Dual-voltage output circuit and electronic equipment

Abstract

The invention discloses a double-voltage output circuit and electronic equipment, and belongs to the technical field of power output control. The double-voltage output circuit comprises a sawtooth wave circuit, a first error amplifier, a first comparator, a first output circuit, a first feedback circuit, a second error amplifier, a second comparator, a second output circuit and a second feedback circuit. The double-voltage output circuit shares the sawtooth wave circuit, so that the circuit design cost is saved. Moreover, the first pulse width modulation signal and the second pulse width modulation signal are generated by comparing the same sawtooth wave with respective error signals, so that the switching frequencies of the positive and negative output voltages are ensured to be completely synchronous. Each voltage output circuit is provided with an independent error amplifier, a feedback circuit and a comparator, so that each path of output voltage can be subjected to quick response and independent closed-loop regulation. The feedback circuit can generate feedback voltage according to the current of the output circuit, when the load current suddenly changes, the duty ratio of the pulse width modulation signal can be rapidly changed, and the voltage is kept stable.

Description

Technical Field

[0001] This application belongs to the field of power output control technology, specifically relating to a dual-voltage output circuit and electronic device. Background Technology

[0002] Existing control schemes for simultaneous positive and negative power output involve transformer-to-negative power conversion, charge pump-to-negative power conversion, independent control of the positive and negative power supplies, DC-DC (DC-to-DC converter) step-down, and LDO (Low Dropout Regulator) step-down. These solutions suffer from limitations such as single-function circuitry, large PCB (Printed Circuit Board) footprint, and non-adjustable output voltage, making them unsuitable for applications requiring small PCB sizes and high load current. While charge pump topologies reduce size and cost to some extent, their control methods are relatively simple, and their output voltage load capacity is limited, failing to meet the comprehensive requirements for voltage accuracy and load capacity in various scenarios. Furthermore, independent output channels lead to redundant overall circuit design, low integration, and increased costs. Therefore, there is an urgent need for a dual-voltage output power supply system that is structurally simple, flexible in control, highly integrated, and cost-effective, to adapt to a wide range of application needs. Summary of the Invention

[0003] The purpose of this application is to provide a dual-voltage output circuit and electronic device that can solve the problems of dual-power output circuits having limited functionality, large PCB area occupation, and unadjustable output voltage.

[0004] In a first aspect, embodiments of this application provide a dual-voltage output circuit, including: Sawtooth wave circuit, used to output sawtooth waves; A first error amplifier is used to acquire a first feedback voltage; the first feedback voltage is amplified according to a preset reference voltage to obtain a first amplified voltage signal; A first comparator is used to receive the sawtooth wave output from the sawtooth wave circuit and the first amplified voltage signal output from the first error amplifier; and to generate a first pulse width modulation signal based on the first amplified voltage signal and the sawtooth wave. A first output circuit is used to acquire the power supply voltage; after receiving the first pulse width modulation signal, it outputs a first voltage to the load based on the power supply voltage. A first feedback circuit is connected to the first output circuit and is used to output the first feedback voltage to the first error amplifier according to the output current of the first output circuit. A second error amplifier is used to acquire a second feedback voltage; the second feedback voltage is amplified according to a preset reference voltage to obtain a second amplified voltage signal; The second comparator is used to receive the sawtooth wave output from the sawtooth wave circuit and the second amplified voltage signal output from the second error amplifier; and to generate a second pulse width modulation signal based on the second amplified voltage signal and the sawtooth wave. The second output circuit is used to acquire the power supply voltage; after receiving the second pulse width modulation signal, it outputs a second voltage to the load based on the power supply voltage; one of the first voltage and the second voltage is a positive voltage and the other is a negative voltage; The second feedback circuit, connected to the second output circuit, is used to output the second feedback voltage to the second error amplifier according to the output current of the second output circuit.

[0005] Optionally, the first output circuit includes: a first switching transistor, a first inductor, a first diode, a first capacitor, and a second capacitor; the control terminal of the first switching transistor is used to receive the first pulse width modulation signal; the input terminal of the first switching transistor is connected to the input power supply; the output terminal of the first switching transistor is connected to the output terminal of the first diode; the input terminal of the first diode is connected to the load; one end of the first capacitor is connected to the input power supply, and the other end of the first capacitor is grounded; one end of the first inductor is connected to the output terminal of the first switching transistor, and the other end of the first inductor is grounded; one end of the second capacitor is connected to the input terminal of the first diode, and the other end of the second capacitor is grounded.

[0006] Optionally, when the first pulse width modulation signal is high, the first switch is turned on so that the first capacitor supplies power to the first inductor, and the second capacitor outputs the first voltage to the load; when the first pulse width modulation signal is low, the first switch is turned off so that the first inductor outputs the first voltage to the load through the first diode.

[0007] Optionally, the second feedback circuit includes: a first resistor and a second resistor; one end of the first resistor is connected to the input terminal of the first diode, the other end of the first resistor is connected to the second resistor, and the other end of the second resistor is connected to the input power supply; the first feedback voltage is connected between the first resistor and the second resistor.

[0008] Optionally, the second output circuit includes: a second switch, a second inductor, a second diode, a third capacitor, and a fourth capacitor; the control terminal of the second switch is used to receive the second pulse width modulation signal, the input terminal of the second switch is connected to the input power supply, and the output terminal of the second switch is connected to the output terminal of the second diode; the input terminal of the second diode is grounded; one end of the third capacitor is connected to the input power supply, and the other end of the third capacitor is grounded; one end of the second inductor is connected to the output terminal of the second switch, and the other end of the first inductor is connected to the load; one end of the fourth capacitor is connected between the second inductor and the load, and the other end of the fourth capacitor is grounded.

[0009] Optionally, when the second pulse width modulation signal is low, the second switch is turned on so that the third capacitor supplies power to the second inductor, and the second inductor outputs the second voltage to the load; when the second pulse width modulation signal is high, the second switch is turned off so that the second inductor outputs the second voltage to the load through the second diode.

[0010] Optionally, the second feedback circuit includes a third resistor and a fourth resistor; one end of the third resistor is connected between the second inductor and the load, the other end of the third resistor is connected to the fourth resistor, and the other end of the fourth resistor is grounded; the second feedback voltage is connected between the third resistor and the fourth resistor.

[0011] Optionally, the dual-voltage output circuit also includes: A first signal control circuit is connected between the first comparator and the first output circuit, and is used to receive the first pulse width modulation signal output by the first comparator; determine the output state of the first pulse width modulation signal according to the level of the first pulse width modulation signal; and output the first pulse width modulation signal to the first output circuit when the output state of the first pulse width modulation signal is normal. The second signal control circuit is connected between the second comparator and the second output circuit. It is used to receive the second pulse width modulation signal output by the second comparator; determine the output state of the second pulse width modulation signal according to the level of the second pulse width modulation signal; and output the second pulse width modulation signal to the second output circuit when the output state of the second pulse width modulation signal is normal.

[0012] Optionally, the first comparator is configured to generate a high-level first pulse width modulation signal when the sawtooth wave is greater than the first amplified voltage signal, and to generate a low-level first pulse width modulation signal when the sawtooth wave is less than the first amplified voltage signal. The second comparator is configured to generate a high-level second pulse width modulation signal when the sawtooth wave is greater than the second amplified voltage signal, and to generate a low-level second pulse width modulation signal when the sawtooth wave is less than the second amplified voltage signal.

[0013] Secondly, embodiments of this application provide an electronic device including the aforementioned dual-voltage output circuit.

[0014] The embodiments of this application have the following advantages: In this embodiment, the dual-voltage output circuit includes: a sawtooth wave circuit, a first error amplifier, a first comparator, a first output circuit, a first feedback circuit, a second error amplifier, a second comparator, a second output circuit, and a second feedback circuit. The dual-voltage output circuit shares the same sawtooth wave circuit, saving circuit design costs. Furthermore, both the first and second pulse width modulation signals are generated by comparing the sawtooth wave generated by the same sawtooth wave circuit with their respective error signals, ensuring complete synchronization of the switching frequencies of the positive and negative output voltages, thereby reducing beat noise caused by the random staggered switching times of the two paths. Each voltage output circuit has its own independent error amplifier, feedback circuit, and comparator, enabling each output voltage to perform rapid response and independent closed-loop regulation, stabilizing the output voltage at the target value set by the preset reference voltage, ensuring the output accuracy and stability of the positive and negative voltages. The feedback circuit can generate a feedback voltage based on the output current of the output circuit. When the load current suddenly changes, the feedback voltage can immediately reflect this change, and the error amplifier adjusts its output voltage accordingly, thereby rapidly changing the duty cycle of the pulse width modulation signal to maintain voltage stability. This application embodiment utilizes a shared sawtooth wave circuit and reference voltage, and through two independent feedback control loops, achieves high-precision and high-stability positive and negative dual voltage output. Attached Figure Description

[0015] Figure 1 This is a structural block diagram of a dual-voltage output circuit according to an embodiment of the present invention; Figure 2 This is a circuit diagram of a dual-voltage output circuit according to an embodiment of the present invention; Figure 3 This is a logic diagram of a dual-voltage output circuit according to an embodiment of the present invention.

[0016] Explanation of reference numerals in the attached figures: Sawtooth wave circuit 11, first error amplifier 12, first comparator 13, first output circuit 14, first feedback circuit 15, second error amplifier 16, second comparator 17, second output circuit 18, second feedback circuit 19, first switch Q1, first inductor L1, first diode D1, first capacitor C1, second capacitor C2, first resistor R1, second resistor R2, second switch Q2, second inductor L2, second diode D2, third capacitor C3, fourth capacitor C4, third resistor R3, fourth resistor R4, first signal control circuit 21, second signal control circuit 22. Detailed Implementation

[0017] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0018] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0019] The following description, in conjunction with the accompanying drawings, details a dual-voltage output circuit and electronic device provided in this application through specific embodiments and application scenarios.

[0020] Reference Figure 1 The diagram illustrates a structural block diagram of a dual-voltage output circuit according to an embodiment of the present invention. The dual-voltage output circuit includes: Sawtooth wave circuit 11 is used to output a sawtooth wave; The first error amplifier 12 is used to acquire the first feedback voltage; and amplify the first feedback voltage according to a preset reference voltage to obtain a first amplified voltage signal. The first comparator 13 is used to receive the sawtooth wave output by the sawtooth wave circuit 11 and the first amplified voltage signal output by the first error amplifier 12; and to generate a first pulse width modulation signal based on the first amplified voltage signal and the sawtooth wave. The first output circuit 14 is used to acquire the power supply voltage; after receiving the first pulse width modulation signal, it outputs a first voltage to the load based on the power supply voltage. The first feedback circuit 15 is connected to the first output circuit 14 and is used to output the first feedback voltage to the first error amplifier 12 according to the output current of the first output circuit 14. The second error amplifier 16 is used to acquire the second feedback voltage; and amplify the second feedback voltage according to the preset reference voltage to obtain the second amplified voltage signal. The second comparator 17 is used to receive the sawtooth wave output by the sawtooth wave circuit 11 and the second amplified voltage signal output by the second error amplifier 16; and to generate a second pulse width modulation signal based on the second amplified voltage signal and the sawtooth wave. The second output circuit 18 is used to acquire the power supply voltage; after receiving the second pulse width modulation signal, it outputs a second voltage to the load based on the power supply voltage; one of the first voltage and the second voltage is a positive voltage and the other is a negative voltage; The second feedback circuit 19 is connected to the second output circuit 18 and is used to output the second feedback voltage to the second error amplifier 16 according to the output current of the second output circuit 18.

[0021] In this embodiment, the sawtooth wave circuit can generate a sawtooth wave in conjunction with the clock signal provided by the oscillator. The frequency of the sawtooth wave signal determines the switching frequency of the subsequent two PWM (Pulse Width Modulation) signals. The first and second error amplifiers receive feedback voltages from their corresponding feedback circuits and compare them with a preset reference voltage. If there is a slight difference between the feedback voltage and the reference voltage, the error amplifier outputs an amplified error signal. The magnitude of this output signal determines the PWM pulse width required to stabilize the output voltage. The first and second comparators receive the amplified voltage signal at one end and the sawtooth wave at the other, comparing these two input signals in real time. When the sawtooth wave voltage is less than the amplified voltage signal, the comparator outputs a high level (or low level); when the sawtooth wave voltage is greater than the amplified voltage signal, the comparator outputs a flipped level, thus generating a pulse width modulation signal. The higher the amplified voltage signal, the wider the high-level portion of the PWM signal (the larger the duty cycle), and vice versa, thereby modulating the analog control signal onto the width of the digital pulse. The first and second output circuits can control the switching transistors to turn on and off according to the PWM signal commands, thereby outputting voltage to the load. The first and second feedback circuits can sample the output state and send it back to the error amplifier. Through the above closed-loop control, the dual-voltage output circuit can provide very stable and pure positive and negative voltages, meeting the needs of various precision analog circuits.

[0022] The dual-voltage output circuit of this application embodiment includes: a sawtooth wave circuit, a first error amplifier, a first comparator, a first output circuit, a first feedback circuit, a second error amplifier, a second comparator, a second output circuit, and a second feedback circuit. The dual-voltage output circuit shares the same sawtooth wave circuit, saving circuit design costs. Furthermore, both the first and second pulse width modulation signals are generated by comparing the sawtooth wave generated by the same sawtooth wave circuit with their respective error signals, ensuring complete synchronization of the switching frequencies of the positive and negative output voltages, thereby reducing beat noise caused by the random staggered switching times of the two paths. Each voltage output circuit has its own independent error amplifier, feedback circuit, and comparator, enabling each output voltage to perform rapid response and independent closed-loop regulation, stabilizing the output voltage at the target value set by a preset reference voltage, ensuring the output accuracy and stability of the positive and negative voltages. The feedback circuit can generate a feedback voltage based on the output current of the output circuit. When the load current suddenly changes, the feedback voltage can immediately reflect this change, and the error amplifier adjusts its output voltage accordingly, thereby rapidly changing the duty cycle of the pulse width modulation signal and maintaining voltage stability. This application embodiment utilizes a shared sawtooth wave circuit and reference voltage, and through two independent feedback control loops, achieves high-precision and high-stability positive and negative dual voltage output.

[0023] Reference Figure 2 The diagram shows a circuit diagram of a dual-voltage output circuit according to an embodiment of the present invention.

[0024] In one embodiment, such as Figure 2 The first output circuit 14 includes: a first switch Q1, a first inductor L1, a first diode D1, a first capacitor C1, and a second capacitor C2; the control terminal of the first switch Q1 is used to receive the first pulse width modulation signal, the input terminal of the first switch Q1 is connected to the input power supply, and the output terminal of the first switch Q1 is connected to the output terminal of the first diode D1; the input terminal of the first diode D1 is connected to the load; one end of the first capacitor C1 is connected to the input power supply, and the other end of the first capacitor C1 is grounded; one end of the first inductor L1 is connected to the output terminal of the first switch Q1, and the other end of the first inductor L1 is grounded; one end of the second capacitor C2 is connected to the input terminal of the first diode D1, and the other end of the second capacitor C2 is grounded.

[0025] In this embodiment, the control terminal of the first switch Q1 receives a first pulse width modulation (PWM) signal. When the PWM signal is high, Q1 is turned on, and the input power supply voltage is connected to the circuit; when the PWM signal is low, Q1 is turned off, cutting off the input power supply. By controlling the ratio of its on and off times (duty cycle), the energy output to the load can be regulated. The first inductor L1 can store and filter energy. When Q1 is on, current flows through L1, and electrical energy is stored in the inductor in the form of magnetic field energy, simultaneously supplying power to the load and the output capacitor C2. When Q1 is off, the inductor generates a back electromotive force to maintain a constant current, and its current continues to supply power to the load through the freewheeling diode D1. The first diode D1 can be a freewheeling diode. When Q1 is off, the current in inductor L1 cannot change abruptly. At this time, D1 provides a continuous loop for the inductor current, preventing the inductor from generating extremely high peak voltages that could damage the switch Q1, and ensuring the continuity of the load current. The second capacitor C2 and the inductor L1 together form an LC filter, further smoothing the output voltage, filtering out switching noise, and making the output voltage more stable and pure. Simultaneously, it can provide or absorb instantaneous current during load transient changes, stabilizing the output voltage. The first capacitor C1 can provide a large instantaneous current to the switching transistor Q1 nearby, absorb noise from the input power line, and prevent high-frequency noise generated by the switching circuit from interfering with the input power supply of the preceding stage.

[0026] In one embodiment, when the first pulse width modulation signal is high, the first switch Q1 is turned on so that the first capacitor C1 supplies power to the first inductor L1, and the second capacitor C2 outputs the first voltage to the load; when the first pulse width modulation signal is low, the first switch Q1 is turned off so that the first inductor L1 outputs the first voltage to the load through the first diode D1.

[0027] In this embodiment, the switching transistor Q1 operates mostly in a fully on (low power consumption) or fully off (near-zero power consumption) state, avoiding the continuous power consumption of the regulating transistor in a linear regulator. The first inductor L1 acts as an energy transfer station; when Q1 is on, L1 absorbs and stores energy (magnetic field energy) from the power supply and C1; when Q1 is off, L1 releases its stored energy to the load. Although the input is intermittent pulses, the current supplied to the load through the inductor's energy storage and release is continuous and smooth. This ensures that the output voltage will not be interrupted or drastically drop during the switching transistor's off period. When Q1 is on and L1 is charging, C2 is responsible for maintaining the output voltage and filtering noise; when Q1 is off and L1 is discharging, C2 and L1 together form an LC filter, further smoothing the current released by the inductor. When load changes cause the output voltage to deviate from the set value, the control loop can immediately adjust the duty cycle of the PWM signal, thereby affecting the on and off time ratio of Q1 in each cycle. This rapidly adjusts the energy supplied to L1 and the final load, improving the circuit's response speed to load changes and effectively suppressing output voltage overshoot and undershoot caused by load step changes, thus maintaining system stability.

[0028] In one embodiment, such as Figure 2 The second feedback circuit 19 includes: a first resistor R1 and a second resistor R2; one end of the first resistor R1 is connected to the input terminal of the first diode D1, the other end of the first resistor R1 is connected to the second resistor R2, and the other end of the second resistor R2 is connected to the input power supply; the first feedback voltage is connected between the first resistor R1 and the second resistor R2.

[0029] In this embodiment, the first feedback voltage is determined by the voltage division ratio of resistors R1 and R2. By selecting different values ​​for R1 and R2, different output voltages can be flexibly set. If high-precision, low-temperature-drift resistors are used, a very stable and accurate voltage division ratio can be obtained, thereby ensuring the accuracy of the output voltage.

[0030] In one embodiment, such as Figure 2The second output circuit 18 includes: a second switch Q2, a second inductor L2, a second diode D2, a third capacitor C3, and a fourth capacitor C4; the control terminal of the second switch Q2 is used to receive the second pulse width modulation signal, the input terminal of the second switch Q2 is connected to the input power supply, and the output terminal of the second switch Q2 is connected to the output terminal of the second diode D2; the input terminal of the second diode D2 is grounded; one end of the third capacitor C3 is connected to the input power supply, and the other end of the third capacitor C3 is grounded; one end of the second inductor L2 is connected to the output terminal of the second switch Q2, and the other end of the first inductor L1 is connected to the load; one end of the fourth capacitor C4 is connected between the second inductor L2 and the load, and the other end of the fourth capacitor C4 is grounded.

[0031] In this embodiment, the second switch Q2 is a power switch, controlled by the second pulse width modulation signal at its control terminal for high-frequency switching on and off. The second inductor L2 stores and transfers energy. The second diode D2 can be a freewheeling diode, providing a path for the inductor current when Q2 is off and determining the polarity of the output voltage. The fourth capacitor C4 is an output filter capacitor, filtering together with L2 to stabilize and smooth the negative output voltage. The third capacitor C3 is an input filter capacitor, providing instantaneous current to the switch Q2 to stabilize the input voltage. The second output circuit generates a positive voltage at the output terminal by controlling the switching of the switch Q2, changing the energy storage and release path of the inductor L2. The second output circuit shares the same oscillator and input power supply with the first output circuit, and is driven by a control loop with the same structure. The two PWM signals have the same frequency, eliminating beat frequency noise, simplifying EMI design, and the two output voltages have the same level of accuracy, stability, and dynamic response speed.

[0032] In one embodiment, when the second pulse width modulation signal is low, the second switch Q2 is turned on so that the third capacitor C3 supplies power to the second inductor L2, and the second inductor L2 outputs the second voltage to the load; when the second pulse width modulation signal is high, the second switch Q2 is turned off so that the second inductor L2 outputs the second voltage to the load through the second diode D2.

[0033] In this embodiment, the LC filter composed of the second inductor L2 and the fourth capacitor C4 works together to smooth the intermittent pulse energy into a stable DC during the stage when Q2 is off and L2 supplies power to the load. During the Q2 off-peak period, D2 provides a loop for the inductor current, preventing the high-voltage spikes generated by the inductor from breaking down Q2. The entire feedback loop can adjust the PWM duty cycle in real time, thereby adjusting the amount of energy stored in the inductor during the Q2 on-peak period, thus precisely controlling the energy released to the load during the off-peak period. When load changes cause negative voltage fluctuations, the fluctuations can be offset by changing the energy distribution, maintaining the stability of the output voltage and exhibiting excellent dynamic response performance.

[0034] In one embodiment, such as Figure 2 The second feedback circuit 19 includes a third resistor R3 and a fourth resistor R4; one end of the third resistor R3 is connected between the second inductor L2 and the load, the other end of the third resistor R3 is connected to the fourth resistor R4, and the other end of the fourth resistor R4 is grounded; the second feedback voltage is connected between the third resistor R3 and the fourth resistor R4.

[0035] In this embodiment, the current drawn from the output terminal by the resistor divider is small, and the sampling process has a negligible impact on the load of the output stage, without significantly increasing the burden on the output circuit or reducing the overall efficiency. The third and fourth resistors provide a stable DC feedback signal, ensuring the authenticity of the sampled voltage and avoiding errors introduced by the sampling circuit.

[0036] In one embodiment, such as Figure 2 The dual-voltage output circuit also includes: The first signal control circuit 21 is connected between the first comparator 13 and the first output circuit 14, and is used to receive the first pulse width modulation signal output by the first comparator 13; determine the output state of the first pulse width modulation signal according to the level of the first pulse width modulation signal; and output the first pulse width modulation signal to the first output circuit 14 when the output state of the first pulse width modulation signal is normal. The second signal control circuit 22 is connected between the second comparator 17 and the second output circuit 18. It is used to receive the second pulse width modulation signal output by the second comparator 17; determine the output state of the second pulse width modulation signal according to the level of the second pulse width modulation signal; and output the second pulse width modulation signal to the second output circuit 18 when the output state of the second pulse width modulation signal is normal.

[0037] In this embodiment, the signal control circuit can determine the output pulse width modulation (PWM) level. If the output is a constant high level or a constant low level, the output state of the PWM signal is usually determined to be abnormal. When the output state of the PWM signal is normal, outputting the PWM signal to the output circuit ensures signal accuracy and circuit control reliability.

[0038] In one embodiment, the first comparator 13 is configured to generate a high-level first pulse width modulation signal when the sawtooth wave is greater than the first amplified voltage signal, and to generate a low-level first pulse width modulation signal when the sawtooth wave is less than the first amplified voltage signal. The second comparator 17 is used to generate a high-level second pulse width modulation signal when the sawtooth wave is greater than the second amplified voltage signal, and to generate a low-level second pulse width modulation signal when the sawtooth wave is less than the second amplified voltage signal.

[0039] In this embodiment, assuming the feedback voltage signal is 0.8V, it is amplified to 2.4V. The sawtooth wave can be compared with 2.4V; when it is higher than 2.4V, a high level is output, and when it is lower than 2.4V, a low level is output, thus forming a regular high and low level pattern. If the feedback voltage changes, the amplified voltage value will also change, and the duty cycle of the output high and low levels will change, thereby generating pulse width modulation.

[0040] The dual-voltage output circuit of this application embodiment includes: a sawtooth wave circuit, a first error amplifier, a first comparator, a first output circuit, a first feedback circuit, a second error amplifier, a second comparator, a second output circuit, and a second feedback circuit. The dual-voltage output circuit shares the same sawtooth wave circuit, saving circuit design costs. Furthermore, both the first and second pulse width modulation signals are generated by comparing the sawtooth wave generated by the same sawtooth wave circuit with their respective error signals, ensuring complete synchronization of the switching frequencies of the positive and negative output voltages, thereby reducing beat noise caused by the random staggered switching times of the two paths. Each voltage output circuit has its own independent error amplifier, feedback circuit, and comparator, enabling each output voltage to perform rapid response and independent closed-loop regulation, stabilizing the output voltage at the target value set by a preset reference voltage, ensuring the output accuracy and stability of the positive and negative voltages. The feedback circuit can generate a feedback voltage based on the output current of the output circuit. When the load current suddenly changes, the feedback voltage can immediately reflect this change, and the error amplifier adjusts its output voltage accordingly, thereby rapidly changing the duty cycle of the pulse width modulation signal and maintaining voltage stability. This application embodiment utilizes a shared sawtooth wave circuit and reference voltage, and through two independent feedback control loops, achieves high-precision and high-stability positive and negative dual voltage output.

[0041] Reference Figure 3 The diagram illustrates a logic diagram of a dual-voltage output circuit according to an embodiment of the present invention. The oscillator primarily provides the clock signal for system operation and is a crucial component of the system. The clock signal, in conjunction with a related sawtooth wave circuit, generates a sawtooth wave. The error amplifier amplifies the system feedback voltage against a reference voltage; otherwise, a small error value would lead to system error deviation. The comparator compares the amplified signal with the sawtooth wave to generate a pulse-width modulated square wave. The PWM control circuit controls the switching of the PWM signal. If the PWM signal is normal, the PWM control signal is turned on, and the PWM signal is output; if the PWM signal is abnormal, the PWM control signal is turned off, and the PWM signal output is disabled.

[0042] The specific process of the first output circuit working normally is as follows: When MOSFET Q1 is turned on by the PWM signal, the current flows from: Vin -> Q1 -> L1 -> GND -> C1 -> Vin. At this time, the input power supply Vin is directly connected to the inductor L1, and the input voltage Vin directly charges the inductor, causing the inductor current to gradually increase. This process is mainly powered by the input capacitor C1. Since Q1 is on, the voltages across diode D1 are Vin and Vout1, respectively. Because Vout1 is negative, diode D1 is reverse-biased and cut off. The output Vout1 provides energy to the load by discharging through capacitor C2.

[0043] When MOSFET Q1 is turned off by PWM signal, input terminal Vin charges input capacitor C1. Since the inductor current cannot change abruptly at the output terminal, inductor L1 provides energy to capacitor C2 and load through freewheeling diode D1. The current flow is from C2->D1->L1->C2.

[0044] Since the output voltage is converted from the input power supply, the voltage across MOSFET Q1 and diode D1 is at its highest when it is Vin + Vout1. The derivation of the calculation for the negative power supply voltage Vout1 is as follows: The voltage difference across R2 is (VFB1-Vin), so the current flowing through it is (VFB1-Vin) / R2. As shown in the diagram, the current flowing through R1 is also (VFB1-Vin) / R2. Therefore, the voltage across (R1+R2) is current * resistance, i.e., ((VFB1-Vin) / R2)*(R1+R2). Vout1-Vin is the voltage across (R1+R2).

[0045] ((VFB1-Vin) / R2)*(R1+R2)=Vout1-Vin, Vout1 = VFB1 + (VFB1 - Vin)R1 / R2.

[0046] According to the design, VFB1 needs to be set in advance, which is the reference voltage Vref at the + terminal of the op-amp. Assuming VFB1=Vref=0.9V, input power supply voltage Vin=12V, R1=27K, R2=51K, we can get Vout1=0.9+(0.9-12)*(27 / 51)=-4.976V.

[0047] The specific process of the second output circuit working normally is as follows: When MOSFET Q2 is turned on via PWM signal control, the current flows from Vin -> Q2 -> L2 -> C4 -> GND -> C3 -> Vin. At this time, the input power supply Vin is directly connected to the inductor L2, and the input voltage Vin directly charges the inductor, causing the inductor current to gradually increase. This process is mainly powered by the input capacitor C3. Since Q2 is on, the voltages across diode D2 are Vin and GND respectively, and diode D2 is reverse-biased and cut off. The output Vout2 relies on inductor L2 to provide energy to the load.

[0048] When MOSFET Q2 is turned off via a PWM signal, the input capacitor C3 is charged at the input terminal Vin. At the output terminal, since the inductor current cannot change abruptly, inductor L2 provides energy to the load through capacitor C4 and freewheeling diode D2. The current flow is L2->C4->D2->L2.

[0049] Since the output voltage is converted from the input power supply, the voltage across MOSFET Q2 and diode D2 is at its highest value, Vin. The derivation for calculating the positive power supply voltage Vout2 is as follows: according to Figure 1 In the system block diagram, the voltage difference across R4 is (VFB2-GND), so the current flowing through it is VFB2 / R4. As shown in the diagram, the current flowing through R3 is also VFB2 / R4. Therefore, the voltage across (R3+R4) is current * resistance, i.e., (VFB2 / R4)*(R3+R4), and Vout2 is the voltage across (R3+R4).

[0050] (VFB2 / R4)*(R3+R4)=Vout2, Vout2 = VFB2 * (1 + R3 / R4).

[0051] According to the design, VFB2 is preset, which is the reference voltage Vref at the + terminal of the op-amp. Assuming VFB2=Vref=0.9V, input power supply voltage Vin=12V, R3=100K, R4=22K, we can get Vout2=0.9*(1+100 / 22)=4.991V.

[0052] This application's embodiments are based on common materials, avoiding the use of high-cost components, and employ a pulse width modulation (PWM) control circuit. By selecting different feedback reference voltage positions, varying PWM duty cycles, and different feedback voltage values, different output voltages are controlled. This offers high cost-effectiveness, achieving dual-output power supply control, and is applicable to a wide range of scenarios. Furthermore, using PWM control, the power supply topology differs from that using a charge pump. By comparing the feedback voltage with the reference voltage and amplifying the error through an amplifier, and through error comparison and PWM control, the dual-output voltage system shares an internal oscillator and sawtooth wave circuit, saving circuit design costs and exhibiting a high degree of circuit integration. Further expansion can be achieved by introducing a temperature compensation circuit to optimize the performance consistency of the oscillator and sawtooth wave circuit under different temperatures. Adjusting the duty cycle based on real-time changes in the feedback voltage improves the system's adaptability. Using PWM control enhances the system's load capacity, improves product reliability, and reduces circuit costs through integrated circuit design. Moreover, the PWM-based dual-voltage output method allows for the use of surface mount technology to replace through-hole components, reducing the number of external components and improving assembly efficiency in conjunction with high circuit integration design. Using PWM control, by differentiating the feedback voltage reference point and comparing it with a reference voltage, then amplifying the error value, comparing the error, and performing PWM control, it is more practical and reliable than using a transformer-output dual power supply. It reduces PCB footprint, increases output voltage drive current, and has a high matching degree for control systems with high load drive capability requirements.

[0053] This application also provides an electronic device including the dual-voltage output circuit described above.

[0054] In the embodiments of this application, the above-mentioned dual-voltage output circuit can be integrated into an electronic device, forming an efficient and reliable core power supply architecture for the device.

[0055] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, it should be noted that the scope of the methods and apparatuses in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

[0056] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) and includes several instructions to cause a terminal (which may be a mobile phone, computer, server, air conditioner, or network device, etc.) to execute the methods described in the various embodiments of this application.

[0057] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A dual-voltage output circuit, characterized in that, include: Sawtooth wave circuit, used to output sawtooth waves; A first error amplifier is used to obtain a first feedback voltage; The first feedback voltage is amplified according to a preset reference voltage to obtain a first amplified voltage signal; The first comparator is used to receive the sawtooth wave output by the sawtooth wave circuit and the first amplified voltage signal output by the first error amplifier. A first pulse width modulation signal is generated based on the first amplified voltage signal and the sawtooth wave; The first output circuit is used to obtain the power supply voltage; Upon receiving the first pulse width modulation signal, a first voltage is output to the load based on the power supply voltage; A first feedback circuit is connected to the first output circuit and is used to output the first feedback voltage to the first error amplifier according to the output current of the first output circuit. The second error amplifier is used to obtain the second feedback voltage; The second feedback voltage is amplified according to a preset reference voltage to obtain a second amplified voltage signal; The second comparator is used to receive the sawtooth wave output by the sawtooth wave circuit and the second amplified voltage signal output by the second error amplifier; A second pulse width modulation signal is generated based on the second amplified voltage signal and the sawtooth wave; The second output circuit is used to acquire the power supply voltage; after receiving the second pulse width modulation signal, it outputs a second voltage to the load based on the power supply voltage; one of the first voltage and the second voltage is a positive voltage and the other is a negative voltage; The second feedback circuit, connected to the second output circuit, is used to output the second feedback voltage to the second error amplifier according to the output current of the second output circuit.

2. The dual-voltage output circuit according to claim 1, characterized in that, The first output circuit includes: a first switching transistor, a first inductor, a first diode, a first capacitor, and a second capacitor; the control terminal of the first switching transistor is used to receive the first pulse width modulation signal; the input terminal of the first switching transistor is connected to the input power supply; the output terminal of the first switching transistor is connected to the output terminal of the first diode; the input terminal of the first diode is connected to the load; one end of the first capacitor is connected to the input power supply, and the other end of the first capacitor is grounded; one end of the first inductor is connected to the output terminal of the first switching transistor, and the other end of the first inductor is grounded; one end of the second capacitor is connected to the input terminal of the first diode, and the other end of the second capacitor is grounded.

3. The dual-voltage output circuit according to claim 2, characterized in that, When the first pulse width modulation signal is high, the first switch is turned on so that the first capacitor supplies power to the first inductor, and the second capacitor outputs the first voltage to the load; when the first pulse width modulation signal is low, the first switch is turned off so that the first inductor outputs the first voltage to the load through the first diode.

4. The dual-voltage output circuit according to claim 2, characterized in that, The second feedback circuit includes: a first resistor and a second resistor; one end of the first resistor is connected to the input terminal of the first diode, the other end of the first resistor is connected to the second resistor, and the other end of the second resistor is connected to the input power supply; the first feedback voltage is connected between the first resistor and the second resistor.

5. The dual-voltage output circuit according to claim 1, characterized in that, The second output circuit includes: a second switching transistor, a second inductor, a second diode, a third capacitor, and a fourth capacitor; the control terminal of the second switching transistor is used to receive the second pulse width modulation signal, the input terminal of the second switching transistor is connected to the input power supply, and the output terminal of the second switching transistor is connected to the output terminal of the second diode; the input terminal of the second diode is grounded; one end of the third capacitor is connected to the input power supply, and the other end of the third capacitor is grounded; one end of the second inductor is connected to the output terminal of the second switching transistor, and the other end of the first inductor is connected to the load; one end of the fourth capacitor is connected between the second inductor and the load, and the other end of the fourth capacitor is grounded.

6. The dual-voltage output circuit according to claim 5, characterized in that, When the second pulse width modulation signal is low, the second switch is turned on so that the third capacitor supplies power to the second inductor, and the second inductor outputs the second voltage to the load; when the second pulse width modulation signal is high, the second switch is turned off so that the second inductor outputs the second voltage to the load through the second diode.

7. The dual-voltage output circuit according to claim 5, characterized in that, The second feedback circuit includes a third resistor and a fourth resistor; one end of the third resistor is connected between the second inductor and the load, the other end of the third resistor is connected to the fourth resistor, and the other end of the fourth resistor is grounded; the second feedback voltage is connected between the third resistor and the fourth resistor.

8. The dual-voltage output circuit according to claim 1, characterized in that, Also includes: A first signal control circuit is connected between the first comparator and the first output circuit, and is used to receive the first pulse width modulation signal output by the first comparator. The output state of the first pulse width modulation signal is determined based on the level of the first pulse width modulation signal; if the output state of the first pulse width modulation signal is normal, the first pulse width modulation signal is output to the first output circuit. The second signal control circuit is connected between the second comparator and the second output circuit, and is used to receive the second pulse width modulation signal output by the second comparator; The output state of the second pulse width modulation signal is determined based on the level of the second pulse width modulation signal; When the output state of the second pulse width modulation signal is normal, the second pulse width modulation signal is output to the second output circuit.

9. The dual-voltage output circuit according to claim 1, characterized in that, The first comparator is configured to generate a high-level first pulse width modulation signal when the sawtooth wave is greater than the first amplified voltage signal, and to generate a low-level first pulse width modulation signal when the sawtooth wave is less than the first amplified voltage signal. The second comparator is configured to generate a high-level second pulse width modulation signal when the sawtooth wave is greater than the second amplified voltage signal, and to generate a low-level second pulse width modulation signal when the sawtooth wave is less than the second amplified voltage signal.

10. An electronic device, characterized in that, Includes the dual-voltage output circuit as described in any one of claims 1-9 above.

Images