Voltage regulating device

Abstract

The embodiment of the invention provides a voltage regulation device and a low dropout regulator. The voltage regulation device includes: a first transistor coupled between a voltage input terminal and a voltage output terminal of the voltage regulation device; a detection circuit; a first error amplification circuit coupled between the first transistor and the detection circuit and configured to output a control signal to a control terminal of the first transistor based on a comparison of a first detection voltage from the detection circuit and a first reference voltage; and a second error amplification circuit coupled between the first transistor and the detection circuit and configured to output a control signal to a control terminal of the first transistor based on a comparison of a second detection voltage from the detection circuit and a second reference voltage, the desired output voltage corresponding to the second reference voltage is lower than the desired output voltage corresponding to the first reference voltage. According to the scheme, certain voltage and current output capacity can be provided when the power supply voltage is obviously lower than the normal voltage, and load power failure is avoided.

Description

Technical Field

[0001] The present disclosure relates to the field of power and electronic technology, and more particularly, to a voltage regulating device. Background Art

[0002] Devices such as low dropout regulators (LDOs) can use power transistors to form a variable resistance between input and output, and adjust the resistance through a feedback mechanism to provide a stable voltage output. Such devices have the advantages of simple structure and fast response, and are widely used as power supplies to power various electronic devices or electronic circuits.

[0003] Devices such as LDOs usually require input voltages of a certain magnitude, and if the input voltage is too low, it may cause the gate of the power transistor to be uncontrolled, or even trigger protection measures to completely shut down the circuit, forcing the power load to lose power. Currently, there is a lack of effective means to solve the power supply problem of linear voltage regulator circuits under low input voltage conditions. Summary of the invention

[0004] In order to at least partially solve the above and other possible problems, an embodiment of the present disclosure provides a voltage regulating device.

[0005] According to a first aspect of the present disclosure, a voltage regulating device is provided, which includes: a first transistor coupled between a voltage input terminal and a voltage output terminal of the voltage regulating device; a detection circuit configured to detect a voltage at the voltage output terminal; a first error amplification circuit coupled between the first transistor and the detection circuit, and configured to output a control signal to a control terminal of the first transistor based on a comparison between a first detection voltage from the detection circuit and a first reference voltage; and a second error amplification circuit coupled between the first transistor and the detection circuit, and configured to output a control signal to the control terminal of the first transistor based on a comparison between a second detection voltage from the detection circuit and a second reference voltage, wherein an expected output voltage corresponding to the second reference voltage is lower than an expected output voltage corresponding to the first reference voltage.

[0006] In some embodiments of the present disclosure, the second error amplifier circuit includes: a third transistor and a fourth transistor, which form a differential input circuit and are coupled to a current source of the second error amplifier circuit, the control terminal of the third transistor is input with a second reference voltage, and the control terminal of the fourth transistor is input with a voltage detected by the detection circuit; and a fifth transistor and a sixth transistor, which form a current mirror circuit and are coupled to a voltage input terminal to power the second error amplifier circuit through the voltage input terminal, the fifth transistor is coupled to the third transistor, and the sixth transistor is coupled to the fourth transistor, wherein a node between the third transistor and the fifth transistor serves as an output terminal of the second error amplifier circuit.

[0007] In some embodiments of the present disclosure, the voltage regulating device further includes a bandgap reference circuit configured to be powered through the voltage output terminal and to generate a second reference voltage.

[0008] In some embodiments of the present disclosure, the bandgap reference circuit is further configured to generate a current of a current source of the second error amplification circuit, and the current of the current source of the second error amplification circuit is smaller than the current of the current source of the first error amplification circuit.

[0009] In some embodiments of the present disclosure, the voltage accuracy of the second reference voltage is lower than that of the first reference voltage, and / or the current accuracy of the current source of the second error amplifier circuit is lower than that of the current source of the first error amplifier circuit.

[0010] In some embodiments of the present disclosure, the bandgap reference circuit is configured to be turned on in response to receiving an enable signal and to be turned off in response to receiving a disable signal, the enable signal is generated based on the validity of at least one of a state control signal and a BGOK signal, the generation of the state control signal is associated with the voltage magnitude of the voltage input terminal, and the BGOK signal indicates whether the reference voltage of the bandgap reference circuit is successfully established.

[0011] In some embodiments of the present disclosure, the voltage regulating device also includes: a second transistor, coupled between the voltage input terminal and the output terminal of the second error amplifier circuit, and forming a current mirror circuit with the first transistor, wherein the ratio of the current flowing through the current mirror branch where the first transistor is located to the current flowing through the current mirror branch where the second transistor is located is greater than or equal to 1.

[0012] In some embodiments of the present disclosure, the detection circuit includes a first resistor, a second resistor, and a third resistor connected in series between a voltage output terminal and a reference potential, wherein the series node between the first resistor and the second resistor outputs a second detection voltage, and the series node between the second resistor and the third resistor outputs a first detection voltage.

[0013] In some embodiments of the present disclosure, the current flowing through the current mirror branch where the first transistor is located is an integer multiple of the current flowing through the current mirror branch where the second transistor is located.

[0014] In some embodiments of the present disclosure, the voltage regulating device further includes: a buffer coupled between the output terminal of the first error amplifying circuit and the second transistor.

[0015] In some embodiments of the present disclosure, the first error amplifier circuit is coupled to the voltage input terminal to be powered by the voltage input terminal, and wherein the first error amplifier circuit is further configured to be turned off in response to a voltage at the voltage output terminal being lower than a threshold.

[0016] According to a second aspect of the present disclosure, a low voltage dropout linear regulator is provided, comprising the voltage regulating device according to the first aspect.

[0017] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the disclosure, nor is it intended to limit the scope of the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and other objects, features and advantages of the present disclosure will become more apparent through a more detailed description of exemplary embodiments of the present disclosure in conjunction with the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present disclosure.

[0019] Figure 1 A schematic circuit diagram of a voltage regulating device according to an embodiment of the present disclosure is shown.

[0020] Figure 2 A schematic circuit diagram of a voltage regulating device according to another embodiment of the present disclosure is shown.

[0021] Figure 3 FIG. 4 is a schematic circuit diagram of a voltage regulating device according to another embodiment of the present disclosure.

[0022] Figure 4 Schematic waveform diagrams of an input voltage, an output voltage, and a second reference voltage of a voltage regulating device according to an embodiment of the present disclosure are shown.

[0023] Figure 5 Schematic waveform diagrams of an input voltage, an output voltage, and a second reference voltage of a voltage regulating device according to an embodiment of the present disclosure are shown. DETAILED DESCRIPTION

[0024] Embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present disclosure more thorough and complete, and to fully convey the scope of the present disclosure to those skilled in the art. Those skilled in the art can obtain alternative technical solutions from the following description without departing from the spirit and scope of protection of the present disclosure.

[0025] As used herein, the term "including" and its variations mean open inclusion, i.e., "including but not limited to". Unless otherwise stated, the term "or" means "and / or". The term "based on" means "based at least in part on". The term "one embodiment" means "at least one example embodiment". Other explicit and implicit definitions may also be included below.

[0026] As mentioned above, voltage regulator circuits such as LDO may be uncontrolled or shut down in the case of low input voltage, thus failing to maintain power supply to the load. Specifically, linear voltage regulator circuits usually require that the input voltage exceeds the rated output voltage by a certain value to ensure the swing of the power transistor of the voltage regulator circuit, and after the input voltage drops to the minimum rated voltage, the feedback loop of the linear voltage regulator circuit will increase the gate-source voltage of the power transistor as much as possible to increase the output voltage value. However, as the input voltage further decreases, the working state of the higher-precision error amplifier in the linear voltage regulator circuit will be affected, which will cause the gate of the power transistor to be uncontrolled. In addition, some linear voltage regulator circuits will use protection measures such as undervoltage lockout (UVLO), and lower input voltages may trigger such protection measures to completely shut down the power transistor to protect the circuit. Therefore, even if the load can operate at low voltage or maintain a certain state, the linear voltage regulator circuit may fail to maintain power supply to the load due to too low input voltage, forcing the load to power off and shut down. In addition, in some cases, as the input voltage decreases, the linear voltage regulator circuit may attempt to reduce the minimum operating voltage of its internal error amplifier so that the linear voltage regulator circuit can output a certain power at a lower voltage. However, this may cause overshoot when the input voltage or power supply voltage recovers quickly due to excessive gate bias, thereby affecting the load power supply safety.

[0027] The embodiment of the present disclosure provides an improved voltage regulator. In the improved scheme, in addition to the main feedback loop including the first error amplifier circuit, an auxiliary feedback loop including the second error amplifier circuit is also provided, and the second reference voltage for the second error amplifier circuit is lower than the first reference voltage for the first error amplifier circuit. Thus, when the power supply voltage or the input voltage is high enough and meets the normal working voltage, the power transistor of the voltage regulator is controlled by the main feedback loop and its first error amplifier circuit, and when the power supply voltage or the input voltage is reduced to a certain value, the auxiliary feedback loop and its second error amplifier circuit will replace the main feedback loop to control the power transistor. In this way, when the power supply voltage is reduced and the main feedback loop cannot provide control and drive, the auxiliary feedback loop can provide a certain voltage and current driving capability for the output of the voltage regulator, thereby ensuring that the power supply to the load will not be interrupted. For example, when the load is a low-voltage digital circuit or a random access memory (RAM), this uninterrupted low-voltage power supply can ensure that the load can maintain the state without causing data loss or operation interruption due to too low voltage.

[0028] Figure 1 1 shows a schematic circuit diagram of a voltage regulator 100 according to an embodiment of the present disclosure. As an example, the voltage regulator 100 may be included in a linear regulator (eg, LDO). Figure 1As shown, the voltage regulator 100 includes a transistor 110, which is coupled between a voltage input terminal Vin and a voltage output terminal Vout of the voltage regulator 100. As an example, the transistor 110 can be a metal oxide semiconductor field effect transistor (Metal Oxide Semiconductor Field Effect Transistor, MOSFET), such as a power double diffused metal oxide semiconductor field effect transistor (Double-diffused Metal Oxide Semiconductor, DMOS). However, the type of transistor 110 is not limited thereto, but can be other types of transistors that can be applied to the voltage regulator. As an example, the source of the transistor 110 can be coupled to the voltage input terminal Vin, and the drain of the transistor 110 can be coupled to the voltage output terminal Vout. The voltage input terminal Vin is used to connect a DC power supply, such as a battery, a super capacitor, a power converter coupled to a public grid or other power supply, etc. The voltage output terminal Vout is used to connect a load, such as a RAM, a microcontroller or any other type of electronic circuit or electronic device. Since the transistor 110 is connected between the power supply and the load, the conduction degree of the transistor 110 can be controlled and adjusted by controlling the gate-source voltage of the transistor 110 and thereby effectively controlling and adjusting the voltage applied from the power supply to the load.

[0029] The voltage regulating device 100 also includes a detection circuit 120 and a first error amplifier circuit 130. The detection circuit 120 can detect the voltage at the voltage output terminal Vout. As an example, the detection circuit 120 can be a voltage-dividing resistor network coupled between the voltage output terminal Vout and the ground, so as to detect the voltage at the voltage output terminal Vout and generate a voltage signal indicating the magnitude of the output voltage. It is understandable that the implementation of the detection circuit 120 is not limited thereto, but can be any type of voltage sensing circuit or device. Further, the first error amplifier circuit 130 is coupled between the transistor 110 and the detection circuit 120, and outputs a control signal to the control terminal of the transistor 110 based on a comparison of the first detection voltage from the detection circuit 120 with the first reference voltage VREF1. For example, the first error amplifier circuit 130 may be an operational amplifier, the in-phase input terminal of the operational amplifier is connected to the detection circuit 120 to receive a voltage signal indicating the magnitude of the output voltage, and the inverting input terminal of the operational amplifier inputs the first reference voltage VREF1, whereby the first error amplifier circuit 130 can control and adjust the on-off degree of the transistor 110 based on the error between the two, thereby controlling the output voltage to a desired level. For example, when the output voltage at the voltage output terminal Vout decreases due to a change in the power supply voltage or a fluctuation in the load current, and gradually decreases below the target voltage corresponding to the first reference voltage VREF1, the difference between the output voltage detected by the detection circuit 120 and the first reference voltage VREF1 will decrease, whereby the output of the first error amplifier circuit 130 will decrease, so that the conduction degree of the transistor 110 increases, thereby increasing the output voltage at the voltage output terminal Vout. In this way, feedback control and regulation of the output voltage at the voltage output terminal Vout can be effectively achieved, so that the output voltage is stabilized at a desired voltage level.

[0030] According to an embodiment of the present disclosure, the voltage regulating device 100 further includes a second error amplifier circuit 140. The second error amplifier circuit 140 is coupled between the transistor 110 and the detection circuit 120, and outputs a control signal to the control terminal of the transistor 110 based on a comparison between a second detection voltage from the detection circuit 120 and a second reference voltage VREF2, wherein the desired output voltage corresponding to the second reference voltage VREF2 is lower than the desired output voltage corresponding to the first reference voltage VREF1. Specifically, the first error amplifier circuit 130 and the transistor 110 may form a main loop for controlling the output voltage, and the second error amplifier circuit 140 and the transistor 110 may form an auxiliary loop for controlling the output voltage. The first reference voltage VREF1 and the first detection voltage as feedback are used for the control of the main loop, and under the control of the main loop, an output voltage corresponding to the first reference voltage VREF1 is expected to be output at the voltage output terminal Vout. The second reference voltage VREF2 and the second detection voltage as feedback are used for the control of the auxiliary loop, and under the control of the auxiliary loop, another output voltage corresponding to the second reference voltage VREF2 is expected to be output at the voltage output terminal Vout. The voltage magnitudes of the first detection voltage and the second detection voltage may be the same or different, but both represent or indicate the voltage at the voltage output terminal Vout. For example, in the case where the detection circuit 120 adopts a voltage-dividing resistor network, the first detection voltage and the second detection voltage may come from different monitoring nodes in the resistor network, and therefore have different voltage magnitudes, or come from the same monitoring node in the resistor network, and therefore have the same voltage magnitude. The actual setting of the first reference voltage VREF1 and the second reference voltage VREF2 needs to consider the voltage magnitude of the desired output voltage and the voltage magnitude of the detection voltage, and the desired output voltage corresponding to the second reference voltage VREF2 should be lower than the desired output voltage corresponding to the first reference voltage VREF1. For example, the first reference voltage VREF1 may correspond to the target output voltage (e.g., 5V) of the voltage regulating device 100, and the second reference voltage VREF2 may correspond to a lower voltage (e.g., 4 to 4.9V) lower than the target output voltage.

[0031] Thus, when the power supply voltage input to the voltage input terminal Vin is normal, the main loop will control the output of the transistor 110 based on the first reference voltage VREF1, and ensure that the output voltage at the voltage output terminal Vout is stably provided to the load at the target voltage. When the input voltage at the voltage input terminal Vin continues to decrease and the target output voltage cannot be maintained, since the output voltage corresponding to the second reference voltage VREF2 is lower than the target output voltage, the second error amplifier 140 and the auxiliary loop will be started to control the transistor 110 to power the load. At this time, if the main loop is still open, the main loop and the auxiliary loop can work together to make the conduction capacity of the transistor 110 greater, thereby obtaining a stronger load driving capability. If the main loop and the first error discharge circuit 130 cannot effectively control the transistor 110 due to the low input voltage or are closed for protection purposes (such as UVLO), the auxiliary loop can replace the main loop to continue to provide a certain degree of driving capability to power the load. It can be seen that by setting the second error amplifier circuit 140, even if the power supply voltage input to the voltage input terminal Vin drops to a level where the main circuit cannot operate normally, the auxiliary circuit can provide a certain voltage and current driving capability to the load, thereby avoiding power failure of the load. In addition, in the process of power supply voltage recovery, when the main circuit is restored by UVLO or input voltage detection, the main circuit can be restored autonomously when the output voltage is stable. However, the startup of the main circuit may involve, for example, the startup of the reference voltage, the reading of the calibration signal, and more complex system state machine control, so it takes a certain amount of time. The auxiliary circuit can temporarily stabilize the output voltage to an output voltage corresponding to the second reference voltage VREF2 lower than the target voltage during the process of power supply voltage recovery, and wait for a period of time to complete the startup of the main circuit. In other words, due to the maintenance effect of the auxiliary circuit on the output voltage, the main circuit can have more startup and establishment time during the power supply voltage recovery period.

[0032] Figure 2 FIG. 2 shows a schematic circuit diagram of a voltage regulating device 100 according to another embodiment of the present disclosure. Figure 2As shown, in some embodiments, the voltage regulating device 100 may further include a bandgap reference circuit 150. The bandgap reference circuit 150 is powered by the voltage output terminal Vout and generates a second reference voltage VREF2. Specifically, the second reference voltage VREF2 (i.e., bias voltage) can be provided to the second error amplifier circuit 140 of the auxiliary loop by the bandgap reference circuit 150 provided in the voltage regulating device 100. In addition, since the voltage output terminal Vout of the voltage regulating device 100 supplies power to the bandgap reference circuit 150, when the load is too large and the output current is too large and exceeds the maximum output current capacity, the voltage of the voltage output terminal Vout will become too low, causing the bandgap reference circuit 150 and the auxiliary loop to gradually lose power until it is automatically shut down, thereby protecting the circuit, and when the power is turned on again, a normal startup process can be achieved after the main loop is started. In some examples, in addition to providing the second reference voltage VREF2, the bandgap reference circuit 150 can also generate and provide a first reference voltage VREF1. Alternatively, the first reference voltage VREF1 can be provided by an external or additional bandgap reference circuit.

[0033] In some embodiments, the bandgap reference circuit 150 is configured to generate a current of the current source IB of the second error amplifier circuit 140, and the current of the current source IB of the second error amplifier circuit 140 is less than the current of the current source of the first error amplifier circuit 130. The current sources in the first error amplifier circuit 130 and the second error amplifier circuit 140 can be regarded as constant current sources, which are used to provide a stable current output for the error amplifier circuit or the error amplifier and ensure the stable operation and accuracy of the circuit. By providing the current of the current source IB of the second error amplifier circuit 140 by the bandgap reference circuit 150, the reference voltage and reference current (or referred to as the bias voltage and bias current) of the second error amplifier circuit 140 in the auxiliary loop are provided by the bandgap reference circuit 150, so that the auxiliary loop can be regarded as a self-biased auxiliary linear regulator. Since the current source IB of the second error amplifier circuit 140 has a smaller current than the first error amplifier circuit 130, the power consumption of the auxiliary loop and its second error discharge circuit 140 can become lower, which helps to further reduce power consumption and maintain output under low input voltage conditions.

[0034] In some embodiments, the voltage accuracy of the second reference voltage VREF2 is lower than the voltage accuracy of the first reference voltage VREF1. Additionally or alternatively, the current accuracy of the current source IB of the second error amplifier circuit 140 is lower than the current accuracy of the current source of the first error amplifier circuit 130. Thus, a higher-precision reference voltage and reference current can be used for the first error amplifier circuit 130 and the main circuit, while a lower-precision reference voltage and reference current can be used for the second error discharge circuit 140 and the auxiliary circuit. Lower voltage accuracy and / or current accuracy helps to reduce the voltage and power consumption required by the auxiliary circuit when the power supply voltage is low, so as to reduce the pressure on the power supply. In this way, it can be ensured that the voltage regulator provides high-performance output by the main circuit when the power supply voltage is normal, and when the power supply voltage is too low, the low-precision auxiliary circuit maintains a certain degree of output without interrupting the power supply.

[0035] In some embodiments, the bandgap reference circuit 150 is turned on in response to receiving an enable signal and is turned off in response to receiving a disable signal. As an example, the bandgap reference circuit 150 may have an enable terminal EN. For example, in the case where an enable signal (e.g., a high level signal) is input to the enable terminal EN, the bandgap reference circuit 150 is started to provide the second reference voltage VREF2 and the current of the current source IB to the second error amplifier circuit 140, and in the case where a disable signal (e.g., a low level signal) is input to the enable terminal, the bandgap reference circuit 150 is kept in a closed state. Thus, the opening and closing of the bandgap reference circuit 150 is controlled by the enable signal in addition to the output voltage Vout as its power supply, so that more flexible operation of the bandgap reference circuit 150 and the auxiliary loop can be achieved as needed, for example, the auxiliary loop can be always closed with the help of the enable signal, or the auxiliary loop can be opened with the help of the enable signal in some cases.

[0036] In some embodiments, the enable signal is generated based on at least one of the state control signal and the BGOK signal being valid, the generation of the state control signal is associated with the voltage level of the voltage input terminal Vin, and the BGOK signal indicates whether the reference voltage of the bandgap reference circuit 150 is successfully established. EN Provided to the enable terminal EN of the bandgap reference circuit 150. In addition, the identification signal BGOK of the power-on reset (POR) signal of the bandgap reference circuit 150 can also be connected to the enable terminal EN of the bandgap reference circuit 150, and the BGOK signal can indicate whether the reference voltage of the bandgap reference circuit 150 is successfully established. In some cases, when the power supply voltage is too low (for example, the voltage of the voltage input terminal Vin is lower than 2V), the state control of the voltage regulator 100 will be turned off, resulting in the inability to provide the state control signal SEN As an enable signal input to start the bandgap reference circuit 150. By providing the signal generated by the bandgap reference circuit 150 itself as an enable signal to the enable terminal EN, the state control signal S EN In the event of a loss of the state control signal S, the bandgap reference circuit 150 itself maintains its working state without shutting down the bandgap reference circuit 150 and the auxiliary loop, which helps the voltage regulator 100 maintain the output under low input voltage. In one example, an OR gate 151 may be provided, and the state control signal S EN The state control signal S is input to one input terminal of the OR gate, and the identification signal BGOK of the POR signal of the bandgap reference circuit 150 is connected to the other input terminal of the OR gate. EN When at least one of the signal BGOK and the identification signal BGOK is in an effective state, the bandgap reference circuit 150 can be enabled, so that the voltage regulating device 100 can achieve more flexibility and more application functions.

[0037] In some embodiments, the second error amplifier circuit 140 includes a transistor ND0, a transistor ND1, a transistor P0, and a transistor P1. The transistor ND0 and the transistor ND1 form a differential input circuit and are coupled to the current source IB of the second error amplifier circuit 140, wherein the control terminal of the transistor ND0 is input with the second reference voltage VREF2, and the control terminal of the transistor ND1 is input with the voltage detected by the detection circuit 120. The control terminal of the transistor ND0 is similar to the inverting input terminal of the operational amplifier, and the control terminal of the transistor ND1 is similar to the non-inverting input terminal of the operational amplifier, thereby realizing the differential operation of the two input signals. The transistor P0 and the transistor P1 form a current mirror circuit and are coupled to the voltage input terminal Vin to power the second error amplifier circuit 140 through the voltage input terminal Vin, wherein the transistor P0 is coupled to the transistor ND0, and the transistor P1 is coupled to the transistor ND1. The node between the transistor ND0 and the transistor P0 serves as the output terminal of the second error amplifier circuit 140. In this way, a simple and low-cost error amplifier can be constructed for the auxiliary loop, and the error amplifier can operate at a relatively low voltage and has very low power consumption.

[0038] In some embodiments, the first error amplifier circuit 130 is coupled to the voltage input terminal Vin to be powered by the voltage input terminal Vin, and wherein the first error amplifier circuit 130 is further configured to be turned off in response to the voltage of the voltage output terminal Vout being lower than a threshold. As an example, the voltage regulator 100 may include an undervoltage lockout UVLO circuit 160. The UVLO circuit 160 may be coupled to the voltage output terminal Uout, and when the output voltage is lower than a predefined threshold, it is determined that the voltage is low and a UVLO signal is sent to the first error amplifier circuit 130 to turn off the first error discharge circuit 130, thereby protecting the circuit safety of the main loop. In one embodiment, the detection circuit 120 may include a first resistor R1, a second resistor R2, and a third resistor R3 which are sequentially connected in series between the voltage output terminal Vout and a reference potential (e.g., ground potential), and the voltage of the series node between the second resistor R2 and the third resistor R3 is provided as a first detection voltage to the first error amplifier circuit 130, and the voltage of the series node between the first resistor R1 and the second resistor R2 is provided as a second detection voltage to the second error amplifier circuit 140, for example, output to the control terminal of the transistor ND1, thereby feeding back the output voltage to the main loop and the auxiliary loop.

[0039] Understandably, Figure 2 The implementation of the voltage regulating device 100 is not limited thereto, and may also include other components or elements (such as a load capacitor C load ), and some parts and components may be removed or replaced.

[0040] Figure 3 FIG. 2 shows a schematic circuit diagram of a voltage regulating device 100 according to another embodiment of the present disclosure. Figure 3 As shown, in some embodiments, the voltage regulating device 100 may further include a transistor 170. The transistor 170 is coupled between the voltage input terminal Vin and the output terminal of the second error amplifier circuit 140, and forms a current mirror circuit with the transistor 110, wherein the current I flowing through the current mirror branch where the transistor 110 is located is RB The current I flowing through the current mirror branch where the transistor 170 is located LB The ratio M is greater than or equal to 1. Thus, the auxiliary loop includes a bandgap reference circuit 150, a second error amplifier circuit 140 (for example, including transistors ND0, ND1, P0 and P1), a transistor 170, a transistor 110 and a detection circuit 120 (for example, including resistors R1, R2 and R3). When the power supply voltage is too low, the main loop may be closed and only the auxiliary loop is still working. In this case, the current I flowing through the branch where the transistor 170 is located LBThe maximum current I can be equal to the current of the current source IB. According to the current ratio relationship of the current mirror circuit, the current I flowing through the current mirror branch where the transistor 110 is located RB The maximum value can be M times the current of the current source IB. Therefore, when the power supply voltage is too low, although a sufficiently high output voltage cannot be provided to the load, a certain load current can still be provided. For example, when the input voltage is too low, the voltage level input to the control end of the transistor ND1 will be significantly lower than VREF2 input to the control end of the transistor ND0 through the feedback of the detection circuit 120. At this time, the current of the current source IB will basically flow from the branch LB where the transistor 170 is located through the node between the transistor ND0 and the transistor P0 and the transistor ND0, that is, the current flowing through the branch LB can be roughly equal to the current of the current source IB. Therefore, according to the current ratio relationship of the current mirror circuit, the current flowing through the branch RB where the transistor 110 is located can be close to M times the current of the current source IB, which ensures that the voltage regulator 100 can still provide a certain current output to drive the load. In addition, since the output current of the auxiliary circuit is limited to within M times the current of the current source IB, it helps to effectively limit the output current of the voltage regulating device 100 during the power supply voltage recovery process, which allows the voltage at the voltage output terminal Vout to recover to the target output voltage at a fixed slew rate without overshooting during the voltage recovery process.

[0041] In one embodiment, the current I flowing through the current mirror branch where the transistor 110 is located is RB is the current I flowing through the current mirror branch where transistor 170 is located LB As an example, in order to meet the high power output requirement of the voltage regulator, the transistor 110 may be a large-size power transistor, and may be much larger than the size of the transistor 170, so that a larger current ratio M can be easily achieved in the current mirror circuit composed of the transistor 110 and the transistor 170. Thus, the current of the current source IB of the second error amplifier circuit 140 can be set as small as possible to reduce the power consumption of the auxiliary loop, and can still output a sufficiently large output current (i.e., an integer multiple of the current of the current source IB) to maintain a certain degree of load driving capability when the power supply voltage is low.

[0042] In some embodiments, the voltage regulator 100 may further include a buffer 180. The buffer 180 is coupled between the output terminal of the first error amplifier circuit 130 and the transistor 170. Thus, the main loop includes the first error amplifier circuit 130, the buffer 180, the transistor 170, the transistor 110, and the detection circuit 120 (for example, including resistors R1, R2, and R3). The buffer 180 can further reduce the output impedance of the first error amplifier circuit 130, thereby enhancing the driving capability of the first error amplifier circuit 130. Here, the transistor 170 can be used as a dynamic load, and can be regarded as a part of the buffer 180 in the main loop. The transistor 170 as a dynamic load can adjust the output impedance according to the output current of the buffer 180 to further reduce the output impedance when the output current increases, thereby enhancing the regulation capability. Alternatively, the transistor 170 as a dynamic load can also be disconnected from other circuit parts through a switch (not shown) when the input voltage of the voltage regulator is normal, and is only connected to the circuit when the input voltage is low. In other words, the transistor 170 may not participate in the operation of the main loop, but only operate as part of the auxiliary loop.

[0043] Understandably, Figure 3 The implementation of the voltage regulating device 100 is not limited thereto, and other components or elements not shown in the figure may be included as needed, and some components and elements may be removed or replaced.

[0044] In an embodiment of the present disclosure, an auxiliary circuit is further provided on the basis of the main circuit of the voltage regulating device. Thus, a certain voltage output capacity can be maintained when the input voltage continues to decrease and is lower than the normal voltage, thereby avoiding power failure of the load. This voltage maintenance function is very beneficial for some loads, for example, it can provide a maintenance voltage for various state data of RAM and microcontroller to avoid data loss. The auxiliary circuit can adopt a low-cost and low-power architecture, for example, relative to the main circuit, a lower output voltage and current accuracy and as low power consumption as possible are adopted to make the power consumption of the auxiliary circuit extremely low to relieve the pressure on the power supply, thereby helping the auxiliary circuit to be suitable for low-voltage operating conditions. For example, when the target output voltage is 5V, the auxiliary circuit can normally provide an output voltage at a power supply voltage above 1.8V, and even in some cases, when there is no DC load on the output, the auxiliary circuit can still maintain a certain voltage output capacity when the power supply voltage is as low as 1V. Thus, the voltage regulating device provides high-performance output during normal operation and provides an output voltage maintenance function at a low input voltage. Through the control of the auxiliary circuit, the output voltage can also be maintained at a certain voltage lower than the target voltage for a period of time during the rapid recovery process after the input voltage is reduced, so as to reserve enough time for the recovery and startup of the main circuit. In addition, since the auxiliary loop can provide limited current output capability, the problem of overshoot of the output voltage can be prevented. In some embodiments, by providing a bandgap reference circuit powered by the output voltage, the auxiliary loop can be automatically shut down due to the drop of the output voltage when the input voltage is low and a large load occurs, thereby achieving overcurrent protection at low input voltage.

[0045] In addition, the voltage regulating device in some embodiments of the present disclosure can also provide more technical advantages. The auxiliary circuit of the voltage regulating device can provide the load with an output current that is several times the current of the current source IB under low input voltage conditions, and presents a limited current output capability, thereby maintaining the load current driving capability under low input voltage while preventing overshoot that may occur during the rapid recovery of the input voltage. In addition, the output target voltage of the auxiliary circuit is lower than the output target voltage of the main circuit, so the auxiliary circuit will not affect the operation of the main circuit when the input voltage is normal. For example, Figure 2 and Figure 3Taking the second error amplifier circuit 140 in the example, when the input voltage is normal, the voltage level input to the control terminal of the transistor ND1 will be significantly greater than the reference voltage level input to the control terminal of the transistor ND0, so that the current of the current source IB will flow through the current branch of Vin, the transistor P0, and the transistor ND0, and no longer flow through the branch LB. Therefore, the auxiliary loop only has an additional pull-up current (for example, the current of the current source IB) for the output terminal of the buffer 180 or the first error amplifier circuit 130, and will not affect or interfere with the normal operation of the main loop.

[0046] Figure 4 FIG. 4 shows a schematic waveform diagram of the input voltage Vin, the output voltage Vout and the second reference voltage VREF2 of the voltage regulating device 100 without an auxiliary loop. Figure 4 In the embodiment, the auxiliary loop including the second error amplifier circuit 140 is always closed, for example, by inputting a disable signal to the enable terminal EN of the bandgap reference circuit 150 to close the auxiliary loop. Figure 4 As shown, the auxiliary loop is always closed, and the second reference voltage VREF2 is zero. Assuming that there is a current load of 2mA on the load side, during 20ms to 40ms, the input voltage Vin slowly decreases from 13V to 2V, and during 40ms to 60ms, the input voltage Vin slowly increases back to the normal voltage of 13V. At 70ms, the input voltage Vin drops rapidly to 2V, and at 80ms, the input voltage Vin quickly recovers to the normal voltage of 13V. When the input voltage decreases slowly or drops rapidly, the first error amplifier circuit 130 of the main loop is actively closed due to the low voltage to play a protective role, thereby, the output voltage Vout continues to decrease until it reaches the ground potential. Since the main loop requires startup time, the output voltage Vout, whether it is slowly recovered or quickly recovered, quickly returns to the normal output voltage 5V after waiting for a while. It can be seen that in the absence of an auxiliary circuit, the voltage regulator 100 does not provide a low-voltage maintenance function, resulting in a power failure of the load of the voltage regulator 100 during the process of the output voltage dropping to 2V.

[0047] Figure 5Schematic waveform diagrams of the input voltage Vin, the output voltage Vout and the second reference voltage VREF2 of the voltage regulating device 100 with an auxiliary loop are shown. Assuming that there is a current load of 2 mA on the load side, during the period from 0 ms to 3 ms, in the process of the input voltage Vin starting to power on from 0 V, since the initial value of the output voltage Vout is 0, the bandgap reference circuit 150 and the auxiliary loop have not yet started, and the second reference voltage VREF2 is zero. During the period from 3 ms to 5 ms, after the output voltage Vout is established, the bandgap reference circuit 150 is powered and started, for example, by inputting an enable signal to the enable terminal EN, thereby the auxiliary loop is started, and the second reference voltage VREF2 rises from zero to about 1.04 V. During the period from 20 ms to 40 ms, the input voltage Vin slowly decreases from 13 V to 2 V, and during the period from 40 ms to 60 ms, the input voltage Vin slowly rises back to the normal voltage of 13 V. During this period, the auxiliary loop maintains the output to the load, and still has a current output capability of more than 2 mA to ensure that the load does not lose power. At 70ms, the input voltage Vin drops to 2V at 10V / μs, and at 80ms, the input voltage Vin recovers to the normal voltage of 13V at 10V / μs. During the rapid jump of the input voltage Vin, even if the load capacitor C load The auxiliary circuit can still maintain the stability of the output voltage Vout to a certain extent, thereby avoiding power failure of the load. In addition, it can be seen that no matter whether the input voltage Vin is restored in a slow rising manner or in a fast jumping manner, in the period of input voltage Vin recovery, the output voltage Vout first stabilizes and recovers to the target voltage 4.2V corresponding to the second reference voltage VREF2, and after waiting for a period of time at 4.2V to complete the startup of the main circuit, the output voltage Vout quickly recovers to the target voltage 5V corresponding to the first reference voltage VREF1, and there is no overshoot. It can be understood that if the startup of the main circuit can be completed quickly in a short time, the waiting time of the output voltage Vout at 4.2V can also be eliminated, so that the output voltage Vout quickly recovers to the normal output voltage of 5V without overshoot.

[0048] Through the teachings given in the above description and the related drawings, many modifications and other embodiments of the present disclosure given here will be recognized by those skilled in the art of the present disclosure. Therefore, it is to be understood that the embodiments of the present disclosure are not limited to the specific embodiments disclosed, and modifications and other embodiments are intended to be included in the scope of the present disclosure. In addition, although the above description and the related drawings describe the example embodiments in the context of some example combinations of parts and / or functions, it should be appreciated that different combinations of parts and / or functions can be provided by alternative embodiments without departing from the scope of the present disclosure. In this regard, for example, other combinations of parts and / or functions that are different from those clearly described above are also expected to be within the scope of the present disclosure. Although specific terms are used here, they are only used in a general and descriptive sense and are not intended to be limited.

Claims

1. A voltage regulating device (100), comprising: A first transistor (110) coupled between a voltage input terminal (Vin) and a voltage output terminal (Vout) of the voltage regulating device (100); A detection circuit (120) configured to detect a voltage at the voltage output terminal (Vout); a first error amplifier circuit (130) coupled between the first transistor (110) and the detection circuit (120), and configured to output a control signal to a control terminal of the first transistor (110) based on a comparison between a first detection voltage from the detection circuit (120) and a first reference voltage (VREF1); as well as A second error amplifier circuit (140) is coupled between the first transistor (110) and the detection circuit (120), and is configured to output a control signal to a control terminal of the first transistor (110) based on a comparison of a second detection voltage from the detection circuit (120) and a second reference voltage (VREF2), wherein an expected output voltage corresponding to the second reference voltage (VREF2) is lower than an expected output voltage corresponding to the first reference voltage (VREF1).

2. The voltage regulating device (100) according to claim 1, wherein the second error amplifying circuit (140) comprises: A third transistor (ND0) and a fourth transistor (ND1) forming a differential input circuit and coupled to a current source (IB) of the second error amplifier circuit (140), wherein the control terminal of the third transistor (ND0) is input with the second reference voltage (VREF2), and the control terminal of the fourth transistor (ND1) is input with the second detection voltage detected by the detection circuit (120); as well as A fifth transistor (P0) and a sixth transistor (P1) form a current mirror circuit and are coupled to the voltage input terminal (Vin) to power the second error amplifier circuit (140) through the voltage input terminal (Vin), the fifth transistor (P0) is coupled to the third transistor (ND0), and the sixth transistor (P1) is coupled to the fourth transistor (ND1), wherein a node between the third transistor (ND0) and the fifth transistor (P0) serves as an output terminal of the second error amplifier circuit (140).

3. The voltage regulating device (100) according to claim 1 or 2, further comprising: The bandgap reference circuit (150) is configured to be powered through the voltage output terminal (Vout) and generate the second reference voltage (VREF2).

4. The voltage regulating device (100) according to claim 3, wherein the bandgap reference circuit (150) is further configured to generate a current for a current source (IB) of the second error amplifier circuit (140), and the current of the current source (IB) of the second error amplifier circuit (140) is smaller than the current of the current source of the first error amplifier circuit (130).

5. The voltage regulating device (100) according to claim 4, wherein the voltage accuracy of the second reference voltage (VREF2) is lower than the voltage accuracy of the first reference voltage (VREF1), and / or The current accuracy of the current source (IB) of the second error amplifier circuit (140) is lower than the current accuracy of the current source of the first error amplifier circuit (130).

6. The voltage regulating device (100) according to claim 3, wherein the bandgap reference circuit (150) is configured to be turned on in response to receiving an enable signal and to be turned off in response to receiving a disable signal, the enable signal being generated based on at least one of a state control signal and a BGOK signal being valid, the generation of the state control signal being associated with the voltage level of the voltage input terminal (Vin), and the BGOK signal indicating whether the reference voltage of the bandgap reference circuit (150) is successfully established.

7. The voltage regulating device (100) according to claim 1, further comprising: A second transistor (170) is coupled between the voltage input terminal (Vin) and the output terminal of the second error amplifier circuit (140), and forms a current mirror circuit with the first transistor (110), wherein a current (I RB ) and the current (I LB ) is greater than or equal to 1.

8. The voltage regulating device (100) according to claim 1, wherein the detection circuit (120) comprises a first resistor (R1), a second resistor (R2) and a third resistor (R3) which are sequentially connected in series between a voltage output terminal (Vout) and a reference potential, wherein a series node between the first resistor (R1) and the second resistor (R2) outputs the second detection voltage, and a series node between the second resistor (R2) and the third resistor (R3) outputs the first detection voltage.

9. The voltage regulating device (100) according to claim 1, wherein the first error amplifier circuit (130) is coupled to the voltage input terminal (Vin) to be powered by the voltage input terminal (Vin), and wherein the first error amplifier circuit (130) is also configured to be turned off in response to the voltage of the voltage output terminal (Vout) being lower than a threshold.

10. A low voltage dropout linear regulator, comprising the voltage regulating device according to any one of claims 1 to 9.

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