Current sense circuit for charge pump

Abstract

The application provides a kind of overcurrent detection circuit for charge pump, wherein the charge pump is connected to the battery of electronic terminal, to simultaneously supply power to the battery by at least two power supply branches, wherein the overcurrent detection circuit is used to detect the overcurrent of a corresponding power supply branch in the at least two power supply branches, wherein the overcurrent detection circuit comprises: a reference unit configured to generate a reference voltage of the corresponding power supply branch according to a first voltage at the positive electrode of the battery;A detection unit is configured to generate a detection voltage according to the current on the corresponding power supply branch;And an output unit is configured to generate an overcurrent detection signal according to the comparison result of the detection voltage and the reference voltage, wherein the overcurrent detection signal indicates whether the current on the corresponding power supply branch is overcurrent.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of circuits, and more particularly, to an overcurrent detection circuit for a charge pump. BACKGROUND

[0002] With the continuous development of electronic terminal performance, the requirement for charging efficiency of electronic terminals is also getting higher and higher. Therefore, as a non-inductive DC-DC voltage converter, the charge pump is increasingly applied to the fast charging process of electronic terminals due to its low loss and high conversion efficiency.

[0003] The non-inductive charge pump usually performs voltage conversion through switching of switching elements and charging and discharging of energy storage elements, and the size of the current flowing through the switching elements is crucial to the safety of the switching elements. In particular, when the current flowing through the switching elements of the charge pump is relatively large, if the voltage in the charge pump fluctuates, the switching elements may be damaged due to overcurrent, which will affect the fast charging of the electronic terminal and even bring safety hazards to the electronic terminal. Therefore, during the operation of the charge pump, overcurrent detection of the charge pump is usually required.

[0004] Generally, a closed-loop form of an operational amplifier is adopted to perform overcurrent detection of the charge pump. However, the overcurrent detection time of this way is usually in the order of microseconds (μs), and under the detection time in this order of magnitude, when the overcurrent of the charge pump is detected, the switching elements in the charge pump may have been damaged due to long-time overcurrent.

[0005] Therefore, a way capable of efficiently performing overcurrent detection of the charge pump is needed. SUMMARY

[0006] According to an exemplary embodiment of the present application, an overcurrent detection circuit for a charge pump is provided, wherein the charge pump is connected to a battery of an electronic terminal to supply power to the battery through at least two power supply branches at the same time, wherein the overcurrent detection circuit is used to perform overcurrent detection on a corresponding power supply branch in the at least two power supply branches, wherein the overcurrent detection circuit comprises: a reference unit configured to generate a reference voltage of the corresponding power supply branch according to a first voltage at a positive electrode of the battery; a detection unit configured to generate a detection voltage according to a current on the corresponding power supply branch; and an output unit configured to generate an overcurrent detection signal according to a comparison result of the detection voltage and the reference voltage, wherein the overcurrent detection signal indicates whether the current on the corresponding power supply branch is overcurrent.

[0007] The overcurrent detection circuit for charge pump according to the exemplary embodiment of the present application can generate a reference voltage and a detection voltage for a power supply branch of the charge pump, and quickly generate an overcurrent detection signal indicating whether the power supply branch is overcurrent according to comparison between the reference voltage and the detection voltage, thereby effectively avoiding damage of elements in the power supply branch due to overcurrent. BRIEF DESCRIPTION OF DRAWINGS

[0008] The present application can be better understood with reference to the following descriptions and drawings in which:

[0009] Figure 1 A circuit diagram of a charge pump according to one exemplary embodiment is shown.

[0010] Figure 2 A block diagram of an overcurrent detection circuit for a charge pump according to one exemplary embodiment of the present application is shown.

[0011] Figure 3 A detailed block diagram of an overcurrent detection circuit for a charge pump according to one exemplary embodiment of the present application is shown.

[0012] Figure 4 A circuit diagram of an overcurrent detection circuit for a charge pump according to one exemplary embodiment of the present application is shown.

[0013] Figure 5 A circuit diagram of an overcurrent detection circuit for a charge pump according to another exemplary embodiment of the present application is shown. DETAILED DESCRIPTION

[0014] Features and exemplary embodiments of various aspects of the present application will be described in detail below. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, it will be apparent to one of ordinary skill in the art that the present application can be practiced without some or all of these specific details. The description of the embodiments is merely intended to provide a better understanding of the present application by showing examples of the present application. The present application is not limited to any particular configuration and algorithm set forth below, but covers any modifications, equivalents, and alternatives falling within the spirit of the present application. In the drawings and the following description, well-known structures and techniques are not shown in order to avoid unnecessary obscuring of the present application.

[0015] The overcurrent detection circuit for charge pump according to the exemplary embodiment of the present application can be used in a charge pump connected to a battery of an electronic terminal to supply power to the battery through at least two power supply branches simultaneously. In particular, the overcurrent detection circuit according to the exemplary embodiment of the present application is used to detect overcurrent for a corresponding power supply branch among the at least two power supply branches.

[0016] Figure 1 A circuit diagram of the charge pump 200 is shown according to one example embodiment.

[0017] Referring to Figure 1 , Figure 1 The charge pump 200 shown can supply power to the battery 300 according to a predetermined clock signal, each clock cycle of the predetermined clock signal including a first working phase and a second working phase (e.g., corresponding to a high level phase and a low level phase of the clock signal, respectively), the charge pump 200 supplying power to the battery 300 through a first power supply branch and a second power supply branch simultaneously in each of the first working phase (e.g., the high level phase) and the second working phase (e.g., the low level phase).

[0018] As an example, in the first working phase, the switching elements Q1, Q3, Q6 and Q8 of the charge pump 200 can be turned on, and the switching elements Q2, Q4, Q5 and Q7 can be turned off.

[0019] At this time, the charge pump 200 supplies power to the battery 300 (having a voltage VOUT) through an external power supply (having a voltage PMID), the switching element Q1, the capacitor CF1 (having a voltage CFH1 at the positive electrode and a voltage CFL1 at the negative electrode), the switching element Q3 (as shown by the left solid arrow), which is a first power supply branch of the first working phase, the first power supply branch supplying power to the battery 300 through the external power supply and charging the capacitor CF1 at the same time. Figure 1

[0020] At the same time, the charge pump 200 also supplies power to the battery 300 through the switching element Q8, the capacitor CF2 (having a voltage CFH2 at the positive electrode and a voltage CFL2 at the negative electrode), the switching element Q6 (as shown by the right solid arrow), which is a second power supply branch of the first working phase, the second power supply branch supplying power to the battery 300 through discharging of the capacitor CF2. Figure 1

[0021] In the second working phase, the switching elements Q1, Q3, Q6 and Q8 of the charge pump 200 can be turned off, and the switching elements Q2, Q4, Q5 and Q7 can be turned on.

[0022] At this time, the charge pump 200 supplies power to the battery 300 (having a voltage VOUT) through an external power supply (having a voltage PMID), the switching element Q5, the capacitor CF2, the switching element Q7 (as shown by the right dashed arrow), which is a first power supply branch of the second working phase, the first power supply branch supplying power to the battery 300 through the external power supply and charging the capacitor CF2 at the same time. Figure 1

[0023] ​​​At the same time, the charge pump 200 also supplies power to the battery 300 through the switch element Q4, the capacitor CF1, and the switch element Q2 (eg Figure 1 (as indicated by the dotted arrow on the left), this is the second power supply branch in the second working phase, and the second power supply branch supplies power to the battery 300 by discharging the capacitor CF1.

[0024] That is to say, in Figure 1 In the example charge pump 200, capacitors CF1 and CF2 serve as energy storage elements. In both the first and second operating stages, the first power supply branch refers to the branch that supplies power from an external power source, through the first energy storage element, and associated switching elements, to the battery. The second power supply branch refers to the branch that supplies power from the second energy storage element, through associated switching elements, to the battery.

[0025] In other words, the first energy storage element (CF1) in the first power supply branch in the first operating phase is the second energy storage element (CF1) in the second power supply branch in the second operating phase, and the second energy storage element (CF2) in the second power supply branch in the first operating phase is the first energy storage element (CF1) in the first power supply branch in the second operating phase. That is, in both the first and second operating phases, the first power supply branch can represent a power supply branch that supplies power from an external power source (having a voltage PMID) to the battery, and the second power supply branch can represent a power supply branch that supplies power from the energy storage element to the battery.

[0026] For example, in order to adapt to the operating voltage and current of the charge pump, the switching elements Q1 to Q8 can be set as power transistors, and the control signals of the switching elements Q1, Q3, Q6 and Q8 can be set to be turned on in the first working stage, and the control signals of the switching elements Q2, Q4, Q5 and Q7 can be set to be turned on in the second working stage, so as to realize the above-mentioned first power supply branch and second power supply branch in the above-mentioned first working stage and second working stage.

[0027] Figure 1 The two power supply branches of the charge pump 200 in the first working stage and the two power supply branches in the second working stage may be symmetrical. That is, the first power supply branch in the first working stage may have the same circuit structure as the first power supply branch in the second working stage, and the second power supply branch in the first working stage may have the same circuit structure as the second power supply branch in the second working stage.

[0028] For example, Figure 1Charge pump 200 functions as a DC-DC converter that halves the external power supply voltage and doubles the current. In this case, external power supply voltage PMID can be twice the voltage VOUT at the battery's positive terminal. As external power supply voltage PMID increases, it becomes greater than twice the voltage VOUT at the battery's positive terminal. This increases the current in charge pump 200, potentially causing an overcurrent.

[0029] The overcurrent detection circuit for a charge pump according to the present invention can be used to perform overcurrent detection on the first power supply branch or the second power supply branch of the charge pump 200 in the first working stage or the second working stage.

[0030] Figure 2 FIG. 1 is a block diagram of an overcurrent detection circuit 100 for a charge pump according to an exemplary embodiment of the present invention.

[0031] Reference Figure 2 , an overcurrent detection circuit 100 for a charge pump according to an exemplary embodiment of the present invention may include a reference unit 110 , a detection unit 120 , and an output unit 130 .

[0032] The reference unit 110 is configured to determine the voltage of the positive electrode of the battery 300 according to the first voltage (eg, Figure 1 The voltage at the positive electrode of the battery (VOUT) is used to generate a reference voltage for the corresponding power supply branch.

[0033] For example, the corresponding power supply branch may be Figure 1 Any power supply branch in one of the first working stage and the second working stage of the charge pump 200.

[0034] For example, the reference unit 110 may obtain the first voltage by being connected to the charge pump 200 or being connected to the battery 300 .

[0035] According to one embodiment, the reference unit 110 may be configured to generate a reference voltage based on the first voltage, the internal resistance of a predetermined switching element of the corresponding power supply branch, and the overcurrent threshold current of the corresponding power supply branch. In this case, the predetermined switching element may be a switching element in the corresponding power supply branch that is connected to the positive electrode of the battery 300 to input current to the battery 300 (for example, Figure 1 In the example of FIG. 1 , the switching element Q3 of the first power supply branch in the first working phase, the switching element Q2 of the second power supply branch in the second working phase, and so on) is used.

[0036] For example, the overcurrent threshold current can be a current value determined based on the specific voltage converted by the charge pump 200 and the specific internal resistance of the predetermined switching element. For example, the overcurrent threshold current can be the normal operating current of the predetermined switching element, or it can be a current slightly larger than the normal operating current (for example, a predetermined percentage larger than the normal operating current).

[0037] It should be understood that the above voltage values and current values are only examples, and different voltage values and current values can be set according to actual requirements.

[0038] The detection unit 120 is configured to generate a detection voltage according to the current on the corresponding power supply branch.

[0039] For example, the detection unit 120 can generate the detection voltage for any of the power supply branches in one of the first working phase and the second working phase of the charge pump 200. Figure 1

[0040] The output unit 130 is configured to generate an overcurrent detection signal according to the comparison result of the detection voltage and the reference voltage. The overcurrent detection signal indicates whether the current on the corresponding power supply branch is overcurrent.

[0041] According to one embodiment, the output unit 130 can be configured to generate a first overcurrent detection signal (for example, one of high level and low level) when the detection voltage is greater than the reference voltage, and generate a second overcurrent detection signal (for example, the other one of high level and low level) when the detection voltage is not greater than the reference voltage.

[0042] The first overcurrent detection signal can indicate that the current on the corresponding power supply branch is overcurrent, and can be used to turn off at least one switching element in the corresponding power supply branch to turn off the corresponding power supply branch. The second overcurrent detection signal can indicate that the current on the corresponding power supply branch is not overcurrent.

[0043] For example, the first overcurrent detection signal can be used to turn off the predetermined switching element (for example, Q3 or Q2) in the above example and / or other switching elements in the same power supply branch as the predetermined switching element.

[0044] It should be understood that the overcurrent detection circuit 100 according to the exemplary embodiment of the present application can periodically perform overcurrent detection on the corresponding power supply branch of the charge pump, and / or can trigger overcurrent detection on the corresponding power supply branch of the charge pump according to a predetermined event and / or user input.

[0045] Figure 3 A detailed block diagram of an overcurrent detection circuit for a charge pump according to one exemplary embodiment of the present application is shown.

[0046] Referring to Figure 3 According to one embodiment, Figure 2 The reference unit 130 in the detection unit 120 can include a first current source 111, a first voltage dividing subunit 112 and a second voltage dividing subunit 113 connected in series between the second voltage node 220 of the charge pump 200 and the first voltage node 210 of the charge pump 200.

[0047] ​That is, the reference unit 130 may be connected between the first voltage node 210 and the second voltage node 220 of the charge pump 200. The first voltage node 210 may have a first voltage (eg, Figure 1 The second voltage at the second voltage node 220 may be greater than the first voltage.

[0048] The first current source 111 can be used to provide the reference unit 110 with an operating current that is in a predetermined proportion to the overcurrent threshold current. The reference voltage can be a first connection node ( Figure 3 The voltage at any point on the line between the first voltage dividing subunit 112 and the second voltage dividing subunit 113 in FIG.

[0049] For example, in order to use a current source with a smaller current to save costs, the predetermined ratio may be one in tens of thousands or one in hundreds of thousands, such as one in two hundred thousand.

[0050] According to one embodiment, the second voltage divider unit 113 may include a first resistor and a first switching element connected in series, wherein the first resistor is connected between the first connection node and the first switching element. The internal resistance of the predetermined switching element in the corresponding power supply branch of the charge pump may be in a predetermined ratio to the internal resistance of the first switching element.

[0051] For example, when the predetermined ratio is 1 / 200,000 in the above example, the internal resistance of the first switching element may be 200,000 times that of the predetermined switching element (eg, the switching element Q3 or Q2 in the above example).

[0052] According to one embodiment, Figure 2 The detection unit 120 may include a second current source 121 , a third voltage dividing subunit 122 , and a fourth voltage dividing subunit 123 sequentially connected in series between the second voltage node 220 of the charge pump 200 and the third voltage node 230 of the charge pump 200 .

[0053] That is, the detection unit 120 may be connected between the second voltage node 220 and the third voltage node 230 of the charge pump 200. The third voltage at the third voltage node 230 may be lower than the second voltage and higher than the first voltage.

[0054] The second current source 121 may be the same as the first current source 111, and the internal resistance of the first voltage divider unit 112 may be the same as the internal resistance of the third voltage divider unit 122 (for example, both may be ordinary transistor switch elements or power transistor switch elements). The detection voltage may be the second connection node ( Figure 3 The voltage at any point on the line between the third voltage dividing subunit 122 and the fourth voltage dividing subunit 123 in FIG.

[0055] According to an embodiment, the fourth voltage dividing subunit 123 can include a second resistor. The second resistor can be the same as the first resistor of the second voltage dividing subunit 113.

[0056] According to an embodiment, Figure 2 The output unit 130 in the charge pump 100 can include a third current source 131 and a control switch 132 connected in series between the second voltage node 220 and a second connection node (between the third voltage dividing subunit 122 and the fourth voltage dividing subunit 123).

[0057] That is, the output unit 130 is connected between the second voltage node 220 and the second connection node of the charge pump 200.

[0058] The third current source 131 can be the same as the first current source 111 and the second current source 121, and a control terminal of the control switch 132 can be connected to any point on a connection line between the third voltage dividing subunit 122 and the second current source 121 (between the third current source 131 and the control switch 132). Figure 3

[0059] In addition, the output unit 130 can further include a logic subunit 133 connected between a fourth connection node (any point on a connection line between the third current source 131 and the control switch 132) and an output terminal of the overcurrent detection circuit. Figure 3

[0060] The logic subunit 133 is configured to generate and output the first overcurrent detection signal when the control switch 132 is turned on, and generate and output the second overcurrent detection signal when the control switch 132 is turned off.

[0061] According to an embodiment, the logic subunit 133 can include an inverter connected to the fourth connection node, and an AND gate connected to the inverter. A first input terminal of the AND gate can receive an output signal of the inverter, a second input terminal of the AND gate can receive a control signal for controlling turning on or turning off of the above predetermined switching element, and an output terminal of the AND gate outputs the first overcurrent detection signal or the second overcurrent detection signal.

[0062] ​​In the above embodiments, by making the overcurrent detection circuit 100 according to the exemplary embodiment of the present invention include only switching elements, resistors, current sources and logic elements, the overcurrent detection time can be shortened to a range of less than 10 nanoseconds, which greatly improves the overcurrent detection efficiency, thereby enabling the corresponding power supply branch to be disconnected in time before the switching element of the charge pump is damaged due to overcurrent, thereby improving the safety of the charge pump charging the battery of the electronic terminal.

[0063] In addition, since the power supply branch of the charge pump 200 corresponding to the overcurrent detection circuit 100 according to the exemplary embodiment of the present invention can operate in one of the two working phases of the clock signal, that is, the corresponding power supply branch can have a working phase and a non-working phase, therefore, in order to further shorten the overcurrent detection time of the overcurrent detection circuit 100, the overcurrent detection circuit 100 according to the exemplary embodiment of the present invention may also include: a current holding unit, which can be connected between the above reference unit 110 and the detection unit 120 to maintain the working current in the overcurrent detection circuit 100 in the non-working phase of the corresponding power supply branch, so as to be used for overcurrent detection in the next working phase of the corresponding power supply branch.

[0064] By means of the above current holding unit, the time for the overcurrent detection circuit 100 to establish the operating current can be shortened, thereby further shortening the time for the overcurrent detection circuit 100 to perform overcurrent detection.

[0065] Figure 4 FIG. 1 shows a circuit diagram of an overcurrent detection circuit 100 for a charge pump according to an exemplary embodiment of the present invention.

[0066] Reference Figure 4 , the left side is a circuit diagram of an overcurrent detection circuit 100 according to an embodiment of the present invention, and the right side shows Figure 1 part of the charge pump 200 .

[0067] Figure 4 The overcurrent detection circuit 100 corresponds to the first power supply branch of the charge pump, that is, the power supply branch that supplies power to the battery from the external voltage via the first energy storage element and the related switching elements. Figure 4 FIG. 1 shows a first power supply branch of the charge pump in the first working phase (the charge pump 200 supplies power to the battery 300 (with voltage VOUT) via an external power supply (with voltage PMID), a switching element Q1, a capacitor CF1, a switching element Q3, and a voltage VOUT). Figure 4 )).

[0068] It should be understood that Figure 4 The overcurrent detection circuit 100 shown is also applicable to Figure 1The first power supply branch of the second working phase of the charge pump (the charge pump 200 supplies power to the battery 300 (with voltage VOUT) through the external power supply (with voltage PMID), the switching element Q5, the capacitor CF2, the switching element Q7) because Figure 1 The first working phase and the second working phase of the charge pump 200 are symmetrical.

[0069] Reference Figure 4 ,because Figure 4 The same current flows through the switch element Q1 and the switch element Q3 in the first power supply branch shown in FIG. 4 . Therefore, the overcurrent detection of the first power supply branch can be performed by detecting whether the switch element Q3 is overcurrent. Figure 2 、 Figure 3 The predetermined switching element.

[0070] exist Figure 4 In the embodiment, the first voltage may be VOUT, the second voltage may be the positive electrode voltage CFH1 of the capacitor CF1 (the first energy storage element), and the third voltage may be the negative electrode voltage CFL1 of the capacitor CF1.

[0071] The input unit 110 of the overcurrent detection circuit 100 may include a current source I0 (a first current source 111), a switching element NM2 (a first voltage divider unit 112), a resistor (a first resistor of a second voltage divider unit 113, having an internal resistance R) and a switching element Q3_sense (a first switching element of the second voltage divider unit 113).

[0072] The detection unit 120 of the overcurrent detection circuit 100 may include a current source I0 (a second current source 121 ), a switch element NM3 (a third voltage divider unit 122 ), and a resistor (a second resistor 123 having an internal resistance R).

[0073] The output unit 130 of the overcurrent detection circuit 100 may include a current source I0 (third current source 131), a control switch 132, an inverter 133-1, and an AND gate 133-2 (logic subunit 133). The AND gate 133-2 outputs the overcurrent detection signal ocp13.

[0074] The holding unit of the overcurrent detection circuit may be a diode switch element NM1 , which can only allow current to flow from left to right, ie, functions as a diode.

[0075] exist Figure 4 In the circuit, the three current sources I0 are connected to each other. The internal resistance of the switching elements NM2 and NM3 is the same and they are always kept on. The reference voltage is V2 and the detection voltage is V1. The internal resistance of the switching element Q3 (the above predetermined switching element) is Ron, and the internal resistance of the switching element Q3_sense is N times Ron ( Figure 4 N*Ron in).

[0076] The current provided by the current source I0 may be 1 / N of the current of the switch element Q3. The switch element Q3_sense and the switch element Q3 are turned on or off according to the same control signal g3 (for example, the switch element Q3 may be turned on when the control signal g3 is high).

[0077] Under the above configuration, when the current flowing through switch element Q3 of charge pump 200 is not overcurrent, detection voltage V1 is equal to or slightly less than reference voltage V2 (depending on whether the threshold overcurrent current is equal to or slightly greater than the normal operating current of switch element Q3). This is because switch element Q3 and Q3_sense have internal resistances proportional to 1 / N and currents approximately proportional to N, the first resistor and the second resistor have the same resistance, and current flows toward the node with the first voltage (VOUT). At this point, switch element 132 is in the off state. The input of inverter 133-1 is at a high level, and the output is at a low level. AND gate 133-2 receives the low level output of inverter 133-1 at one input and control signal g3 (e.g., a high level) at the other input. The AND gate then outputs a second overcurrent detection signal (e.g., a low level) indicating that the current flowing through the corresponding power supply branch is not overcurrent.

[0078] When an overcurrent flows through switch element Q3 of charge pump 200, the voltage across switch element Q3 increases, causing voltage CFL1 to increase, and thus detection voltage V1 to increase. When detection voltage V1 increases, for example, exceeding reference voltage V2, control switch 132 turns on, causing the input of inverter 133-1 to go low and the output of inverter 133-1 to go high. At this point, AND gate 133-2 receives the high-level output of inverter 133-1 at one input and control signal g3 (e.g., a high-level output) at the other input. The output of the AND gate becomes a first overcurrent detection signal (e.g., a high-level output), indicating an overcurrent in the corresponding power supply branch. This first overcurrent detection signal can turn off switch element Q3 and / or switch element Q1.

[0079] When the power supply branch where the switching element Q3 is located is in a non-working stage (for example, the second working stage), the switching element Q3_sense is disconnected (for example, the control signal g3 becomes a low level). At this time, the current source I0 of the input unit 110 and the first sub-voltage divider unit NM2 will be connected to the fourth voltage divider sub-unit (the second resistor) through the current holding unit NM1, and then connected to the negative electrode of the capacitor CF1 (having the voltage CFL1), so that the first sub-voltage divider unit NM2 in the reference unit 110 maintains an operating current, thereby shortening the time for the next overcurrent detection of the power supply branch of the charge pump 200.

[0080] Through the above analysis, we can see that Figure 4 The overcurrent detection circuit has the same operating voltage domain (i.e., a voltage domain between voltage CFH1 and voltage CFL1) as the power supply branch of the switching element Q3 in the previous operating stage (i.e., the second power supply branch in the second operating stage), thereby avoiding the introduction of a level shift circuit, thereby avoiding the increase in overcurrent detection time caused by the level shift circuit.

[0081] Figure 5 A circuit diagram 100 is shown of an overcurrent detection circuit for a charge pump according to another exemplary embodiment of the present invention.

[0082] Reference Figure 5 , the left side is a circuit diagram of an overcurrent detection circuit 100 according to another embodiment of the present invention, and the right side shows Figure 1 part of the charge pump 200 .

[0083] Figure 5 The overcurrent detection circuit 100 in the embodiment corresponds to the second power supply branch of the charge pump 200, ie, the power supply branch that supplies power from the second energy storage element to the battery via the relevant switch element. Figure 5 FIG2 shows a second power supply branch of the charge pump in the second working phase (the charge pump 200 supplies power to the battery 300 (having a voltage VOUT) via the switch element Q4, the capacitor CF1, and the switch element Q2). Figure 5 )).

[0084] It should be understood that Figure 5 The overcurrent detection circuit 100 shown is also applicable to Figure 1 The second power supply branch of the first working phase of the charge pump (the charge pump 200 supplies power to the battery 300 through the switching element Q8, the capacitor CF2, and the switching element Q6) is because Figure 1 The first working phase and the second working phase of the charge pump 200 are symmetrical.

[0085] Reference Figure 5 ,because Figure 5 The same current flows through the switch element Q2 and the switch element Q4 in the second power supply branch shown in FIG. 4 , so the overcurrent detection of the second power supply branch can be performed by detecting whether the switch element Q2 is overcurrent. Figure 2 、 Figure 3 The predetermined switching element.

[0086] Figure 5 The overcurrent detection circuit and Figure 4 The overcurrent detection circuit is similar to that of Figure 5The second voltage in the circuit is the external power supply voltage (PMID), the third voltage is the positive electrode voltage CFH1 of capacitor CF1 (the second energy storage element), and the first switch element Q2_sense of reference unit 110 remains on at all times. Furthermore, reference unit 110 also includes a second switch element NM4, and detection unit 120 also includes a third switch element NM5. The second switch element NM4 and the third switch element NM5 have the same internal resistance. The second switch element NM4 remains on at all times, and the third switch element NM5 and the predetermined switch element Q2 in the corresponding power supply branch are turned on or off according to the same control signal g2. Furthermore, the current holding unit is a fourth switch element NM1, which is connected between a fifth connection node and the second connection node. The fifth connection node is a node between the first resistor and the first switch element Q2_sense. The fourth switch element NM1 and the predetermined switch element Q2 are turned on or off according to opposite control signals (g2 and g2b).

[0087] Under the above configuration, when the current flowing through switch element Q2 of charge pump 200 is not overcurrent, detection voltage V1 is equal to or slightly less than reference voltage V2 (depending on whether the threshold overcurrent current is equal to or slightly greater than the normal operating current of switch element Q2). This is because switch elements Q2 and Q2_sense have internal resistances proportional to 1 / N and currents approximately proportional to N, the first and second resistors have the same resistance, the second and third switch elements NM4 and NM5 have the same internal resistance, and current flows toward the node with the first voltage (VOUT). At this point, switch element 132 is in the off state. The input of inverter 133-1 is high, and the output is low. AND gate 133-2 receives the low output of inverter 133-1 at one input and control signal g2 (e.g., high) at the other input. The AND gate then outputs a second overcurrent detection signal (e.g., low) indicating that the current flowing through the corresponding power supply branch is not overcurrent.

[0088] When an overcurrent condition occurs in switch element Q2 of charge pump 200, the voltage across switch element Q2 increases, causing voltage CFH1 to increase, which in turn causes detection voltage V1 to increase. When detection voltage V1 increases, for example, exceeding reference voltage V2, control switch 132 turns on, causing the input of inverter 133-1 to go low and the output of inverter 133-1 to go high. At this point, AND gate 133-2 receives the high-level output of inverter 133-1 at one input and control signal g2 (e.g., a high-level output) at the other input. The output of the AND gate becomes a first overcurrent detection signal (e.g., a high-level output), indicating an overcurrent condition in the corresponding power supply branch. This first overcurrent detection signal can disconnect switch element Q2 and / or switch element Q4.

[0089] When the power supply branch where switch element Q2 resides is in a non-operating phase (e.g., the first operating phase), switch element NM5 is disconnected (e.g., control signal g2 becomes low). At this point, current source I0 and third sub-voltage divider unit NM3 of detection unit 120 are connected to second sub-voltage divider unit Q2_sense via current holding unit NM1. This maintains an operating current in first sub-voltage divider unit NM2 of detection unit 120, thereby shortening the next overcurrent detection time for the power supply branch of charge pump 200. Furthermore, the parasitic diode of third switch element NM5 prevents excessive voltage across the source and drain of switch element NM1 when it is turned on, thereby ensuring the safety of switch element NM1.

[0090] Through the above analysis, we can see that Figure 5 The overcurrent detection circuit has the same operating voltage domain (i.e., the voltage domain between voltage PMID and voltage CFH1) as the power supply branch of the switching element Q2 in the previous working stage (i.e., the first power supply branch in the first working stage), thereby avoiding the introduction of a level shifting circuit, thereby avoiding the increased overcurrent detection time caused by the level shifting circuit.

[0091] According to an exemplary embodiment of the present invention, an overcurrent detection circuit for a charge pump can generate a reference voltage and a detection voltage for a power supply branch of the charge pump, and quickly generate an overcurrent detection signal indicating whether the power supply branch is overcurrent based on a comparison between the reference voltage and the detection voltage, thereby effectively preventing components in the power supply branch from being damaged due to overcurrent.

[0092] The present invention may be implemented in other specific forms without departing from its spirit and essential characteristics. For example, the algorithms described in the specific embodiments may be modified without departing from the basic spirit of the present invention. Therefore, the present embodiments are to be considered in all respects as illustrative and not restrictive, the scope of the invention is defined by the appended claims rather than the foregoing description, and all modifications coming within the meaning and scope of equivalents of the claims are intended to be included within the scope of the present invention.

Claims

1. An overcurrent detection circuit for a charge pump, wherein: The charge pump is connected to a battery of the electronic terminal to simultaneously supply power to the battery through at least two power supply branches, wherein the overcurrent detection circuit is used to perform overcurrent detection on a corresponding power supply branch of the at least two power supply branches, wherein the overcurrent detection circuit includes: a reference unit configured to generate a reference voltage based on a first voltage at the positive electrode of the battery, an internal resistance of a predetermined switching element of the corresponding power supply branch, and an overcurrent threshold current of the corresponding power supply branch, wherein the predetermined switching element is a switching element in the corresponding power supply branch connected to the positive electrode of the battery to input current to the battery; a detection unit configured to generate a detection voltage according to the current on the corresponding power supply branch; and An output unit is configured to generate an overcurrent detection signal according to a comparison result between the detection voltage and the reference voltage, wherein the overcurrent detection signal indicates whether the current on the corresponding power supply branch is overcurrent, wherein The reference unit is connected between a first voltage node and a second voltage node of the charge pump, the first voltage node has the first voltage, and the second voltage node has a second voltage greater than the first voltage. The reference unit includes a first current source, a first voltage divider unit, and a second voltage divider unit connected in series between the second voltage node and the first voltage node, the first current source is used to provide the reference unit with an operating current that is in a predetermined proportion to the overcurrent threshold current, the reference voltage is the voltage at the first connection node between the first voltage divider unit and the second voltage divider unit, the second voltage divider unit includes a first resistor and a first switching element connected in series, the first resistor is connected between the first connection node and the first switching element, and the internal resistance of the predetermined switching element is in the predetermined proportion to the internal resistance of the first switching element.

2. The overcurrent detection circuit according to claim 1, wherein: The output unit is configured to generate a first overcurrent detection signal when the detection voltage is greater than the reference voltage, and to generate a second overcurrent detection signal when the detection voltage is not greater than the reference voltage. The first overcurrent detection signal indicates an overcurrent on the corresponding power supply branch and is used to disconnect at least one switching element in the corresponding power supply branch to disconnect the corresponding power supply branch. The second overcurrent detection signal indicates that the current on the corresponding power supply branch is not overcurrent.

3. The overcurrent detection circuit according to claim 2, wherein: The detection unit is connected between the second voltage node and a third voltage node, wherein a third voltage at the third voltage node is less than the second voltage and greater than the first voltage. The detection unit includes a second current source, a third voltage divider unit, and a fourth voltage divider unit, which are sequentially connected in series between the second voltage node and the third voltage node. The second current source is the same as the first current source, the internal resistance of the first voltage divider unit is the same as the internal resistance of the third voltage divider unit, The detection voltage is a voltage at a second connection node between the third voltage dividing subunit and the fourth voltage dividing subunit.

4. The overcurrent detection circuit according to claim 3, wherein: The output unit is connected between the second voltage node and the second connection node, The output unit includes a third current source and a control switch connected in series between the second voltage node and the second connection node. The third current source is the same as the first current source and the second current source, and the control end of the control switch is connected to a third connection node between the third voltage divider unit and the second current source, so as to turn on the control switch when the detection voltage is greater than the reference voltage. In which, the output unit also includes a logic subunit connected between a fourth connection node and the output end of the overcurrent detection circuit, and the logic subunit is used to generate and output the first overcurrent detection signal when the control switch is turned on, and to generate and output the second overcurrent detection signal when the control switch is turned off, wherein the fourth connection node is a node between the third current source and the control switch.

5. The overcurrent detection circuit according to claim 4, wherein: The fourth voltage dividing subunit includes a second resistor, wherein the second resistor is the same as the first resistor.

6. The overcurrent detection circuit according to claim 4 or 5, wherein: The logic subunit includes an inverter connected to the fourth connection node and an AND gate connected to the inverter, a first input end of the AND gate receives an output signal of the inverter, a second input end of the AND gate receives a control signal for controlling the connection or disconnection of the predetermined switching element, and an output end of the AND gate outputs the first overcurrent detection signal or the second overcurrent detection signal.

7. The overcurrent detection circuit according to claim 5, wherein: The charge pump supplies power to the battery according to a predetermined clock signal, each clock cycle of the predetermined clock signal includes a first working phase and a second working phase, and in each of the first working phase and the second working phase, the charge pump supplies power to the battery simultaneously through the first power supply branch and the second power supply branch. Wherein, when the corresponding power supply branch is the first power supply branch, the corresponding power supply branch supplies power to the battery from an external power source via the first energy storage element and the predetermined switch element, Wherein, when the corresponding power supply branch is the second power supply branch, the corresponding power supply branch supplies power to the battery from the second energy storage element via the predetermined switch element. The first energy storage element in the first power supply branch in the first working phase is the second energy storage element in the second power supply branch in the second working phase, and the second energy storage element in the second power supply branch in the first working phase is the first energy storage element in the first power supply branch in the second working phase.

8. The overcurrent detection circuit according to claim 7, further comprising: A current holding unit is connected between the reference unit and the detection unit to maintain the operating current in the overcurrent detection circuit during the non-working phase of the corresponding power supply branch, so as to be used for overcurrent detection in the next working phase of the corresponding power supply branch.

9. The overcurrent detection circuit according to claim 8, wherein: In the case where the corresponding power supply branch is the first power supply branch, The second voltage is the positive electrode voltage of the first energy storage element, and the third voltage is the negative electrode voltage of the first energy storage element. The first switching element and the predetermined switching element are turned on or off according to the same control signal. The current holding unit is a diode switch element connected between the first connection node and the second connection node.

10. The overcurrent detection circuit according to claim 8, wherein: In the case where the corresponding power supply branch is the second power supply branch, The second voltage is an external power supply voltage, the third voltage is a positive electrode voltage of the second energy storage element, wherein the first switch element is always kept in the on state, The second voltage dividing subunit further includes a second switch element connected between the first resistor and the first connection node, and the fourth voltage dividing subunit further includes a third switch element connected between the second resistor and the second connection node. The second switch element and the third switch element have the same internal resistance, the second switch element is always kept on, and the third switch element and the predetermined switch element are turned on or off according to the same control signal. The current holding unit is a fourth switch element connected between the fifth connection node and the second connection node, and the fifth connection node is a node between the first resistor and the first switch element. The fourth switch element and the predetermined switch element are connected or disconnected according to an inverted control signal.

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