Low dropout regulator and control method

Abstract

The invention discloses a low dropout linear regulator and a control method, a mode control circuit in the low dropout linear regulator compares a power supply voltage with a reference voltage threshold value, and outputs a target level signal of a corresponding level state according to a comparison result; the feedback circuit triggers a corresponding gating state according to the target level signal; wherein in different gating states, the resistance values of the resistors connected between the error amplification module and the grounding end of the feedback circuit are different, and the feedback voltages, output to the error amplification module based on the power supply voltage, of the feedback circuit are different; and a power output circuit of the low dropout regulator outputs corresponding power supply voltage according to the error signal output by the error amplification module. The low-dropout linear regulator can output different power supply voltages according to different power supply voltages, the actual requirement for inputting different power supply voltages to different modules of an analog circuit and a digital circuit is met, and internal power supply of a large-scale integrated circuit can be achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of power management modules, and in particular relates to a low voltage drop linear regulator and a control method thereof. Background Art

[0002] A low dropout linear regulator (LDO) can stably convert a higher input voltage into a lower output voltage while minimizing the voltage difference between input and output to provide a stable voltage for the chip.

[0003] As the scale of integrated circuits continues to expand and the degree of integration continues to increase, different modules of analog circuits and digital circuits in the chip have actual needs to input different power supply voltages. Especially in mixed analog and digital circuits, multiple power supply voltages are required to support the working modes of different modules. The power supply voltage provided by the low-dropout linear regulator in the related art can no longer meet the power supply requirements inside large-scale integrated circuits. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a low voltage dropout linear regulator and a control method, aiming to solve the problem that the power supply voltage provided by the low voltage dropout linear regulator in the related art cannot meet the actual power supply demand of the integrated circuit.

[0005] To solve the above technical problems, the present invention is implemented as follows: a low voltage difference linear regulator, comprising: a low voltage difference linear regulator circuit and a mode control circuit; the low voltage difference linear regulator circuit comprises a feedback circuit, an error amplification module, a reference voltage source and a power output circuit; The mode control circuit is used to compare the power supply voltage with a reference voltage threshold, and output a target level signal of a corresponding level state according to the comparison result; The feedback circuit is used to trigger a corresponding gating state according to the target level signal; wherein, in different gating states, the resistance value of the resistor connected to the error amplification module and the ground terminal of the feedback circuit is different, and the feedback voltage obtained by the feedback circuit based on the supply voltage sampled by the power output circuit is different; The error amplification module is used to output a corresponding error signal according to the feedback voltage corresponding to the different gating states and the reference voltage generated by the reference voltage source; The power output circuit is used to output a stable power supply voltage according to the error signal. Further, the mode control circuit includes a first detection module, a second detection module and a logic circuit, the first detection module includes a first power tube and a Schmitt trigger, the second detection module includes a universal comparator, and the level state switching sensitivity of the second detection module is greater than that of the first detection module; The first detection module is used to compare its reference voltage threshold with the power supply voltage, and output a first level signal of a corresponding level state according to the comparison result, wherein the voltage threshold referenced by the first detection module is a threshold voltage of the first power tube entering a subthreshold conduction state; The second detection module is used to compare the voltage threshold referenced by the second detection module with the power supply voltage, and output a second level signal of a corresponding level state according to the comparison result, wherein the voltage threshold referenced by the second detection module is the reference voltage inputted to the universal comparator by the reference voltage source, and the voltage threshold referenced by the first detection module is less than the voltage threshold referenced by the second detection module when the reference voltage source reaches a stable state; The logic circuit is used to perform a logic operation according to the level states of the first level signal and the second level signal, and output the target level signal of the corresponding level state according to the logic operation result.

[0006] Furthermore, the first detection module also includes a Schmitt trigger, and the first power tube is used to output a trigger voltage based on the power supply voltage output to the Schmitt trigger after entering the subthreshold conduction state, and the Schmitt trigger is used to compare the trigger voltage with the voltage threshold of the Schmitt trigger, and output a first level signal of the corresponding level state according to the comparison result.

[0007] Furthermore, the first detection module also includes a first resistor array; The first end of the first resistor array is used to electrically connect to the power supply voltage output end, the gate of the first power tube is electrically connected to the second end of the first resistor array, the source of the first power tube is grounded, the drain of the first power tube is electrically connected to the input end of the Schmitt trigger, the input end of the Schmitt trigger is also electrically connected to the second end of the first resistor array, and the output end of the Schmitt trigger is electrically connected to the input end of the logic circuit.

[0008] Furthermore, the second detection module also includes a second resistor array, a second power tube and an inverter; The first end of the second resistor array is used to electrically connect to the power supply voltage output end, the positive end of the universal comparator is electrically connected to the second end of the second resistor array, the output end of the universal comparator is also electrically connected to the input end of the inverter, the output end of the inverter is electrically connected to the gate of the second power tube, the source of the second power tube is used to electrically connect to the power supply voltage output end, and the gate of the second power tube is electrically connected to the third end of the second resistor array.

[0009] Further, the feedback circuit includes a plurality of feedback resistors and at least one switch module; A plurality of feedback resistors are connected in series and / or in parallel to form a resistor feedback array, a first end of the resistor feedback array is electrically connected to the output end of the power output circuit, a second end of the resistor feedback array is electrically connected to the input end of the error amplification module, and a third end of the resistor feedback array is grounded; Each of the switch modules is connected in series or in parallel with at least part of the feedback resistors, and each of the switch modules is used to switch a switch state according to the target level signal, so that the feedback circuit triggers a corresponding gating state according to the target level signal.

[0010] Furthermore, N feedback resistors are connected in series to form the resistor feedback array, wherein N is a positive integer and N≥3; there is a node between any two feedback resistors, and a resistor path with different resistance values ​​is formed between the first feedback resistor of the resistor feedback array and any one of the nodes; Each of the switch modules includes an output end and at least two input ends, and the output end of each of the switch modules is electrically connected to the input end of the error amplification module, wherein in different selection states, an input end of the switch module is electrically connected to the corresponding node.

[0011] The present invention also provides a control method for a low voltage drop linear regulator, wherein the low voltage drop linear regulator comprises a low voltage drop linear voltage regulator circuit and a mode control circuit; the low voltage drop linear voltage regulator circuit comprises a feedback circuit, an error amplification module, a reference voltage source and a power output circuit; The mode control circuit compares the power supply voltage with a reference voltage threshold, and outputs a target level signal of a corresponding level state according to the comparison result; The feedback circuit triggers a corresponding gating state according to the target level signal; wherein, in different gating states, the resistance value of the resistor connected to the error amplification module and the ground terminal of the feedback circuit is different, and the feedback voltage obtained by the feedback circuit based on the supply voltage sampled by the power output circuit is different; The error amplification module outputs a corresponding error signal according to the feedback voltage corresponding to the different gating states and the reference voltage generated by the reference voltage source; The power output circuit outputs a stable supply voltage according to the error signal.

[0012] Further, the mode control circuit includes a first detection module, a second detection module and a logic circuit, the first detection module includes a first power tube and a Schmitt trigger, the second detection module includes a universal comparator, and the level state switching sensitivity of the second detection module is greater than that of the first detection module; The first detection module compares a voltage threshold referenced by the first detection module with the power supply voltage, and outputs a first level signal of a corresponding level state according to the comparison result, wherein the voltage threshold referenced by the first detection module is a threshold voltage of the first power tube entering a subthreshold conduction state; The second detection module compares a voltage threshold referenced by the second detection module with the power supply voltage, and outputs a second level signal of a corresponding level state according to the comparison result, wherein the voltage threshold referenced by the second detection module is the reference voltage inputted to the universal comparator by the reference voltage source, and the voltage threshold referenced by the first detection module is less than the voltage threshold referenced by the second detection module when the reference voltage source reaches a stable state; The logic circuit performs a logic operation according to the level states of the first level signal and the second level signal, and outputs the target level signal of the corresponding level state according to the logic operation result.

[0013] Furthermore, the first detection module also includes a Schmitt trigger; After entering the subthreshold conduction state, the first power tube outputs a trigger voltage based on the power supply voltage to the Schmitt trigger. The Schmitt trigger compares the trigger voltage with the voltage threshold of the Schmitt trigger and outputs a first level signal of the corresponding level state according to the comparison result.

[0014] Compared with the prior art, the low voltage drop linear regulator and control method in the present invention have the following beneficial effects: The low-voltage difference linear regulator in the present invention has a mode control circuit that can control the feedback circuit to output different feedback voltages according to the detected power supply voltage, and the feedback voltage is input to the error amplification module, and the power output circuit is further made to output the corresponding power supply voltage through the negative feedback control mode of the error amplification module. The low-voltage difference linear regulator can output different power supply voltages according to different power supply voltages, which meets the actual needs of inputting different power supply voltages to different modules of analog circuits and digital circuits, and is conducive to realizing the internal power supply of large-scale integrated circuits. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a circuit structure block diagram of a low voltage dropout linear regulator in an embodiment of the present invention; Figure 2 is a circuit diagram of a low voltage difference linear voltage stabilizing circuit in an embodiment of the present invention; Figure 3 is a circuit structure block diagram of a mode control circuit in an embodiment of the present invention; Figure 4 is a circuit diagram of a first detection module in an embodiment of the present invention; Figure 5is a circuit diagram of a second detection module in an embodiment of the present invention; Figure 6 1 is a basic flow chart of a control method for a low voltage dropout linear regulator according to an embodiment of the present invention.

[0016] In the accompanying drawings, each reference numeral represents: 100, low voltage difference linear voltage regulator circuit; 200, mode control circuit; 210, first detection module; 220, second detection module; 230, logic circuit. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0018] Example: See also Figures 1 to 5 , a low voltage difference linear regulator, comprising: a low voltage difference linear regulator circuit 100 and a mode control circuit 200; the low voltage difference linear regulator circuit 100 comprises a feedback circuit, an error amplification module, a reference voltage source and a power output circuit; The mode control circuit 200 is used to compare the power supply voltage with a reference voltage threshold, and output a target level signal of a corresponding level state according to the comparison result; The feedback circuit is used to trigger a corresponding gating state according to a target level signal; wherein, in different gating states, the resistance value of the resistor connected to the error amplification module and the ground terminal of the feedback circuit is different, and the feedback voltage obtained by the feedback circuit based on the power supply voltage sampled by the power output circuit is different; The error amplification module is used to output a corresponding error signal according to the feedback voltage corresponding to different gating states and the reference voltage VREF generated by the reference voltage source; The power output circuit is used to output a stable power supply voltage according to the error signal. In this embodiment, the mode control circuit 200 can control the feedback circuit to output different feedback voltages according to the detected power supply voltage, and the feedback voltage is input to the error amplification module, and the power output circuit is further made to output the corresponding power supply voltage through the negative feedback control mode of the error amplification module. The low voltage difference linear regulator can output different power supply voltages according to different power supply voltages, which meets the actual needs of inputting different power supply voltages to different modules of analog circuits and digital circuits, and is conducive to realizing the internal power supply of large-scale integrated circuits.

[0019] As an example, Figure 2 As shown, the error amplification module includes an error amplifier and an output power tube.

[0020] The reference voltage source is used to output the reference voltage VREF to the negative end of the error amplifier, the feedback voltage is output to the positive end of the error amplifier, the output end of the error amplifier is used to output the error signal to the gate of the output power tube, the power supply voltage is input to the source of the output power tube, the drain of the power output tube is used to output the corresponding power supply voltage according to the error signal, and the drain of the power output tube is also used to output the power supply voltage to the feedback circuit.

[0021] Further, the feedback circuit includes a plurality of feedback resistors and at least one switch module; A plurality of feedback resistors are connected in series and / or in parallel to form a resistor feedback array, a first end of the resistor feedback array is electrically connected to the output end of the power output circuit, a second end of the resistor feedback array is electrically connected to the input end of the error amplification module, and a third end of the resistor feedback array is grounded; Each switch module is connected in series or in parallel with at least part of the feedback resistors, and each switch module is used to switch the switch state according to the target level signal, so that the feedback circuit triggers the corresponding gating state according to the target level signal.

[0022] In different gating states, each switch module switches to a corresponding switch state, so that the resistance value of the resistor connected to the error amplification module and the ground terminal of the feedback circuit is different.

[0023] Further, N feedback resistors are connected in series to form a resistor feedback array, wherein N is a positive integer and N≥3; there is a node between any two feedback resistors, and a resistor path with different resistance values ​​is formed between the first feedback resistor of the resistor feedback array and any node; Each switch module includes an output terminal and at least two input terminals, and the output terminal of each switch module is electrically connected to the input terminal of the error amplification module, wherein in different selection states, an input terminal of the switch module is electrically connected to the corresponding node.

[0024] In this embodiment, if Figure 2 As shown, the resistor feedback array includes feedback resistors R1, R2 and R3 connected in series. There is a first node between the feedback resistors R1 and R2, and there is a second node between the feedback resistors R2 and R3. The feedback circuit includes a switch module, which is a dual-way gate switch, and the dual-way gate switch includes two input terminals S1 and S2.

[0025] The mode control circuit 200 outputs a target level signal SEL to the control end of the dual-way switch. The target level signal SEL controls the input end S1 of the dual-way switch to be selected with the first node, or the target level signal SEL controls the input end S2 of the dual-way switch to be selected with the second node, so that the error amplifier inputs different feedback voltages, so that the low-dropout linear regulator can output two different supply voltages VOUT_H and VOUT_L.

[0026] Specifically, Figure 2 As shown, the steps for a low dropout linear regulator to output two different supply voltages are as follows: (1) Working mode: S1 is disconnected, S2 is enabled When the dual-channel gate switch S2 is turned on, the output power tube MP1 converts the output level of the error amplifier EA into the current IH. At this time, the supply voltage of the output power tube MP1 is:

[0027] In the resistor feedback array setting of the operating mode, the feedback voltage is:

[0028] When the voltage is regulated, the voltage at the positive terminal and the negative terminal of the error amplifier are the same, that is, VFB=VREF. Then the first supply voltage of the regulated output of the low-dropout linear regulator in the working mode is:

[0029] (2) Hold mode: S1 is on, S2 is off When the dual-channel gate switch S1 is turned on, the output power tube MP1 converts the output level of the error amplifier EA into the current IL. At this time, the supply voltage of the output power tube MP1 is:

[0030] With the resistor feedback array set in hold mode, the feedback voltage is:

[0031] When the voltage is regulated, the voltage of the positive terminal and the negative terminal of the error amplifier EA are the same, that is, VFB=VREF. Then the second supply voltage of the regulated output of the low-dropout linear regulator in the holding mode is:

[0032] In this way, by switching the dual-path gate switches S1 and S2 , the low voltage difference linear regulator can have two power supply modes with regulated outputs, and the first power supply voltage VOUT_H>the second power supply voltage VOUT_L.

[0033] It can be understood that in other embodiments, it is not limited to the resistor feedback array formed by multiple feedback resistors connected in series. The feedback resistor can be a variable resistor or a resistor with a fixed resistance. The switch module is not limited to only one. The switch module can also be a single-pole single-throw switch or other types of switches.

[0034] Furthermore, if Figures 3 to 5, the mode control circuit 200 includes a first detection module 210, a second detection module 220 and a logic circuit 230, the first detection module 210 includes a first power tube and a Schmitt trigger, the second detection module 220 includes a universal comparator COMP, and the level state switching sensitivity of the second detection module 220 is greater than that of the first detection module 210; The first detection module 210 is used to compare its reference voltage threshold with the power supply voltage, and output a first level signal of a corresponding level state according to the comparison result, wherein the voltage threshold referenced by the first detection module 210 is the threshold voltage of the first power tube entering the subthreshold conduction state; The second detection module 220 is used to compare the voltage threshold referenced by it with the power supply voltage, and output a second level signal of a corresponding level state according to the comparison result, wherein the voltage threshold referenced by the second detection module 220 is the reference voltage VREF inputted by the reference voltage source to the universal comparator COMP, and the voltage threshold referenced by the first detection module 210 is less than the voltage threshold referenced by the second detection module 220 when the reference voltage source reaches a stable state; The logic circuit 230 is used to perform a logic operation according to the level states of the first level signal and the second level signal, and output a target level signal of a corresponding level state according to the logic operation result.

[0035] In this embodiment, the voltage threshold referenced by the second detection module 220 is the reference voltage VREF output when the reference voltage source reaches a stable state. During the power-on process of the reference voltage source, the power supply voltage gradually increases. Since it takes some time for the reference voltage to be established stably, the power supply voltage of the second detection module 220 may be greater than the unstable reference voltage, resulting in an erroneous level state of the second level signal output by the second detection module 220.

[0036] Since the voltage threshold referenced by the first detection module 210 is the threshold voltage for the first power tube to enter the subthreshold conduction state, the threshold voltage for the first power tube to enter the subthreshold conduction state will not fluctuate with the power-on process, and the voltage threshold referenced by the first detection module 210 is smaller than the voltage threshold referenced by the second detection module 220 when the reference voltage source reaches a stable state. During the power-on process, the power supply voltage will first be compared with the voltage threshold referenced by the first detection module 210. As long as the power supply voltage does not exceed the voltage threshold referenced by the first detection module 210, the second level signal output by the second detection module 220 will not cause the feedback circuit to change the selection state. The first detection module 210 thereby realizes the power-on detection function, and the first detection module 210 can prevent the second detection module 220 from outputting a second level signal of an erroneous level state.

[0037] The level state switching sensitivity of the second detection module 220 is greater than that of the first detection module 210, because the voltage threshold referenced by the first detection module 210 is the threshold voltage of the first power tube entering the subthreshold conduction state. When the gate voltage of the first power tube is lower than the threshold voltage and still higher than the source voltage, the first power tube enters the subthreshold conduction state. Therefore, the level state switching range of the first detection module 210 is wider, and the level switching sensitivity is lower than that of the second detection module 220, but correspondingly, the first detection module 210 has a larger voltage locking range, is not easily affected by small fluctuations and noise of the power supply voltage, and can also meet the requirements of low power consumption design, and the cost is lower than that of the detection module with higher level state switching sensitivity, which is economical and efficient. The voltage threshold referenced by the second detection module 220 is the reference voltage VREF output when the reference voltage source reaches a stable state. The level state switching of the second level signal output by the second detection module 220 is more accurate, which can enable the feedback circuit to accurately trigger the corresponding gating state according to the target level signal, and the power output circuit outputs the corresponding power supply voltage faster according to the power supply voltage.

[0038] Therefore, the mode control circuit 200 in this embodiment uses two detection modules with different level switching sensitivities and different reference voltage thresholds to make the low-voltage difference linear regulator output the corresponding feedback voltage based on the power supply voltage more stable and accurate, ensuring that the mode control circuit 200 has no abnormal pulses and solving the unstable factors in the feedback voltage regulation during the power-on process.

[0039] Furthermore, if Figure 4 As shown, the first detection module 210 also includes a Schmitt trigger. The first power tube is used to output a trigger voltage based on the power supply voltage to the Schmitt trigger after entering the subthreshold conduction state. The Schmitt trigger is used to compare the trigger voltage with the voltage threshold of the Schmitt trigger and output a first level signal of the corresponding level state according to the comparison result.

[0040] Furthermore, if Figure 4 As shown, the first detection module 210 also includes a first resistor array; The first end of the first resistor array is used to electrically connect to the power supply voltage output end, the gate of the first power tube is electrically connected to the second end of the first resistor array, the source of the first power tube is grounded, the drain of the first power tube is electrically connected to the input end of the Schmitt trigger, the input end of the Schmitt trigger is also electrically connected to the second end of the first resistor array, and the output end of the Schmitt trigger is electrically connected to the input end of the logic circuit 230.

[0041] In this embodiment, if Figure 4As shown, the power supply voltage VDD is divided by the first resistor array R7 and R8 to obtain the gate input voltage VL of the first power tube MN, the drain output voltage VS of the first power tube is connected to the input end of the Schmitt trigger, and the output end of the Schmitt trigger outputs the second level signal VR.

[0042] The threshold voltage of the first power tube is VTH_MN. When the power supply voltage output terminal is not powered, or the power supply voltage VDD is low, that is, when VL<VTH_MN, the first level signal VR output by the Schmitt trigger is low level. When the power supply voltage VDD increases until the gate input voltage VL>VTH_MN of the first power tube MN, the first level signal VR output by the Schmitt trigger flips from low level to high level. In the above two cases, the low voltage difference linear regulator is always in the holding mode, and the regulated output power supply voltage is VOUT_L.

[0043] In the first detection module 210, the Schmitt trigger is mainly used to provide a hysteresis characteristic for the level flip of the first level signal. Since the subthreshold voltage of the first power tube MN is turned on, the drain output voltage VS of the first power tube MN is still greater than the threshold voltage of the Schmitt trigger when VL<VTH_MN. Therefore, compared with the voltage detection method of the second detection module 220 based on the universal comparator COMP, the first detection module 210 has a larger voltage locking range.

[0044] Furthermore, if Figure 5 As shown, the second detection module 220 also includes a second resistor array, a second power tube and an inverter; The first end of the second resistor array is used to electrically connect to the power supply voltage output end, the positive end of the universal comparator COMP is electrically connected to the second end of the second resistor array, the output end of the universal comparator COMP is also electrically connected to the input end of the inverter, the output end of the inverter is electrically connected to the gate of the second power tube, the source of the second power tube is used to electrically connect to the power supply voltage output end, and the gate of the second power tube is electrically connected to the third end of the second resistor array.

[0045] In this embodiment, the power supply voltage VDD is divided by the second resistor array R4, R5 and R6 to obtain the input voltage VH of the positive terminal of the universal comparator COMP, and the input voltage of the negative terminal of the universal comparator COMP is the reference voltage VREF, which is set as the reference threshold voltage of the first detection module 210. When the power supply voltage output terminal is not powered, or the power supply voltage VDD is low and VH<VREF is satisfied, the second level signal VF outputted from the output terminal of the universal comparator COMP is an effective high level, and the low voltage difference linear regulator outputs the first power supply voltage VOUT_H.

[0046] The second detection module 220 adds a second power tube MP2, so that the flipping of the second level signal VF has a hysteresis function, that is, the switching of the working mode of the low voltage drop linear regulator has a hysteresis function, and the switching speed of the working mode is further improved. The steps of the second power tube making the circuit working mode switching have a hysteresis function are as follows: (1) The low-dropout linear regulator switches from holding mode to operating mode When the power supply voltage output terminal is not powered, or the power supply voltage VDD is low, the input voltage VH at the positive terminal of the universal comparator COMP is less than the reference voltage VREF, that is, VH<VREF, the second level signal VF is low level, VF=0, and the low voltage difference linear regulator is in the holding mode.

[0047] The second level signal is input to the gate of the second power tube MP2 through the inverter, and the second power tube MP2 is turned off. At this time, the input voltage VH of the positive terminal of the universal comparator COMP satisfies:

[0048] As the power supply voltage VDD increases, the input voltage VH of the positive terminal of the universal comparator COMP increases until VH>VREF, the second level signal VF flips to a high level, VF=1, and the second power tube MP2 is turned on. At this time, the input voltage VH of the positive terminal of the universal comparator COMP satisfies:

[0049] As the second power tube MP2 is turned on, VH is rapidly increased from VH- to VH+, and the low voltage difference linear regulator is rapidly switched from the holding mode to the working mode.

[0050] For the power supply voltage VDD, when it increases to satisfy VH-=VREF, the low voltage drop linear regulator switches from the holding mode to the working mode, and the threshold voltage VSET_F+ of the positive flip of the second level signal VF satisfies:

[0051] (2) The low-dropout linear regulator switches from operating mode to holding mode When the input voltage VH at the positive end of the universal comparator COMP is greater than the reference voltage VREF, that is, VH is greater than VREF, the second level signal VF is high level, VF=1, the low voltage difference linear regulator is in working mode, and the second power tube MP2 is turned on. At this time, the input voltage VH at the positive end of the universal comparator COMP satisfies:

[0052] As the power supply voltage VDD decreases, the input voltage VH at the positive terminal of the general comparator COMP decreases. When VH < VREF, the second level signal VF flips from high level to low level, and the second power transistor MP2 is turned off. At this time, the input voltage VH at the positive terminal of the general comparator COMP satisfies:

[0053] As the second power transistor MP2 is turned off, VH rapidly decreases from VH+ to VH-, and then the low-dropout linear regulator quickly switches from the working mode to the holding mode.

[0054] For the power supply voltage VDD, when it decreases to satisfy VH+ = VREF, the low-dropout linear regulator switches from the holding mode to the holding mode. Then the threshold voltage VSET_F- at which the second level signal VF flips negatively satisfies:

[0055] Since the threshold voltage for the switching of the circuit working mode caused by the change of the power supply voltage VDD satisfies VSET_F- < VSET_F+, the second detection module 220 has a hysteresis function when performing mode switching, and the hysteresis voltage satisfies:

[0056] Specifically, in this embodiment, the logic circuit 230 is an AND logic gate circuit. Only when the level states of the first level signal and the second level signal are both 1, the AND logic circuit 230 outputs a gating signal SEL = 1. The steps for the low-dropout linear regulator to output a supply voltage during the power-on process are as follows: When the power supply voltage output terminal starts to supply power for the first time, the power supply voltage VDD is low, and the power supply voltage VDD is less than the reference voltage threshold of the first detection module 210, that is, VH < , the first level signal VR is at a low level, VR = 0. At this time, the AND logic gate circuit does not respond to the possible misflipping of the second level signal, and the gating signal SEL output by the AND logic gate circuit is SEL = 0. At this time, although the low-dropout linear regulator operates normally, since the power supply voltage VDD and the reference voltage VREF output by the reference voltage source BG are not yet stable, at this time, the low-dropout linear regulator outputs a third supply voltage, and the third supply voltage changes following the change of the reference voltage VREF.

[0057] As the power supply voltage VDD gradually increases, , the first level signal VR flips to a high level, VR=1, and the first detection module 210 allows the AND logic gate circuit to respond to the effective flip of the second detection module 220. At this time, the low-dropout linear regulator is in the holding mode, and the reference voltage VREF output by the reference voltage source BG has also been stably established. Therefore, the low-dropout linear regulator outputs the second supply voltage VOUT_L:

[0058] As the power supply voltage VDD increases further, When the first level signal VR is still at a high level, VR=1, the power supply voltage VDD is greater than the reference voltage threshold of the second detection module 220, the second level signal VF is flipped to a high level, VF=1, and the selection signal SEL output by the logic gate circuit is 1, the low voltage difference linear regulator switches to the working mode, and outputs the first power supply voltage VOUT_H:

[0059] Furthermore, if the power supply voltage VDD decreases until VDD< When the low-dropout linear regulator switches from operating mode to holding mode, the output supply voltage decreases from VOUT_H to VOUT_L.

[0060] Therefore, the low voltage difference linear regulator provided in this embodiment has two working modes under different power supply voltages VDD, and can generate two regulated supply voltages; the low voltage difference linear regulator provided in this embodiment can also switch between two different working modes to output two different supply voltages when the power supply voltage VDD changes, so as to flexibly meet the power supply requirements of different circuit modules.

[0061] It should be understood that in other embodiments, there may be multiple first detection modules 210 and second detection modules 220, and more than two regulated supply voltages may be achieved by respectively setting different reference voltage thresholds, selecting different logic circuits 230, and designing switch modules in the feedback circuit to switch different resistance paths.

[0062] In actual manufacturing processes, the subthreshold voltages of the first power tubes in the first detection module 210 are slightly different, and the subthreshold voltage ranges of power tubes of different models overlap. Therefore, in actual applications, it is preferred to use only a single first detection module 210.

[0063] See also Figure 6 The present invention also provides a control method for a low voltage dropout linear regulator, wherein the low voltage dropout linear regulator comprises a low voltage dropout linear regulator circuit 100 and a mode control circuit 200; the low voltage dropout linear regulator circuit 100 comprises a feedback circuit, an error amplification module, a reference voltage source and a power output circuit; The mode control circuit 200 compares the power supply voltage with a reference voltage threshold, and outputs a target level signal of a corresponding level state according to the comparison result; The feedback circuit triggers a corresponding gating state according to a target level signal; wherein, in different gating states, the resistance value of the resistor connected to the error amplification module and the ground terminal of the feedback circuit is different, and the feedback circuit obtains a different feedback voltage based on the power supply voltage sampled by the power output circuit; The error amplification module outputs a corresponding error signal according to the feedback voltage corresponding to different gating states and the reference voltage VREF generated by the reference voltage source; The power output circuit outputs a stable supply voltage according to the error signal.

[0064] Further, the mode control circuit 200 includes a first detection module 210, a second detection module 220 and a logic circuit 230, the first detection module 210 includes a first power tube and a Schmitt trigger, the second detection module 220 includes a universal comparator COMP, and the level state switching sensitivity of the second detection module 220 is greater than that of the first detection module 210; The first detection module 210 compares its reference voltage threshold with the power supply voltage, and outputs a first level signal of a corresponding level state according to the comparison result, wherein the voltage threshold referenced by the first detection module 210 is the threshold voltage of the first power tube entering a subthreshold conduction state; The second detection module 220 compares its reference voltage threshold with the power supply voltage, and outputs a second level signal of a corresponding level state according to the comparison result, wherein the reference voltage threshold of the second detection module 220 is the reference voltage VREF input to the universal comparator COMP by the reference voltage source, and the reference voltage threshold of the first detection module 210 is less than the reference voltage threshold of the second detection module 220 when the reference voltage source reaches a stable state; The logic circuit 230 performs a logic operation according to the level states of the first level signal and the second level signal, and outputs a target level signal of a corresponding level state according to the logic operation result.

[0065] Furthermore, the first detection module 210 also includes a Schmitt trigger; After entering the subthreshold conduction state, the first power tube outputs a trigger voltage based on the power supply voltage to the Schmitt trigger. The Schmitt trigger compares the trigger voltage with the voltage threshold of the Schmitt trigger and outputs a first level signal of the corresponding level state according to the comparison result.

[0066] The control method provided in the second part of this embodiment is applied to the low voltage difference linear regulator in the first part of this embodiment. The specific steps of the control method are described accordingly in the first part of this embodiment. The control method corresponds to other parts of this embodiment and can produce similar technical effects, which will not be repeated here.

[0067] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A low dropout linear regulator, It is characterized in that include: Low voltage drop linear voltage regulator circuit and mode control circuit; The low voltage difference linear voltage stabilization circuit comprises a feedback circuit, an error amplification module, a reference voltage source and a power output circuit; The mode control circuit is used to compare the power supply voltage with a reference voltage threshold, and output a target level signal of a corresponding level state according to the comparison result; The feedback circuit is used to trigger a corresponding gating state according to the target level signal; wherein, in different gating states, the resistance value of the resistor connected to the error amplification module and the ground terminal of the feedback circuit is different, and the feedback voltage obtained by the feedback circuit based on the supply voltage sampled by the power output circuit is different; The error amplification module is used to output a corresponding error signal according to the feedback voltage corresponding to the different gating states and the reference voltage generated by the reference voltage source; The power output circuit is used to output a stable power supply voltage according to the error signal.

2. The low dropout linear regulator according to claim 1, It is characterized in that The mode control circuit includes a first detection module, a second detection module and a logic circuit, the first detection module includes a first power tube and a Schmitt trigger, the second detection module includes a universal comparator, and the level state switching sensitivity of the second detection module is greater than that of the first detection module; The first detection module is used to compare its reference voltage threshold with the power supply voltage, and output a first level signal of a corresponding level state according to the comparison result, wherein the voltage threshold referenced by the first detection module is a threshold voltage of the first power tube entering a subthreshold conduction state; The second detection module is used to compare the voltage threshold referenced by the second detection module with the power supply voltage, and output a second level signal of a corresponding level state according to the comparison result, wherein the voltage threshold referenced by the second detection module is the reference voltage inputted to the universal comparator by the reference voltage source, and the voltage threshold referenced by the first detection module is less than the voltage threshold referenced by the second detection module when the reference voltage source reaches a stable state; The logic circuit is used to perform a logic operation according to the level states of the first level signal and the second level signal, and output the target level signal of the corresponding level state according to the logic operation result.

3. The low dropout linear regulator according to claim 2, It is characterized in that The first detection module also includes a Schmitt trigger. The first power tube is used to output a trigger voltage based on the power supply voltage to the Schmitt trigger after entering the subthreshold conduction state. The Schmitt trigger is used to compare the trigger voltage with the voltage threshold of the Schmitt trigger and output a first level signal of the corresponding level state according to the comparison result.

4. The low dropout linear regulator according to claim 3, It is characterized in that The first detection module also includes a first resistor array; The first end of the first resistor array is used to electrically connect to the power supply voltage output end, the gate of the first power tube is electrically connected to the second end of the first resistor array, the source of the first power tube is grounded, the drain of the first power tube is electrically connected to the input end of the Schmitt trigger, the input end of the Schmitt trigger is also electrically connected to the second end of the first resistor array, and the output end of the Schmitt trigger is electrically connected to the input end of the logic circuit.

5. The low dropout linear regulator according to claim 3, It is characterized in that The second detection module also includes a second resistor array, a second power tube and an inverter; The first end of the second resistor array is used to electrically connect to the power supply voltage output end, the positive end of the universal comparator is electrically connected to the second end of the second resistor array, the output end of the universal comparator is also electrically connected to the input end of the inverter, the output end of the inverter is electrically connected to the gate of the second power tube, the source of the second power tube is used to electrically connect to the power supply voltage output end, and the gate of the second power tube is electrically connected to the third end of the second resistor array.

6. The low dropout linear regulator according to claim 1, It is characterized in that The feedback circuit includes a plurality of feedback resistors and at least one switch module; A plurality of feedback resistors are connected in series and / or in parallel to form a resistor feedback array, a first end of the resistor feedback array is electrically connected to the output end of the power output circuit, a second end of the resistor feedback array is electrically connected to the input end of the error amplification module, and a third end of the resistor feedback array is grounded; Each of the switch modules is connected in series or in parallel with at least part of the feedback resistors, and each of the switch modules is used to switch a switch state according to the target level signal, so that the feedback circuit triggers a corresponding gating state according to the target level signal.

7. The low dropout linear regulator according to claim 6, It is characterized in that N feedback resistors are connected in series to form the resistor feedback array, wherein N is a positive integer and N≥3; there is a node between any two feedback resistors, and a resistor path with different resistance values ​​is formed between the first feedback resistor of the resistor feedback array and any one of the nodes; Each of the switch modules includes an output end and at least two input ends, and the output end of each of the switch modules is electrically connected to the input end of the error amplification module, wherein in different selection states, an input end of the switch module is electrically connected to the corresponding node.

8. A control method for a low voltage dropout linear regulator, It is characterized in that The low voltage difference linear regulator comprises a low voltage difference linear voltage regulator circuit and a mode control circuit; the low voltage difference linear voltage regulator circuit comprises a feedback circuit, an error amplification module, a reference voltage source and a power output circuit; The mode control circuit compares the power supply voltage with a reference voltage threshold, and outputs a target level signal of a corresponding level state according to the comparison result; The feedback circuit triggers a corresponding gating state according to the target level signal; wherein, in different gating states, the resistance value of the resistor connected to the error amplification module and the ground terminal of the feedback circuit is different, and the feedback voltage obtained by the feedback circuit based on the supply voltage sampled by the power output circuit is different; The error amplification module outputs a corresponding error signal according to the feedback voltage corresponding to the different gating states and the reference voltage generated by the reference voltage source; The power output circuit outputs a stable supply voltage according to the error signal.

9. The method according to claim 8, It is characterized in that The mode control circuit includes a first detection module, a second detection module and a logic circuit, the first detection module includes a first power tube and a Schmitt trigger, the second detection module includes a universal comparator, and the level state switching sensitivity of the second detection module is greater than that of the first detection module; The first detection module compares a voltage threshold referenced by the first detection module with the power supply voltage, and outputs a first level signal of a corresponding level state according to the comparison result, wherein the voltage threshold referenced by the first detection module is a threshold voltage of the first power tube entering a subthreshold conduction state; The second detection module compares a voltage threshold referenced by the second detection module with the power supply voltage, and outputs a second level signal of a corresponding level state according to the comparison result, wherein the voltage threshold referenced by the second detection module is the reference voltage inputted to the universal comparator by the reference voltage source, and the voltage threshold referenced by the first detection module is less than the voltage threshold referenced by the second detection module when the reference voltage source reaches a stable state; The logic circuit performs a logic operation according to the level states of the first level signal and the second level signal, and outputs the target level signal of the corresponding level state according to the logic operation result.

10. The method according to claim 9, It is characterized in that The first detection module also includes a Schmitt trigger; After entering the subthreshold conduction state, the first power tube outputs a trigger voltage based on the power supply voltage to the Schmitt trigger. The Schmitt trigger compares the trigger voltage with the voltage threshold of the Schmitt trigger and outputs a first level signal of the corresponding level state according to the comparison result.

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