Multi-input voltage regulator

Abstract

The invention relates to a multi-input voltage regulator. An apparatus (100) includes an amplifier (120) configured to compare a feedback input (FB IN) corresponding to a voltage of an output voltage node (110) with a reference input (REF IN) and to provide a control output (130) to control the output voltage node (110) based on a difference between the feedback input (FB IN) and the reference input (REF IN). At least two source circuits (Source Circuit 1-Source Circuit N) are coupled with the output voltage node (110). Source circuits (Source Circuit 1-Source Circuit N) are configured to provide corresponding voltage sources (VIN1-VIN N) to power an output voltage node (110).

Description

[0001] This application is a divisional application of Chinese patent application 201980014957.2, entitled “Multi-input voltage regulator”, filed on March 5, 2019. Technical Field

[0002] The present invention relates generally to circuits, and more particularly, to voltage regulator circuits configured to regulate an output voltage based on multiple input voltages. Background Art

[0003] A voltage regulator is designed to provide a stable DC voltage that is not affected by changes in load current, temperature, and / or AC line voltage. Voltage regulators can use a simple feed-forward design or can include negative feedback. An example regulator is a low dropout (LDO) regulator, which is designed to regulate the output voltage even if the supply voltage is very close to the output voltage. LDO regulators are very useful due to their low switching noise, small device size, and overall simple design. In an LDO circuit where multiple input voltage sources are applied to a common input of the LDO, glitches may occur at the input common to the input of the voltage regulator circuit during transient conditions between the corresponding sources, thereby adversely affecting the associated circuit system. Summary of the invention

[0004] In one example, an apparatus includes an amplifier configured to compare a feedback input corresponding to a voltage of an output voltage node with a reference input and provide a control output to control the output node based on a difference between the feedback input and the reference input. At least two source circuits are coupled to the output voltage node. The source circuits are configured to provide corresponding voltage sources to supply power to the output voltage node.

[0005] In another example, a regulator circuit includes an amplifier including a control output. The amplifier includes a first input coupled to receive a feedback voltage representing a voltage of an output voltage node; and a second input for receiving a reference voltage. A switching network includes an output transistor device having a control input coupled to the control output of the amplifier. The output transistor device is configured to regulate the output voltage node in response to the control output and at least two source input voltages coupled to supply power to the output voltage node. At least two source circuits are configured to drive the source output to the output voltage node in response to the source input voltages. Each source circuit includes a port coupled to receive a corresponding source input voltage of the source input voltages and a corresponding pass transistor / transmission transistor device configured to couple the corresponding source input voltage to the output voltage node.

[0006] In yet another example, a system includes an amplifier configured to provide a control signal based on a feedback signal and a reference signal. The feedback circuit system is configured to provide a feedback signal corresponding to an output voltage at an output voltage node. A plurality of source circuits are included, wherein each source circuit is configured to receive a corresponding source voltage and provide a corresponding source output to the output voltage node in response to the corresponding source voltage. The switching network is configured to adjust the output voltage based on the control signal and the corresponding source voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 An example block diagram of an apparatus for regulating multiple source input voltages supplied to an output node of the apparatus is shown.

[0008] Figure 2 An example block diagram of a regulator circuit for regulating multiple source input voltages that are supplied to an output node of the regulator is shown.

[0009] Figure 3 An example circuit diagram of a regulator circuit for regulating multiple source input voltages that are supplied to an output node of the regulator is shown.

[0010] Figure 4 An example of a system for regulating multiple source input voltages that are supplied to an output node of the regulator is shown.

[0011] Figure 5 Example timing and voltage diagrams for multiple input voltage switching and the effects of multiple input voltage switching on the regulator output voltage are shown. DETAILED DESCRIPTION

[0012] The present specification relates to a voltage regulator circuit that regulates an output voltage based on multiple input voltage sources. The voltage regulator circuit (e.g., a low dropout (LDO) linear regulator) includes an amplifier for comparing a feedback input corresponding to a voltage of an output voltage node of the regulator with a reference input. The amplifier (e.g., a comparator) provides a control output based on the difference between the feedback input and the reference input. An output transistor device (e.g., a metal oxide semiconductor field effect transistor) regulates the output voltage node in response to the control output from the amplifier and based on multiple input voltages. Each of the multiple input voltage sources is connected to the LDO via a corresponding source circuit. For example, each source circuit is coupled to provide an input voltage source to an output voltage node of the regulator circuit and control a bias voltage of the transistor device.

[0013] In some examples, the source circuit is configured as a low voltage diode OR circuit coupled to the regulator output node. This replaces the traditional high voltage diode circuit that performs an OR operation with the input of the existing regulator circuit design. The low voltage characteristic of applying the source input voltage to the output node through the source circuit alleviates the integrated circuit substrate area because low power components can be manufactured on a smaller area than high power components. For example, the diode or circuit can be part of an LDO loop, where each loop fed by its corresponding source circuit remains activated, so its response to transients is improved compared to the input driven or implementation method. The output burr is also reduced and can be set within the specification range of the required power supply transient, which can avoid undervoltage lockout conditions. In some existing regulator circuit designs, the current of the regulator is pulled from the highest power supply feeding the regulator input, where each power supply is not related to each other, thus making the input drive circuit susceptible to output transients, for example, if one of the power supplies drops out. The voltage regulator circuit described herein associates each power supply by sensing the current of each power supply at a common ground pin. The associated current from each supply is evenly distributed (subject to mismatch limitations) between the two or more input supplies powering the output node of the regulator, thereby increasing transient response.

[0014] As used herein, the term "circuit" may include a collection of active and / or passive components that perform a circuit function, such as an analog circuit or a control circuit. Additionally or alternatively, for example, the term "circuit" may include an integrated circuit (IC) in which all or part of the circuit components are fabricated on a common substrate (e.g., a semiconductor substrate such as a die or chip).

[0015] Figure 1 An example of an apparatus 100 is shown that is configured to provide a regulated output voltage (VOUT) at an output node 110 based on multiple input voltage sources that power the apparatus. The apparatus 100 includes an amplifier 120 that is configured to compare a feedback input FB IN corresponding to a voltage VOUT at the output voltage node 110 with a reference input REF IN and to provide a control output 130 based on a difference between the feedback input and the reference input. In an example, the amplifier 120 may be a comparator configured with hysteresis to improve stability under environmental and noise conditions. The transistor device 140 is configured to regulate the VOUT of the output voltage node 110 in response to the control output 130 from the amplifier 120. As used herein, the term transistor device may include any number of transistors, such as one or more. The transistor device 140 may be provided as part of a switching network, such as, for example, such as below with respect to Figure 2 , Figure 3 and Figure 4 Although transistor device 140 is shown as being external to amplifier 120 in this example, in other examples, transistor device 140 may be incorporated as a portion of amplifier 120 .

[0016] In one example, transistor device 140 may be a metal oxide field effect transistor having a source, a drain and a gate. In another example, transistor device 140 may be a junction transistor having an emitter, a collector and a base in another embodiment. At least two source circuits (e.g., a voltage source circuit, a current source circuit, a switch circuit) shown as source circuits 1 to N are coupled to output voltage node 110. Each of source circuits 1 to N is configured to provide a corresponding voltage source shown as VIN 1 to VIN N to output voltage node 110 from a corresponding source output of the source circuit, where N is a positive integer. Voltage sources VIN 1 to VIN N may be received from substantially any voltage source. As an example, a voltage source may be received from an unrelated (e.g., independent and / or unrelated) input power source. For example, each voltage source is a voltage bus configured to receive power from a bus power terminal (e.g., point) of a universal serial bus (USB) connector such as USB type C (USB-C) implemented according to one of the USB power transmission (PD) specifications.

[0017] As a further example, the transistor device 140 includes a gate terminal or base terminal configured to receive the control output 130, a source terminal or emitter terminal configured to drive the output voltage node 110, and a drain terminal or collector terminal configured to set a current drawn through the transistor device, such as a current sourced from each of the source circuits 1 to N. The feedback circuit 150 may be configured to sense a voltage VOUT of the output voltage node 110 and provide feedback to a feedback input FB IN of the amplifier 120. For example, the feedback circuit 150 may include at least one of a resistor divider network or a capacitor network to sense the output voltage VOUT.

[0018] In some examples, a universal serial bus (USB) connection can be configured to connect to each voltage source input VIN1 to a voltage source input VIN N to receive a corresponding voltage source. Figure 4 ) can be configured to operate with the voltage of the output voltage node 110 and selectively electrically connect the corresponding voltage sources VIN 1 to VIN N to other circuit systems of an associated system (e.g., a personal computer or mobile phone motherboard), for example in response to the voltage VOUT of the output voltage node 110 reaching a threshold.

[0019] Figure 2An example of a regulator circuit 200 is shown that is configured to provide a regulated output voltage at an output node 210 based on multiple input voltage sources (e.g., unrelated power supplies) provided to the regulator circuit. The regulator circuit 200 includes an amplifier 220 that includes a control output 230. The amplifier 220 includes a first input FB IN coupled to receive a feedback voltage representative of the voltage of the output voltage node 210 and a second input REF IN for receiving a reference voltage VREF. A switching network 240 may be provided that includes a transistor device 244 and one or more loop transistor devices 246 that are activated based on the input voltage sources and, when activated, provide current through the transistor device 244. The transistor device 244 includes a control input coupled to the control output 230 of the amplifier 220. Transistor device 244 is configured to regulate output voltage node 210 in response to control output 230 and at least two source outputs, shown as output 250, output 254, and output 258, which are coupled to output voltage node 210. Feedback circuit 260 feeds back voltage VOUT from output voltage node 210 to amplifier 220 to generate an error signal configured to cause output voltage VOUT to be regulated relative to VREF.

[0020] At least two source circuits, shown as source voltage circuits 1 to N, may be configured to drive source outputs 250-258. Each source circuit 1-N includes a port for receiving a corresponding input voltage source VIN 1 to VIN N and a corresponding pass transistor device (not shown, see FIG. 1 ) configured to couple the corresponding input voltage source to the output voltage node 210 via the corresponding source output 250-258. Figure 3 ). The transistor device 244 includes a gate terminal or base terminal configured to receive the control output 230, a source terminal or emitter terminal configured to drive the output voltage node 210, and a drain terminal or collector terminal configured to sense the current from each source circuit 1-N. The transistor device 244 is coupled to a series resistor (not shown, see Figure 3 ), the series resistor is coupled to each source circuit 1-N, the source circuit 1-N is configured to sense current from a corresponding voltage source input VIN 1 to VIN N in response to a corresponding voltage source applied to the corresponding series resistor. Figure 3 Other example aspects of amplifier 220 , switching network 240 , source circuits 1 -N, and feedback circuit 260 are shown and described.

[0021] Figure 3An example of a regulator circuit 300 is shown that is configured to regulate an output voltage at an output node of the regulator based on multiple input voltage sources. The regulator circuit 300 includes an amplifier 310 that is configured to compare a feedback input (e.g., at an inverting input of the amplifier) ​​corresponding to a voltage VOUT at an output voltage node 320 with a reference input (e.g., at a non-inverting input of the amplifier) ​​and provide a control output (e.g., an error signal) 330 based on the difference between the feedback input and the reference input. The reference voltage can be set to the magnitude of the desired regulated output voltage VOUT. Capacitor C1 can be coupled between the amplifier output 330 and ground to remove noise and help stabilize the error signal provided at the control output 330. Transistor device M3 is configured to regulate the output voltage node 320 in response to the control output 330 from the amplifier 310. In Figure 3 In the example of , transistor device M3 forms part of a switching network 334 including pass transistors M1 and M2. Each of M1 and M2 is coupled to ground (GND) through resistor R1. R1 is configured to establish a current from source circuits 340 and 344, and when an input voltage is applied to each source circuit, the current is divided by M1 and M2.

[0022] In this example, two source circuits 340 and 344 are coupled to the output voltage node 320. As described above, there may be any number of two or more such source circuits. Each of the source circuits 340 and 344 is configured to couple a corresponding voltage source, shown as VBUS1 and VBUS2, from the power output of the corresponding source circuit to the output voltage node 320.

[0023] Also in this example, transistor device M3 includes a gate terminal coupled to receive a control output from amplifier 310. The source terminal is coupled to drive an output voltage node 320 having a regulated output voltage VOUT. The drain terminal is coupled to the source terminals of M1 and M2, and is therefore coupled to ground through R1. Transistors M1 and M2 in switching network 334 and series resistors R2 and R3 are coupled to each source circuit 340 and 344 and are configured to pull current from the corresponding source circuit 340 and 344 in response to corresponding voltage sources VBUS1 and VBUS2 and based on an error signal applied to the gate of M3. As shown, the bias voltage supply Vb can be configured to bias the gate terminals of transistors M1 and M2 coupled to each corresponding source circuit 340 and 344 (e.g., to provide a voltage to bias transistors in a linear region to facilitate transient response). Advantageously, the bias voltage Vb can be provided to maintain M1 and M2 continuously effective so that the supply loop provided by the source circuit remains effective to help improve the response to transients. In previous circuit designs, multiple input sources were applied to the input of the regulator circuit. If one of the sources dropped or came online, the regulator receiving the source at its input could produce a transient at its output because there is no correlation between the sources. Figure 3 In the circuit of , the correlation is provided by resistor R1, which is configured to operate as a current source to pull a current shared by M1 and M2.

[0024] As an example, R1 correlates the collective current by providing common path coupling to each of the corresponding series resistors R2 and R3 of the corresponding source circuits 340 and 344 (e.g., coupling current between corresponding sources that is not considered in existing non-correlated designs). This correlation and current sharing through M1 and M2 can mitigate glitches in previous circuit implementations, for example, if one of the voltage supplies VBUS1 or VBUS2 goes offline or comes online after one of the other supplies is already operating. This is because each supply loop is valid regardless of whether it is powered by the input source, so the response to the transient is direct. Therefore, the output glitch is within the expected specification range for power supply transients. In contrast, the conventional circuit draws all current from the highest supply. Figure 3 The circuit divides the current between the voltage supplies substantially equally (eg, limited to mismatches) between the two input voltage supplies. Thus, in this case, an undervoltage lockout condition can be reduced or completely avoided.

[0025] exist Figure 3In an example of, each of the source circuits 340 and 344 includes a corresponding pass transistor device M4 and M5, which is configured to provide power to the output voltage node 320 from the corresponding voltage sources VBUS1 and VBUS2. Each of the corresponding transistor devices M4 and M5 includes a drain or collector coupled to a diode D1 or D2, which is configured to couple power from the corresponding pass transistor device to the output voltage node 320. In an example, each of the diodes D1 and D2 can be implemented as a low power transistor device, which includes a gate connection or a base connection that is switched and configured to reduce the voltage drop across the diode. An example of such a low power diode is shown and described in U.S. Patent No. 9,696,738, entitled LOW POWER IDEAL DIODE CONTROL CIRCUIT, which is incorporated herein by reference.

[0026] The feedback circuit (e.g., R4 and R5 in this example) is configured to sense the voltage of the output voltage VOUT and provide feedback to the feedback input of the amplifier 310. For example, the feedback circuit is configured as a resistor divider including resistors R4 and R5 connected between the output node 320 and ground. Thus, the node between R4 and R5 provides feedback to the inverting input of the amplifier 310. The capacitor C2 connected in parallel can provide low-pass output filtering of the regulator circuit 300 to further help stabilize the regulated output voltage VOUT.

[0027] As described above, for example, the feedback circuit may include at least one of a resistor divider network, a capacitor network, or other sensors. A universal serial bus (USB) connection may be provided to each voltage source input to provide corresponding voltage sources VBUS1 and VBUS2. A controller (not shown, see Figure 4 ) can be configured to operate from the voltage of the output voltage node 320 and switch the corresponding voltage sources VBUS1 and VBUS2 to another system based on the voltage of the output voltage node reaching a threshold.

[0028] Figure 4 An example of a system 400 is shown that is configured to provide a regulated output voltage VOUT at an output node of a regulator based on multiple input voltage sources supplied to the system. The system 400 includes an amplifier 410 that is configured to provide a control signal 420 based on an error determined from a difference between a feedback signal 424 and a reference signal 426. Feedback circuitry 430 is configured to provide a feedback signal 424 corresponding to the output voltage VOUT at an output node (e.g., output terminal) 440.

[0029] A plurality of source circuits, shown as source circuits 1 through N, are coupled to output node 440. Each source circuit 1-N is configured to receive a corresponding source voltage VIN 1 through VIN N and, in response to the corresponding source voltage, supply a corresponding source output at 450, 454, and 458 to output voltage node 440. Switching network 460 is configured to cooperate with amplifier 410 to regulate output voltage VOUT based on control signal 420 and the corresponding source voltages VIN 1-VIN N.

[0030] As a further example, the controller 470 can be coupled to receive a regulated output voltage VOUT. As an example, when VOUT is disconnected, at power-up, the amplifier and switching network draw power from the corresponding source voltages VIN 1-VIN N until a regulated VOUT is provided at 440. In response to VOUT reaching a threshold level (e.g., 3.3v), at the output voltage of the output voltage node 440, the controller 470 itself is activated and can control power delivery to other system elements. As an example, the controller 470 switches the corresponding voltage source VIN 1-VIN N to one or more other system buses (not shown) based on the voltage of the output voltage node reaching a threshold. An example of another system bus can be a power supply applied to a personal computer motherboard bus, a mobile phone motherboard bus, or essentially any type of bus that may require power switching from the controller. For example, the controller 470 and the system 400 can be manufactured on a substrate forming an integrated circuit of a power management chip.

[0031] Figure 5 An example timing and voltage diagram 500 of multiple input voltage switching and its effect on the regulator output voltage is shown. Voltage is represented in volts on the vertical axis of the diagram 500, while time is represented in milliseconds. Signal 510 represents Figure 3 The source input voltage is represented by VBUS1 in FIG. 520. Figure 3 The source input voltage represented by VBUS2 in FIG. 5 is represented by signal 530 in response to the input source bus voltage represented by signal 510 and signal 520. Figure 3 The linear regulator output is represented at node 320 of . As shown, when both source voltages 510 and 520 are disconnected (as shown at 540), the output of the regulator is zero. If one or the other of the voltages is present, as shown at 550, the output voltage of 530 is in regulation. If both voltages are present, as shown at 560, the output voltage is also in regulation.

[0032] In this specification, the term "based on" means at least partially based on. In addition, when this specification expresses "one / a", "first" or "another" component or similar expressions, it includes one or more than one such component, and neither requires nor excludes two or more such components.

[0033] The described embodiments may be modified, as may other embodiments, within the scope of the claims.

Claims

1. A device comprising: an amplifier configured to compare a feedback input corresponding to a voltage of an output voltage node with a reference input and to provide a control output based on a difference between the feedback input and the reference input to control the voltage of the output voltage node; as well as At least two source circuits are coupled to the output voltage node, each of the source circuits being configured to provide a corresponding voltage source to supply power to the output voltage node.

2. The apparatus of claim 1 , further comprising an output transistor device configured to regulate the output voltage node in response to the control output from the amplifier, wherein The transistor device includes a gate terminal coupled to receive the control output, a source terminal coupled to drive the output voltage node, and a drain terminal coupled to provide current from each of the source circuits.

3. The device according to claim 2, further comprising: A loop transistor device is connected between the corresponding source circuit and a common node at the drain of the output transistor device. 4 . The apparatus of claim 3 , further comprising a bias power supply configured to bias a gate terminal of each of the loop transistor devices coupled to each corresponding source circuit.

5. The device according to claim 3, further comprising: A common ground resistor, i.e., a CG resistor, couples the drain terminal of the output transistor device and the source terminal of each of the loop transistor devices to ground, wherein the CG resistor is configured to establish a total current from each of the corresponding source circuits and the output transistor device.

6. The device according to claim 1, wherein: Each of the source circuits further includes a corresponding pass transistor device configured to provide power from the corresponding voltage source to the output voltage node.

7. The device according to claim 6, wherein: Each of the source circuits further includes a diode coupled between a drain of the corresponding pass transistor device and the output voltage node such that the diodes together are configured as a diode-OR circuit.

8. The apparatus of claim 1, further comprising a feedback circuit configured to sense the voltage of the output voltage node and provide feedback to the feedback input of the amplifier.

9. The device according to claim 8, wherein: The feedback circuit includes a voltage divider network connected between the output voltage node and ground, with an intermediate node of the voltage divider network connected to an input of the amplifier.

10. The device according to claim 1, wherein: Each of the source circuits is configured to receive the corresponding voltage source from a power terminal of a universal serial bus.

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