CN219328995U - Reverse proportion voltage regulating circuit and switching power supply - Google Patents

Reverse proportion voltage regulating circuit and switching power supply Download PDF

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CN219328995U
CN219328995U CN202223312656.6U CN202223312656U CN219328995U CN 219328995 U CN219328995 U CN 219328995U CN 202223312656 U CN202223312656 U CN 202223312656U CN 219328995 U CN219328995 U CN 219328995U
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voltage
resistor
power supply
switching power
dividing circuit
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姚世耀
郭靖
陈仕敏
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Mornsun Guangzhou Science and Technology Ltd
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Mornsun Guangzhou Science and Technology Ltd
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    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

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Abstract

The utility model discloses a reverse proportion voltage regulating circuit and a switching power supply, wherein the switching power supply comprises a control IC, the reference voltage source voltage of a feedback pin of the control IC is a fixed value, and the reverse proportion voltage regulating circuit comprises: the first voltage dividing circuit, the second voltage dividing circuit, the third voltage dividing circuit, the first input end, the second input end, the output end and the grounding end; one end of the first voltage dividing circuit is a first input end and is used for inputting a first voltage signal representing the output voltage of the switching power supply, one end of the third voltage dividing circuit is a second input end and is used for inputting a first adjusting voltage, the other end of the first voltage dividing circuit, one end of the second voltage dividing circuit and the other end of the third voltage dividing circuit are connected together to form an output end and are used for being connected with a feedback pin of the control IC, and the other end of the second voltage dividing resistor is used for being grounded. The utility model realizes reverse proportion voltage regulation by using fewer devices and simpler control logic, and can be widely applied to the development of switching power supply products requiring voltage regulation.

Description

Reverse proportion voltage regulating circuit and switching power supply
Technical Field
The utility model relates to a voltage regulating circuit in the field of switching power supplies, in particular to a reverse proportion voltage regulating circuit.
Background
In a switching power supply, especially a high-voltage output power supply, when a load needs different output voltages, one way is to adjust the voltage of a reference voltage source to obtain different output voltages, for example, there is a similar control manner in the patent specification of a control circuit of application number 201921696000.4, and the output voltage control circuit in this patent is shown in fig. 1, and its principle is that: the external reference voltage source Vref is connected to the non-inverting input end of the operational amplifier IC2A, and the output sampling resistors R1 and R2 are used for sampling and dividing the output of the switching power supply and then connected to the inverting input end of the operational amplifier IC 2A. The capacitor C4, the resistor R4 and the operational amplifier IC2A form an error amplifier, the voltage input into the non-inverting input end and the inverting input end of the operational amplifier is subjected to error operation, and then a feedback voltage signal Vfb is output, the feedback voltage signal Vfb controls the on and off of a main power switch tube of the switching power supply and the duty ratio of the main power switch tube, so that the output voltage is controlled, and when the voltage Vref of an external reference voltage source is changed, the output voltage is changed.
However, the output voltage control method in the above patent is realized based on the fact that the voltage of the reference voltage source can be adjusted, and the control needs to be performed by matching with a relatively complex operational amplifier circuit, and the output voltage can only be adjusted in the forward direction, namely, when the voltage of the reference voltage source is increased, the output voltage is also increased. When a customer needs reverse proportion voltage regulation, the problem cannot be considered, the control thought is complex, and the required devices are more, so that the product miniaturization is not facilitated.
The other way is to adjust the output voltage by adjusting the pull-up resistor on the feedback pin of the switching power supply control IC, but the reference voltage source voltage of most of the feedback pins of the power supply control IC currently on the market is a fixed value, and the output voltage is determined only by determining the sampling resistor of the output voltage (i.e. the pull-up resistor on the feedback pin of the control IC). The output voltage sampling resistor can only be changed to realize the output voltage regulation without adding other circuits, and in fact, the change of the output voltage sampling resistor is not a judicious choice in practical application. When additional circuits such as an operational amplifier circuit are added for control, more devices are added, the operational amplifier control circuit is more complex, and the product development difficulty is greatly increased.
The reference voltage source voltage of the feedback pin of the control IC is generated by a reference voltage source inside the control IC, and the reference voltage source voltage of the feedback pin of the control IC is fixed, for example, SGM6607A control IC of Santa Clay microelectronics (Beijing) Co., ltd, and the reference voltage source voltage of the feedback pin is a fixed value 1.229V.
Disclosure of Invention
In view of the above, the present utility model provides a reverse proportional voltage regulating circuit and a switching power supply, which overcome at least one of the above drawbacks in the prior art.
As a first aspect of the present utility model, a technical solution of an embodiment of a reverse proportional voltage regulating circuit is provided as follows:
a reverse proportional regulating circuit applied to a switching power supply, the switching power supply comprising a control IC, a reference voltage source voltage of a feedback pin of the control IC being a fixed value, the reverse proportional regulating circuit comprising: the first voltage dividing circuit, the second voltage dividing circuit, the third voltage dividing circuit, the first input end, the second input end, the output end and the grounding end; one end of the first voltage dividing circuit is the first input end and is used for inputting a first voltage signal representing the output voltage of the switching power supply, one end of the third voltage dividing circuit is the second input end and is used for inputting a first regulating voltage, the other end of the first voltage dividing circuit, one end of the second voltage dividing circuit and the other end of the third voltage dividing circuit are connected together to form the output end and are used for being connected with a feedback pin of the control IC, and the other end of the second voltage dividing circuit is used for being grounded.
Preferably, the first voltage dividing circuit is a resistor with a fixed resistance value.
Preferably, the second voltage dividing circuit is a resistor with a fixed resistance value.
Preferably, the third voltage dividing circuit is a resistor with a fixed resistance value or an adjustable resistance value.
Further, two ends of the second voltage dividing circuit are connected with a capacitor in parallel.
The utility model provides a reverse proportion voltage regulation circuit, is applied to switching power supply, switching power supply includes control IC, the benchmark reference voltage source voltage of control IC feedback foot is fixed value, reverse proportion voltage regulation circuit includes: the first resistor, the second resistor, the third resistor, the first input end, the second input end, the output end and the grounding end; one end of the first resistor is the first input end and is used for inputting a first voltage signal representing the output voltage of the switching power supply, one end of the third resistor is the second input end and is used for inputting a first regulating voltage, the other end of the first resistor, one end of the second resistor and the other end of the third resistor are connected together to form the output end and are used for being connected with a feedback pin of the control IC, and the other end of the second resistor is used for being grounded; the first resistor, the second resistor and the third resistor are resistors with fixed resistance values.
Further, a capacitor is connected in parallel with two ends of the second resistor.
The utility model provides a reverse proportion voltage regulation circuit, is applied to switching power supply, switching power supply includes control IC, the benchmark reference voltage source voltage of control IC feedback foot is fixed value, reverse proportion voltage regulation circuit includes: the first resistor, the second resistor, the third resistor, the first input end, the second input end, the output end and the grounding end; one end of the first resistor is the first input end and is used for inputting a first voltage signal representing the output voltage of the switching power supply, one end of the third resistor is the second input end and is used for inputting a first regulating voltage, the other end of the first resistor, one end of the second resistor and the other end of the third resistor are connected together to form the output end and are used for being connected with a feedback pin of the control IC, and the other end of the second resistor is used for being grounded; the first resistor and the second resistor are resistors with fixed resistance values, and the third resistor is a resistor with an adjustable resistance value.
Further, a capacitor is connected in parallel with two ends of the second resistor.
As a second aspect of the present utility model, a technical solution of an embodiment of a switching power supply is provided as follows:
the switching power supply comprises a control IC, wherein the voltage of a reference voltage source of a feedback pin of the control IC is a fixed value, and the switching power supply further comprises the reverse proportion voltage regulating circuit in any one of the first aspect.
The working principle of the utility model is analyzed in detail in the detailed description, and the utility model has the following beneficial effects:
1. the reverse proportion adjustment of the output voltage of the switching power supply is realized by adjusting the voltage value of the first adjusting voltage or the voltage division value of the third voltage division circuit.
2. The circuit device is few, the control logic is simple, and the integration and miniaturization of the switch power supply product are realized.
Drawings
FIG. 1 is a schematic block diagram of an output voltage control circuit in the patent specification of application number 201921696000.4;
FIG. 2 is a schematic block diagram of a reverse proportional voltage regulator circuit according to a first embodiment of the present utility model;
FIG. 3 is a schematic block diagram of a first embodiment of a reverse proportional voltage regulator circuit according to the present utility model;
FIG. 4 is a schematic diagram of a second embodiment of a reverse proportional voltage regulator circuit according to the first embodiment of the present utility model;
fig. 5 is a schematic diagram of a third embodiment of a reverse proportional voltage regulator circuit according to a first embodiment of the present utility model.
Detailed Description
So that the manner in which the above recited objects, features and advantages of the present utility model can be understood in detail, a more particular description of the utility model, briefly summarized below, may be had by reference to embodiments, some of which are illustrated in the appended drawings. All other embodiments, which can be made by one of ordinary skill in the art based on the embodiments herein without making any inventive effort, shall fall within the scope of the present application.
It should be noted that the terms "comprising" and "having," and any variations thereof, as described in the specification and claims of this application are intended to cover a non-exclusive inclusion, for example, comprising a series of elements or unit circuits that are not necessarily limited to those elements or unit circuits explicitly listed, but may include elements or unit circuits that are not explicitly listed or inherent to such circuits.
In addition, embodiments and features of embodiments in this application may be combined with each other without conflict.
It will be understood that, in the description and in the claims, when an element is described as being "connected" to another element, the element may be "directly connected" to the other element or "connected" to the other element through a third element.
First embodiment
The present embodiment provides a reverse proportion voltage regulating circuit, which is applied to a switching power supply, the switching power supply includes a control IC, a reference voltage source voltage of a feedback pin of the control IC is a fixed value, fig. 2 is a schematic block diagram of the reverse proportion voltage regulating circuit of the present embodiment, please refer to fig. 2, the reverse proportion voltage regulating circuit of the present embodiment includes: the first voltage dividing circuit, the second voltage dividing circuit, the third voltage dividing circuit, the first input end, the second input end, the output end and the grounding end; one end of the first voltage dividing circuit is a first input end and is used for inputting a first voltage signal Vo representing the output voltage of the switching power supply, one end of the third voltage dividing circuit is a second input end and is used for inputting a first adjusting voltage Vadj, the other end of the first voltage dividing circuit, one end of the second voltage dividing circuit and the other end of the third voltage dividing circuit are connected together to form an output end and are used for being connected with a feedback pin of the control IC, and the other end of the second voltage dividing circuit is used for being grounded GND.
FIG. 3 is a schematic block diagram of a first embodiment of a reverse proportional voltage regulator circuit according to the present utility model; FIG. 4 is a schematic diagram of a second embodiment of a reverse proportional voltage regulator circuit according to the first embodiment of the present utility model; fig. 5 is a schematic diagram of a third embodiment of a reverse proportional voltage regulator circuit according to a first embodiment of the present utility model.
Referring to fig. 3, 4 and 5, the first voltage dividing circuit is a resistor R1 with a fixed resistance.
Referring to fig. 3, 4 and 5, the second voltage dividing circuit is a resistor R2 with a fixed resistance.
Referring to fig. 3 and fig. 5, the third voltage dividing circuit is a resistor R3 with a fixed resistance value; or refer to fig. 4, wherein the third voltage dividing circuit is a resistor R3 with an adjustable resistance.
Referring to fig. 5, a capacitor C2 is further connected in parallel to the two ends of the second voltage dividing circuit, so as to filter and smooth the voltage fluctuation when the voltage value of the first regulating voltage Vadj is noisy or fluctuates.
The working principle of this embodiment is explained below with reference to fig. 3 as follows:
let the resistance of the resistor R1 be R1, the resistance of the resistor R2 be R2, the resistance of the resistor R3 be R3, the output voltage required by the switching power supply be Vox, as known from kirchhoff's current law, the sum of the current flowing in the resistor R1 and the current flowing in the resistor R3 be equal to the current flowing in the resistor R2, the voltage divided by the resistor R1 be Vo-VFB, the voltage divided by the resistor R3 be Vadj-VFB, the voltage divided by the resistor R2 be VFB, and the ohm's law can be combined to obtain:
Figure SMS_1
the above relation is transformed into:
Figure SMS_2
according to the above relation, when the adjustment first regulation voltage Vadj increases, the first voltage signal Vox decreases, that is, the output voltage of the switching power supply decreases; when the regulated first regulation voltage Vadj decreases, the first voltage signal Vox increases, i.e. the output voltage of the switching power supply increases, vadj being inversely proportional to the first voltage signal Vox. When the first regulated voltage is set from Vadj-0, the first voltage signal is adjustable in the range of 0-Vo, then there are:
Figure SMS_3
Figure SMS_4
when the calculation is performed, the value of one of R1, R2 or R3 can be given firstly, then the values of the other two resistors can be calculated through the formulas (1) and (2), and then the reverse proportion adjustment of the output voltage of the switching power supply can be realized by adjusting the voltage value of the first adjusting voltage Vadj.
When the third voltage dividing resistor is the resistor R3 with the adjustable resistance as shown in fig. 4, the output voltage can be adjusted by adjusting the Vadj voltage, and meanwhile, the resistance of the resistor R3 can be adjusted for calibration, so that the output voltage value is more accurate.
Second embodiment
The embodiment provides a switching power supply, which comprises a control IC, wherein the voltage of a reference voltage source of a feedback pin of the control IC is a fixed value, and the switching power supply further comprises any one of the reverse proportion adjusting circuits in the first embodiment.
The embodiment comprises any one of the reverse proportion voltage regulating circuits in the first embodiment, so that the reverse proportion regulation of the output voltage of the switching power supply can be realized, and the reverse proportion regulating circuit has fewer devices and simple control logic, thereby being beneficial to realizing the integration and miniaturization of the switching power supply product.
The above is only a preferred embodiment of the present utility model, and those skilled in the art to which the present utility model pertains may also make alterations and modifications to the above detailed description, and these improvements and modifications should also be regarded as the scope of the present utility model. Therefore, the utility model is not limited to the specific embodiments disclosed and described above, but some modifications and changes of the utility model should be also included in the scope of the claims of the utility model. In addition, although specific terms are used in the present specification, these terms are for convenience of description only and do not limit the present utility model in any way.

Claims (10)

1. The utility model provides a reverse proportion voltage regulation circuit, is applied to switching power supply, switching power supply includes control IC, control IC's feedback foot's benchmark reference voltage source voltage is fixed value, its characterized in that, reverse proportion voltage regulation circuit includes: the first voltage dividing circuit, the second voltage dividing circuit, the third voltage dividing circuit, the first input end, the second input end, the output end and the grounding end; one end of the first voltage dividing circuit is the first input end and is used for inputting a first voltage signal representing the output voltage of the switching power supply, one end of the third voltage dividing circuit is the second input end and is used for inputting a first regulating voltage, the other end of the first voltage dividing circuit, one end of the second voltage dividing circuit and the other end of the third voltage dividing circuit are connected together to form the output end and are used for being connected with a feedback pin of the control IC, and the other end of the second voltage dividing circuit is used for being grounded.
2. The reverse proportional voltage regulating circuit of claim 1, wherein: the first voltage dividing circuit is a resistor with a fixed resistance value.
3. The reverse proportional voltage regulating circuit of claim 1, wherein: the second voltage dividing circuit is a resistor with a fixed resistance value.
4. The reverse proportional voltage regulating circuit of claim 1, wherein: the third voltage dividing circuit is a resistor with a fixed resistance value or an adjustable resistance value.
5. The reverse proportional voltage regulating circuit of any of claims 1-4, wherein: and two ends of the second voltage dividing circuit are also connected with a capacitor in parallel.
6. The utility model provides a reverse proportion voltage regulation circuit, is applied to switching power supply, switching power supply includes control IC, control IC feedback pin's benchmark reference voltage source voltage is fixed value, its characterized in that, reverse proportion voltage regulation circuit includes: the first resistor, the second resistor, the third resistor, the first input end, the second input end, the output end and the grounding end; one end of the first resistor is the first input end and is used for inputting a first voltage signal representing the output voltage of the switching power supply, one end of the third resistor is the second input end and is used for inputting a first regulating voltage, the other end of the first resistor, one end of the second resistor and the other end of the third resistor are connected together to form the output end and are used for being connected with a feedback pin of the control IC, and the other end of the second resistor is used for being grounded; the first resistor, the second resistor and the third resistor are resistors with fixed resistance values.
7. The reverse proportional voltage regulating circuit of claim 6, wherein: and two ends of the second resistor are also connected with a capacitor in parallel.
8. The utility model provides a reverse proportion voltage regulation circuit, is applied to switching power supply, switching power supply includes control IC, control IC feedback pin's benchmark reference voltage source voltage is fixed value, its characterized in that, reverse proportion voltage regulation circuit includes: the first resistor, the second resistor, the third resistor, the first input end, the second input end, the output end and the grounding end; one end of the first resistor is the first input end and is used for inputting a first voltage signal representing the output voltage of the switching power supply, one end of the third resistor is the second input end and is used for inputting a first regulating voltage, the other end of the first resistor, one end of the second resistor and the other end of the third resistor are connected together to form the output end and are used for being connected with a feedback pin of the control IC, and the other end of the second resistor is used for being grounded; the first resistor and the second resistor are resistors with fixed resistance values, and the third resistor is a resistor with an adjustable resistance value.
9. The reverse proportional voltage regulating circuit of claim 8, wherein: and two ends of the second resistor are also connected with a capacitor in parallel.
10. The utility model provides a switching power supply, switching power supply includes control IC, control IC feeds back the benchmark reference voltage source voltage of foot and is fixed value, its characterized in that: the switching power supply further comprises the reverse proportional voltage regulating circuit of any one of claims 1 to 9.
CN202223312656.6U 2022-12-09 2022-12-09 Reverse proportion voltage regulating circuit and switching power supply Active CN219328995U (en)

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