Low dropout regulator with overcurrent protection function and electronic equipment

Abstract

The invention discloses a low dropout linear regulator with an overcurrent protection function and electronic equipment, the low dropout linear regulator comprises an output power tube, a load, a load capacitor, a current sampling circuit, a partial pressure feedback circuit, a current turn-back protection circuit and a control circuit, the first input end of the control circuit is connected with the current sampling circuit, and the second input end of the control circuit is connected with the load capacitor. The second input end of the control circuit is connected with the partial pressure feedback circuit, the output end of the control circuit is connected with the third end of the output power tube, the control circuit is used for receiving the reference voltage, the first voltage and the second voltage, and when the first voltage is larger than or equal to the second voltage, the output current of the output power tube is limited based on the first voltage. By means of the mode, the low dropout linear regulator uses a control loop, control and compensation of the whole loop are simplified, and therefore the difficulty of design and debugging is lowered.

Description

Technical Field

[0001] The present application relates to the technical field of low-voltage-dropout linear regulators, and in particular to a low-voltage-dropout linear regulator and electronic equipment with an overcurrent protection function. Background Art

[0002] Overcurrent protection is crucial when using a low-dropout linear regulator (LDO). It effectively prevents damage to the device caused by excessive load current and effectively limits the LDO's output current, thereby protecting the entire circuit system and ensuring stable operation.

[0003] Currently, common LDO structures with overcurrent protection primarily acquire the output current of the output power tube through a current sampling circuit and feed the output current into a current comparison circuit to generate an overcurrent signal, which is then fed into a current limiting circuit to limit the output current of the output power tube and implement overcurrent protection. Furthermore, LDO structures with overcurrent protection also monitor the output voltage of the output power tube through a voltage comparison circuit. When the output voltage drops to a preset threshold, the voltage comparison circuit outputs a valid signal, and the current comparison circuit modifies the current comparison threshold, further controlling the current limiting circuit to implement overcurrent protection functions such as current foldback protection and step foldback protection. However, LDO structures with overcurrent protection have multiple control loops, making circuit implementation and loop control more complex, increasing the difficulty of design and debugging. Summary of the Invention

[0004] This application mainly provides a low-voltage difference linear regulator and electronic equipment with overcurrent protection function, which solves the problem that the LDO structure with overcurrent protection function has multiple control loops, the loop control and compensation are relatively complex, and the difficulty of design and debugging is increased.

[0005] The present application provides a low-dropout linear regulator with an overcurrent protection function, comprising:

[0006] an output power tube, wherein a first end of the output power tube receives an input voltage;

[0007] a load, one end of the load being connected to the second end of the output power tube, and the other end of the load being grounded;

[0008] a load capacitor, one end of the load capacitor being connected to the second end of the output power tube, and the other end of the load capacitor being grounded;

[0009] a current sampling circuit, connected to the output power tube, configured to sample an output current of the output power tube and convert the output current into a first voltage;

[0010] a voltage dividing feedback circuit connected with the second end of the output power tube, configured to receive an output voltage of the output power tube and output a second voltage after voltage dividing of the output voltage;

[0011] a current foldback protection circuit connected with the voltage dividing feedback circuit and the current sampling circuit respectively;

[0012] a control circuit, a first input end of the control circuit connected with the current sampling circuit, a second input end of the control circuit connected with the voltage dividing feedback circuit, and an output end of the control circuit connected with the third end of the output power tube, the control circuit configured to receive a reference voltage, the first voltage and the second voltage, and limit the output current of the output power tube based on the first voltage when the first voltage is greater than or equal to the second voltage.

[0013] wherein, when the low-dropout linear regulator is in a normal working state, the second voltage is equal to the reference voltage, the first voltage is less than the second voltage, the set output voltage of the output power tube is obtained by dividing the reference voltage by a voltage dividing ratio of the voltage dividing feedback circuit, and the control circuit controls the output voltage of the low-dropout linear regulator to be the set output voltage based on the second voltage.

[0014] wherein, when the output current is equal to a first overcurrent protection threshold, the first voltage is equal to the reference voltage, the first voltage is equal to the second voltage, and the control circuit controls the output current of the output power tube to be the first overcurrent protection threshold based on the first voltage.

[0015] wherein, when the load demand current increases and the output voltage of the output power tube decreases, the first voltage is greater than the second voltage when the second voltage is less than the reference voltage, the first voltage is equal to the reference voltage, and the control circuit controls the output current of the output power tube to be the first overcurrent protection threshold based on the first voltage.

[0016] wherein, when the output voltage is equal to a current foldback protection threshold, the current foldback protection circuit outputs the current foldback protection effective signal to the current sampling circuit, the current sampling circuit outputs the first voltage based on the current foldback protection effective signal and the output current of the output power tube, the control circuit controls the output current of the output power tube to be a second overcurrent protection threshold based on the first voltage, and the second overcurrent protection threshold is less than the first overcurrent protection threshold.

[0017] The control circuit comprises an operational amplifier and a voltage buffer circuit, a first input end of the operational amplifier is connected with the current sampling circuit, a second input end of the operational amplifier is connected with the voltage division feedback circuit, and a third input end of the operational amplifier receives the reference voltage; and the voltage buffer circuit is connected with an output end of the operational amplifier and a third end of the output power tube respectively.

[0018] The control circuit comprises a selection control circuit, an operational amplifier and a voltage buffer circuit, the selection control circuit is connected with a first input end of the operational amplifier, the current sampling circuit and the voltage division feedback circuit respectively, a second input end of the operational amplifier receives the reference voltage, and the voltage buffer circuit is connected with an output end of the operational amplifier and a third end of the output power tube respectively.

[0019] The current sampling circuit comprises a first switch tube, a second switch tube, a third switch tube, a fourth switch tube, a fifth switch tube, a first resistor, a second resistor, a third resistor and a fourth resistor, a first end of the first switch tube is connected with a first end of the output power tube, a second end of the first switch tube is connected with a first end of the third switch tube, a third end of the first switch tube is connected with the voltage buffer circuit, a second end of the third switch tube is connected with one end of the second resistor, and the other end of the second resistor is grounded; a first end of the second switch tube is connected with a second end of the output power tube, a second end of the second switch tube is connected with one end of the first resistor, the other end of the first resistor is grounded, a third end of the second switch tube is connected with a third end of the third switch tube, and the second end of the second switch tube is connected with the third end of the second switch tube; a first end of the fifth switch tube is connected with the other end of the first resistor, a second end of the fifth switch tube is connected to the first resistor through the third resistor between one end of the first resistor and the second end of the second switch tube; a first end of the fourth switch tube is connected with the other end of the second resistor, a second end of the fourth switch tube is connected to the second resistor through the fourth resistor between one end of the second resistor and the second end of the third switch tube, and a third end of the fourth switch tube is connected with a third end of the fifth switch tube.

[0020] The current foldback protection circuit comprises a sixth switch tube, a first inverter, a second inverter and a constant current source, and the voltage division feedback circuit comprises a fifth resistor, a sixth resistor and a seventh resistor; one end of the fifth resistor is connected between one end of the load capacitor and the second end of the output power tube, the other end of the fifth resistor is connected with one end of the sixth resistor, the other end of the sixth resistor is connected with one end of the seventh resistor and the second input end of the control circuit respectively, the other end of the seventh resistor is grounded, the first end of the sixth switch tube is connected between one end of the fifth resistor and the second end of the output power tube, the second end of the sixth switch tube is grounded through the constant current source, the second end of the sixth switch tube is connected with the input end of the first inverter, the output end of the first inverter is connected with the input end of the second inverter, and the output end of the second inverter is connected between the third end of the fifth switch tube and the third end of the fourth switch tube.

[0021] The application further provides an electronic device comprising the low dropout linear regulator.

[0022] The application has the beneficial effects that: the first input end of the control circuit is connected with the current sampling circuit, the second input end of the control circuit is connected with the voltage division feedback circuit, and the output end of the control circuit is connected with the third end of the output power tube, the control circuit is used for receiving a reference voltage, a first voltage and a second voltage, and the output current of the output power tube is limited based on the first voltage when the first voltage is greater than or equal to the second voltage; the current sampling circuit and the voltage division feedback circuit are directly connected with the control circuit, overcurrent protection is realized, at this time, the overcurrent protection of the low dropout linear regulator and the overall loop control share one loop, an independent overcurrent protection loop does not need to be additionally added, and the control and implementation of the overall loop are simplified; and the current foldback protection circuit is connected with the voltage division feedback circuit and the current sampling circuit respectively, the overcurrent protection of the low dropout linear regulator is increased with the current foldback protection function, thereby the implementation and loop control of the circuit are simplified, and the difficulty of design and debugging is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings. Among them:

[0024] Figure 1 is a circuit schematic diagram of an embodiment of the LDO structure with overcurrent protection function provided by the application;

[0025] Figure 2is a circuit schematic diagram of an embodiment of a low-dropout linear regulator with over-current protection provided in the present application;

[0026] Figure 3 is an example diagram of working conditions of low-dropout linear regulator over-current protection provided in the present application;

[0027] Figure 4 is a circuit schematic diagram of another embodiment of a low-dropout linear regulator with over-current protection provided in the present application;

[0028] Figure 5 is Figure 2 and Figure 4 is a circuit schematic diagram of an embodiment of a current sampling circuit, a current foldback protection circuit, a voltage dividing feedback circuit, an output power transistor, a load and a load capacitor. DETAILED DESCRIPTION

[0029] The embodiments of the technical solutions of the present application will be described in detail below with reference to the drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, and therefore only serve as examples, and cannot limit the protection scope of the present application.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present application; the terms "include" and "have" and any variations thereof in the specification and claims of the present application and the above description of drawings are intended to cover non-exclusive inclusion.

[0031] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features.

[0032] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the present application. The appearance of the phrase in various places in the specification does not necessarily all refer to the same embodiment, nor is it necessarily independent or alternative embodiments to other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0033] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. In addition, the character " / " in this paper generally represents a "or" relationship between the front and rear associated objects.

[0034] In the description of the embodiments of the present application, the term "a plurality of" refers to two or more (including two), and similarly, "a plurality of groups" refers to two or more groups (including two groups), and "a plurality of pieces" refers to two or more pieces (including two pieces).

[0035] In the description of the embodiments of the present application, unless otherwise explicitly specified and limited, the technical terms "mounting", "connecting", "connecting", "fixing" and the like should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be connected between, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0036] Referring to Figure 1 as shown, Figure 1 is a circuit schematic diagram of an embodiment of the LDO structure with overcurrent protection function provided by the present application. The LDO structure with overcurrent protection function 100 of the embodiment includes an output power tube M0, a load RL, a load capacitor CL, a voltage division feedback circuit 110, a current sampling circuit 120, a voltage comparison circuit 130, a current comparison circuit 140, a current limiting circuit 150, a voltage buffer circuit 160 and an operational amplifier 170.

[0037] As Figure 1 shown, the LDO structure with overcurrent protection function 100 mainly obtains the output current of the output power tube M0 through the current sampling circuit 120, then sends the output current into the current comparison circuit 140 to obtain an overcurrent signal, and further sends the overcurrent signal into the current limiting circuit 150 to limit the output current of the output power tube M0, so as to realize the overcurrent protection function. In addition, the LDO structure with overcurrent protection function 100 also monitors the output voltage of the output power tube M0 through the voltage comparison circuit 130, when the output voltage drops to a preset threshold, the voltage comparison circuit 130 outputs an effective signal, the current comparison circuit 140 modifies the current comparison threshold, and further controls the current limiting circuit 150, to realize the overcurrent protection functions such as current foldback protection and step foldback protection.

[0038] The LDO structure with overcurrent protection function 100 of the embodiment has multiple control loops, and the implementation and loop control of the circuit are relatively complex, which increases the difficulty of design and debugging.

[0039] Referring to Figure 2 as shown, Figure 2This is a circuit diagram of an embodiment of a low-dropout linear regulator with overcurrent protection provided by the present application. The low-dropout linear regulator 1 with overcurrent protection in this embodiment includes an output power transistor M0, a load RL, a load capacitor CL, a current sampling circuit 10, a voltage divider feedback circuit 20, a current foldback protection circuit 30, and a control circuit 40.

[0040] The first terminal of the output power transistor M0 receives the input voltage Vin. The output power transistor M0 is usually used as a regulating element in the low voltage drop linear regulator 1 to adjust the output voltage Vout or output current Iout by controlling the conduction degree of the output power transistor M0.

[0041] Optionally, the first end of the output power tube M0 is connected to a battery to receive an input voltage Vin. In other embodiments, the first end of the output power tube M0 is connected to another power module to receive an input voltage Vin.

[0042] One end of the load RL is connected to the second end of the output power transistor M0, and the other end of the load RL is grounded. One end of the load capacitor CL is connected to the second end of the output power transistor M0, and the other end of the load capacitor CL is grounded.

[0043] In some embodiments, the second end of the output power transistor M0 is connected to one end of the load RL and one end of the load capacitor CL, respectively, to provide a stable output voltage Vout. The load capacitor CL is also called the output capacitor, and the load RL can be equivalent to a resistor, such as Figure 2 shown.

[0044] In some embodiments, in the low-voltage dropout linear regulator 1, the output current Iout of the output power tube M0 is equal to the output current Iout of the low-voltage dropout linear regulator 1; the output current Iout of the low-voltage dropout linear regulator 1 is equal to the output current Iout of the load RL plus the current flowing through the voltage divider feedback circuit 20. Since the current flowing through the voltage divider feedback circuit 20 is small, under normal circumstances, the output current Iout of the low-voltage dropout linear regulator 1 is approximately equal to the output current Iout of the load RL, that is, the output current Iout of the output power tube M0 is approximately equal to the output current Iout of the load RL; the output voltage Vout of the output power tube M0 is equal to the output voltage Vout of the low-voltage dropout linear regulator 1.

[0045] The current sampling circuit 10 is connected to the output power tube M0 and is used to sample the output current Iout of the output power tube M0 and convert the output current Iout into a first voltage V OCP_FB .

[0046] The current sampling circuit 10 includes but is not limited to current mirror sampling, resistor sampling or operational amplifier sampling.

[0047] In some embodiments, when the current sampling circuit 10 samples the current by using the current mirror, an equivalent current is obtained by using the current mirror, and the equivalent current is converted into a corresponding voltage signal, i.e., the first voltage V OCP_FB ; at this time, the conversion formula is: V OCP_FB = Iout*m*R OCP , where m is a sampling ratio of the output current Iout, and R OCP is an equivalent resistance value of the sampled output current Iout converted into the first voltage V OCP_FB .

[0048] Exemplarily, the input end of the current sampling circuit 10 is connected with the third end of the output power tube M0, as shown in the figure. Figure 2 In other embodiments, the input end of the current sampling circuit 10 is connected with the first end and / or the second end of the output power tube M0.

[0049] The voltage dividing feedback circuit 20 is connected with the second end of the output power tube M0, and is used to receive the output voltage Vout of the output power tube M0 and output the second voltage V FB after voltage dividing the output voltage Vout.

[0050] In some embodiments, the voltage dividing feedback circuit 20 includes at least one resistor, and the output voltage Vout is proportionally voltage-divided by using the voltage dividing characteristics of the resistor; at this time, the output second voltage V FB = Vout*n, where n is a voltage dividing ratio.

[0051] The current foldback protection circuit 30 is connected with the voltage dividing feedback circuit 20 and the current sampling circuit 10, respectively. The current foldback protection circuit 30 is used to acquire the output voltage Vout, detect the output voltage Vout, and output a current foldback protection effective signal to the current sampling circuit 10, so as to realize the current foldback protection function.

[0052] The first input end of the control circuit 40 is connected with the current sampling circuit 10, the second input end of the control circuit 40 is connected with the voltage dividing feedback circuit 20, and the output end of the control circuit 40 is connected with the third end of the output power tube M0. The control circuit 40 is used to receive the reference voltage Vref, the first voltage V OCP_FB and the second voltage V FB , and limit the output current Iout of the output power tube M0 based on the first voltage V OCP_FB when the first voltage V FB is greater than or equal to the second voltage V OCP_FB .

[0053] In some embodiments, the control circuit 40 receives the reference voltage Vref, the first voltage V OCP_FB and the second voltage V FB, the control circuit 40 controls the output current Iout of the low-dropout linear regulator 1 by the higher voltage between the first voltage V OCP_FB and the second voltage V FB ; since the first voltage V OCP_FB is converted by the output current Iout, when the load increases, i.e., the output current Iout increases, the first voltage V OCP_FB increases, and when the first voltage V OCP_FB is greater than or equal to the second voltage V FB , the control circuit 40 limits the output current Iout of the output power transistor M0 based on the first voltage V OCP_FB to achieve overcurrent protection.

[0054] In this embodiment, the first input end of the control circuit 40 is connected with the current sampling circuit 10, the second input end of the control circuit 40 is connected with the voltage dividing feedback circuit 20, and the output end of the control circuit 40 is connected with the third end of the output power transistor M0, the control circuit 40 is used for receiving the reference voltage Vref, the first voltage V OCP_FB and the second voltage V FB , and when the first voltage V OCP_FB is greater than or equal to the second voltage V FB , the output current Iout of the output power transistor M0 is limited based on the first voltage V OCP_FB ; by directly connecting the current sampling circuit 10 and the voltage dividing feedback circuit 20 to the control circuit 40, overcurrent protection is achieved; at this time, the overcurrent protection of the low-dropout linear regulator 1 and the overall loop control share one loop, without the need to additionally increase an independent overcurrent protection loop, thereby simplifying the control and implementation of the entire loop; and by connecting the current foldback protection circuit 30 with the voltage dividing feedback circuit 20 and the current sampling circuit 10 respectively, the overcurrent protection of the low-dropout linear regulator 1 increases the current foldback protection function, thereby simplifying the implementation and loop control of the circuit and reducing the difficulty of design and debugging.

[0055] According to some embodiments of the present application, when the low-dropout linear regulator 1 is in a normal working state, the second voltage V FB is equal to the reference voltage Vref, the first voltage V OCP_FB is less than the second voltage V FB , the reference voltage Vref is divided by the voltage dividing ratio n of the voltage dividing feedback circuit 20 to obtain the set output voltage Vo set of the output power transistor M0, and the control circuit 40 controls the output voltage Vout of the low-dropout linear regulator 1 to be the set output voltage Vo set based on the second voltage V FB .

[0056] In some embodiments, when the low-dropout linear regulator 1 is in a normal working state, the second voltage VFB Equal to the reference voltage Vref, that is, V FB =Vout*n=Vref, the first voltage V OCP_FB Less than the second voltage V FB , that is, V OCP_FB <V FB At this time, the control circuit 40 passes the second voltage V FB Control the output voltage Vout of the low-dropout linear regulator 1 to the set output voltage Vo set =Vref / n.

[0057] This embodiment realizes accurate voltage division feedback and control through the voltage division feedback circuit 20 and the control circuit 40, and the output voltage Vout can be stably maintained at the set value, that is, the output voltage Vo is set set , ensuring that the load RL obtains a stable power supply.

[0058] According to some embodiments of the present application, see Figure 3 As shown, Figure 3 This is an example diagram of the working condition of the low voltage difference linear voltage regulator overcurrent protection provided by this application. In this embodiment, when the output current Iout is equal to the first overcurrent protection threshold I OCP1 When the first voltage V OCP_FB is equal to the reference voltage Vref, the first voltage V OCP_FB Equal to the second voltage V FB , the control circuit 40 is based on the first voltage V OCP_FB Control the output current Iout of the output power tube M0 to the first overcurrent protection threshold I OCP1 .

[0059] Among them, the first overcurrent protection threshold I OCP1 The first overcurrent protection threshold I is preset and stored in the current sampling circuit 10. OCP1 The reference voltage Vref is divided by the sampled output current Iout to convert it into a first voltage V OCP_FB The equivalent resistance R OCP The product of the sampling ratio m of the output current Iout is I OCP1 =Vref / (R OCP *m)=V OCP_FB / (R OCP *m).

[0060] Since the first voltage V OCP_FB It is obtained by converting the output current Iout. According to the above conversion formula V OCP_FB =Iout*m*R OCP It can be seen that when the load RL demand current increases, that is, the output current Iout increases, the first voltage V OCP_FBWhen the output current Iout reaches the preset first overcurrent protection threshold I OCP1 When the output current Iout is equal to the first overcurrent protection threshold I OCP1 , the first voltage V OCP_FB is equal to the reference voltage Vref, the first voltage V OCP_FB Equal to the second voltage V FB , the first voltage V OCP_FB Participate in controlling the output current Iout of the low voltage difference linear regulator 1, the control circuit 40 controls the output current Iout of the low voltage difference linear regulator 1 by the first voltage V OCP_FB Control the output current Iout of the output power tube M0 to the first overcurrent protection threshold I OCP1 , limiting the output current Iout of the low-dropout linear regulator 1 from increasing, such as Figure 3 shown.

[0061] In this embodiment, the control circuit 40 can be used to control the output current Iout to reach the first overcurrent protection threshold I OCP1 When the output current Iout is stabilized at the threshold, in the case of overcurrent, the low voltage difference linear regulator 1 can still operate stably to avoid excessive current from damaging the output power tube M0 and subsequent equipment.

[0062] According to some embodiments of the present application, after the overcurrent protection is triggered, the load RL demand current increases, the output voltage Vout of the output power tube M0 decreases, and the voltage Vout decreases at the second voltage V FB When the first voltage V is less than the reference voltage Vref, OCP_FB Greater than the second voltage V FB , the control circuit 40 is based on the first voltage V OCP_FB Control the output current Iout of the output power tube M0 to the first overcurrent protection threshold I OCP1 .

[0063] like Figure 3 As shown, when the load RL demand current continues to increase, the output voltage Vout will continue to decrease, and the second voltage V FB is less than the reference voltage Vref, the first voltage V OCP_FB Greater than the second voltage V FB ; At this time, the first voltage V OCP_FB The output current Iout of the low voltage drop linear regulator 1 is fully controlled by the control circuit 40 through the first voltage V OCP_FB Control the output current Iout of the output power tube M0 to the first overcurrent protection threshold I OCP1 .

[0064] According to some embodiments of the present application, see Figure 2 and Figure 3 As shown, when the output voltage Vout is equal to the current foldback protection threshold V foldbackWhen the current foldback protection circuit 30 outputs a current foldback protection valid signal to the current sampling circuit 10, the current sampling circuit 10 outputs a first voltage V based on the current foldback protection valid signal and the output current Iout of the output power tube M0. OCP_FB , the control circuit 40 is based on the first voltage V OCP_FB Control the output current Iout of the output power tube M0 to the second overcurrent protection threshold I OCP2 , the second overcurrent protection threshold I OCP2 Less than the first overcurrent protection threshold I OCP1 .

[0065] like Figure 3 As shown in the figure, the load RL demand current continues to increase, and the output voltage Vout continues to decrease. When the output voltage Vout drops to the current foldback protection threshold V foldback At this time, the current foldback protection circuit 30 generates a current foldback protection valid signal and sends the current foldback protection valid signal to the current sampling circuit 10. The current sampling circuit 10 sets the first overcurrent protection threshold I OCP1 Lowered to the lower second overcurrent protection threshold I OCP2 At the same time, the current sampling circuit 10 outputs a first voltage V according to the output current Iout of the output power tube M0 OCP_FB , the control circuit 40 passes the first voltage V OCP_FB Control the output current Iout of the output power tube M0 to the second overcurrent protection threshold I OCP2 .

[0066] In this embodiment, when the output voltage Vout drops to the current foldback protection threshold V foldback When the current foldback protection circuit 30 outputs a current foldback protection valid signal to the current sampling circuit 10, the control circuit 40 is based on the first voltage V OCP_FB Control the output current Iout of the output power tube M0 to the lower second overcurrent protection threshold I OCP2 , reducing the output current Iout of the output power tube M0 to avoid thermal damage to the output power tube M0.

[0067] According to some embodiments of the present application, see Figure 2 As shown, the control circuit 40 of this embodiment includes an operational amplifier 41 and a voltage buffer circuit 42. The first input terminal of the operational amplifier 41 is connected to the current sampling circuit 10, the second input terminal of the operational amplifier 41 is connected to the voltage divider feedback circuit 20, the third input terminal of the operational amplifier 41 receives the reference voltage Vref, and the voltage buffer circuit 42 is respectively connected to the output terminal of the operational amplifier 41 and the third terminal of the output power tube M0.

[0068] The first input terminal and the second input terminal of the operational amplifier 41 are positive phase input terminals, and the third input terminal is a negative phase input terminal. The higher voltage signal at the positive phase input terminal of the operational amplifier 41 is the second voltage V FB When the second voltage V FB Control the output voltage Vout of the low voltage drop linear regulator 1; the higher voltage signal at the positive input terminal of the operational amplifier 41 is the first voltage V OCP_FB When the first voltage V OCP_FB The maximum output current (output current Iout) of the low-dropout linear regulator 1 is controlled.

[0069] This embodiment can accurately compare the input signal (the first voltage V OCP_FB and the second voltage V FB ) and adjusts the output to ensure the stability of the output voltage Vout and the output current Iout. The high gain characteristic of the operational amplifier 41 can quickly respond to changes in the input signal, thereby improving the accuracy of the low-dropout linear regulator 1; and through the voltage buffer circuit 42, it is ensured that the output signal of the operational amplifier 41 can quickly drive the output power tube M0. At the same time, the parasitic capacitance of the output power tube M0 and the output impedance of the operational amplifier 41 are isolated, thereby simplifying loop compensation and improving system stability.

[0070] According to some embodiments of the present application, see Figure 4 As shown, Figure 4 This is a circuit diagram of another embodiment of a low-dropout linear regulator with overcurrent protection provided by the present application. The control circuit 40 of this embodiment includes a selection control circuit 43, an operational amplifier 41, and a voltage buffer circuit 42. The selection control circuit 43 is respectively connected to the first input terminal of the operational amplifier 41, the current sampling circuit 10, and the voltage divider feedback circuit 20. The second input terminal of the operational amplifier 41 receives a reference voltage Vref. The voltage buffer circuit 42 is respectively connected to the output terminal of the operational amplifier 41 and the third terminal of the output power transistor M0.

[0071] The selection control circuit 43 is used to receive the first voltage V OCP_FB and the second voltage V FB , and the first voltage V OCP_FB and the second voltage V FB After comparison, the higher voltage is selected as the effective voltage V FBSEL , and outputs it to the non-inverting input terminal of the operational amplifier 41, which then outputs it to the non-inverting input terminal of the operational amplifier 41 through the effective voltage V FBSEL Control the output current Iout or output voltage Vout of the output power tube M0.

[0072] The selection control circuit 43 includes, but is not limited to, a comparator, an AND gate, and a switch circuit.

[0073] The embodiment can select appropriate input signals (first voltage V OCP_FB and second voltage V FB ) according to different working modes (such as normal working mode, over-current protection mode, current foldback protection mode, etc.) through the selection control circuit 43, thereby enhancing the adaptability of the system.

[0074] According to some embodiments of the present application, referring to Figure 5 , the current sampling circuit, the current foldback protection circuit, the voltage division feedback circuit, the output power tube, the load, and the load capacitor are shown in the circuit schematic diagram of an embodiment. Figure 5 Figure 2 and Figure 4 The current sampling circuit 10 includes a first switch tube M1, a second switch tube M2, a third switch tube M3, a fourth switch tube M4, a fifth switch tube M5, a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4.

[0075] The first switch tube M0 is a power tube of the same type as the output power tube M0, including but not limited to a PLDMOS tube.

[0076] The first end of the first switch tube M1 is connected to the first end of the output power tube M0, the second end of the first switch tube M1 is connected to the first end of the third switch tube M3, the third end of the first switch tube M1 is connected to the voltage buffer circuit 42, the second end of the second resistor R2 is connected to the second end of the third switch tube M3, and the other end of the second resistor R2 is grounded; the first end of the second switch tube M2 is connected to the second end of the output power tube M0, one end of the first resistor R1 is connected to the second end of the second switch tube M2, and the other end of the first resistor R1 is grounded, the third end of the second switch tube M2 is connected to the third end of the third switch tube M3, and the second end of the second switch tube M2 is connected to the third end; the other end of the first resistor R1 is connected to the first end of the fifth switch tube M5, the second end of the fifth switch tube M5 is connected to the first end of the first resistor R1 and the second end of the second switch tube M2 through the third resistor R3; the other end of the second resistor R2 is connected to the first end of the fourth switch tube M4, the second end of the fourth switch tube M4 is connected to the first end of the second resistor R2 and the second end of the third switch tube M3 through the fourth resistor R4, and the third end of the fourth switch tube M4 is connected to the third end of the fifth switch tube M5.

[0077] The first switch tube M1 and the output power tube M0 both receive the output of the voltage buffer circuit 42; the current sampling circuit 10 outputs the first voltage V OCP_FB through one end of the second resistor R2 and the fourth resistor R4.

[0078] ​The current sampling circuit 10 in this embodiment is only one of the current mirror structures, and other current mirror structures can be used in other embodiments.

[0079] According to some embodiments of the present application, referring to Figure 5 As shown in the figure, the current foldback protection circuit 30 includes a sixth switch tube M6, a first inverter I0, a second inverter I1, and a constant current source I2, and the voltage division feedback circuit 20 includes a fifth resistor R5, a sixth resistor R6, and a seventh resistor R7.

[0080] One end of the fifth resistor R5 is connected between one end of the load capacitor CL and the second end of the output power tube M0, the other end of the fifth resistor R5 is connected with one end of the sixth resistor R6, the other end of the sixth resistor R6 is connected with one end of the seventh resistor R7 and the second input end of the control circuit 40 respectively, the other end of the seventh resistor R7 is grounded, the first end of the sixth switch tube M6 is connected between one end of the fifth resistor R5 and the second end of the output power tube M0, the second end of the sixth switch tube M6 is grounded through the constant current source I2, the second end of the sixth switch tube M6 is connected with the input end of the first inverter I0, the output end of the first inverter I0 is connected with the input end of the second inverter I1, and the output end of the second inverter I1 is connected between the third end of the fifth switch tube M5 and the third end of the fourth switch tube M4.

[0081] Optionally, the first switch tube M1 and the output power tube M0 are PLDMOS tubes, the first switch tube M1 is a current mirror, the output power tube M0 is used to provide the output current Iout of the LDO, and the first switch tube M1 is used to detect the output current Iout of the LDO; the first end of the output power tube M0 and the first end of the first switch tube M1 are source electrodes, the second end of the output power tube M0 and the second end of the first switch tube M1 are drain electrodes, and the third end of the output power tube M0 and the third end of the first switch tube M1 are gate electrodes.

[0082] Optionally, the second switch tube M2, the third switch tube M3, and the sixth switch tube M6 are PMOS tubes, the first end of the second switch tube M2, the first end of the third switch tube M3, and the first end of the sixth switch tube M6 are source electrodes, the second end of the second switch tube M2, the second end of the third switch tube M3, and the second end of the sixth switch tube M6 are drain electrodes, and the third end of the second switch tube M2, the third end of the third switch tube M3, and the third end of the sixth switch tube M6 are gate electrodes; the second switch tube M2 and the third switch tube M3 are mainly used to control the source and drain voltage difference of the output power tube M0 and the first switch tube M1 (current mirror) to be the same by using the current mirror function of the current mirror, so as to ensure the mirror accuracy of the current mirror; the sixth switch tube M6 is mainly used to form a current source load single-stage common source amplifier structure with the constant current source I2, and the sixth switch tube M6 is a common source amplifier signal input tube; the voltage division feedback circuit 20 is used to detect the drop of the output voltage Vout.

[0083] Optionally, the fourth switch tube M4 and the fifth switch tube M5 are NMOS tubes, the first end of the fourth switch tube M4 and the first end of the fifth switch tube M5 are sources, the second end of the fourth switch tube M4 and the second end of the fifth switch tube M5 are drains, and the third end of the fourth switch tube M4 and the third end of the fifth switch tube M5 are gates.

[0084] Another embodiment of the present application also provides an electronic device comprising the low-dropout linear voltage regulator 1 of the above-mentioned embodiments. The electronic device includes, but is not limited to, a mobile phone, a tablet, a computer, or a blood glucose meter.

[0085] In summary, the present application directly connects the current sampling circuit 10 and the voltage division feedback circuit 20 to the control circuit 40 to achieve overcurrent protection. At this time, the overcurrent protection of the low-dropout linear voltage regulator 1 and the overall loop control share one loop, and there is no need to additionally increase an independent overcurrent protection loop, thereby simplifying the control and implementation of the overall loop. Moreover, by connecting the current foldback protection circuit 30 to the voltage division feedback circuit 20 and the current sampling circuit 10, respectively, the overcurrent protection of the low-dropout linear voltage regulator 1 is increased with a current foldback protection function, thereby simplifying the implementation and loop control of the circuit and reducing the difficulty of design and debugging.

[0086] The above is merely an embodiment of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent flow transformation using the content of the specification and drawings, or direct or indirect application in other related technical fields, is also included in the patent protection scope of the present application.

Claims

1. A low voltage dropout linear regulator with overcurrent protection function, characterized in that: include: an output power tube, wherein a first end of the output power tube receives an input voltage; a load, one end of the load being connected to the second end of the output power tube, and the other end of the load being grounded; a load capacitor, one end of the load capacitor being connected to the second end of the output power tube, and the other end of the load capacitor being grounded; a current sampling circuit, connected to the output power tube, configured to sample an output current of the output power tube and convert the output current into a first voltage; a voltage-dividing feedback circuit connected to the second end of the output power tube, configured to receive the output voltage of the output power tube, divide the output voltage, and output a second voltage; a current foldback protection circuit, connected to the voltage divider feedback circuit and the current sampling circuit respectively; A control circuit, wherein a first input end of the control circuit is connected to the current sampling circuit, a second input end of the control circuit is connected to the voltage divider feedback circuit, and an output end of the control circuit is connected to the third end of the output power tube. The control circuit is used to receive a reference voltage, the first voltage and the second voltage, and when the first voltage is greater than or equal to the second voltage, limit the output current of the output power tube based on the first voltage.

2. The low-dropout linear regulator according to claim 1, wherein: When the low-voltage-dropout linear regulator is in a normal working state, the second voltage is equal to the reference voltage, the first voltage is less than the second voltage, the reference voltage is divided by the voltage-dividing ratio of the voltage-dividing feedback circuit to obtain the set output voltage of the output power tube, and the control circuit controls the output voltage of the low-voltage-dropout linear regulator to be the set output voltage based on the second voltage.

3. The low-dropout linear regulator according to claim 2, wherein: When the output current is equal to a first overcurrent protection threshold, the first voltage is equal to the reference voltage, the first voltage is equal to the second voltage, and the control circuit controls the output current of the output power tube to be the first overcurrent protection threshold based on the first voltage.

4. The low-dropout linear regulator according to claim 3, wherein: The load demand current increases, and the output voltage of the output power tube decreases. When the second voltage is less than the reference voltage, the first voltage is greater than the second voltage, and the first voltage is equal to the reference voltage. The control circuit controls the output current of the output power tube to be the first overcurrent protection threshold based on the first voltage.

5. The low-dropout linear regulator according to claim 4, wherein: When the output voltage is equal to the current foldback protection threshold, the current foldback protection circuit outputs the current foldback protection effective signal to the current sampling circuit, and the current sampling circuit outputs the first voltage based on the current foldback protection effective signal and the output current of the output power tube. The control circuit controls the output current of the output power tube to be the second overcurrent protection threshold based on the first voltage, and the second overcurrent protection threshold is less than the first overcurrent protection threshold.

6. The low dropout linear regulator according to claim 1, wherein: The control circuit includes an operational amplifier and a voltage buffer circuit, the first input terminal of the operational amplifier is connected to the current sampling circuit, the second input terminal of the operational amplifier is connected to the voltage divider feedback circuit, the third input terminal of the operational amplifier receives the reference voltage, and the voltage buffer circuit is respectively connected to the output terminal of the operational amplifier and the third terminal of the output power tube.

7. The low-dropout linear regulator according to claim 1, wherein: The control circuit includes a selection control circuit, an operational amplifier and a voltage buffer circuit. The selection control circuit is respectively connected to the first input terminal of the operational amplifier, the current sampling circuit and the voltage divider feedback circuit. The second input terminal of the operational amplifier receives the reference voltage. The voltage buffer circuit is respectively connected to the output terminal of the operational amplifier and the third terminal of the output power tube.

8. The low-dropout linear regulator according to claim 6 or 7, characterized in that: The current sampling circuit includes a first switching transistor, a second switching transistor, a third switching transistor, a fourth switching transistor, a fifth switching transistor, a first resistor, a second resistor, a third resistor, and a fourth resistor. The first end of the first switching transistor is connected to the first end of the output power transistor, the second end of the first switching transistor is connected to the first end of the third switching transistor, the third end of the first switching transistor is connected to the voltage buffer circuit, the second end of the third switching transistor is connected to one end of the second resistor, and the other end of the second resistor is grounded. The first end of the second switching transistor is connected to the second end of the output power transistor, the second end of the second switching transistor is connected to one end of the first resistor, and the other end of the first resistor is grounded. The third end of the second switching transistor is connected to the third end of the third switching transistor, and the second end of the second switching transistor is connected to the third end. The first end of the fifth switching transistor is connected to the other end of the first resistor, and the second end of the fifth switching transistor is connected between one end of the first resistor and the second end of the second switching transistor through the third resistor. The first end of the fourth switching transistor is connected to the other end of the second resistor, and the second end of the fourth switching transistor is connected between one end of the second resistor and the second end of the third switching transistor through the fourth resistor. The third end of the fourth switching transistor is connected to the third end of the fifth switching transistor.

9. The low-dropout linear regulator according to claim 8, wherein: The current foldback protection circuit includes a sixth switch tube, a first inverter, a second inverter, and a constant current source. The voltage divider feedback circuit includes a fifth resistor, a sixth resistor, and a seventh resistor. One end of the fifth resistor is connected between one end of the load capacitor and the second end of the output power tube, the other end of the fifth resistor is connected to one end of the sixth resistor, the other end of the sixth resistor is respectively connected to one end of the seventh resistor and the second input end of the control circuit, and the other end of the seventh resistor is grounded. The first end of the sixth switch tube is connected between one end of the fifth resistor and the second end of the output power tube, the second end of the sixth switch tube is grounded through the constant current source, the second end of the sixth switch tube is connected to the input end of the first inverter, the output end of the first inverter is connected to the input end of the second inverter, and the output end of the second inverter is connected between the third end of the fifth switch tube and the third end of the fourth switch tube.

10. An electronic device, characterized in that: The invention comprises a low voltage dropout linear regulator as claimed in any one of claims 1 to 9.

Images