(即,GATE信號處於高位準),輸出電感電流從零逐漸增大,在控制晶片驅動關斷後輸出電感的退磁時間內(即,GATE信號處於低位準),輸出電感電流逐漸降低至零。在控制晶片驅動關斷時(即GATE信號在高位準到低位準的轉變時),輸出電感電流達到峰值IL_PEAKNext is the output inductor current IL curve. It can be seen that during the turn-on time of the control chip (that is, the GATE signal is at a high level), the output inductor current gradually increases from zero. After the control chip is driven off, the output inductor current During the demagnetization time (that is, the GATE signal is at a low level), the output inductor current gradually decreases to zero. When the control chip drive is turned off (that is, when the GATE signal transitions from a high level to a low level), the output inductor current reaches the peak value I L_PEAK .

接下來是控制電容兩端的電壓VC曲線,從其中可見,在控制晶片驅動開通延遲一段時間後(這段時間對應於GATE信號曲線中從控制晶片驅動開通到進入TON_DELAY之間的那段延遲時間),控制電容兩端的電壓即降為零,即清零復位。之後,在控制晶片驅動關斷後輸出電感的退磁時間TDMG內,由於控制電容被控制晶片的內部電流ISET充電而逐漸增大。在圖中,控制電容兩端的峰值電壓均小於取樣電阻的峰值電壓VCS_PEAKNext is the voltage V C curve across the control capacitor. It can be seen that after the control chip drive is turned on for a period of time (this time corresponds to the delay from the control chip drive on to the T ON_DELAY in the GATE signal curve) Time), the voltage across the control capacitor drops to zero, that is, clears and resets. After that, during the demagnetization time T DMG of the output inductor after the control chip is driven off, the control capacitor is gradually increased due to the internal current I SET of the control chip being charged. In the figure, the peak voltage across the control capacitor is less than the peak voltage V CS_PEAK of the sampling resistor.

接下來是過壓感測電路的感測結果信號OVP曲線,從其 中可見,在控制晶片的驅動開通時間內,且在控制電容兩端的電壓VC復位清零之前,過壓感測電路的感測結果信號OVP處於高位準,因此感測到過壓狀態,進而啟動過壓保護。 Next is the OVP curve of the sensing result signal of the overvoltage sensing circuit. It can be seen from it that during the driving on time of the control chip and before the voltage V C across the control capacitor is reset and cleared, the sensing of the overvoltage sensing circuit The measurement result signal OVP is at a high level, so the overvoltage state is sensed, and the overvoltage protection is activated.

第6圖與第5圖不同的是控制電容兩端的電壓VC和過壓感測電路的感測結果信號OVP曲線。由於每一開關週期內控制電容兩端的峰值電壓均大於取樣電阻的峰值電壓VCS_PEAK。因此,在這兩個開關週期內均未感測到過壓狀態。 The difference between Figure 6 and Figure 5 is the voltage V C across the control capacitor and the OVP curve of the sensing result signal of the overvoltage sensing circuit. Because the peak voltage across the control capacitor in each switching cycle is greater than the peak voltage V CS_PEAK of the sampling resistor. Therefore, the overvoltage condition is not sensed during these two switching cycles.

根據本發明的輸出過壓感測系統,可以便於在控制晶片的基準地無法直接感測輸出電壓或輸出電感兩端的電壓時實現電壓感測並進而實現輸出過壓保護功能,而無需額外的輔助電路,因此能夠有助於減小系統體積並進而降低成本。 According to the output overvoltage sensing system of the present invention, it is convenient to realize voltage sensing and then realize the output overvoltage protection function when the reference ground of the control chip cannot directly sense the output voltage or the voltage across the output inductor, without additional auxiliary The circuit can therefore help reduce the size of the system and thereby reduce costs.

第7圖示出了根據本發明實施例的一種輸出過壓感測方法的流程圖。如第7圖所示,該輸出過壓保護方法包括步驟S701-S705。 Figure 7 shows a flowchart of an output overvoltage sensing method according to an embodiment of the present invention. As shown in Figure 7, the output overvoltage protection method includes steps S701-S705.

在步驟S701,採集控制晶片中控制電容兩端的電壓,其中,控制電容在控制晶片驅動開通延遲一段時間後進行放電清零,並在控制晶片驅動關斷後輸出電感的退磁時間由控制晶片的電流源充電,其中,控制晶片的電流源的電流大小由控制晶片外部耦合的電阻設定。 In step S701, the voltage across the control capacitor in the control chip is collected, where the control capacitor is discharged and cleared after a period of delay when the control chip is driven on, and the demagnetization time of the output inductor is determined by the current of the control chip after the control chip is driven off. Source charging, where the current size of the current source of the control chip is set by a resistor externally coupled to the control chip.

在步驟S702,獲取取樣電阻上的當前開關週期的峰值電壓。 In step S702, the peak voltage of the current switching cycle on the sampling resistor is obtained.

在步驟S703,將控制電容兩端的電壓與所述峰值電壓進行對比。 In step S703, the voltage across the control capacitor is compared with the peak voltage.

在步驟S704和步驟S705,回應於指示控制晶片驅動關斷後輸出電感完全退磁的退磁結束信號,基於比較的比較結果來確定是否感測到過壓狀態。在一些實施例中,當比較器的比較結果指示控制電容兩端的電壓低於電流取樣電阻上的當前開關週期的峰值電壓時,感測到過壓狀態;在比較器的比較結果指示控制電容兩端的電壓高於電流取樣電阻上的當前開關週期的峰值電壓時,未感測到過壓狀態,控制晶片照常工作。 In step S704 and step S705, in response to a demagnetization end signal indicating that the output inductor is completely demagnetized after the control chip is driven off, it is determined whether an overvoltage state is sensed based on the comparison result. In some embodiments, when the comparison result of the comparator indicates that the voltage across the control capacitor is lower than the peak voltage of the current switching cycle on the current sampling resistor, the overvoltage state is sensed; the comparison result of the comparator indicates that the two When the voltage at the terminal is higher than the peak voltage of the current switching cycle on the current sampling resistor, the overvoltage state is not sensed and the control chip works as usual.

在一些實施例中,通過系統的狀態及輸出電感的退磁時間開來確定控制晶片的通斷時間。具體地,控制晶片還可包括第一開關和第二開關,第一開關跨接在控制電容兩端,並且第二開關串聯在控制電容與電流源之間,並且其中,在控制晶片的驅動開通時,第二開關被關斷,延遲一段時間後,第一開關被開通,並且在控制晶片驅動關斷後輸出電感退磁時,第一開關被關斷,而第二開關被開通。 In some embodiments, the on-off time of the control chip is determined by the state of the system and the demagnetization time of the output inductor. Specifically, the control chip may further include a first switch and a second switch, the first switch is connected across the control capacitor, and the second switch is connected in series between the control capacitor and the current source, and wherein the driving of the control chip is turned on When the second switch is turned off, after a delay, the first switch is turned on, and when the output inductor is demagnetized after the control chip is driven off, the first switch is turned off and the second switch is turned on.

第8圖示出了根據本發明實施例的一種輸出過壓感測方法的具體示例的流程圖。如8圖所示,該示例的輸出過壓感測方法包括步驟S801-S808。 Fig. 8 shows a flowchart of a specific example of a method for output overvoltage sensing according to an embodiment of the present invention. As shown in Figure 8, the output overvoltage sensing method of this example includes steps S801-S808.

在步驟S801,通過控制晶片外部耦合的電阻RSET來設定控制晶片的電流源的電流ISET。電流ISET作為施加到控制晶片的內部電流。 In step S801, the current I SET of the current source of the control chip is set by controlling the resistor R SET externally coupled to the chip. The current I SET is used as the internal current applied to the control chip.

在步驟S802,在控制晶片的輸出電感的退磁時間內,電流源的電流ISET對控制晶片中的控制電容進行充電。 In step S802, during the demagnetization time of the output inductor of the control chip, the current I SET of the current source charges the control capacitor in the control chip.

在步驟S803,採集控制電容兩端的電壓。 In step S803, the voltage across the control capacitor is collected.

在步驟S804,獲取取樣電阻上的當前開關週期的峰值電壓。 In step S804, the peak voltage of the current switching cycle on the sampling resistor is obtained.

在步驟S805,將控制電容兩端的電壓與所述峰值電壓進行對比。 In step S805, the voltage across the control capacitor is compared with the peak voltage.

在步驟S806和步驟S807,回應於指示控制晶片驅動關斷後輸出電感完全退磁的退磁結束信號,基於比較的比較結果來確定是否感測到過壓狀態。在一些實施例中,當比較器的比較結果指示控制電容兩端的電壓低於電流取樣電阻上的當前開關週期的峰值電壓時,感測到過壓狀態;在比較器的比較結果指示控制電容兩端的電壓高於電流取樣電阻上的當前開關週期的峰值電壓時,未感測到過壓狀態,控制晶片照常工作。 In step S806 and step S807, in response to a demagnetization end signal indicating that the output inductor is completely demagnetized after the control chip is driven off, it is determined whether an overvoltage state is sensed based on the comparison result. In some embodiments, when the comparison result of the comparator indicates that the voltage across the control capacitor is lower than the peak voltage of the current switching cycle on the current sampling resistor, the overvoltage state is sensed; the comparison result of the comparator indicates that the two When the voltage at the terminal is higher than the peak voltage of the current switching cycle on the current sampling resistor, the overvoltage state is not sensed and the control chip works as usual.

在步驟S808,控制晶片驅動開通延遲一段時間後,控制電容進行放電清零。 In step S808, after the control chip drive is turned on for a period of time delay, the control capacitor is discharged and cleared.

根據上述實施例的輸出過壓感測方法,可以便於在控制 晶片的基準地無法直接感測輸出電壓或輸出電感兩端的電壓時實現電壓感測並進而實現輸出過壓保護功能,而無需額外的輔助電路,因此能夠有助於減小系統體積並進而降低成本。 According to the output overvoltage sensing method of the above embodiment, it is convenient to control The chip's reference ground cannot directly sense the output voltage or the voltage across the output inductor to achieve voltage sensing and then realize the output over-voltage protection function without additional auxiliary circuits, so it can help reduce the size of the system and thereby reduce the cost .

下面給出本發明的實施輸出過壓保護的技術原理。如上所述,控制晶片進入過壓保護的條件為:

Figure 108109140-A0101-12-0010-1
The technical principle of implementing output overvoltage protection of the present invention is given below. As mentioned above, the conditions for controlling the chip to enter the overvoltage protection are:
Figure 108109140-A0101-12-0010-1

此外,輸出電感在退磁階段將電感能量傳輸至輸出電容,其運算式為:V OUT T DMG =LI CS_PEAK (2) In addition, the output inductor transfers the energy of the inductor to the output capacitor during the demagnetization phase, and the calculation formula is: V OUT . T DMG = L. I CS_PEAK (2)

通過上述兩個運算式,可以得出VOUT電壓進入保護的條件為:

Figure 108109140-A0101-12-0010-11
Through the above two calculation formulas, it can be concluded that the conditions for the V OUT voltage to enter the protection are:
Figure 108109140-A0101-12-0010-11

其中VC表示控制電容兩端的電壓,C為控制電容的電容值,ISET為控制晶片的內部電流,TDMG表示控制晶片驅動關斷後輸出電感的退磁時間,VCS_PEAK表示取樣電阻的峰值電壓,ICS_PEAK表示流過取樣電阻的電流,RCS表示取樣電阻的電阻值,L為輸出電感的電感值,VOUT表示輸出電壓。控制電容的電容值C為固定值,輸出電感的電感值L與取樣電阻的電阻值RCS在同一系統下也為固定值。 Where V C represents the voltage across the control capacitor, C is the capacitance value of the control capacitor, I SET is the internal current of the control chip, T DMG is the demagnetization time of the output inductor after the control chip is driven off, and V CS_PEAK is the peak voltage of the sampling resistor , I CS_PEAK represents the current flowing through the sampling resistor, R CS represents the resistance value of the sampling resistor, L is the inductance value of the output inductor, and V OUT represents the output voltage. The capacitance value C of the control capacitor is a fixed value, and the inductance value L of the output inductor and the resistance value R CS of the sampling resistor are also fixed values under the same system.

因此,只需通過調整RSET電阻阻值改變ISET電流,即可設置輸出電壓的輸出過壓保護閾值。因此,在不便直接感測輸出電壓或輸出電感兩端的電壓的情況下,通過感測控制電容兩端的電壓並與取樣電阻的當前開關週期的峰值電壓進行比較來感測是否感測到過壓狀態,並進而決定是否啟動過壓保護。 Therefore, only by adjusting the resistance of the R SET resistor to change the I SET current, the output overvoltage protection threshold of the output voltage can be set. Therefore, when it is inconvenient to directly sense the output voltage or the voltage across the output inductor, the overvoltage state is sensed by sensing the voltage across the control capacitor and comparing it with the peak voltage of the current switching cycle of the sampling resistor , And then decide whether to activate the overvoltage protection.

請注意,在上文中提到了“一個實施例”、“另一實施例”、“又一實施例”,然而應理解,在各個實施例中提及的特徵並不一定只能應 用於該實施例,而是可能用於其他實施例。一個實施例中的特徵可以應用於另一實施例,或者可以被包括在另一實施例中。 Please note that “one embodiment”, “another embodiment”, and “another embodiment” are mentioned above. However, it should be understood that the features mentioned in each embodiment are not necessarily only applicable Used in this embodiment, but may be used in other embodiments. Features in one embodiment may be applied to another embodiment, or may be included in another embodiment.

上文中提到了“第一”、“第二”....等序數詞。然而應理解這些表述僅僅是為了敘述和引用的方便,所限定的物件並不存在次序上的先後關係。 The ordinal numbers such as "first" and "second" are mentioned above. However, it should be understood that these expressions are only for the convenience of narrative and reference, and there is no sequence relationship between the defined objects.

本發明可以以其他的具體形式實現,而不脫離其精神和本質特徵。例如,特定實施例中所描述的演算法可以被修改,而系統體系結構並不脫離本發明的基本精神。因此,當前的實施例在所有方面都被看作是示例性的而非限定性的,本發明的範圍由所附申請專利範圍而非上述描述定義,並且,落入申請專利範圍的含義和等同物的範圍內的全部改變從而都被包括在本發明的範圍之中。 The present invention can be implemented in other specific forms without departing from its spirit and essential characteristics. For example, the algorithm described in the specific embodiment can be modified, and the system architecture does not deviate from the basic spirit of the present invention. Therefore, the current embodiments are regarded as illustrative rather than restrictive in all aspects, and the scope of the present invention is defined by the scope of the attached patent application rather than the above description, and the meaning and equivalents falling within the scope of the patent application All changes within the scope of things are thus included in the scope of the present invention.

301‧‧‧控制晶片 301‧‧‧control chip

302‧‧‧電阻 302‧‧‧Resistor

303‧‧‧負載 303‧‧‧Load

3011‧‧‧電流源 3011‧‧‧Current source

3012‧‧‧控制電容 3012‧‧‧Control capacitor

3013‧‧‧比較器 3013‧‧‧Comparator

3014‧‧‧過壓感測電路 3014‧‧‧Overvoltage sensing circuit

Claims (8)

一種輸出過壓感測系統,包括:控制晶片,電阻,位於所述控制晶片外部並與所述控制晶片耦合;其特徵在於,所述控制晶片包括電流源、控制電容、比較器、過壓感測電路,其中,所述電流源的電流大小由所述控制晶片外部耦合的所述電阻設定,其中,所述控制電容在所述控制晶片驅動開通延遲一段時間後進行放電清零,並在所述控制晶片驅動關斷後輸出電感的退磁時間內由所述控制晶片的電流源充電其中,所述比較器對所述控制電容兩端的電壓與取樣電阻上的當前開關週期的峰值電壓進行對比;並且其中,所述過壓感測電路回應於指示所述控制晶片驅動關斷後所述輸出電感完全退磁的退磁結束信號,基於所述比較器的比較結果來確定是否感測到過壓狀態。 An output overvoltage sensing system, comprising: a control chip, a resistor, located outside the control chip and coupled with the control chip; characterized in that, the control chip includes a current source, a control capacitor, a comparator, an overvoltage sensor The measuring circuit, wherein the magnitude of the current of the current source is set by the resistor externally coupled to the control chip, wherein the control capacitor is discharged and cleared after the control chip is turned on for a period of time. The output inductor is charged by the current source of the control chip during the demagnetization time after the control chip is driven off, wherein the comparator compares the voltage across the control capacitor with the peak voltage of the current switching cycle on the sampling resistor; In addition, the overvoltage sensing circuit responds to a demagnetization end signal indicating that the output inductor is completely demagnetized after the control chip is driven off, and determines whether an overvoltage state is sensed based on the comparison result of the comparator. 根據申請專利範圍第1項所述的輸出過壓感測系統,其中,當所述比較器的比較結果指示所述控制電容兩端的電壓低於所述取樣電阻上的當前開關週期的峰值電壓時,所述過壓感測電路感測到過壓狀態。 The output overvoltage sensing system according to item 1 of the scope of patent application, wherein, when the comparison result of the comparator indicates that the voltage across the control capacitor is lower than the peak voltage of the current switching cycle on the sampling resistor , The overvoltage sensing circuit senses an overvoltage state. 根據申請專利範圍第1項所述的輸出過壓感測系統,其中,當所述比較器的比較結果指示所述控制電容兩端的電壓高於所述取樣電阻上的當前開關週期的峰值電壓時,所述過壓感測電路未感測到過壓狀態。 The output overvoltage sensing system according to item 1 of the scope of patent application, wherein, when the comparison result of the comparator indicates that the voltage across the control capacitor is higher than the peak voltage of the current switching cycle on the sampling resistor , The overvoltage sensing circuit does not sense an overvoltage state. 根據申請專利範圍第1項所述的輸出過壓感測系統,所述控制晶片還包括第一開關和第二開關,所述第一開關跨接在所述控制電容兩端,並且所述第二開關串聯在所述控制電容與所述電流源之間,並且其中,在所述控制晶片驅動開通時,所述第二開關被關斷,延遲所述一段時間後,所述第一開關被開通,並且在所述控制晶片驅動關斷後所述 輸出電感退磁時,所述第一開關被關斷,而所述第二開關被開通。 According to the output overvoltage sensing system described in item 1 of the scope of patent application, the control chip further includes a first switch and a second switch, the first switch is connected across the control capacitor, and the first switch Two switches are connected in series between the control capacitor and the current source, and wherein, when the control chip is turned on, the second switch is turned off. After a delay of the period of time, the first switch is turned off. Turn on, and after the control chip is driven off, the When the output inductor is demagnetized, the first switch is turned off and the second switch is turned on. 一種輸出過壓感測方法,包括採集控制晶片中控制電容兩端的電壓,其特徵在於,所述控制電容在所述控制晶片驅動開通延遲一段時間後進行放電清零,並在所述控制晶片驅動關斷後輸出電感的退磁時間內由所述控制晶片的電流源充電,其中,所述控制晶片的電流源的電流大小由所述控制晶片外部耦合的電阻設定;採集取樣電阻上的當前開關週期的峰值電壓;將所述控制電容兩端的電壓與所述峰值電壓進行對比;以及回應於指示所述控制晶片驅動關斷後所述輸出電感完全退磁的退磁結束信號,基於所述比較的比較結果來確定是否感測到過壓狀態。 An output overvoltage sensing method, including collecting the voltage across a control capacitor in a control chip, characterized in that the control capacitor is discharged and cleared after the control chip is turned on for a period of time, and the control chip is driven The output inductor is charged by the current source of the control chip during the demagnetization time after the switch is turned off, wherein the current of the current source of the control chip is set by the resistor externally coupled to the control chip; the current switching period on the sampling resistor is collected Comparing the voltage across the control capacitor with the peak voltage; and responding to the demagnetization end signal indicating that the output inductor is completely demagnetized after the control chip is driven off, based on the comparison result of the comparison To determine whether an overvoltage condition is sensed. 根據申請專利範圍第5項所述的輸出過壓感測方法,其中,當所述比較器的比較結果指示所述控制電容兩端的電壓低於所述取樣電阻上的當前開關週期的峰值電壓時,感測到過壓狀態。 The output overvoltage sensing method according to item 5 of the scope of patent application, wherein when the comparison result of the comparator indicates that the voltage across the control capacitor is lower than the peak voltage of the current switching cycle on the sampling resistor , The overvoltage condition is sensed. 根據申請專利範圍第5項所述的輸出過壓感測方法,其中,當所述比較器的比較結果指示所述控制電容兩端的電壓高於所述取樣電阻上的當前開關週期的峰值電壓時,未感測到過壓狀態。 The output overvoltage sensing method according to item 5 of the scope of patent application, wherein, when the comparison result of the comparator indicates that the voltage across the control capacitor is higher than the peak voltage of the current switching cycle on the sampling resistor , The overvoltage state is not sensed. 根據申請專利範圍第5項所述的輸出過壓感測方法,其中,所述控制晶片還包括第一開關和第二開關,所述第一開關跨接在所述控制電容兩端,並且所述第二開關串聯在所述控制電容與所述電流源之間,並且其中,在所述控制晶片驅動開通時,所述第二開關被關斷,延遲所述一段時間後,所述第一開關被開通,並且在所述控制晶片驅動關斷後所述輸出電感的退磁時,所述第一開關被關斷,而所述第二開關被開通。 The output overvoltage sensing method according to item 5 of the scope of patent application, wherein the control chip further includes a first switch and a second switch, the first switch is connected across the control capacitor, and The second switch is connected in series between the control capacitor and the current source, and wherein, when the control chip is driven to turn on, the second switch is turned off. After a delay of the period of time, the first The switch is turned on, and when the output inductor is demagnetized after the control chip is turned off, the first switch is turned off and the second switch is turned on.
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