CN215120576U

CN215120576U - Switching power supply circuit and control chip thereof

Info

Publication number: CN215120576U
Application number: CN202120348751.8U
Authority: CN
Inventors: 孙运; 方烈义
Original assignee: On Bright Electronics Shanghai Co Ltd
Current assignee: On Bright Electronics Shanghai Co Ltd
Priority date: 2021-02-07
Filing date: 2021-02-07
Publication date: 2021-12-10
Anticipated expiration: 2031-02-07
Also published as: TWM619036U

Abstract

Provided are a switching power supply circuit and a control chip thereof. A control chip for switching power supply circuit includes supply voltage input pin, the inside power supply foot of chip and connects the step-down converting circuit between supply voltage input pin and the inside power supply foot of chip, wherein: the power supply voltage input pin is used for receiving chip power supply voltage from the outside of the control chip, the chip internal power supply pin is used for providing internal power supply voltage inside the control chip, and the voltage reduction conversion circuit generates the internal power supply voltage by carrying out voltage reduction rectification on the chip power supply voltage under the condition that the chip power supply voltage is greater than a preset threshold value and outputs the internal power supply voltage to the chip internal power supply pin.

Description

Switching power supply circuit and control chip thereof

Technical Field

The utility model relates to a circuit field especially relates to a switching power supply circuit and control chip thereof.

Background

With the continuous development of electronic technology, the third generation power switch is becoming popular. Due to the characteristics of the power switch, the gate driving voltage for the power switch is required to be low, and the stability and the anti-interference performance are required to be strong. However, in the application of wide-range output voltage, because the output voltage range is wide, the supply voltage range of the control chip for providing the gate driving voltage to the power switch is also wide, and the control chip needs to step down the supply voltage of the control chip under the condition that the supply voltage is far higher than the safe driving voltage of the power switch so as to provide the gate driving voltage meeting the requirement to the power switch. At present, the loss of a voltage reduction structure inside a control chip is large, the anti-interference and noise filtering capabilities are weak, and the defects are more obvious when the power supply voltage of the control chip is higher. How to improve the power supply efficiency of the control chip, improve the stability of the gate driving voltage provided by the control chip to the power device, and improve the anti-interference capability of the control chip is a problem that needs to be solved urgently.

SUMMERY OF THE UTILITY MODEL

In view of one or more of the above problems, the present invention provides a switching power supply circuit and a control chip thereof.

According to the utility model discloses a control chip for switching power supply circuit, including supply voltage input foot, the inside power supply foot of chip and connect the step-down converting circuit between supply voltage input foot and the inside power supply foot of chip, wherein: the power supply voltage input pin is used for receiving chip power supply voltage from the outside of the control chip, the chip internal power supply pin is used for providing internal power supply voltage inside the control chip, and the voltage reduction conversion circuit generates the internal power supply voltage by carrying out voltage reduction rectification on the chip power supply voltage under the condition that the chip power supply voltage is greater than preset voltage, and outputs the internal power supply voltage to the chip internal power supply pin.

According to the utility model discloses control chip can satisfy the needs that wide range output voltage used, has efficient, interference immunity and the good characteristics of voltage stability to can effectively promote circuit system's efficiency and reliability.

According to the utility model discloses switching power supply circuit, including the above-mentioned control chip who is used for switching power supply circuit.

According to the utility model discloses switching power supply circuit can provide wide range output voltage to its system efficiency and reliability are high.

Drawings

The invention may be better understood from the following description of particular embodiments thereof taken in conjunction with the accompanying drawings, in which:

fig. 1 shows an exemplary pin arrangement schematic diagram for a control chip of a switching power supply circuit according to an embodiment of the present invention;

fig. 2 shows an exemplary circuit schematic of a switching power supply circuit to which the control chip shown in fig. 1 is applied.

Detailed Description

Features and exemplary embodiments of various aspects of the present invention will be described in detail below. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the invention by illustrating examples of the invention. The present invention is in no way limited to any specific configuration set forth below, but covers any modification, replacement or improvement of elements and components without departing from the spirit of the present invention. In the drawings and the following description, well-known structures and techniques are not shown in order to avoid unnecessarily obscuring the present invention. Note that, the term "a and B are connected" as used herein may mean "a and B are directly connected" or "a and B are indirectly connected via one or more other elements".

In view of one or more problems that exist at present in a control chip for a switching power supply circuit, the utility model provides a control chip for a switching power supply circuit.

Fig. 1 shows an exemplary pin arrangement schematic diagram of a control chip 100 for a switching power supply circuit according to an embodiment of the present invention. As shown in fig. 1, the control chip 100 includes a supply voltage input pin VDD, an internal chip supply pin AVDD, and a buck conversion circuit 102 connected between the supply voltage input pin VDD and the internal chip supply pin AVDD, wherein: the supply voltage input pin VDD is configured to receive a chip supply voltage VDD from outside the control chip 100, the chip internal supply pin AVDD is configured to provide an internal supply voltage AVDD inside the control chip 100, and the step-down converting circuit 102 generates the internal supply voltage AVDD by step-down rectifying the chip supply voltage VDD when the chip supply voltage VDD is greater than a predetermined threshold (e.g., an internal supply voltage at the chip internal supply pin AVDD), and outputs the internal supply voltage AVDD to the chip internal supply pin AVDD.

In some embodiments, as shown in fig. 1, the control chip 100 may further include a buck circuit switch leg SW serving as an output terminal of a buck switch for controlling the turn-on and turn-off of the buck conversion circuit 102.

In some embodiments, as shown in fig. 1, the control chip 100 may further include a driving voltage output pin GATE for providing a GATE driving voltage to a power switch connected between the primary winding of the transformer in the switching power supply circuit and ground.

In some embodiments, as shown in fig. 1, the control chip 100 may further include a primary current sensing pin CS for receiving a primary current sensing signal from outside the control chip 100, which is indicative of a current flowing through a primary winding of a transformer in the switching power supply circuit.

In some embodiments, as shown in fig. 1, the control chip 100 may further include an output voltage feedback pin FB for receiving an output voltage feedback signal representing the output voltage of the switching power supply circuit from outside the control chip.

In some embodiments, as shown in fig. 1, the control chip 100 may further include a ground pin GND for providing a reference ground inside the control chip 100.

In some embodiments, the buck conversion circuit 102 directly takes the chip supply voltage VDD as the internal supply voltage AVDD if the chip supply voltage VDD is not greater than the predetermined threshold. Here, due to the buck rectification of the chip supply voltage by the buck conversion circuit 102, the internal supply voltage of the control chip 100 is lower and more stable, suitable for wide range output voltage applications. Meanwhile, the power supply efficiency of the control chip can be improved, and the stability and the anti-interference capability of the grid driving voltage provided by the control chip to the power switch are improved.

Fig. 2 shows an exemplary circuit schematic of a switching power supply circuit 200 to which the control chip 100 shown in fig. 1 is applied. Here, each pin of the control chip 100 and relevant parts in the switching power supply circuit 200 are described taking flyback application as an example. It should be noted that although fig. 1 and 2 both show 7 pins of the control chip 100, the control chip 100 may include more than 7 pins. As shown in fig. 2, the connection relationship between the respective pins of the control chip 100 and the relevant portions in the switching power supply circuit 200 is as follows:

the supply voltage input pin VDD is connected to the auxiliary winding of the transformer in the switching power supply circuit 200, as indicated by the dashed line (r). The voltage Vaux on the auxiliary winding of the transformer is rectified and filtered by a diode and a capacitor to obtain a stable dc voltage (i.e., the chip supply voltage VDD).

The switch pin SW of the voltage reduction circuit is connected to one end of the external inductor L, as shown by the dotted line (c). The chip supply voltage VDD is output to the outside of the control chip 100 through the step-down circuit switch pin SW via a step-down switch for controlling the on and off of the step-down conversion circuit 102.

The power supply pin AVDD inside the chip is connected to the other end of the external inductor L, as shown by the dotted line (c). The voltage output by the switching pin SW of the voltage reduction circuit is filtered by the external inductor L and the bypass capacitor C to obtain a stable low-voltage direct-current voltage (i.e., an internal power supply voltage AVDD) which is connected to the internal power supply pin AVDD of the chip and used for controlling the internal power supply of the chip 100. Here, the external inductor L also plays a role in energy storage and voltage reduction.

The driving voltage output pin GATE is connected to the GATE of a power switch (for example, a MOS transistor) connected between the primary winding of the transformer in the switching power supply circuit 100 and the ground, as indicated by a dotted line (r).

The primary current sensing pin CS is connected to the source of a power switch (e.g., MOS transistor) connected between the primary winding of the transformer and ground in the switching power supply circuit 100, as indicated by the dashed line.

The output voltage feedback pin FB is connected to the optocoupler, as shown by the dashed line (c), and receives an output voltage feedback signal indicative of the output voltage of the secondary winding of the transformer in the switching power supply circuit 100 (i.e., the output voltage of the switching power supply circuit 100).

The ground pin GND is connected to the system ground, as shown by the dotted line c, and serves as a reference ground inside the control chip 100.

According to the utility model discloses switching power supply circuit 200 can provide wide range output voltage to its system efficiency and reliability are high.

The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The present embodiments are to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims

1. A control chip for a switching power supply circuit, comprising a supply voltage input pin, a chip internal supply pin, and a step-down conversion circuit connected between the supply voltage input pin and the chip internal supply pin, wherein:

the supply voltage input pin is used for receiving a chip supply voltage from outside the control chip,

the chip internal supply pin is used for providing an internal supply voltage inside the control chip,

the step-down conversion circuit generates the internal power supply voltage by performing step-down rectification on the chip power supply voltage when the chip power supply voltage is greater than a predetermined threshold value, and outputs the internal power supply voltage to the chip internal power supply pin.

2. The control chip of claim 1, further comprising a buck circuit switch pin as an output of a buck switch for controlling the turn-on and turn-off of the buck converter circuit.

3. The control chip according to claim 1 or 2, further comprising a driving voltage output pin for providing a gate driving voltage to a power switch connected between a primary winding of a transformer in the switching power supply circuit and ground.

4. The control chip of claim 1 or 2, further comprising a primary current sense pin for receiving a primary current sense signal from outside the control chip indicative of current flowing through a primary winding of a transformer in the switching power supply circuit.

5. The control chip of claim 1 or 2, further comprising an output voltage feedback pin for receiving an output voltage feedback signal from outside the control chip indicative of an output voltage of the switching power supply circuit.

6. The control chip of claim 1 or 2, further comprising a ground pin for providing a reference ground inside the control chip.

7. The control chip of claim 1 or 2, wherein the buck conversion circuit directly takes the chip supply voltage as the internal supply voltage if the chip supply voltage is not greater than the predetermined threshold.

8. A switching power supply circuit comprising the control chip according to any one of claims 1 to 7.

9. The switching power supply circuit according to claim 8, further comprising an external inductor connected between the buck circuit switch pin of the control chip and the chip internal power supply pin, and a bypass capacitor connected between the chip internal power supply pin and ground.

10. The switching power supply circuit according to claim 8, further comprising an optocoupler connected between an output voltage feedback pin of the control chip and ground.