阅读说明：本技术 一种啸叫抑制电路及方法 (Howling suppression circuit and method ) 是由 宋珂 申同 于 2020-10-21 设计创作，主要内容包括：本发明提供一种啸叫抑制电路及方法,均用于存在轻载模式和正常工作模式的VR芯片的电感及电容的啸叫抑制,均：通过检流电阻检测VR芯片的负载电流；采用运放电路放大检流电阻两端的压差；运放电路的输出端与控制电路的输入端相连；控制电路的输出端,与MOS管Q3的栅极相连；MOS管Q3的源极连接所述的负载电阻后接地；MOS管Q3的漏极,用于连接在检流电阻与用电设备之间的连接线路上；在运放电路输出的电平达到控制电路中预先设定的高电平阈值时,触发控制电路输出低电平控制第三MOS管Q3截止；在运放电路输出的电平低于控制电路中预先设定的低电平阈值时,触发控制电路输出高电平控制MOS管Q3导通。本发明用于抑制VR芯片上变换器拓扑中电容与电感啸叫。(The invention provides a howling suppression circuit and a howling suppression method, which are used for the howling suppression of an inductor and a capacitor of a VR chip with a light load mode and a normal working mode, and both comprise the following steps: detecting the load current of the VR chip through a current detection resistor; amplifying the voltage difference between two ends of the current detecting resistor by using an operational amplifier circuit; the output end of the operational amplifier circuit is connected with the input end of the control circuit; the output end of the control circuit is connected with the grid electrode of the MOS transistor Q3; the source electrode of the MOS transistor Q3 is connected with the load resistor and then grounded; the drain electrode of the MOS tube Q3 is used for being connected to a connecting circuit between the current detection resistor and the electric equipment; when the level output by the operational amplifier circuit reaches a preset high level threshold value in the control circuit, the control circuit is triggered to output a low level to control the third MOS transistor Q3 to be cut off; when the level of the output of the operational amplifier circuit is lower than a low level threshold preset in the control circuit, the control circuit is triggered to output a high level to control the conduction of the MOS tube Q3. The method is used for inhibiting the capacitor and inductor squeal in the VR on-chip converter topology.)

1. A howling suppression circuit is characterized in that the howling suppression circuit is applied to a VR chip with a light load mode and a normal working mode; the howling suppression circuit comprises a current detection resistor R _ sense, an operational amplifier circuit, a control circuit, a third MOS transistor Q3 and a load resistor R _ load, wherein:

the current detection resistor R _ sense is used for being connected in series between the VR chip and the electric equipment;

the input end of the operational amplifier circuit is connected with the current detection resistor R _ sense in parallel and is used for amplifying the voltage difference between the two ends of the current detection resistor R _ sense;

the output end of the operational amplifier circuit is connected with the input end of the control circuit;

the output end of the control circuit is connected with the grid electrode of the third MOS tube Q3;

the source electrode of the third MOS tube Q3 is connected with the load resistor R _ load and then grounded;

the drain electrode of the third MOS transistor Q3 is used for being connected to a connection circuit between the current detection resistor R _ sense and the electric equipment;

when the level output by the operational amplifier circuit reaches a preset high level threshold value in the control circuit, the control circuit outputs a low level to control the third MOS transistor Q3 to be cut off;

when the level output by the operational amplifier circuit is lower than a low level threshold preset in the control circuit, the control circuit outputs a high level to control the conduction of the third MOS tube Q3.

2. The howling suppression circuit according to claim 1, wherein the control circuit employs any one of a schmitt trigger, a CPLD, and an FPGA.

3. The howling suppression circuit as claimed in claim 1, wherein the operational amplifier circuit comprises a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, and an operational amplifier OPA 1;

a first end of the third resistor R3 is connected to a connection line between the current detection resistor R _ sense and the electric equipment; a second end of the third resistor R3 is connected with a non-inverting input end of the operational amplifier OPA 1;

the second resistor R2 is connected in series between the output end and the non-inverting input end of the operational amplifier OPA 1;

a first end of the first resistor R1 and a first end of the fourth resistor R4 are both connected to the inverting input terminal of the operational amplifier OPA 1; the second end of the first resistor R1 is grounded; the second end of the fourth resistor R4 is connected in parallel to the signal input end of the current-sensing resistor R _ sense.

4. The howling suppression circuit as claimed in claim 3, wherein R1-R2 and R3-R4.

5. The howling suppression circuit of any one of claims 1-4, wherein the VR chip is configured with a Buck circuit topology.

6. The howling suppression circuit of claim 5, wherein the Buck circuit topology comprises a first MOS transistor Q1, a second MOS transistor Q2, an inductor Lout, and two capacitors Cout;

the grid electrode of the first MOS tube Q1 and the grid electrode of the second MOS tube Q2 are electrically connected with the VR chip;

the source electrode of the first MOS transistor Q1 is connected with the drain electrode of the second MOS transistor Q2;

the drain electrode of the first MOS tube Q1 is connected with the positive power supply output end of the direct-current power supply DC, and the negative power supply output end of the direct-current power supply DC and the source electrode of the second MOS tube Q2 are both grounded; a direct current power supply DC is an output power supply of the VR chip;

a first end of the inductance coil Lout is connected to a connecting wire between the source electrode of the first MOS transistor Q1 and the drain electrode of the second MOS transistor Q2;

the second terminal of the inductance Lout is connected with the signal input terminal of the current detecting resistor R _ sense,

the two capacitors Cout are connected in parallel;

one end of a parallel circuit of the two capacitors Cout is grounded, and the other end is connected to a connecting line between the inductance coil Lout and the current detection resistor R _ sense.

7. A howling suppression method is characterized in that the howling suppression method is applied to the howling suppression of an inductor and a capacitor of a VR chip with a light load mode and a normal working mode; the howling suppression method is based on the howling suppression circuit of any one of claims 1 to 6, and comprises the following steps:

detecting the load current of the VR chip through a current detection resistor R _ sense;

amplifying the voltage difference between two ends of the current detection resistor R _ sense by adopting an operational amplifier circuit;

when the level output by the operational amplifier circuit reaches a preset high level threshold value in the control circuit, the control circuit is triggered to output a low level to control the third MOS transistor Q3 to be cut off;

when the level output by the operational amplifier circuit is lower than a low level threshold preset in the control circuit, the trigger control circuit outputs a high level to control the third MOS tube Q3 to be conducted.

Technical Field

The invention relates to the field of server and switch products, in particular to a howling suppression circuit and a howling suppression method, which are mainly applied to howling suppression of inductors and capacitors of VR chips with a light load mode and a normal working mode.

Background

In server and switch products, VR (Voltage Regulator) chips are commonly used. Generally, in order to achieve light load efficiency, a VR chip is usually integrated with a converter topology, so that a light load mode (PFM) and a normal operation mode (PWM) exist in the VR chip. PFM is pulse frequency modulation, and PWM (pulse Width modulation) is pulse Width modulation. In a converter topology commonly used on a VR chip, such as a Buck topology, an inductor and a capacitor are usually used to form a low-pass filter.

For VR chips with light load mode (PFM) and normal operating mode (PWM), converter topologies integrated thereon, such as the Buck topology described above: in the light load mode, the VR chip generally enters a high efficiency mode (i.e., a normal operation mode), that is, in the light load mode, the VR operates in the PFM mode, and after the load is increased, the VR operates in the PWM control mode. In the light load mode, the ripple voltage of the output voltage is large, and the frequency of the alternating current flowing through the capacitor is also discrete, so that a howling event is likely to occur. In addition, if the threshold for switching from the Normal operating mode (PWM) in the light load mode is not properly set, the system may still stay in the light load mode and cannot switch into the Normal PWM mode (i.e., the Normal operating mode (PWM)) when the load current is relatively low, and thus the discrete switching pulses may easily cause the capacitor howling. In addition, in the PFM mode, the reduced frequency tends to fall within the audible range of 20Hz to 20kHz of the human ear, and howling of the power inductor occurs. Therefore, the capacitor and inductor squeal in the converter topology on the VR chip can be caused for a plurality of reasons, and the avoidance measures are difficult to take into consideration.

Therefore, the present invention provides a howling suppression circuit and method for solving the above problems.

Disclosure of Invention

In view of the above disadvantages of the prior art, the present invention provides a howling suppression circuit and method for suppressing capacitive and inductive howling in a VR on-chip converter topology.

In a first aspect, the present invention provides a howling suppression circuit, which is applied to a VR chip having a light load mode (i.e., PFM mode) and a normal operation mode (i.e., PWM mode); the howling suppression circuit comprises a current detection resistor R _ sense, an operational amplifier circuit, a control circuit, a third MOS transistor Q3 and a load resistor R _ load, wherein:

the current detection resistor R _ sense is used for being connected in series between the VR chip and the electric equipment;

the input end of the operational amplifier circuit is connected with the current detection resistor R _ sense in parallel and is used for amplifying the voltage difference between the two ends of the current detection resistor R _ sense;

the output end of the operational amplifier circuit is connected with the input end of the control circuit;

the output end of the control circuit is connected with the grid electrode of the third MOS tube Q3;

the source electrode of the third MOS tube Q3 is connected with the load resistor R _ load and then grounded;

the drain electrode of the third MOS transistor Q3 is used for being connected to a connection circuit between the current detection resistor R _ sense and the electric equipment;

when the level output by the operational amplifier circuit reaches a preset high level threshold value in the control circuit, the control circuit outputs a low level to control the third MOS transistor Q3 to be cut off;

when the level output by the operational amplifier circuit is lower than a low level threshold preset in the control circuit, the control circuit outputs a high level to control the conduction of the third MOS tube Q3.

Furthermore, the control circuit adopts any one of a Schmitt trigger, a CPLD and an FPGA.

Further, the operational amplifier circuit comprises a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4 and an operational amplifier OPA 1;

a first end of the third resistor R3 is connected to a connection line between the current detection resistor R _ sense and the electric equipment; a second end of the third resistor R3 is connected with a non-inverting input end of the operational amplifier OPA 1;

the second resistor R2 is connected in series between the output end and the non-inverting input end of the operational amplifier OPA 1;

a first end of the first resistor R1 and a first end of the fourth resistor R4 are both connected to the inverting input terminal of the operational amplifier OPA 1; the second end of the first resistor R1 is grounded; the second end of the fourth resistor R4 is connected in parallel to the signal input end of the current-sensing resistor R _ sense.

Further, R1 ═ R2, and R3 ═ R4.

Further, the VR chip is configured with a Buck circuit topology.

Further, the Buck circuit topology structure comprises a first MOS transistor Q1, a second MOS transistor Q2, an inductor Lout and two capacitors Cout;

the grid electrode of the first MOS tube Q1 and the grid electrode of the second MOS tube Q2 are electrically connected with the VR chip;

the source electrode of the first MOS transistor Q1 is connected with the drain electrode of the second MOS transistor Q2;

the drain electrode of the first MOS tube Q1 is connected with the positive power supply output end of the direct-current power supply DC, and the negative power supply output end of the direct-current power supply DC and the source electrode of the second MOS tube Q2 are both grounded; a direct current power supply DC is an output power supply of the VR chip;

a first end of the inductance coil Lout is connected to a connecting wire between the source electrode of the first MOS transistor Q1 and the drain electrode of the second MOS transistor Q2;

the second terminal of the inductance Lout is connected with the signal input terminal of the current detecting resistor R _ sense,

the two capacitors Cout are connected in parallel;

one end of a parallel circuit of the two capacitors Cout is grounded, and the other end is connected to a connecting line between the inductance coil Lout and the current detection resistor R _ sense.

In a second aspect, the present invention provides a howling suppression method, which is applied to howling suppression of inductors and capacitors of VR chips in a light load mode and a normal operating mode; the howling suppression method is based on the howling suppression circuit in each aspect, and comprises the following steps:

detecting the load current of the VR chip through a current detection resistor R _ sense;

amplifying the voltage difference between two ends of the current detection resistor R _ sense by adopting an operational amplifier circuit;

when the level output by the operational amplifier circuit reaches a preset high level threshold value in the control circuit, the control circuit is triggered to output a low level to control the third MOS transistor Q3 to be cut off;

when the level output by the operational amplifier circuit is lower than a low level threshold preset in the control circuit, the trigger control circuit outputs a high level to control the third MOS tube Q3 to be conducted.

The beneficial effect of the invention is that,

the howling suppression circuit and the howling suppression method provided by the invention can enable the VR chip to work in the PWM mode all the time, thereby preventing the VR chip from working in the PFM mode, preventing the VR chip from being switched from the PFM mode to the PWM mode, and being favorable for preventing the capacitor and the inductor from howling caused by the VR chip working in the PFM mode or switching from the PFM mode to the PWM mode.

In addition, the invention has reliable design principle, simple structure and very wide application prospect.

Drawings

In order to more clearly illustrate the embodiments or technical solutions in the prior art of the present invention, the drawings used in the description of the embodiments or prior art will be briefly described below, and it is obvious for those skilled in the art that other drawings can be obtained based on these drawings without creative efforts.

Fig. 1 is a schematic circuit diagram of a howling suppression circuit according to an embodiment of the present invention.

Fig. 2 is a schematic circuit diagram of the howling suppression circuit shown in fig. 1 applied to a VR chip with a Buck circuit topology.

FIG. 3 is a schematic flow chart diagram of a method of one embodiment of the present invention.

Detailed Description

In order to make those skilled in the art better understand the technical solution of the present invention, the technical solution in the embodiment of the present invention will be clearly and completely described below with reference to the drawings in the embodiment of the present invention, and it is obvious that the described embodiment is only a part of the embodiment of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Fig. 1 is a schematic circuit diagram of a howling suppression circuit according to an embodiment of the present invention. The howling suppression circuit is applied to VR chips with a light load mode and a normal working mode.

As shown in fig. 1, the howling suppression circuit includes a current detection resistor R _ sense, an operational amplifier circuit 100, a control circuit 200, a third MOS transistor Q3, and a load resistor R _ load. Wherein:

the current detection resistor R _ sense is used for being connected in series between the VR chip and the electric equipment 500;

the input end of the operational amplifier circuit 100 is connected in parallel with the current detection resistor R _ sense and is used for amplifying the voltage difference between two ends of the current detection resistor R _ sense;

the output end of the operational amplifier circuit 100 is connected with the input end of the control circuit 200;

the output end of the control circuit 200 is connected with the gate of the third MOS transistor Q3;

the source electrode of the third MOS tube Q3 is connected with the load resistor R _ load and then grounded;

the drain of the third MOS transistor Q3 is connected to the connection line between the current detection resistor R _ sense and the electric equipment 500;

when the level output by the operational amplifier circuit 100 reaches a preset high level threshold value in the control circuit 200, the control circuit 200 outputs a low level to control the third MOS transistor Q3 to be turned off;

when the level output by the operational amplifier circuit 100 is lower than the low level threshold preset in the control circuit 200, the control circuit 200 outputs a high level to control the conduction of the third MOS transistor Q3.

In this embodiment, the operational amplifier circuit 100 includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, and an operational amplifier OPA 1. A first end of the third resistor R3 is connected to a connection line between the current detection resistor R _ sense and the electric equipment 500. The second terminal of the third resistor R3 is connected to the non-inverting input of the operational amplifier OPA 1. The second resistor R2 is connected in series between the output terminal and the non-inverting input terminal of the operational amplifier OPA 1. The first terminal of the first resistor R1 and the first terminal of the fourth resistor R4 are both connected to the inverting input terminal of the operational amplifier OPA 1. The second end of the first resistor R1 is grounded; the second end of the fourth resistor R4 is connected in parallel to the signal input end of the current-sensing resistor R _ sense. R1 ═ R2, R3 ═ R4.

In this embodiment, the VR chip is configured with a Buck circuit topology 300. In particular, those skilled in the art can also configure any other related converter topology in the prior art for the VR chip according to the actual situation, so that the VR chip has a light load mode (PFM) and a normal operating mode (PWM).

In this embodiment, the Buck circuit topology 300 includes a first MOS transistor Q1, a second MOS transistor Q2, an inductor Lout, and two capacitors Cout;

the grid electrode of the first MOS tube Q1 and the grid electrode of the second MOS tube Q2 are electrically connected with the VR chip;

the source electrode of the first MOS transistor Q1 is connected with the drain electrode of the second MOS transistor Q2;

the drain electrode of the first MOS tube Q1 is connected with the positive power supply output end of the direct-current power supply DC, and the negative power supply output end of the direct-current power supply DC and the source electrode of the second MOS tube Q2 are both grounded; a direct current power supply DC is an output power supply of the VR chip;

a first end of the inductance coil Lout is connected to a connecting wire between the source electrode of the first MOS transistor Q1 and the drain electrode of the second MOS transistor Q2;

the second terminal of the inductance Lout is connected with the signal input terminal of the current detecting resistor R _ sense,

the two capacitors Cout are connected in parallel;

one end of a parallel circuit of the two capacitors Cout is grounded, and the other end is connected to a connecting line between the inductance coil Lout and the current detection resistor R _ sense.

In practical implementation, a person skilled in the art can replace the Buck circuit topology 300 in the present embodiment with any other Buck circuit topology in the prior art according to practical situations.

Fig. 2 is a schematic diagram of a circuit used by the howling suppression circuit. For the sake of circuit simplification, the VR chip is not shown in fig. 2, and only the DC power DC output from the VR chip is shown. The connection between the VR chip and the gates of the first MOS transistor Q1 and the second MOS transistor Q2 can be implemented by those skilled in the art according to the prior art. As shown in fig. 2, in the figure, a first MOS transistor Q1, a second MOS transistor Q2, an inductor Lout, and two capacitors Cout form a Buck topology of the VR chip. The VR chip controls the first MOS tube Q1 and the second MOS tube Q2 to be alternately opened by controlling the PWM duty ratio of the grid electrodes of the first MOS tube Q1 and the second MOS tube Q2, and the voltage reduction of the output voltage of the DC power supply DC is realized.

When the howling suppression circuit is used:

(1) current detection resistor R _ sense

The current detection resistor R _ sense is connected in series between the VR chip and the electric device 500.

The R _ sense acts as a current sensing resistor, and the current flowing through the R _ sense is the load current on the path. The load current creates a voltage drop across R sense.

(2) Operational amplifier circuit 100

The voltage value output from the operational amplifier OPA1 is proportional to the voltage difference across the current sensing resistor R _ sense, i.e., proportional to the magnitude of the load current. The voltage value output by the operational amplifier OPA1 increases with increasing load current.

(3) Third MOS transistor Q3

The drain of the third MOS transistor Q3 is connected to a connection line between the current detection resistor R _ sense and the electric equipment 500.

(4) Control circuit 200

When the operating current of the back-end load (i.e., the powered device 500) increases to a certain level, the voltage difference across R _ sense increases and the output level of OPA1 increases.

When the level output by the OPA1 reaches a high level threshold preset in the control circuit 200, the trigger control circuit 200 outputs a low level to control the third MOS transistor Q3 to be turned off.

When the level output by the OPA1 is lower than the low level threshold preset in the control circuit 200, the trigger control circuit 200 outputs a high level to control the third MOS transistor Q3 to be turned on.

In this embodiment, the control circuit 200 employs a schmitt trigger, the high level threshold is a high level threshold of the schmitt trigger, and the low level threshold is a low level threshold of the schmitt trigger. When the transistor is used specifically, when the level output by the OPA1 reaches the high level threshold of the Schmitt trigger, the Schmitt trigger is triggered to output low level to control the Q3 of the third MOS transistor to be cut off; when the level output by the OPA1 is lower than the low level threshold of the Schmitt trigger, the Schmitt trigger is triggered to output high level to control the third MOS tube Q3 to be conducted.

In specific implementation, any one of a CPLD and an FPGA can be adopted to replace the Schmitt trigger.

(5) Load resistor R _ load

The R _ load is used to provide a load to make the VR chip skip the PFM mode, thereby always operating in the PWM mode.

In general, for a VR chip without a forced PWM mode (i.e., there are two modes of the PFM mode and the PWM mode), the load current is not too large, so the current I on R _ load is not too large, so when Q3 is turned off, the current flowing through R _ senses will suddenly reduce the current I, and in particular, the value of R _ load can be adjusted, so that Q3 is not turned on due to the current I suddenly reduced on R _ sense. Thereby enabling the VR chip to always operate in PWM mode.

The invention ensures that the load current of the VR chip is not very large, avoids the VR chip from entering a PFM mode, and also avoids the mode conversion from the PFM mode to the PWM mode of the VR chip, thereby avoiding the squeaking of capacitance and inductance on the VR chip to a certain extent.

When the Load current increases to a level that causes the OPA1 to output, the trigger control circuit 200 controls the third MOS transistor Q3 to turn off, the circuit in which R _ Load is located is broken, and energy consumption of R _ Load is avoided to a certain extent.

In addition, the invention also provides a howling suppression method, which is applied to the howling suppression of the inductor and the capacitor of the VR chip with a light load mode and a normal working mode. The howling suppression method is based on the howling suppression circuit in the aspects. As shown in fig. 3, the howling suppression method 400 includes:

step 410: detecting the load current of the VR chip through a current detection resistor R _ sense;

step 420: amplifying the voltage difference between two ends of the current detecting resistor R _ sense by using the operational amplifier circuit 100;

step 430: when the level output by the operational amplifier circuit 100 reaches a preset high level threshold value in the control circuit 200, triggering the control circuit 200 to output a low level to control the third MOS transistor Q3 to be cut off;

step 440: when the level output by the operational amplifier circuit 100 is lower than the low level threshold preset in the control circuit 200, the trigger control circuit 200 outputs a high level to control the third MOS transistor Q3 to be turned on.

The same and similar parts in the various embodiments in this specification may be referred to each other.

In summary, the VR chip can be operated in the PWM mode all the time, so that the VR chip is prevented from operating in the PFM mode, mode switching from the PFM mode to the PWM mode of the VR chip is also prevented, and howling of the capacitor and the inductor due to switching from the PFM mode or from the PFM mode to the PWM mode of the VR chip is avoided.

Although the present invention has been described in detail by referring to the drawings in connection with the preferred embodiments, the present invention is not limited thereto. Various equivalent modifications or substitutions can be made on the embodiments of the present invention by those skilled in the art without departing from the spirit and scope of the present invention, and these modifications or substitutions are within the scope of the present invention/any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.