Feedback follower circuit, switching power supply, power supply system and power distribution system

Abstract

The utility model discloses a feedback follower circuit, a switching power supply, a power supply system and a power distribution system, and the feedback follower circuit comprises a triode, a collector current generation circuit, an emitter voltage drop generation circuit, a first voltage generation circuit, and a second voltage generation circuit. The connection point of the collector of the triode and one end of the collector current generation circuit is connected with an FB pin of the feedback loop, the other end of the collector current generation circuit is grounded, and the connection point of one end of the emitter voltage drop generation circuit and one end of the first voltage generation circuit is connected with the connection point of the output end of the switching power supply and the input end of the linear voltage-stabilized power supply. The other end of the emitter voltage drop generation circuit is connected with the triode emitter, the connection point of the other end of the first voltage generation circuit and one end of the second voltage generation circuit is connected with the triode base, and the other end of the second voltage generation circuit is connected with the output end of the linear voltage-stabilized power supply. According to the utility model, the loss of a post-stage linear voltage-stabilized power supply can be reduced, and the efficiency of a switching power supply and a power distribution system is effectively improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to power supply technical field, especially relates to a feedback follow circuit, switching power supply, power supply system and the power distribution system with the switching power supply of having. BACKGROUND

[0002] The switching power supply has the advantages of high conversion efficiency, small size, wide input voltage range, but the output ripple is big, and the interference is easy to produce, the linear voltage stabilizing power supply output ripple is small, and the response is fast, and the design is simple, but the switching power supply is heavy, and the conversion efficiency is low.

[0003] In the switching power supply plus linear voltage stabilizing power supply system, the high-efficiency energy conversion of the front-stage switching power supply is realized to the linear power supply voltage stabilizing output, but in the output adjustable switching power supply plus linear voltage stabilizing power supply system, if the output of the front-stage switching power supply is a fixed value, then when the whole power supply system needs to output a low voltage, the linear voltage stabilizing power supply of the rear stage needs to bear a larger voltage difference, and the loss on the linear voltage stabilizing power supply of the rear stage is increased, which will directly lead to the problems of large loss and low efficiency in the application of switching power supply and even power distribution system. UTILITY MODEL CONTENTS

[0004] Therefore, the utility model wants to solve the technical problem to provide a feedback follow circuit, switching power supply, power supply system and power distribution system, and at least the deficiency of the prior art problem can be solved to a certain extent.

[0005] As a first aspect of the application, the technical scheme of the embodiment of the feedback follow circuit provided is as follows:

[0006] A feedback follow circuit is applied to a power supply system, the power supply system comprises a switching power supply in a front stage and a linear voltage regulator in a rear stage, the output voltage of the switching power supply is the input voltage of the linear voltage regulator, the output voltage of the switching power supply is greater than the output voltage of the linear voltage regulator, the switching power supply adjusts the driving signal through the FB pin of the feedback loop to realize the output voltage stability, and the output voltage of the linear voltage regulator is adjustable, wherein: the feedback follow circuit comprises a transistor, a collector current generating circuit, an emitter voltage drop generating circuit, a first voltage generating circuit and a second voltage generating circuit, the connection point of the collector of the transistor and one end of the collector current generating circuit is used for connecting the FB pin of the feedback loop, the other end of the collector current generating circuit is used for grounding, the connection point of one end of the emitter voltage drop generating circuit and one end of the first voltage generating circuit is used for connecting the connection point of the output end of the switching power supply and the input end of the linear voltage regulator, the other end of the emitter voltage drop generating circuit is connected with the emitter of the transistor, the connection point of the other end of the first voltage generating circuit and one end of the second voltage generating circuit is connected with the base of the transistor, and the other end of the second voltage generating circuit is used for connecting the output end of the linear voltage regulator.

[0007] When the power supply system works, the FB pin of the feedback loop is stabilized as a first set voltage, so that the current flowing through the collector of the transistor is a first set current, the current flowing through the emitter of the transistor is controlled, and then the voltage between the two ends of the first voltage generating circuit is clamped as a second set voltage, so that the current flowing through the first voltage generating circuit is a second set current, the current flowing through the second voltage generating circuit is controlled as a second set current, and then the voltage between the two ends of the second voltage generating circuit is controlled as a third set voltage, so that the output voltage of the switching power supply is the sum of the output voltage of the linear voltage regulator, the second set voltage and the third set voltage.

[0008] Further, the transistor is a PNP transistor.

[0009] Preferably, the collector current generating circuit is a resistor R6.

[0010] Preferably, the emitter voltage drop generating circuit is a resistor R7.

[0011] Preferably, the first voltage generating circuit is a resistor R8.

[0012] Preferably, the second voltage generating circuit is a resistor R9.

[0013] Preferably, the collector current generating circuit is a resistor R6, the emitter voltage drop generating circuit is a resistor R7, the first voltage generating circuit is a resistor R8, and the second voltage generating circuit is a resistor R9.

[0014] As a second aspect of the present application, the provided embodiment of the switching power supply has the following technical solutions:

[0015] A switching power supply, wherein the feedback follower circuit of any one of the first aspect is provided.

[0016] Further, the collector of the triode and the connection point between one end of the collector current generating circuit and the other end of the first voltage generating circuit and one end of the second voltage generating circuit are connected with a capacitor C6.

[0017] As a third aspect of the present application, the provided embodiment of the power supply system has the following technical solutions:

[0018] A power supply system, wherein the switching power supply in the front stage and the linear voltage stabilizing power supply in the rear stage are provided, the output voltage of the switching power supply is the input voltage of the linear voltage stabilizing power supply, the output voltage of the switching power supply is greater than the output voltage of the linear voltage stabilizing power supply, the output voltage of the switching power supply is stabilized through the adjustment of the feedback loop, and the output voltage of the linear voltage stabilizing power supply is adjustable, wherein the feedback follower circuit of any one of the first aspect is provided in the power supply system.

[0019] As a third aspect of the present application, a power distribution system is provided, wherein the feedback follower circuit of any one of the above solutions is provided. Compared with the prior art, the present application has the following advantages and beneficial effects:

[0020] The utility model discloses a clever use of the component characteristic of triode, first, the base current of triode is very small and can be ignored, and the collector current of triode is equal to the emitter current, thereby the current flowing through the emitter of triode can be controlled to be the preset value, second, the emitter junction voltage of triode is a fixed value, thereby the voltage between the two ends of the first voltage generating circuit is clamped to the second set voltage, and the current flowing through the first voltage generating circuit is a fixed value, and third, the base current of triode is very small and can be ignored, and the current flowing through the second voltage generating circuit is equal to the current flowing through the first voltage generating circuit, thereby the voltage between the two ends of the second voltage generating circuit is designed as the third set voltage, and the output voltage of switching power supply is the sum of the output voltage of linear regulated power supply, the second set voltage and the third set voltage, since the second set voltage and the third set voltage are preset fixed voltage values, and the output voltage of linear regulated power supply is an artificial adjusted voltage value, thereby the output voltage of the front-stage switching power supply successfully follows the output voltage of the rear-stage linear regulated power supply, through the proper parameter design, the output voltage of switching power supply can be slightly higher than the output voltage of the rear-stage linear regulated power supply, for example, about 1.7V, so that the voltage difference between the two ends of the rear-stage linear regulated power supply is stabilized as the sum of the second set voltage and the third set voltage in the whole adjustable output voltage range of power supply system, thereby the loss of the rear-stage linear regulated power supply is reduced, and the efficiency of switching power supply, power supply system and power distribution system at low voltage output is improved. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 A specific circuit application of the feedback following circuit of the first embodiment of the utility model is applied to a specific power supply system. DETAILED DESCRIPTION

[0022] In order to make the above-mentioned purpose, features and advantages of the utility model more apparent, obvious and easy to understand, the specific embodiment of the utility model is described in detail below with reference to the drawings, obviously, the described embodiment is a part of the embodiment of the utility model, rather than all the embodiments. Based on the embodiment in the application, all the other embodiments obtained by the person skilled in the art without creative labor should belong to the protection scope of the application.

[0023] It should be noted that the terms "include" and "have" and any variation thereof described in the specification and claims of the present application are intended to cover the non-exclusive inclusion, for example, a series of components, unit circuits or control time sequences are not necessarily limited to the clearly listed components, unit circuits or control time sequences, but can include the components, unit circuits or control time sequences not clearly listed or inherent to the circuit.

[0024] In addition, the embodiments in the present application and the features in the embodiments can be combined with each other in the case of no conflict.

[0025] It should be understood that, in the specification and claims, when it is described that an element is "connected" to another element, the element can be "directly connected" to the other element, or "connected" to the other element through a third element; when it is described that a step is followed by another step, the step can be directly followed by the other step, or followed by the other step through a third step.

[0026] First embodiment

[0027] The embodiment provides a feedback following circuit, which is applied to a power supply system, the power supply system comprising a switching power supply located at a front stage and a linear voltage stabilizing power supply located at a rear stage, an output voltage of the switching power supply being an input voltage of the linear voltage stabilizing power supply, the output voltage of the switching power supply being greater than an output voltage of the linear voltage stabilizing power supply, the switching power supply adjusting a driving signal through an FB pin of a feedback loop to realize output voltage stabilization, and the output voltage of the linear voltage stabilizing power supply being adjustable.

[0028] Figure 1 A specific circuit of the feedback following circuit of the first embodiment of the utility model is applied to a principle diagram of a specific power supply system, please refer to Figure 1 The switching power supply comprises a control chip and a main power inductor L1, the control chip is a DC voltage reduction chip, a high-side switch tube, a low-side switch tube and their driving circuits are integrated in the control chip, and the switching power supply topology composed of the control chip and the main power inductor L1 is a BUCK converter topology. The BST pin of the control chip is a bootstrap pin, which is used for the bootstrap circuit in the chip; the SW pin is a switch control pin, which controls the switch action and adjusts the power output; the FB pin is an output voltage feedback pin, which provides the feedback signal of the output voltage and is used for output voltage adjustment. The linear voltage stabilizing power supply is provided with a SET port, through which the output voltage of the linear voltage stabilizing power supply can be adjusted. The output voltage V PRE The input voltage V OUT .

[0029] It should be understood that, Figure 1The power supply system in the feedback follow-up circuit is only an example, and should not be regarded as a limitation on the power supply system to which the feedback follow-up circuit of the embodiment is applied. The switching power supply in the power supply system to which the feedback follow-up circuit of the embodiment is applied is not limited in terms of topology type, control loop control strategy, and selected control chip type, as long as the driving signal can be adjusted through the FB pin of the feedback loop to achieve stable output voltage. In addition, the output voltage of the linear voltage stabilizing power supply in the power supply system to which the feedback follow-up circuit of the embodiment is applied is adjustable, and the adjustment range can be designed by a person skilled in the art as needed, and the specific range is not limited by the utility model, for example, it can be designed to be set to 5 gears in the range of 5V to 20V.

[0030] Please continue to see Figure 1 The feedback follow-up circuit comprises a transistor Q1, a collector current generating circuit, an emitter voltage drop generating circuit, a first voltage generating circuit, and a second voltage generating circuit. The connection point of the collector of the transistor Q1 and one end of the collector current generating circuit is used to connect the FB pin of the feedback loop, the other end of the collector current generating circuit is used to ground, the connection point of one end of the emitter voltage drop generating circuit and one end of the first voltage generating circuit is used to connect the connection point of the output end of the switching power supply and the input end of the linear voltage stabilizing power supply, the other end of the emitter voltage drop generating circuit is connected to the emitter of the transistor Q1, the connection point of the other end of the first voltage generating circuit and one end of the second voltage generating circuit is connected to the base of the transistor Q1, and the other end of the second voltage generating circuit is used to connect the output end Vout of the linear voltage stabilizing power supply.

[0031] When the power supply system is working, the FB pin of the feedback loop is stabilized to a first set voltage V1, so that the current flowing through the collector of the transistor is a first set current, the current flowing through the emitter of the transistor is controlled, and the voltage across the first voltage generating circuit is clamped to a second set voltage V2, so that the current flowing through the first voltage generating circuit is a second set current, the current flowing through the second voltage generating circuit is controlled to be a second set current, and the voltage across the second voltage generating circuit is controlled to be a third set voltage V3, so that the output voltage of the switching power supply is the sum of the output voltage of the linear voltage stabilizing power supply, the second set voltage V2, and the third set voltage V3.

[0032] It should be noted that the FB pin of the feedback loop is stabilized to the first set voltage V1, which is determined by the working principle of the switching power supply. In the steady state, the FB pin voltage of the feedback loop is equal to the reference voltage inside the switching power supply, which is a fixed value.

[0033] The component characteristics of the triode are ingeniously used in the embodiment. Firstly, the base current of the triode is very small and can be ignored, so the collector current of the triode is equal to the emitter current, thereby the current flowing through the emitter of the triode can be controlled to be a preset value. Secondly, the emitter junction voltage of the triode is a fixed value, thereby the voltage across the first voltage generating circuit is clamped to a second set voltage, and the current flowing through the first voltage generating circuit is a fixed value. Thirdly, the base current of the triode is very small and can be ignored, so the current flowing through the second voltage generating circuit is equal to the current flowing through the first voltage generating circuit, thereby the voltage across the second voltage generating circuit is designed to be a third set voltage. As known from the circuit connection relationship, the output voltage of the switching power supply is the sum of the output voltage of the linear voltage regulator, the second set voltage and the third set voltage. Since the second set voltage and the third set voltage are preset fixed voltage values, and the output voltage of the linear voltage regulator is an artificially adjusted voltage value, the output voltage of the front-stage switching power supply successfully follows the output voltage of the rear-stage linear voltage regulator. Through appropriate parameter design, the output voltage of the switching power supply can be slightly higher than the output voltage of the rear-stage linear voltage regulator, for example, about 1.7 V higher, so that the voltage difference across the rear-stage linear voltage regulator is stabilized to the sum of the second set voltage and the third set voltage in the entire adjustable output voltage range of the power supply system, thereby reducing the loss of the rear-stage linear voltage regulator and improving the efficiency of the power supply system at low voltage output.

[0034] Further, the triode is a PNP triode.

[0035] Please continue to refer to Figure 1 The collector current generating circuit is a resistor R6, the emitter voltage drop generating circuit is a resistor R7, the first voltage generating circuit is a resistor R8, and the second voltage generating circuit is a resistor R9.

[0036] Second embodiment

[0037] The embodiment provides a switching power supply, wherein the feedback following circuit in any one of the first embodiment is arranged.

[0038] The switching power supply of the embodiment can realize the function that the output of the front-stage switching power supply follows the output of the rear-stage linear voltage regulator when the switching power supply is used in combination with the rear-stage linear voltage regulator, so that the voltage drop of the rear-stage linear voltage regulator is fixed at a small value, the loss of the linear voltage regulator is reduced, and the efficiency is improved.

[0039] Further, the connection point between the collector of the triode and the end of the collector current generating circuit is connected with the connection point between the other end of the first voltage generating circuit and the end of the second voltage generating circuit, and the capacitor C6 is connected between the two connection points, and the capacitor C6 provides loop compensation to compensate the loop gain and phase of the switching power supply system, thereby improving the transient response speed of the switching power supply system to the load and more effectively responding to the high-frequency interference on the output voltage, and the capacitance of the capacitor C6 can be selected according to the actual application.

[0040] Third embodiment

[0041] The embodiment provides a power supply system, which comprises a switching power supply in a front stage and a linear voltage stabilizing power supply in a rear stage, the output voltage of the switching power supply is the input voltage of the linear voltage stabilizing power supply, the output voltage of the switching power supply is greater than the output voltage of the linear voltage stabilizing power supply, the output voltage of the switching power supply is stabilized through the adjustment of a feedback loop, and the output voltage of the linear voltage stabilizing power supply is adjustable, and wherein: the feedback following circuit in any one of the first embodiments is arranged in the power supply system.

[0042] The power supply system of the embodiment can realize the function that the output of the switching power supply in the front stage follows the output of the linear voltage stabilizing power supply in the rear stage, fix the voltage drop of the linear voltage stabilizing power supply in the rear stage at a small value, reduce the loss of the linear voltage stabilizing power supply, and improve the efficiency, due to the feedback following circuit in any one of the first embodiments arranged in the power supply system.

[0043] The switching power supply disclosed by the application is specifically applied to a power distribution system and can be widely used in the fields of industrial control, intelligent transportation, intelligent power grid, smart medical treatment, new energy, Internet of Things, communication and the like, and meets the necessary power distribution demand of system operation.

[0044] The above specific embodiments further specifically describe the purpose, technical scheme and beneficial effects of the utility model, and it should be understood that the above description is only the specific embodiments of the utility model and is not used to limit the protection scope of the utility model, and any modification, equivalent replacement, improvement and the like made within the spirit and principle of the utility model should be included in the protection scope of the utility model.

Claims

1. A feedback follower circuit applied to a power supply system, the power supply system comprising a switching power supply in the preceding stage and a linear regulated power supply in the following stage, wherein the output voltage of the switching power supply is the input voltage of the linear regulated power supply, the output voltage of the switching power supply is greater than the output voltage of the linear regulated power supply, the switching power supply achieves output voltage stability by adjusting the drive signal through the FB pin of the feedback loop, and the output voltage of the linear regulated power supply is adjustable, characterized in that: The feedback follower circuit includes a transistor, a collector current generation circuit, an emitter voltage drop generation circuit, a first voltage generation circuit, and a second voltage generation circuit. The connection point between the collector of the transistor and one end of the collector current generation circuit is used to connect to the FB pin of the feedback loop. The other end of the collector current generation circuit is used to ground. The connection point between one end of the emitter voltage drop generation circuit and one end of the first voltage generation circuit is used to connect to the connection point between the output terminal of the switching power supply and the input terminal of the linear regulated power supply. The other end of the emitter voltage drop generation circuit is connected to the emitter of the transistor. The connection point between the other end of the first voltage generation circuit and one end of the second voltage generation circuit is connected to the base of the transistor. The other end of the second voltage generation circuit is used to connect to the output terminal of the linear regulated power supply. When the power supply system is working, the FB pin of the feedback loop is stabilized at a first set voltage, so that the current flowing through the collector of the transistor is a first set current. The magnitude of the current flowing through the emitter of the transistor is controlled, thereby clamping the voltage across the first voltage generation circuit to a second set voltage, so that the current flowing through the first voltage generation circuit is a second set current. The current flowing through the second voltage generation circuit is controlled to a second set current, thereby controlling the voltage across the second voltage generation circuit to a third set voltage. This achieves the output voltage of the switching power supply being the sum of the output voltage of the linear regulated power supply, the second set voltage, and the third set voltage.

2. The feedback follower circuit according to claim 1, characterized in that: The transistor is a PNP transistor.

3. The feedback follower circuit according to claim 1, characterized in that: The collector current generating circuit is a resistor R6.

4. The feedback follower circuit according to claim 1, characterized in that: The emitter voltage drop generation circuit is resistor R7.

5. The feedback follower circuit according to claim 1, characterized in that: The first voltage generating circuit is a resistor R8.

6. The feedback follower circuit according to claim 1, characterized in that: The second voltage generating circuit is resistor R9.

7. The feedback follower circuit according to claim 1, characterized in that: The collector current generating circuit is resistor R6, the emitter voltage drop generating circuit is resistor R7, the first voltage generating circuit is resistor R8, and the second voltage generating circuit is resistor R9.

8. A switching power supply, characterized in that: It is provided with the feedback follower circuit as described in any one of claims 1 to 7.

9. The switching power supply according to claim 8, characterized in that: A capacitor C6 is connected between the connection point of the collector of the transistor and one end of the collector current generating circuit and the connection point of the other end of the first voltage generating circuit and one end of the second voltage generating circuit.

10. A power supply system comprising a switching power supply at a front stage and a linear regulated power supply at a rear stage, wherein the output voltage of the switching power supply is the input voltage of the linear regulated power supply, the output voltage of the switching power supply is greater than the output voltage of the linear regulated power supply, the switching power supply stabilizes its output voltage through a feedback loop, and the output voltage of the linear regulated power supply is adjustable, characterized in that: The power supply system is provided with the feedback follower circuit as described in any one of claims 1 to 7.

11. A power distribution system, characterized in that: It is provided with the feedback follower circuit as described in any one of claims 1 to 7.

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