Boost device completed by comparator

Abstract

The utility model discloses a voltage boosting device completed by a comparator. The voltage boosting device comprises a triangular wave generating circuit, a direct current level circuit, a PWM waveform generating circuit, a push-pull driving circuit, a Boost topology, a current feedback circuit and a voltage feedback circuit. Triangular waves generated by the triangular wave generating circuit and direct-current level output by the direct-current level circuit are input into the PWM waveform generating circuit, the PWM waveform generating circuit adopts a comparator, the comparator forms PWM wave signals with high and low changes, the PWM wave signals switch on and off power switch tubes in the Boost topological structure through the push-pull driving circuit, and the power switch tubes are switched on and off through the push-pull driving circuit. Meanwhile, the output end of the Boost topology is connected with a current feedback circuit and a voltage feedback circuit, and the current feedback circuit and the voltage feedback circuit are used for controlling the duty ratio of the PWM wave signal to form a required output voltage value. According to the utility model, no software participates in boosting, all the boosting is realized by hardware, and the boosting function of an integrated circuit can be realized by building a plurality of low-cost discrete components.

Description

TECHNICAL FIELD

[0001] The utility model relates to a kind of boost circuit, in particular to a kind of boost device completed by comparator. BACKGROUND

[0002] Most of the existing boost circuit adopts integrated circuit scheme, realizes boost function using integrated chip, and the cost is higher, and a small part of boost circuit is through setting independent oscillation circuit for generating PWM signal, and boost part is according to the PWM signal to input voltage and outputs boost voltage, and oscillation circuit combines feedback signal, adjusts the duty cycle of PWM and reaches the purpose of adjusting output voltage. However, such boost circuit needs independent oscillation circuit, leading to increased manufacturing cost.

[0003] Therefore, it is urgent to provide a new boost device to solve the above problems. UTILITY MODEL CONTENT

[0004] The utility model solves the technical problem to provide a kind of boost device completed by comparator, and the boost function of integrated circuit can be realized by several low-cost discrete components.

[0005] To solve the above technical problems, one technical scheme of the utility model is: provide a kind of boost device completed by comparator, including triangle wave generation circuit, direct current level circuit, PWM waveform generating circuit, push-pull drive circuit, Boost boost topology, current feedback circuit, voltage feedback circuit;

[0006] The triangle wave generated by the triangle wave generation circuit is input to the PWM waveform generating circuit with the direct current level output by direct current level circuit, the PWM waveform generating circuit adopts comparator, and the triangle wave and direct current level form the PWM wave signal of high-low change by comparator, the PWM wave signal is switched through the push-pull drive circuit power switch tube in the Boost boost topology structure, and the output end of Boost boost topology is connected with current feedback circuit and voltage feedback circuit, to control the duty cycle size of PWM wave signal and form the required output voltage value.

[0007] In the utility model, the triangle wave generating circuit includes hysteresis comparator U1.1, resistance R1-R4, R18, capacitor C1, C8, the one end of resistance R2 and the one end of R3 are connected in the positive phase input end of hysteresis comparator U1.1, the other end of R2 is connected voltage VCC, the other end of R3 is grounded, resistance R4 is connected between the positive phase input end and the output end of hysteresis comparator U1.1, resistance R1 is connected between the inverting input end and the output end of hysteresis comparator U1.1, one end of resistance R18 is connected voltage VCC, the other end is connected the output end of hysteresis comparator U1.1, one end of capacitor C1 is connected in the inverting input end of hysteresis comparator U1.1, the other end is grounded, one end of capacitor C8 is connected voltage VCC, the other end is grounded.

[0008] In the utility model, the direct current level circuit includes triode Q4, adjustable resistance R6, resistance R5, R24, capacitor C6, C13, one end of adjustable resistance R6 and one end of resistance R5 are connected in the base of triode Q4, the other end of adjustable resistance R6 is connected voltage VCC, the other end of resistance R5 is grounded, one end of resistance R24 is connected the emitter of triode Q4, the other end is connected voltage VCC, one end of capacitor C13 is connected the emitter of triode Q4, the other end is grounded, capacitor C6 is connected between voltage VCC and ground.

[0009] In the utility model, the PWM waveform generating circuit includes hysteresis comparator U1.2, resistance R7, R19, capacitor C2, the triangle wave generated by the triangle wave generating circuit is input to the inverting input end of hysteresis comparator U1.2, the direct current level output by the direct current level circuit is input to the positive phase input end of hysteresis comparator U1.2, one end of resistance R7 and one end of R19 are connected with the output end of hysteresis comparator U1.2, the other end of R19 is connected voltage VCC, the other end of R7 is connected with capacitor C2.

[0010] Further, the hysteresis comparator adopts LM339 chip.

[0011] In the utility model, the push-pull drive circuit adopts push-pull output structure, including upper triode Q1, lower triode Q2, resistance R8, R9, schottky diode D2, the emitter of upper triode Q1, the emitter of lower triode Q2 and one end of resistance R8, one end of R9 are connected, the other end of resistance R9 is connected with the cathode of schottky diode D2, the other end of resistance R8 is connected with the anode of schottky diode D2, the anode of schottky diode D2 is connected with the gate of MOS tube in Boost boost topology structure.

[0012] Further, the upper triode Q1 adopts S8050, the lower triode Q2 adopts S8550, and the Schottky diode D2 adopts SS34.

[0013] In a preferred embodiment of the utility model, the Boost topology includes a boost power inductor L1, a power switch tube Q3, a fast recovery Schottky boost diode D1, input and output filter capacitors C19 and C3, resistors R10-R12 and R23, and an adjustable resistor R22, wherein the resistors R11, the adjustable resistor R22, and the resistor R12 are connected in series, form a resistor string for output voltage voltage division, and serve as a voltage sampling signal of the voltage feedback circuit; the resistor R23 is connected in parallel between the gate and the source of the power switch tube Q3; the source of the power switch tube Q3 is connected to the upper end of the sampling resistor R10; the lower end of the resistor R10 is grounded; and the voltage at the upper end of the resistor R10 serves as a current sampling signal of the current feedback circuit.

[0014] Further, the power switch tube Q3 adopts an N-channel MOS tube with model number NCE6050.

[0015] In a preferred embodiment of the utility model, both the current feedback circuit and the voltage feedback circuit adopt a comparator circuit.

[0016] The device of the utility model realizes boost without any software participation, and is entirely realized by hardware, and can realize the boost function of an integrated circuit by building with a plurality of low-cost discrete components. The PWM signal of the device does not use a special chip, but uses a PWM waveform generating circuit, a direct current level circuit forms a PWM wave through an LM339 comparator, the PWM wave switches a MOS tube through a driving push-pull circuit, and the required output voltage value is formed by controlling the duty cycle of the PWM wave. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a structural block diagram of a boost device completed by a comparator of the utility model;

[0018] Figure 2 is a circuit diagram of the boost device completed by the comparator. DETAILED DESCRIPTION

[0019] The preferred embodiments of the utility model are described in detail below with reference to the drawings, so that the advantages and features of the utility model can be more easily understood by those skilled in the art, and the protection scope of the utility model can be more clearly and definitely defined.

[0020] Please refer to Figure 1 and Figure 2 The utility model embodiment includes:

[0021] A boost device completed by a comparator, comprising a triangular wave generating circuit, a direct current level circuit, a PWM waveform generating circuit, a push-pull driving circuit, a Boost topology, a current feedback circuit and a voltage feedback circuit.

[0022] The triangular wave generated by the triangular wave generating circuit and the direct current level output by the direct current level circuit are input to the PWM waveform generating circuit, the PWM waveform generating circuit adopts a comparator, the triangular wave and the direct current level form a high-low change PWM wave signal by the comparator, the PWM wave signal switches the power switch tube in the Boost topology through the push-pull driving circuit, and the output end of the Boost topology is connected with the current feedback circuit and the voltage feedback circuit to control the duty cycle of the PWM wave signal to form the required output voltage value.

[0023] Referring to Figure 2 , the triangular wave generating circuit comprises a hysteresis comparator U1.1, resistors R1-R4, R18, capacitors C1 and C8, one end of the resistor R2 and one end of the resistor R3 are connected to the positive input end of the hysteresis comparator U1.1, the other end of the resistor R2 is connected to the voltage VCC, the other end of the resistor R3 is grounded, the resistor R4 is connected in parallel between the positive input end and the output end of the hysteresis comparator U1.1, the resistor R4 is connected in parallel between the negative input end and the output end of the hysteresis comparator U1.1, one end of the resistor R18 is connected to the voltage VCC and the other end is connected to the output end of the hysteresis comparator U1.1, one end of the capacitor C1 is connected to the negative input end of the hysteresis comparator U1.1 and the other end is grounded, one end of the capacitor C8 is connected to the voltage VCC and the other end is grounded, and the components and their connection relationship are shown in the figure. Preferably, the hysteresis comparator adopts an LM339 chip. The approximate triangular wave on the capacitor charging and discharging pin of the hysteresis comparator U1.1, if a strict sense of triangular wave is required, an integral circuit can be additionally added to the output pin (2 pin) of the hysteresis comparator to complete it. The triangular wave oscillation frequency can be adjusted to the required frequency by adjusting C1 and R1. It has been verified that the actual application MOS tube switching frequency of the device can reach 200KHz.

[0024] The direct current level circuit comprises a transistor Q4, an adjustable resistor R6, resistors R5 and R24, capacitors C6 and C13, one end of the adjustable resistor R6 and one end of the resistor R5 are connected to the base of the transistor Q4, the other end of the adjustable resistor R6 is connected to the voltage VCC, the other end of the resistor R5 is grounded, one end of the resistor R24 is connected to the emitter of the transistor Q4 and the other end is connected to the voltage VCC, one end of the capacitor C13 is connected to the emitter of the transistor Q4 and the other end is grounded, the capacitor C6 is connected in parallel between the voltage VCC and the ground, and the components and their connection relationship are shown in the figure. Preferably, the model of the transistor Q4 is S8550. The direct current level is formed by charging the capacitor through the resistor, and the voltage value on the capacitor C13 is adjusted by the voltage dividing resistors R5 and R6 and the transistor Q4, and the capacitor C13 is selected to have a slightly larger capacitance value (4.7uF), so as to ensure that the direct current potential rises at a slower speed than the triangular wave forming speed when the device is powered on, which is a soft start function of gradually increasing PWM to prevent the MOS tube from being continuously turned on and broken down at the moment of power-on.

[0025] The PWM waveform generating circuit comprises a hysteresis comparator U1.2, resistors R7 and R19, and a capacitor C2, the triangular wave generated by the triangular wave generating circuit is input to the inverting input end of the hysteresis comparator U1.2 through the inverting input end of the hysteresis comparator U1.1, the direct current level output by the direct current level circuit is input to the non-inverting input end of the hysteresis comparator U1.2 through the emitter of the transistor Q4, one end of the resistor R7 and one end of the resistor R19 are connected to the output end of the hysteresis comparator U1.2, the other end of the resistor R19 is connected to the voltage VCC, and the other end of the resistor R7 is connected to the capacitor C2, and the components and their connection relationship are shown in the figure. Preferably, the hysteresis comparator uses an LM339 chip. The triangular wave and the direct current potential are respectively input to the inverting and non-inverting input ends of the LM339 comparator for comparison, and the output end outputs a PWM waveform with high and low changes, and the PWM drives the push-pull drive circuit to switch the MOS tube.

[0026] The push-pull drive circuit adopts a push-pull output structure, enhances the driving capability, has good frequency characteristics, and can quickly switch the MOS tube, thereby avoiding the MOS tube from being seriously heated or even unable to normally work in the fast switching state. The push-pull drive circuit comprises an upper triode Q1, a lower triode Q2, resistors R8 and R9, and a Schottky diode D2. The emitter of the upper triode Q1 and the emitter of the lower triode Q2 are connected to one end of the resistor R8 and one end of the resistor R9. The other end of the resistor R9 is connected to the cathode of the Schottky diode D2. The other end of the resistor R8 is connected to the anode of the Schottky diode D2. The anode of the Schottky diode D2 is connected to the gate of the MOS tube in the Boost voltage conversion topology. The components and their connection relationship are shown in the figure. Preferably, the upper triode Q1 is an NPN transistor with the model number S8050. The lower triode Q2 is a PNP transistor with the model number S8550. The Schottky diode D2 has the model number SS34. When the PWM output high level, the upper NPN tube is turned on, the voltage follows the output high level, and the MOS tube behind is turned on. When the PWM waveform output low level, the lower PNP is turned on, and the MOS tube behind is turned off.

[0027] The Boost voltage conversion topology comprises a boost power inductor L1, a power switch tube Q3, a fast recovery Schottky boost diode D1, input and output filter capacitors C19 and C3, resistors R10-R12 and R23, and an adjustable resistor R22. The resistors R11, R22 and R12 are connected in series to form a resistor string for voltage division of the output voltage of the power switch tube Q3 and as a voltage sampling signal of the voltage feedback circuit. The resistor R23 is connected in parallel between the gate and the source of the power switch tube Q3. The source of the power switch tube Q3 is connected to the upper end of the sampling resistor R10. The lower end of the resistor R10 is grounded. The voltage at the upper end of the resistor R10 is a current sampling signal of the current feedback circuit. The components and their connection relationship are shown in the figure. Preferably, the power switch tube Q3 is an N-channel MOS tube with the model number NCE6050. The fast recovery Schottky boost diode D1 has the model number HS1M. When the switch tube Q3 is turned on, the VCC voltage charges the inductor L1 through L1->Q3->GND to store energy. At this time, C3 provides energy to the load. When the switch tube Q3 is turned off, the induced voltage and the VCC voltage of L1 are superimposed through D1->C3->GND to provide energy to the load, and L1 releases the stored energy. Q3 stores energy in the inductor L1 by continuously switching, releases energy, and provides a certain output voltage and output current to the load. The output voltage sampling signal is 2.5V generated by voltage division of the output voltage through the resistor string.

[0028] The stability of the output voltage cannot be achieved without the feedback circuit. The current feedback loop and the voltage feedback loop are added in the device. The current feedback circuit and the voltage feedback circuit both adopt a comparator circuit.

[0029] The voltage feedback circuit comprises a comparator U1.4, resistors R13, R14, R20, a capacitor C10, a voltage reference chip U4, the inverting input of the comparator U1.4 is connected to the adjustable end of the adjustable resistor R22, the non-inverting input is connected to the first pin of the voltage reference chip U4, and the output is connected to the base of the transistor Q4 of the direct current level circuit through the resistor R14, and the components and their connection relationship are shown in the figure.

[0030] The current feedback circuit comprises a comparator U1.3, resistors R23, R10, R15, R17, R21, capacitors C12, C14, a voltage reference chip U9, one end of the resistor R23 is connected to the gate of the power switch tube Q, the other end is connected to the inverting input of the comparator U1.3, the inverting input of the comparator U1.3 is connected to the source of the power switch tube Q3, one end of the resistor R10 is connected to the source of the power switch tube Q3, and the other end is grounded, and the voltage on the resistor R10 is used as the input signal of the current feedback circuit. The non-inverting input of the comparator U1.3 is connected to the first pin of the voltage reference chip U9, and the output is connected to the base of the transistor Q4 of the direct current level circuit through the resistor R17, and the components and their connection relationship are shown in the figure.

[0031] Preferably, the models of the comparators U1.3 and U1.4 are LM339, and the models of the voltage reference chips U4 and U9 are LM431. The output voltage is generated by the resistor voltage division method, and the 2.5V reference voltage formed by TL431 is input to the inverting and non-inverting inputs of the comparator for comparison, so as to monitor whether the output voltage is too high. When the output voltage Vout is too high, the voltage divided by the resistor will exceed 2.5V, the voltage at the inverting input of the comparator will be higher than the 2.5V reference voltage at the non-inverting input, the comparator will output a low level, thereby reducing the potential of the low level circuit, reducing the duty cycle of the PWM wave, reducing the on time of the MOS tube, and reducing the output voltage. The current feedback is a resistor R10 with very small resistance connected in series between the source of the N-MOS tube and the GND. The voltage on the resistor is sampled by the comparator U1.3, compared with the LM431 reference voltage, and the potential of the direct current level circuit is pulled down to reduce the on time of the MOS.

[0032] The device realizes the voltage boosting without any software participation, and the voltage boosting function of the integrated circuit can be realized by building a plurality of low-cost discrete components.

[0033] The above is only the embodiment of the utility model, and does not limit the patent range of the utility model, and any equivalent structure or equivalent process transformation using the utility model specification and the attached drawings, or direct or indirect application in other related technical fields, are also included in the patent protection range of the utility model.

Claims

1. A voltage boosting device accomplished by a comparator, characterized by, The circuit comprises a triangular wave generating circuit, a direct current level circuit, a PWM waveform generating circuit, a push-pull driving circuit, a Boost voltage-boosting topology, a current feedback circuit and a voltage feedback circuit. The triangular wave generated by the triangular wave generating circuit and the direct current level output by the direct current level circuit are input to the PWM waveform generating circuit, the PWM waveform generating circuit adopts a comparator, the triangular wave and the direct current level form a high-low change PWM wave signal by the comparator, the PWM wave signal is switched by the push-pull driving circuit to the power switch tube in the Boost voltage-boosting topology, and the output end of the Boost voltage-boosting topology is connected with the current feedback circuit and the voltage feedback circuit to control the duty cycle of the PWM wave signal and form the required output voltage value.

2. The voltage boosting device accomplished by a comparator according to claim 1, characterized by, The triangular wave generating circuit comprises a hysteresis comparator U1.1, resistors R1-R4 and R18, capacitors C1 and C8, one end of the resistor R2 and one end of the resistor R3 are connected to the positive input end of the hysteresis comparator U1.1, the other end of the resistor R2 is connected to a voltage VCC, the other end of the resistor R3 is grounded, the resistor R4 is connected in parallel between the positive input end and the output end of the hysteresis comparator U1.1, the resistor R1 is connected in parallel between the negative input end and the output end of the hysteresis comparator U1.1, one end of the resistor R18 is connected to the voltage VCC and the other end is connected to the output end of the hysteresis comparator U1.1, one end of the capacitor C1 is connected to the negative input end of the hysteresis comparator U1.1 and the other end is grounded, one end of the capacitor C8 is connected to the voltage VCC and the other end is grounded.

3. The voltage boosting device accomplished by a comparator according to claim 1, wherein The direct current level circuit comprises a transistor Q4, an adjustable resistor R6, resistors R5 and R24, and capacitors C6 and C13, one end of the adjustable resistor R6 and one end of the resistor R5 are connected to the base of the transistor Q4, the other end of the adjustable resistor R6 is connected to the voltage VCC, the other end of the resistor R5 is grounded, one end of the resistor R24 is connected to the emitter of the transistor Q4 and the other end is connected to the voltage VCC, one end of the capacitor C13 is connected to the emitter of the transistor Q4 and the other end is grounded, and the capacitor C6 is connected in parallel between the voltage VCC and the ground.

4. The voltage boosting device accomplished by a comparator according to claim 1, wherein The PWM waveform generating circuit comprises a hysteresis comparator U1.2, resistors R7 and R19, and a capacitor C2, the triangular wave generated by the triangular wave generating circuit is input to the negative input end of the hysteresis comparator U1.2, the direct current level output by the direct current level circuit is input to the positive input end of the hysteresis comparator U1.2, one end of the resistor R7 and one end of the resistor R19 are connected to the output end of the hysteresis comparator U1.2, the other end of the resistor R19 is connected to the voltage VCC, and the other end of the resistor R7 is connected to the capacitor C2.

5. The voltage boosting device accomplished by a comparator according to claim 2 or 4, characterized by, The hysteresis comparator adopts an LM339 chip.

6. The voltage boosting device accomplished by a comparator according to claim 1, wherein The push-pull driving circuit adopts a push-pull output structure, comprising an upper triode Q1, a lower triode Q2, resistors R8 and R9, and a Schottky diode D2; one end of the resistor R8 and one end of the resistor R9 are connected to the emitter of the upper triode Q1 and the emitter of the lower triode Q2; the other end of the resistor R9 is connected to the cathode of the Schottky diode D2; the other end of the resistor R8 is connected to the anode of the Schottky diode D2; and the anode of the Schottky diode D2 is connected to the gate of a MOS transistor in a Boost voltage boosting topology.

7. The voltage boosting device accomplished by a comparator according to claim 6, characterized by, The upper triode Q1 is S8050, the lower triode Q2 is S8550, and the Schottky diode D2 is SS34.

8. The voltage boosting device accomplished by a comparator according to claim 1, wherein The Boost voltage boosting topology comprises a boost power inductor L1, a power switch tube Q3, a fast recovery Schottky boost diode D1, input and output filter capacitors C19 and C3, resistors R10-R12 and R23, and an adjustable resistor R22; the resistors R11, the adjustable resistor R22, and the resistor R12 are connected in series to form a resistor string for voltage division on an output voltage and to serve as a voltage sampling signal of the voltage feedback circuit; the resistor R23 is connected in parallel between the gate and the source of the power switch tube Q3; the source of the power switch tube Q3 is connected to the upper end of the sampling resistor R10; and the voltage at the upper end of the resistor R10 is a current sampling signal of the current feedback circuit.

9. The voltage boosting device accomplished by a comparator according to claim 8, characterized by, The power switch tube Q3 is an N-channel MOS transistor, and the model number is NCE6050.

10. The voltage boosting device accomplished by a comparator according to claim 1, wherein Both the current feedback circuit and the voltage feedback circuit adopt a comparator circuit.

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