Low dropout regulator with output voltage switching circuit

Abstract

The invention discloses a low dropout regulator with an output voltage switching circuit. The low-dropout linear voltage stabilizing circuit outputs a voltage stabilizing signal according to the voltage difference between the voltage of the second end of the transistor and the voltage of a voltage stabilizing critical voltage signal or the voltage difference between the voltage of the second end of the transistor and a reference voltage. The switch error amplification circuit outputs a pull-up control signal according to the difference between the voltage of the second end of the transistor and the voltage of a voltage pull-up switching signal. When the voltage selection circuit selects the voltage stabilization signal, the transistor operates according to the voltage stabilization signal to adjust the output voltage of the low dropout regulator. When the voltage selection circuit selects the pull-up control signal, the switch assembly is turned on according to the pull-up control signal, so that the input voltage directly pulls up the output voltage of the low dropout regulator.

Description

Technical Field

[0001] The present invention relates to a low dropout linear regulator, and more particularly to a low dropout linear regulator having an output voltage switching circuit. Background Art

[0002] As a power management component, a low dropout linear regulator (LDO) can provide a low-noise and high-precision stable supply voltage for noise-sensitive circuit components, and thus is widely used. However, the currently developed low dropout linear regulators (LDOs) still cannot quickly boost their output voltage to supply sufficient power required for the operation of the load, and further improvement is needed. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a low dropout linear regulator having an output voltage switching circuit in view of the deficiencies of the prior art. The low dropout linear regulator having an output voltage switching circuit includes a transistor, a low dropout linear voltage regulation circuit, a switching error amplification circuit, a switching component, and a voltage selection circuit. The first end of the transistor is coupled to an input voltage. The second end of the transistor is grounded. The second end of the transistor serves as the output end of the low dropout linear regulator. The low dropout linear voltage regulation circuit is connected to the output end of the low dropout linear regulator. The low dropout linear voltage regulation circuit is configured to output a voltage regulation signal based on the voltage difference between the output voltage of the low dropout linear regulator and a voltage regulation critical voltage signal or between the output voltage of the low dropout linear regulator and a reference voltage. The switching error amplification circuit is connected to the output end of the low dropout linear regulator. The switching error amplification circuit is configured to output a boosting control signal based on the voltage difference between the output voltage of the low dropout linear regulator and the voltage of a voltage boosting switching signal. The first end of the switching component is coupled to the input voltage. The second end of the switching component is connected to the output end of the low dropout linear regulator. The control end of the switching component is connected to the switching error amplification circuit. The switching component is configured to operate based on the boosting control signal received from the switching error amplification circuit. The voltage selection circuit is connected to the low dropout linear voltage regulation circuit, the switching error amplification circuit, and the control end of the transistor. The voltage selection circuit is configured to select one of the voltage regulation signal and the boosting control signal. When the voltage selection circuit selects the voltage regulation signal, the voltage selection circuit transmits the voltage regulation signal to the control end of the transistor, and the transistor operates based on the voltage regulation signal to adjust the output voltage of the low dropout linear regulator. When the voltage selection circuit selects the boosting control signal, the switching component is turned on based on the boosting control signal received from the switching error amplification circuit, and the input voltage directly boosts the output voltage of the low dropout linear regulator through the switching component.

[0004] In an embodiment, the low dropout linear regulator having an output voltage switching circuit further includes an output capacitor. A first end of the output capacitor is connected to a second end of the transistor, and a second end of the output capacitor is grounded. A voltage at the first end of the output capacitor serves as the output voltage of the low dropout linear regulator.

[0005] In an embodiment, the voltage selection circuit compares a voltage value of the regulated signal received from the low dropout linear regulation circuit with a voltage value of the boost control signal received from the switching error amplification circuit to select one of the regulated signal and the voltage boost switching signal.

[0006] In an embodiment, the low dropout linear regulation circuit includes a first error amplifier. A first input terminal of the first error amplifier is coupled to the reference voltage. A second input terminal of the first error amplifier is connected to an external regulation indication circuit to receive the regulation critical voltage signal from the external regulation indication circuit. A third input terminal of the first error amplifier is connected to an output terminal of the low dropout linear regulator. An output terminal of the first error amplifier is connected to an input terminal of the voltage selection circuit.

[0007] In an embodiment, the switching error amplification circuit includes a second error amplifier. A first input terminal of the second error amplifier is connected to an output terminal of the low dropout linear regulator. A second input terminal of the second error amplifier is connected to an external boost enabling circuit to receive the voltage boost switching signal from the external boost enabling circuit. An output terminal of the second error amplifier is connected to a control terminal of the switching component.

[0008] In an embodiment, the voltage selection circuit includes a multiplexer. A first input terminal of the multiplexer is connected to an output terminal of the first error amplifier. A second input terminal of the multiplexer is connected to an output terminal of the second error amplifier. An output terminal of the multiplexer is connected to a control terminal of the transistor.

[0009] In an embodiment, the low dropout linear regulator having an output voltage switching circuit further includes a voltage dividing circuit. An input terminal of the voltage dividing circuit is connected between the second end of the transistor and the ground. An output terminal of the voltage dividing circuit is connected to the third input terminal of the first error amplifier and the first input terminal of the second error amplifier.

[0010] In an embodiment, the voltage dividing circuit includes a first resistor and a second resistor. A first end of the first resistor is connected to a second end of the transistor. A first end of the second resistor is connected to a second end of the first resistor. A second end of the second resistor is grounded. A third input terminal of the first error amplifier and a first input terminal of the second error amplifier are connected to a node between the second end of the first resistor and the first end of the second resistor.

[0011] In an embodiment, the low dropout linear regulator having an output voltage switching circuit further includes a switching component. A control end of the switching component is connected to an output end of the second error amplifier. A first end of the switching component is connected to an input end of the voltage selection circuit and the control end of the switching component. A second end of the switching component is grounded.

[0012] In an embodiment, the low dropout linear regulator having an output voltage switching circuit further includes a charge pump. The charge pump is connected to the control end of the switching component and the first end of the switching component. The charge pump is configured to supply power to the control end of the switching component.

[0013] In addition, the present invention provides a low dropout linear regulator having an output voltage switching circuit. The low dropout linear regulator having an output voltage switching circuit includes a transistor, a low dropout linear voltage regulation circuit, a switching error amplification circuit, a switching component, and a voltage selection circuit. The voltage selection circuit is coupled to a reference voltage. The voltage selection circuit is connected to an external pull-up enable circuit to receive a voltage pull-up switching signal from the external pull-up enable circuit. The voltage selection circuit is configured to select one of the reference voltage and the voltage pull-up switching signal to output a voltage selection signal. A first end of the transistor is coupled to an input voltage. A second end of the transistor is grounded, and the second end of the transistor serves as an output end of the low dropout linear regulator. The low dropout linear voltage regulation circuit is connected to the output end of the low dropout linear regulator, a control end of the transistor, and an output end of the voltage selection circuit. The low dropout linear voltage regulation circuit is configured to output a voltage regulation signal to the control end of the transistor according to a voltage difference between an output voltage of the low dropout linear regulator and a voltage of the voltage selection signal or a voltage of a voltage regulation critical voltage signal. The switching error amplification circuit is connected to the output end of the low dropout linear regulator and the external pull-up enable circuit. The switching error amplification circuit is configured to output a pull-up control signal according to a voltage difference between an output voltage of the low dropout linear regulator and a voltage of the voltage pull-up switching signal received from the external pull-up enable circuit. A first end of the switching component is coupled to the input voltage. A second end of the switching component is connected to the output end of the low dropout linear regulator. A control end of the switching component is connected to the switching error amplification circuit and operates according to the pull-up control signal received from the switching error amplification circuit.

[0014] In an embodiment, the low dropout linear voltage regulation circuit includes a first error amplifier. A first input end of the first error amplifier is connected to the output end of the voltage selection circuit. A second input end of the first error amplifier is connected to an external voltage regulation indication circuit to receive the voltage regulation critical voltage signal from the external voltage regulation indication circuit. A third input end of the first error amplifier is connected to the output end of the low dropout linear regulator. An output end of the first error amplifier is connected to the control end of the transistor.

[0015] In an embodiment, the switching error amplification circuit includes a second error amplifier. A first input end of the second error amplifier is connected to the output end of the low dropout linear regulator. A second input end of the second error amplifier is connected to the external pull-up enable circuit to receive the voltage pull-up switching signal from the external pull-up enable circuit. An output end of the second error amplifier is connected to the control end of the switching component.

[0016] In an embodiment, the voltage selection circuit includes a multiplexer. A first input terminal of the multiplexer is coupled to the reference voltage. A second input terminal of the multiplexer is connected to the external boosting enable circuit to receive the voltage boosting switching signal from the external boosting enable circuit. An output terminal of the multiplexer is connected to a first input terminal of the first error amplifier.

[0017] In an embodiment, the low dropout linear regulator having the output voltage switching circuit further includes a switching component. A control terminal of the switching component is connected to an output terminal of the second error amplifier. A first terminal of the switching component is connected to a control terminal of the switching component. A second terminal of the switching component is grounded.

[0018] As described above, the present invention provides a low dropout linear regulator having an output voltage switching circuit. In the low dropout linear regulator of the present invention, a low dropout linear voltage regulation circuit is provided to control the operation of the transistor, and at the same time, a switching error amplification circuit is provided to turn on or off the switching component. The low dropout linear voltage regulation circuit and the switching error amplification circuit in the low dropout linear regulator of the present invention are appropriately and quickly switched alternately to quickly bring the output voltage to the target voltage value required by the load, such as quickly boosting the output voltage. Therefore, the low dropout linear regulator of the present invention can quickly provide sufficient power for the load to operate.

[0019] To enable a further understanding of the features and technical content of the present invention, please refer to the following detailed description and drawings of the present invention. However, the provided drawings are only for reference and illustration, and are not intended to limit the present invention. Description of the Drawings

[0020] Figure 1 It is a circuit diagram of a low dropout linear regulator having an output voltage switching circuit according to a first embodiment of the present invention.

[0021] Figure 2 It is a waveform diagram of signals of a low dropout linear regulator having an output voltage switching circuit according to first to fifth embodiments of the present invention.

[0022] Figure 3 It is a circuit diagram of a low dropout linear regulator having an output voltage switching circuit according to a second embodiment of the present invention.

[0023] Figure 4 It is a circuit diagram of a low dropout linear regulator having an output voltage switching circuit according to a third embodiment of the present invention.

[0024] Figure 5 It is a circuit diagram of a low dropout linear regulator having an output voltage switching circuit according to a fourth embodiment of the present invention.

[0025] Figure 6Circuit diagram of a low dropout linear regulator with an output voltage switching circuit according to the fifth embodiment of the present invention. Detailed implementation manners

[0026] The following are specific embodiments to illustrate the implementation manners of the present invention. Those skilled in the art can understand the advantages and effects of the present invention from the content disclosed in this specification. The present invention can be implemented or applied through other different specific embodiments, and various details in this specification can also be modified and changed based on different viewpoints and applications without departing from the concept of the present invention. Additionally, the drawings of the present invention are only for simple schematic illustration and are not drawn according to actual dimensions, which is stated in advance. The following implementation manners will further detail the related technical content of the present invention, but the disclosed content is not used to limit the protection scope of the present invention. In addition, the term "or" used herein should, depending on the actual situation, may include any one or a combination of more of the associated listed items.

[0027] Please refer to Figure 1 and Figure 2 where Figure 1 is the circuit diagram of a low dropout linear regulator with an output voltage switching circuit according to the first embodiment of the present invention, Figure 2 is the waveform diagram of the signals of the low dropout linear regulator with an output voltage switching circuit according to the first to fifth embodiments of the present invention.

[0028] In the first embodiment, the low dropout linear regulator of the present invention includes a transistor T11, a low dropout linear voltage regulation circuit LDO, a switching error amplification circuit SWT, a switching component SW11, and a voltage selection circuit SEL. If necessary, the low dropout linear regulator of the present invention may further include an output capacitor Cout.

[0029] The first end of the transistor T11 is coupled to an input voltage VIN. The second end of the transistor T11 is grounded and can be connected to the first end of the output capacitor Cout. The second end of the output capacitor Cout is grounded. The second end of the transistor T11 or the first end of the output capacitor Cout serves as the output end of the low dropout linear regulator of the present invention, and the voltage at the output end of the low dropout linear regulator of the present invention is the output voltage VOUT as shown in Figure 1 .

[0030] The second end of the transistor T11 or the first end of the output capacitor Cout (i.e., the output end of the low dropout linear regulator of the present invention) is used to supply the output voltage VOUT to the connected load. Therefore, the low dropout linear voltage regulation circuit LDO and the switching error amplification circuit SWT are connected to the second end of the transistor T11 or the first end of the output capacitor Cout (i.e., the output end of the low dropout linear regulator of the present invention) to receive the output voltage VOUT of the low dropout linear regulator.

[0031] In the first embodiment, the output voltage VOUT of the low dropout linear regulator is fed back as a feedback voltage VFB to the low dropout linear regulator circuit LDO and the switching error amplifier circuit SWT, but the present invention is not limited thereto.

[0032] In practice, the low dropout linear regulator of the present invention may further include a voltage dividing circuit. The voltage dividing circuit is connected between the second end of the transistor T11 or the first end of the output capacitor Cout and the low dropout linear regulator circuit LDO, and is connected between the second end of the transistor T11 or the first end of the output capacitor Cout and the switching error amplifier circuit SWT. The voltage dividing circuit may divide the output voltage VOUT of the low dropout linear regulator of the present invention to form a divided voltage as a feedback voltage VFB, and feed it back to the low dropout linear regulator circuit LDO and the switching error amplifier circuit SWT, but the present invention is not limited thereto.

[0033] The low dropout linear regulator circuit LDO outputs a regulated voltage signal based on the voltage difference between a feedback voltage VFB (i.e., the output voltage VOUT of the low dropout linear regulator of the present invention or its divided voltage) and a regulated critical voltage signal SSLDO (received from the connected external voltage regulation indication circuit) or the voltage between a reference voltage VREF.

[0034] The switching error amplifier circuit SWT outputs a boosting control signal based on the voltage difference between a feedback voltage VFB (i.e., the output voltage VOUT of the low dropout linear regulator of the present invention or its divided voltage) and the voltage of a voltage boosting switching signal SSSW (received from the connected external boosting enabling circuit).

[0035] The voltage selection circuit SEL is connected to the control ends of the low dropout linear regulator circuit LDO, the switching error amplifier circuit SWT, and the transistor T11. The voltage selection circuit SEL selects one of a regulated voltage signal from the low dropout linear regulator circuit LDO and a boosting control signal from the switching error amplifier circuit SWT.

[0036] For example, the voltage selection circuit SEL may compare the voltage value of a regulated voltage signal received from the low dropout linear regulator circuit LDO with the voltage value of a boosting control signal received from the switching error amplifier circuit SWT, so as to select one of the regulated voltage signal and a boosting control signal, for example but not limited to selecting the one with the lower voltage value.

[0037] The switch component SW11 can be a transistor, a switching component, or other components with the same function. The first end of the switch component SW11 is coupled to the input voltage VIN. The second end of the switch component SW11 is connected to the second end of the transistor T11 or the first end of the output capacitor Cout (i.e., the output end of the low dropout linear regulator of the present invention). The control end of the switch component SW11 is connected to the switch error amplifier circuit SWT. The switch component SW11 operates according to a boost control signal received from the switch error amplifier circuit SWT.

[0038] When the voltage selection circuit SEL selects a regulated voltage signal from a regulated voltage signal from the low dropout linear regulator circuit LDO and a boost control signal from the switch error amplifier circuit SWT, the voltage selection circuit SEL transmits this regulated voltage signal to the control end of the transistor T11. The transistor T11 operates according to this regulated voltage signal received from the voltage selection circuit SEL to adjust the output voltage VOUT of the low dropout linear regulator of the present invention.

[0039] When the voltage selection circuit SEL selects a boost control signal from a regulated voltage signal from the low dropout linear regulator circuit LDO and a boost control signal from the switch error amplifier circuit SWT, the voltage selection circuit SEL does not transmit this regulated voltage signal to the control end of the transistor T11. At the same time, the switch component SW11 is turned on according to a boost control signal received from the switch error amplifier circuit SWT, so that the input voltage VIN coupled to the first end of the switch component SW11 directly boosts the output voltage VOUT of the low dropout linear regulator (to be equal to or close to the input voltage VIN, as Figure 2 shown).

[0040] For example, when the transistor T11 operates according to a regulated voltage signal output by the low dropout linear regulator circuit LDO, so that the load connected to the output end of the low dropout linear regulator of the present invention obtains sufficient power, the low dropout linear regulator circuit LDO can be continuously used to control the operation of the transistor T11 to adjust the output voltage VOUT output by the low dropout linear regulator of the present invention to the load.

[0041] However, the input voltage VIN (such as, but not limited to, the voltage of a battery) coupled to the first end of the transistor T11 may be reduced to be lower than the power required by the load connected to the output end of the low dropout linear regulator of the present invention due to long-term use.

[0042] When the transistor T11 operates according to a regulated signal output by the low dropout linear regulator circuit LDO, but the load connected to the output terminal of the low dropout linear regulator of the present invention cannot obtain sufficient power, the switching error amplifier circuit SWT turns on the switching component SW11. As a result, in the low dropout linear regulator of the present invention, the input voltage VIN coupled to the first end of the switching component SW11 directly raises the output voltage VOUT of the low dropout linear regulator (to be equal to or close to the input voltage VIN, as Figure 2 shown).

[0043] Therefore, even if the input voltage VIN coupled to the first end of the transistor T11 of the low dropout linear regulator of the present invention, for example but not limited to, the voltage of a battery (after long-term use) is too low, the load connected to the output terminal of the low dropout linear regulator of the present invention can still obtain sufficient power from the low dropout linear regulator of the present invention.

[0044] That is to say, in the low dropout linear regulator of the present invention, the low dropout linear regulator of the present invention quickly alternates between a low dropout linear regulation mode and a load switching mode. In a low dropout linear regulation mode, the low dropout linear regulator of the present invention controls the transistor T11 through the low dropout linear regulator circuit LDO to regulate the output voltage VOUT. In a load switching mode, the low dropout linear regulator of the present invention turns on the switching component SW11 through the switching circuit SWT to raise the output voltage VOUT. Therefore, the output voltage VOUT supplied by the low dropout linear regulator of the present invention to the load can reach the target voltage as Figure 2 shown quickly, so as to efficiently supply sufficient power required by the load.

[0045] Please refer to Figure 3 , which is the circuit diagram of the low dropout linear regulator with an output voltage switching circuit according to the second embodiment of the present invention.

[0046] In the low dropout linear regulator of the second embodiment of the present invention, the low dropout linear regulator circuit includes a first error amplifier EA11, the switching error amplifier circuit includes a second error amplifier EA2, the voltage selection circuit includes a multiplexer MUX, and the voltage dividing circuit DRV includes a first resistor R1 and a second resistor R2.

[0047] The first end of the transistor T11 is coupled to an input voltage VIN. The second end of the transistor T11 is connected to the first end of the first resistor R1 (i.e., the input end of the voltage dividing circuit DRV) and the first end of the output capacitor Cout. The second end of the first resistor R1 is connected to the first end of the second resistor R2. The second end of the second resistor R2 and the second end of the output capacitor Cout are grounded.

[0048] The first input terminal of the first error amplifier EA11, such as the inverting input terminal, is coupled to the reference voltage VREF. The second input terminal of the first error amplifier EA11, such as the inverting input terminal, is connected to an external voltage regulation indication circuit to receive a voltage regulation critical voltage signal SSLDO from this external voltage regulation indication circuit.

[0049] In the second embodiment, the node between the second terminal of the first resistor R1 and the first terminal of the second resistor R2 is connected to the third input terminal of the first error amplifier EA11, such as the non-inverting input terminal, and the first input terminal of the second error amplifier EA2, such as the non-inverting input terminal.

[0050] The second terminal of the transistor T11 or the first terminal of the output capacitor Cout (i.e., the output terminal of the low dropout linear regulator of the present invention) is used to supply the output voltage VOUT to the connected load.

[0051] In the second embodiment, the voltage at the node between the second terminal of the first resistor R1 and the first terminal of the second resistor R2 (i.e., the output terminal of the voltage dividing circuit DRV), which is a feedback voltage VFB, that is, a divided voltage of the output voltage VOUT of the low dropout linear regulator of the present invention, is fed back to the third input terminal of the first error amplifier EA11, such as the non-inverting input terminal, and the first input terminal of the second error amplifier EA2, such as the non-inverting input terminal.

[0052] The second input terminal of the second error amplifier EA2, such as the inverting input terminal, is connected to an external pull-up enabling circuit to receive a voltage pull-up switching signal SSSW from this external pull-up enabling circuit. The output terminal of the second error amplifier EA2 is connected to the control terminal of the switch component SW11.

[0053] The first error amplifier EA11 multiplies the voltage difference between the feedback voltage VFB (i.e., a divided voltage of the output voltage VOUT of the low dropout linear regulator of the present invention) and the voltage of a voltage regulation critical voltage signal SSLDO or the voltage of a reference voltage VREF by a gain to output a voltage regulation signal.

[0054] The second error amplifier EA2 multiplies the voltage difference between the feedback voltage VFB (i.e., a divided voltage of the output voltage VOUT of the low dropout linear regulator of the present invention) and the voltage of a voltage pull-up switching signal SSSW by a gain to output a pull-up control signal.

[0055] The first input terminal 1 of the multiplexer MUX is connected to the output terminal of the first error amplifier EA11 of the low dropout linear regulator circuit to receive a regulated voltage signal from the output terminal of the first error amplifier EA11. The second input terminal 0 of the multiplexer MUX is connected to the output terminal of the second error amplifier EA2 of the switching error amplification circuit to receive a boost control signal from the second error amplifier EA2. The output terminal of the multiplexer MUX is connected to the control terminal of the transistor T11.

[0056] The multiplexer MUX selects one of a regulated voltage signal output from the first error amplifier EA11 and a boost control signal output from the second error amplifier EA2 of the switching error amplification circuit. For example, in the second embodiment, the one with the smallest voltage value is selected, but the present invention is not limited thereto.

[0057] The first terminal of the switch component SW11 is coupled to the input voltage VIN. The second terminal of the switch component SW11 is connected to the second terminal of the transistor T11 or the first terminal of the output capacitor Cout (i.e., the output terminal of the low dropout linear regulator of the present invention). The control terminal of the switch component SW11 is connected to the output terminal of the second error amplifier EA2 of the switching error amplification circuit to operate according to a boost control signal received from the output terminal of the second error amplifier EA2.

[0058] For example, when the multiplexer MUX selects a regulated voltage signal, the multiplexer MUX transmits this regulated voltage signal to the control terminal of the transistor T11. The transistor T11 operates according to a regulated voltage signal received from the multiplexer MUX to adjust the output voltage VOUT of the low dropout linear regulator of the present invention.

[0059] Conversely, when the multiplexer MUX selects a boost control signal, the multiplexer MUX does not transmit a regulated voltage signal to the control terminal of the transistor T11. At the same time, a boost control signal output from the output terminal of the second error amplifier EA2 to the control terminal of the switch component SW11 will turn on the switch component SW11. As a result, an input voltage VIN coupled to the first terminal of the switch component SW11 boosts the voltage of the second terminal of the transistor T11 or the voltage of the first terminal of the output capacitor Cout (i.e., the output voltage VOUT of the low dropout linear regulator of the present invention) (to be equal to or close to the input voltage VIN).

[0060] In practice, the voltage-dividing circuit DRV can be omitted. In this case, the second terminal of the transistor T11 or the first terminal of the output capacitor Cout (i.e., the output terminal of the low-dropout linear regulator of the present invention) serves as a feedback node and is directly connected to the third input terminal, such as the non-inverting input terminal, of the first error amplifier EA11 and the first input terminal, such as the non-inverting input terminal, of the second error amplifier EA2. The output voltage VOUT of the low-dropout linear regulator of the present invention serves as a feedback voltage VFB and is directly fed back to the third input terminal, such as the non-inverting input terminal, of the first error amplifier EA11 and the first input terminal, such as the non-inverting input terminal, of the second error amplifier EA2.

[0061] Please refer to Figure 4 , which is the circuit diagram of the low-dropout linear regulator with an output voltage switching circuit according to the third embodiment of the present invention. The similarities between the third embodiment and the second embodiment of the present invention will not be elaborated herein.

[0062] As Figure 3 shown, in the second embodiment, the transistor T11 included in the low-dropout linear regulator of the present invention is a P-type metal-oxide-semiconductor field-effect transistor (PMOSFET), and the switching component SW11 is also a P-type metal-oxide-semiconductor field-effect transistor (PMOSFET).

[0063] As Figure 4 shown, in the third embodiment, the transistor T12 included in the low-dropout linear regulator of the present invention is an N-type metal-oxide-semiconductor field-effect transistor (NMOSFET), and the switching component SW12 is also an N-type metal-oxide-semiconductor field-effect transistor (NMOSFET).

[0064] Therefore, as Figure 4 shown, in the third embodiment, the low-dropout linear regulator of the present invention further includes a switching component ST and a charge pump PUM for the switching component SW12 of the NMOSFET.

[0065] It should be understood that the types and forms of the transistors and switching components included in the low-dropout linear regulator of the present invention described herein are only illustrative examples, and the present invention is not limited thereto.

[0066] The output terminal of the second error amplifier EA2 is connected to the control terminal of the switching component ST. The first terminal of the switching component ST is connected to the second input terminal 0 of the multiplexer MUX of the voltage selection circuit and the control terminal of the switching component SW12. The second terminal of the switching component ST is grounded.

[0067] The first input terminal, such as the non-inverting input terminal, of the first error amplifier EA12 is coupled to a reference voltage VREF. The second input terminal, such as the non-inverting input terminal, of the first error amplifier EA12 is connected to an external voltage regulation indication circuit to receive a regulated critical voltage signal SSLDO from this external voltage regulation indication circuit. The third input terminal, such as the inverting input terminal, of the first error amplifier EA12 is connected to the node between the second end of the first resistor R1 and the first end of the second resistor R2.

[0068] The first input terminal 1 of the multiplexer MUX is connected to the output terminal of the first error amplifier EA12 to receive a regulated voltage signal from the output terminal of the first error amplifier EA12. The second input terminal 0 of the multiplexer MUX receives the signal from the first end of the switching component ST.

[0069] The multiplexer MUX selects one of the regulated voltage signal output from the first error amplifier EA12 and the signal from the first end of the switching component ST, for example, selects the one with the largest voltage value in the third embodiment, but the present invention is not limited thereto.

[0070] The charge pump PUM is connected to the control terminal of the switch component SW12 and the first end of the switching component ST. The charge pump PUM can continuously supply power. When a pull-up control signal output from the output terminal of the second error amplifier EA2 turns on the switching component ST, the control terminal of the switch component SW12 and the control terminal of the charge pump PUM are connected to the ground through the turned-on switching component ST. As a result, the power supplied by the charge pump PUM flows to the ground, and the voltage value at the control terminal of the switch component SW12 is pulled to zero, causing the switch component SW12 to be in the off state.

[0071] Please refer to Figure 5 , which is the circuit diagram of the low dropout linear regulator with an output voltage switching circuit according to the fourth embodiment of the present invention.

[0072] In the fourth embodiment, the low dropout linear regulator of the present invention includes a transistor T12, a low dropout linear voltage regulation circuit (including the first error amplifier EA12), a switching error amplification circuit (including the second error amplifier EA2), a switch component SW11, and a voltage selection circuit (including the multiplexer MUX). If necessary, the low dropout linear regulator of the present invention may also include an output capacitor Cout and a voltage division circuit DRV as shown in Figure 5 .

[0073] The first input terminal 1 of the multiplexer MUX is coupled to a reference voltage VREF. The second input terminal 0 of the multiplexer MUX is connected to an external pull-up enabling circuit to receive a voltage pull-up switching signal SSSW from this external pull-up enabling circuit.

[0074] The first input terminal of the first error amplifier EA12 of the low-dropout linear voltage regulator circuit, for example, the inverting input terminal, is connected to the output terminal of the multiplexer MUX of the voltage selection circuit. The multiplexer MUX selects one of the reference voltage VREF and a voltage boost switching signal SSSW, for example, selects the one with the largest voltage value, and accordingly outputs a voltage selection signal, which is input to the first input terminal of the first error amplifier EA12, for example, the non-inverting input terminal.

[0075] The second input terminal of the first error amplifier EA12 of the low-dropout linear voltage regulator circuit, for example, the non-inverting input terminal, is connected to an external voltage regulation indication circuit to receive a voltage regulation critical voltage signal SSLDO from this external voltage regulation indication circuit.

[0076] The third input terminal of the first error amplifier EA12 of the low-dropout linear voltage regulator circuit, for example, the inverting input terminal, is connected to the node between the second end of the first resistor R1 and the first end of the second resistor R2 (i.e., the output terminal of the voltage divider circuit DRV).

[0077] The output terminal of the first error amplifier EA12 is connected to the control terminal of the transistor T12. The first end of the transistor T12 is coupled to an input voltage VIN. The second end of the transistor T12 is connected to the first end of the first resistor R1.

[0078] The first input terminal of the second error amplifier EA2, for example, the non-inverting input terminal, is connected to the node between the second end of the first resistor R1 and the first end of the second resistor R2 (i.e., the output terminal of the voltage divider circuit DRV). The second input terminal of the second error amplifier EA2, for example, the inverting input terminal, is connected to an external boost enabling circuit to receive a voltage boost switching signal SSSW from this external boost enabling circuit.

[0079] The output terminal of the second error amplifier EA2 is connected to the control terminal of the switch component SW11, which is connected to the charge pump PUM. The first end of the switch component SW11 is coupled to an input voltage VIN. The second end of the switch component SW11 is connected to the second end of the transistor T12 or the first end of the output capacitor Cout (i.e., the output terminal of the low-dropout linear voltage regulator of the present invention).

[0080] Please refer to Figure 6 , which is the circuit diagram of the low-dropout linear voltage regulator with an output voltage switching circuit according to the fifth embodiment of the present invention. The similarities between the fifth embodiment of the present invention and the first to fourth embodiments will not be elaborated herein.

[0081] The differences between the fifth embodiment of the present invention and the fourth embodiment are described in detail as follows.

[0082] As Figure 5As shown, in the fifth embodiment, the switching component SW11 included in the low dropout linear regulator of the present invention is a P-type metal-oxide-semiconductor field-effect transistor (PMOSFET).

[0083] As Figure 6 shown, in the fifth embodiment, the switching component SW12 included in the low dropout linear regulator of the present invention is an N-type metal-oxide-semiconductor field-effect transistor (NMOSFET). Therefore, in the fifth embodiment, the low dropout linear regulator of the present invention further includes a switching component ST and a charge pump PUM for the switching component SW12 of NMOSFET type. The configuration and operation of the switching component ST and the charge pump PUM are the same as those of the same components in the fourth embodiment of the present invention, so they will not be described herein again.

[0084] On the other hand, as Figure 5 shown, in the fifth embodiment, the transistor T12 included in the low dropout linear regulator of the present invention is an N-type metal-oxide-semiconductor field-effect transistor (NMOSFET). As Figure 6 shown, in the fifth embodiment, the transistor T11 included in the low dropout linear regulator of the present invention is a P-type metal-oxide-semiconductor field-effect transistor (PMOSFET). Therefore, as Figure 5 shown, the inverting input terminal and non-inverting input terminal of the first error amplifier EA12 and the first error amplifier EA11 as Figure 6 shown are configured differently.

[0085] The content disclosed above is only the preferred feasible embodiments of the present invention, and does not limit the claims of the present invention. Therefore, all equivalent technical changes made by using the description and drawings of the present invention are included in the claims of the present invention.

Claims

1. A low dropout linear regulator with an output voltage switching circuit, characterized in that, the low dropout linear regulator with an output voltage switching circuit includes: a transistor, a first end of the transistor is coupled to an input voltage, a second end of the transistor is grounded, and the second end of the transistor serves as an output end of the low dropout linear regulator; a low dropout linear voltage regulation circuit, connected to the output end of the low dropout linear regulator, configured to output a regulated voltage signal according to a voltage difference between the output voltage of the low dropout linear regulator and a regulated critical voltage signal or a voltage difference between the output voltage of the low dropout linear regulator and a reference voltage; a switching error amplification circuit, connected to the output end of the low dropout linear regulator, configured to output a boosting control signal according to a voltage difference between the output voltage of the low dropout linear regulator and a voltage of a voltage boosting switching signal; a switching component, a first end of the switching component is coupled to the input voltage, a second end of the switching component is connected to the output end of the low dropout linear regulator, a control end of the switching component is connected to the switching error amplification circuit, and the switching component is configured to operate according to the boosting control signal received from the switching error amplification circuit; and a voltage selection circuit, connected to the low dropout linear voltage regulation circuit, the switching error amplification circuit, and a control end of the transistor, configured to select one of the regulated voltage signal and the boosting control signal; wherein, when the voltage selection circuit selects the regulated voltage signal, the voltage selection circuit transmits the regulated voltage signal to the control end of the transistor, and the transistor operates according to the regulated voltage signal to adjust the output voltage of the low dropout linear regulator; wherein, when the voltage selection circuit selects the boosting control signal, the switching component is turned on according to the boosting control signal received from the switching error amplification circuit, and the input voltage directly boosts the output voltage of the low dropout linear regulator through the switching component.

2. The low dropout linear regulator with an output voltage switching circuit according to claim 1, characterized in that, the low dropout linear regulator with an output voltage switching circuit further includes: an output capacitor, a first end of the output capacitor is connected to the second end of the transistor, a second end of the output capacitor is grounded, and a voltage at the first end of the output capacitor serves as the output voltage of the low dropout linear regulator.

3. The low dropout linear regulator with an output voltage switching circuit according to claim 1, characterized in that, the voltage selection circuit compares a voltage value of the regulated voltage signal received from the low dropout linear voltage regulation circuit with a voltage value of the boosting control signal received from the switching error amplification circuit to select one of the regulated voltage signal and the voltage boosting switching signal.

4. The low dropout linear regulator with an output voltage switching circuit according to claim 1, characterized in that, the low dropout linear voltage regulation circuit includes: A first error amplifier, wherein a first input terminal of the first error amplifier is coupled to the reference voltage, a second input terminal of the first error amplifier is connected to an external voltage regulation indication circuit to receive the regulated critical voltage signal from the external voltage regulation indication circuit, a third input terminal of the first error amplifier is connected to an output terminal of the low dropout linear regulator, and an output terminal of the first error amplifier is connected to an input terminal of the voltage selection circuit.

5. The low dropout linear regulator with an output voltage switching circuit according to claim 4, wherein, the switching error amplification circuit includes: A second error amplifier, wherein a first input terminal of the second error amplifier is connected to the output terminal of the low dropout linear regulator, a second input terminal of the second error amplifier is connected to an external boosting enable circuit to receive the voltage boosting switching signal from the external boosting enable circuit, and an output terminal of the second error amplifier is connected to a control terminal of the switching component.

6. The low dropout linear regulator with an output voltage switching circuit according to claim 5, wherein, the voltage selection circuit includes: A multiplexer, wherein a first input terminal of the multiplexer is connected to the output terminal of the first error amplifier, a second input terminal of the multiplexer is connected to the output terminal of the second error amplifier, and an output terminal of the multiplexer is connected to a control terminal of the transistor.

7. The low dropout linear regulator with an output voltage switching circuit according to claim 5, wherein, the low dropout linear regulator with an output voltage switching circuit further includes: A voltage dividing circuit, wherein an input terminal of the voltage dividing circuit is connected between a second terminal of the transistor and the ground, and an output terminal of the voltage dividing circuit is connected to a third input terminal of the first error amplifier and a first input terminal of the second error amplifier.

8. The low dropout linear regulator with an output voltage switching circuit according to claim 7, wherein, the voltage dividing circuit includes: A first resistor, wherein a first end of the first resistor is connected to the second terminal of the transistor; and A second resistor, wherein a first end of the second resistor is connected to a second end of the first resistor, and a second end of the second resistor is grounded; wherein a third input terminal of the first error amplifier and a first input terminal of the second error amplifier are connected to a node between the second end of the first resistor and the first end of the second resistor.

9. The low dropout linear regulator with an output voltage switching circuit according to claim 6, wherein, the low dropout linear regulator with an output voltage switching circuit further includes: A switching component, wherein a control terminal of the switching component is connected to the output terminal of the second error amplifier, a first end of the switching component is connected to the input terminal of the voltage selection circuit and the control terminal of the switching component, and a second end of the switching component is grounded.

10. The low dropout linear regulator with an output voltage switching circuit according to claim 9, wherein, the low dropout linear regulator with an output voltage switching circuit further includes: A charge pump is connected to the control terminal of the switching component and the first terminal of the switching component, and is configured to supply power to the control terminal of the switching component.

11. A low dropout linear regulator with an output voltage switching circuit Characterized in that The low dropout linear regulator with an output voltage switching circuit includes: A voltage selection circuit is coupled to a reference voltage, connected to an external pull-up enabling circuit to receive a voltage pull-up switching signal from the external pull-up enabling circuit, and is configured to select one of the reference voltage and the voltage pull-up switching signal to output a voltage selection signal; A transistor, the first terminal of the transistor is coupled to an input voltage, the second terminal of the transistor is grounded, and the second terminal of the transistor serves as the output terminal of the low dropout linear regulator; A low dropout linear voltage regulation circuit is connected to the output terminal of the low dropout linear regulator, the control terminal of the transistor, and the output terminal of the voltage selection circuit, and is configured to output a voltage regulation signal to the control terminal of the transistor according to the voltage difference between the output voltage of the low dropout linear regulator and the voltage of the voltage selection signal or the voltage of a voltage regulation critical voltage signal; A switching error amplification circuit is connected to the output terminal of the low dropout linear regulator and the external pull-up enabling circuit, and is configured to output a pull-up control signal according to the voltage difference between the output voltage of the low dropout linear regulator and the voltage of the voltage pull-up switching signal received from the external pull-up enabling circuit; And A switching component, the first terminal of the switching component is coupled to the input voltage, the second terminal of the switching component is connected to the output terminal of the low dropout linear regulator, and the control terminal of the switching component is connected to the switching error amplification circuit to operate according to the pull-up control signal received from the switching error amplification circuit.

12. The low dropout linear regulator with an output voltage switching circuit according to claim 11 Characterized in that The low dropout linear regulator with an output voltage switching circuit further includes: An output capacitor, the first terminal of the output capacitor is connected to the second terminal of the transistor, the second terminal of the output capacitor is grounded, and the voltage of the first terminal of the output capacitor serves as the output voltage of the low dropout linear regulator.

13. The low dropout linear regulator with an output voltage switching circuit according to claim 11 Characterized in that The low dropout linear voltage regulation circuit includes: A first error amplifier, the first input terminal of the first error amplifier is connected to the output terminal of the voltage selection circuit, the second input terminal of the first error amplifier is connected to an external voltage regulation indication circuit to receive the voltage regulation critical voltage signal from the external voltage regulation indication circuit, the third input terminal of the first error amplifier is connected to the output terminal of the low dropout linear regulator, and the output terminal of the first error amplifier is connected to the control terminal of the transistor.

14. The low dropout linear regulator with an output voltage switching circuit according to claim 13 Characterized in that The switching error amplification circuit includes: A second error amplifier, wherein a first input terminal of the second error amplifier is connected to an output terminal of the low dropout linear regulator, a second input terminal of the second error amplifier is connected to the external boosting enabling circuit to receive the voltage boosting switching signal from the external boosting enabling circuit, and an output terminal of the second error amplifier is connected to a control terminal of the switching component.

15. The low dropout linear regulator with an output voltage switching circuit according to claim 14, wherein, the voltage selection circuit includes: a multiplexer, a first input terminal of the multiplexer is coupled to the reference voltage, a second input terminal of the multiplexer is connected to the external boosting enabling circuit to receive the voltage boosting switching signal from the external boosting enabling circuit, and an output terminal of the multiplexer is connected to a first input terminal of the first error amplifier.

16. The low dropout linear regulator with an output voltage switching circuit according to claim 14, wherein, the low dropout linear regulator with an output voltage switching circuit further includes: a voltage dividing circuit, an input terminal of the voltage dividing circuit is connected between a second terminal of the transistor and the ground, and an output terminal of the voltage dividing circuit is connected to a third input terminal of the first error amplifier and a first input terminal of the second error amplifier.

17. The low dropout linear regulator with an output voltage switching circuit according to claim 16, wherein, the voltage dividing circuit includes: a first resistor, a first end of the first resistor is connected to the second terminal of the transistor; and a second resistor, a first end of the second resistor is connected to a second end of the first resistor, and a second end of the second resistor is grounded; wherein a third input terminal of the first error amplifier and a first input terminal of the second error amplifier are connected to a node between the second end of the first resistor and the first end of the second resistor.

18. The low dropout linear regulator with an output voltage switching circuit according to claim 14, wherein, the low dropout linear regulator with an output voltage switching circuit further includes: a switching component, a control terminal of the switching component is connected to an output terminal of the second error amplifier, a first end of the switching component is connected to a control terminal of the switching component, and a second end of the switching component is grounded.

19. The low dropout linear regulator with an output voltage switching circuit according to claim 18, wherein, the low dropout linear regulator with an output voltage switching circuit further includes: a charge pump, connected to the control terminal of the switching component and the first end of the switching component, configured to supply power to the control terminal of the switching component.

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