阅读说明：本技术 一种无过充的输出线补偿电路 (Output line compensation circuit without overcharging ) 是由 林新春 张�杰 朱敏 于 2021-03-24 设计创作，主要内容包括：本发明涉及一种无过充的输出线补偿电路,用以接入初始化信号并输出第一电压反馈信号,第一电压反馈信号输入至电源控制芯片中其他模块用以调节电源输出符合负载的输出电压,包括依次连接的线补控制模块、第一运放模块、分压模块及第二运放模块；其中,线补控制模块控制第一运放模块的下拉电流,分压模块用以将电源控制芯片的输出反馈电压分压后发送至第二运放模块,第二运放模块同时还接入参考电压信号,第二运放模块根据分压信号和参考电压信号输出第一电压反馈信号。(The invention relates to an output line compensation circuit without overcharge, which is used for accessing an initialization signal and outputting a first voltage feedback signal, wherein the first voltage feedback signal is input to other modules in a power supply control chip to adjust the output voltage of a power supply output according with a load; the line compensation control module controls the pull-down current of the first operational amplifier module, the voltage division module is used for dividing the output feedback voltage of the power control chip and then sending the divided voltage to the second operational amplifier module, the second operational amplifier module is also connected with a reference voltage signal, and the second operational amplifier module outputs a first voltage feedback signal according to the divided voltage signal and the reference voltage signal.)

1. An output line compensation circuit without overcharge is used for accessing an initialization signal and outputting a first voltage feedback signal, wherein the first voltage feedback signal is input to other modules in a power control chip to adjust the output voltage of a power supply output according with a load;

the line compensation control module controls the pull-down current of the first operational amplifier module, the voltage division module is used for dividing the output feedback voltage of the power supply and then outputting a divided voltage signal and sending the divided voltage signal to the second operational amplifier module, the second operational amplifier module is also connected to a reference voltage signal, and the second operational amplifier module outputs the first voltage feedback signal according to the relation between the divided voltage signal and the reference voltage signal.

2. The output line compensation circuit without overcharge of claim 1, wherein the line compensation control module includes a first switch, a control terminal of the first switch is connected to the initialization signal, a first terminal of the first switch is connected to the input terminal of the first operational amplifier module, and a second terminal of the first switch is connected to the output terminal of the second operational amplifier module; the line compensation control module processes the initialization signal and then controls and selects a second voltage feedback signal connected to the first operational amplifier module, and the second voltage feedback signal controls the pull-down current of the first operational amplifier module; when the initialization signal is at a high level, the first switch is closed, the output end of the second operational amplifier module is directly connected with the input end of the first operational amplifier module, and the first operational amplifier module adjusts the pull-down current according to the second voltage feedback signal.

3. The output line compensation circuit without overcharge of claim 2, wherein the line compensation control module further comprises an inverter and a second switch connected to the inverter, an input terminal of the inverter is connected to the initialization signal, an output terminal of the inverter is connected to a control terminal of the second switch, a first terminal of the second switch is connected to the input terminal of the first operational amplifier module, and a second terminal of the second switch is connected to ground; when the initialization signal is at a low level, the first switch is switched off, the phase inverter is used for inverting the initialization signal at the low level to output a signal at a high level, the second switch is switched on, and the line compensation control module controls the second voltage feedback signal to be grounded, so that the first operational amplifier module is controlled to have no pull-down current.

4. The output line compensation circuit without overcharge of claim 2, wherein the first operational amplifier module comprises a first amplifier, a field effect transistor and a first resistor, a non-inverting input terminal of the first amplifier is connected to the second voltage feedback signal, an inverting input terminal of the first amplifier is connected to a first terminal of the first resistor and a source of the field effect transistor, an output terminal of the first amplifier is connected to a gate of the field effect transistor, a drain of the field effect transistor is connected to the voltage dividing module, and a second terminal of the first resistor is connected to ground.

5. An output line compensation circuit without overcharge as claimed in claim 1, wherein the voltage divider module comprises a second resistor, a third resistor and a fourth resistor, a first end of the second resistor is connected to the output feedback voltage of the power supply, a second end of the second resistor is connected to the first end of the third resistor and the drain of the field effect transistor, a second end of the third resistor is connected to the first end of the fourth resistor and is connected to the second operational amplifier module as the divided voltage signal, and a second end of the fourth resistor is grounded.

6. The no-overcharge output line compensation circuit of claim 1, wherein the second operational amplifier module comprises a second amplifier, a non-inverting input terminal of the second amplifier is connected to the divided voltage signal, an inverting input terminal of the second amplifier is connected to the reference voltage signal, and an output terminal of the second amplifier outputs the first voltage feedback signal.

7. The output line compensation circuit without overcharge of claim 4, wherein the complementary control module comprises a first switch, the initialization signal is connected to a control terminal of the first switch, the first operational amplifier module comprises a field effect transistor, the first switch is connected in series to a drain of the field effect transistor, the complementary control module directly controls the operation of the first operational amplifier module, and the first voltage feedback signal is connected to the first operational amplifier module.

8. A switching power supply circuit, characterized by comprising the no-overcharge output line compensation circuit, a high-voltage starting module, a power switch tube, a pulse width modulation module, a current detection module, an oscillation module, a driving module and a protection module according to any one of claims 1 to 7; the output end of the output line compensation circuit without overcharge is connected to the pulse width modulation module and the oscillation module, so that the pulse width modulation module outputs a power supply switch signal subjected to pulse width modulation according to an input signal without overcharge, and the power supply outputs output voltage meeting the load actively.

9. A method of no-overcharge output line compensation using a no-overcharge output line compensation circuit according to any one of claims 1 to 8, the method comprising the steps of:

the line compensation control module controls the pull-down current of the first operational amplifier module;

the voltage division module is used for dividing the output feedback voltage signal of the power supply and outputting the divided voltage signal to the second operational amplifier module;

the second operational amplifier module is also connected with a reference voltage signal, and outputs the first voltage feedback signal according to the relation between the divided voltage signal and the reference voltage signal;

the first voltage feedback signal is input to other modules in the power control chip to adjust the output voltage of the power supply to meet the load.

Technical Field

The invention relates to an output line compensation circuit without overcharge.

Background

The widespread use and increasing development of portable electronic products has led to a vigorous development in the power supply industry. Meanwhile, the market demands for power products are becoming more and more stringent. The feedback circuit in the switching power supply generally only samples the voltage of the output end of the power supply and feeds the voltage back to the control circuit to adjust the related control parameters in real time so as to keep the voltage of the output end stable. However, when the distance between the power supply and the load is long, the difference in resistance of the output lines is caused by the difference in length, thickness and material of the output lines, so that different voltage drops occur on the output lines under different loads, and the accuracy of the output voltage is finally affected, so that the requirement of the output voltage range or the requirement of the output voltage exceeding the output voltage cannot be met. Since the voltage drop of the line reduces the voltage finally delivered to the load, which is not favorable for the stable operation of the load, the design of the output line compensation circuit of the switching power supply becomes one of the designs that designers must consider, please refer to fig. 5, Rcable is the resistance of the output line. Although the output line compensation circuit can solve the problem caused by the voltage drop of the output line under different loads, the output line compensation circuit also causes the problem in the starting process of the power supply. Because the power supply outputs lower voltage in the starting process, the power supply chip can be judged to output overload by mistake, the output voltage can be rapidly increased due to the existence of the output line compensation until the output voltage is greater than the designed output voltage value, the condition of power supply output overcharge is caused, and the stable operation of the load is not facilitated.

Disclosure of Invention

The invention aims to provide an output line compensation circuit which not only meets the output compensation function, but also realizes no output overcharge when a power supply is started.

In order to achieve the purpose, the invention provides the following technical scheme: an output line compensation circuit without overcharge is used for accessing an initialization signal and outputting a first voltage feedback signal, the first voltage feedback signal is input to other modules in a power supply control chip to adjust the output voltage of a power supply output according with a load, and the output line compensation circuit comprises a line compensation control module, a first operational amplifier module, a voltage division module and a second operational amplifier module which are connected in sequence;

the line compensation control module controls the pull-down current of the first operational amplifier module, the voltage division module is used for dividing the output feedback voltage of the power supply and then outputting a divided voltage signal and sending the divided voltage signal to the second operational amplifier module, the second operational amplifier module is also connected to a reference voltage signal, and the second operational amplifier module outputs the first voltage feedback signal according to the relation between the divided voltage signal and the reference voltage signal.

Furthermore, the line compensation control module comprises a first switch, a control end of the first switch is connected to the initialization signal, a first end of the first switch is connected with an input end of the first operational amplifier module, and a second end of the first switch is connected with an output end of the second operational amplifier module; the line compensation control module processes the initialization signal and then controls and selects a second voltage feedback signal connected to the first operational amplifier module, and the second voltage feedback signal controls the pull-down current of the first operational amplifier module; when the initialization signal is at a high level, the first switch is closed, the output end of the second operational amplifier module is directly connected with the input end of the first operational amplifier module, and the first operational amplifier module adjusts the pull-down current according to the second voltage feedback signal.

The line compensation control module further comprises an inverter and a second switch connected with the inverter, the input end of the inverter is connected with the initialization signal, the output end of the inverter is connected with the control end of the second switch, the first end of the second switch is connected with the input end of the first operational amplifier module, and the second end of the second switch is grounded; when the initialization signal is at a low level, the first switch is switched off, the phase inverter is used for inverting the initialization signal at the low level to output a signal at a high level, the second switch is switched on, and the line compensation control module controls the second voltage feedback signal to be grounded, so that the first operational amplifier module is controlled to have no pull-down current.

Further, the first operational amplifier module comprises a first amplifier, a field effect transistor and a first resistor, a positive phase input end of the first amplifier is connected to the second voltage feedback signal, a negative phase input end of the first amplifier is connected to a first end of the first resistor and a source electrode of the field effect transistor, an output end of the first amplifier is connected to a grid electrode of the field effect transistor, a drain electrode of the field effect transistor is connected to the voltage dividing module, and a second end of the first resistor is grounded.

Further, the voltage division module comprises a second resistor, a third resistor and a fourth resistor, a first end of the second resistor is connected with the output feedback voltage of the power supply, a second end of the second resistor is connected with a first end of the third resistor and a drain electrode of the field effect transistor, a second end of the third resistor is connected with a first end of the fourth resistor and serves as the voltage division signal to be connected with the second operational amplifier module, and a second end of the fourth resistor is grounded.

Further, the second operational amplifier module includes a second amplifier, a non-inverting input terminal of the second amplifier is connected to the divided voltage signal, an inverting input terminal of the second amplifier is connected to the reference voltage signal, and an output terminal of the second amplifier outputs the first voltage feedback signal.

Further, the line compensation control module comprises a first switch, the initialization signal is connected with a control end of the first switch, the first switch is connected in series with a drain electrode of the field effect transistor, the line compensation control module directly controls the first operational amplifier module to work, and the first voltage feedback signal is connected with the first operational amplifier module.

The invention also provides a switching power supply circuit, which comprises any one of the output line compensation circuit without overcharge, a high-voltage starting module, a power switching tube, a pulse width modulation module, a current detection module, an oscillation module, a driving module and a protection module; the output end of the output line compensation circuit without overcharge is connected to the pulse width modulation module and the oscillation module, so that the pulse width modulation module outputs a power supply switch signal subjected to pulse width modulation according to an input signal without overcharge, and the power supply outputs output voltage meeting the load actively.

The invention also provides an output line compensation method without overcharge, which adopts the output line compensation circuit without overcharge, and the method comprises the following steps:

the line compensation control module controls the pull-down current of the first operational amplifier module;

the voltage division module is used for dividing the output feedback voltage signal of the power supply and outputting the divided voltage signal to the second operational amplifier module;

the second operational amplifier module is also connected with a reference voltage signal, and outputs the first voltage feedback signal according to the relation between the divided voltage signal and the reference voltage signal;

the first voltage feedback signal is input to other modules in the power control chip to adjust the output voltage of the power supply to meet the load.

The invention has the beneficial effects that: the pull-down current of the first operational amplifier module is controlled through the line compensation control module, the voltage division module is used for dividing the output feedback voltage of the power supply and then outputting a voltage division signal and sending the voltage division signal to the second operational amplifier module, the second operational amplifier module is also connected with a reference voltage signal, the second operational amplifier module outputs a first voltage feedback signal according to the relation between the voltage division signal and the reference voltage signal, the first voltage feedback signal is input to the power supply control chip, other modules are used for adjusting the output voltage of the power supply, the output compensation function is met, and meanwhile, the phenomenon of over-charging is avoided when the power supply is started.

The foregoing description is only an overview of the technical solutions of the present invention, and in order to make the technical solutions of the present invention more clearly understood and to implement them in accordance with the contents of the description, the following detailed description is given with reference to the preferred embodiments of the present invention and the accompanying drawings.

Drawings

FIG. 1 is a schematic diagram of the connection of an output line compensation circuit without overcharge in a voltage drop converter circuit according to the present invention;

FIG. 2 is a circuit diagram of an output line compensation circuit without overcharge according to one embodiment of the present invention;

FIG. 3 is a circuit diagram of an output line compensation circuit without overcharge according to another embodiment of the present invention;

FIG. 4 is a block diagram of an output line compensation circuit without overcharge consistent with the present invention;

fig. 5 is a graph comparing the output voltage variation curves of the output line compensation circuit without overcharge and the output line compensation circuit without overcharge according to the present invention.

Detailed Description

The following detailed description of embodiments of the present invention is provided in connection with the accompanying drawings and examples. The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.

Referring to fig. 1, the output line compensation circuit without overcharge in the first embodiment of the present invention can be applied to a switching power supply circuit, such as a buck power supply circuit and a flyback switching power supply, in the first embodiment, the output line compensation circuit without overcharge is applied to the buck power supply circuit, and the buck power supply circuit includes a first capacitor C1, a control chip, a second capacitor C2 connected to the control chip, a third capacitor C3, a first inductor L1, a first diode D1, a second diode D2, and a load. The control chip comprises an output line compensation circuit without overcharge, a high-voltage starting module HV, a power switch tube Q1, a pulse width modulation module PWM, a current detection module CS, an oscillation module OSC, a driving module DRV and a protection module; the output end of the output line compensation circuit without overcharge is connected with the input end of a pulse width modulation module PWM and the input end of an oscillation module OSC, the output end of the oscillation module OSC is connected with the PWM input end of the pulse width modulation module, the output end of the pulse width modulation module PWM is connected with the input end of a driving module DRV, the output end of the driving module DRV is connected with the base electrode of a power switch tube Q1, the collector electrode of a switch power tube Q1 is connected with the input end of a starting module HV, the emitter electrode of a switch power tube Q1 is connected with the input end of a current detection module CS, and the output end of the current detection module CS is connected with the input end of the pulse width modulation module PWM, so that the pulse width modulation module PWM outputs a power switch signal subjected to pulse width modulation according to an input signal without. The high voltage starting module HV is used to charge the second capacitor C2 when the buck power circuit is powered on, so as to ensure normal start of the control chip. The driving module DRV is configured to convert the switching signal into a driving signal and transmit the driving signal to the driving end of the power switch Q1, the oscillation module OSC is configured to generate an operating frequency of the voltage-drop power circuit, the pulse width modulation module PWM is configured to transmit the switching signal of the power supply to the driving module DRV, the current detection module CS is configured to detect a current signal of a connected loop and output a detection result to the pulse width modulation module PWM, and the power switch Q1 may be integrated inside the control chip or may be disposed outside the control chip. In other embodiments, the output line compensation circuit without overcharge may also be applied to other circuits, and the application of the output line compensation circuit without overcharge is not specifically limited herein.

Referring to fig. 2, in the embodiment, the output line compensation circuit without overcharge is connected to the initialization signal PG of the switching power supply control chip and outputs a first voltage feedback signal FB1, and the output line compensation circuit without overcharge includes a line compensation control module 1, a first operational amplifier module 2, a voltage division module 3, and a second operational amplifier module 4, which are sequentially connected; the initialization signal PG is input into the line compensation control module 1, the line compensation control module 1 outputs a second voltage feedback signal FB2 which is selectively connected to the first operational amplifier module 2, the first operational amplifier module 2 works to generate a pull-down current, so that a voltage division signal VA in the voltage division module 3 is reduced, the voltage division signal VA is input into the second operational amplifier module 4 at the moment, the second operational amplifier module 4 is also connected to a reference voltage signal VREF, and the second operational amplifier module 4 performs error amplification according to the input voltage division signal VA and the reference voltage signal VREF to obtain a first voltage feedback signal FB 1. The line compensation control module 1 comprises a first switch K1, an inverter INV and a second switch K2 connected to the inverter INV; the first operational amplifier module 2 comprises a first amplifier AMP1, a field effect transistor Q2 and a first resistor R1; the voltage dividing module 3 comprises a second resistor R2, a third resistor R3 and a fourth resistor R4; the second operational amplifier module 4 includes a second amplifier AMP 2.

The control end of the first switch K1 and the input end of the inverter INV are respectively connected to the initialization signal PG, the first end of the first switch K1 is connected to the first end of the second switch K2 and is connected to the non-inverting input end of the first amplifier AMP1 in the first operational amplifier module 2, the second end of the first switch K1 is connected to the output end of the second operational amplifier module 4, the output end of the inverter INV is connected to the control end of the second switch K2, the second end of the second switch K2 is grounded, the inverting input end of the first amplifier AMP1 is connected to the source of the fet Q2 and the first end of the first resistor R1, the second end of the first resistor R1 is grounded, the output end of the first amplifier AMP1 is connected to the gate of the fet Q2, the drain of the fet Q2 is connected to the second end of the second resistor R2 and the first end of the third resistor R3, the first end of the second resistor AMP R6 is connected to the feedback voltage, the second end of the third resistor R353527 is connected to the second end of the fourth resistor R4 and the non-inverting input end of the amplifier R4 The second end of the fourth resistor R4 is grounded, the inverting input terminal of the second amplifier AMP2 is connected to the reference voltage VREF, and the output terminal of the second amplifier AMP2 is the first voltage feedback signal FB1 of the output line compensation circuit without overcharging. When the input initialization signal PG is at a low level, the first switch K1 is turned off, the inverter INV is configured to invert the initialization signal PG at a low level to output the initialization signal PG at a high level, the second switch K2 is turned on, the second voltage feedback signal FB2 is grounded, and the first operational amplifier module 2 has no pull-down current. When the switch-in initialization signal PG is at a high level, the inverter INV is configured to invert the high-level initialization signal PG to output the low-level initialization signal PG, at this time, the first switch K1 is closed, the second switch K2 is opened, so that the first voltage feedback signal FB1 is switched into the first operational amplifier module 2 as the second voltage feedback signal FB2, the first operational amplifier module 2 starts to operate, and the fet Q2 starts to have a pull-down current.

When the first operational amplifier module 2 generates a pull-down current, the voltage division signal VA of the fourth resistor R4 in the voltage division module 3 decreases, that is, the non-inverting input terminal VA of the second amplifier AMP2 decreases, the inverting input terminal of the second amplifier AMP2 inputs the reference voltage signal VREF, the output terminal of the second amplifier AMP2 outputs the first voltage feedback signal FB1 to increase, and the first voltage feedback signal FB1 is output to the pulse width modulation module PWM, so that the pulse width modulation module PWM outputs the power switch signal subjected to pulse width modulation according to the change result, thereby increasing the power output voltage and realizing the output voltage compensation function.

Referring to fig. 5, the working principle is specifically as follows: when the power supply is started, the line compensation control module 1 inputs the initialization signal PG at a low level, the first switch K1 is turned off, the second switch K2 is turned on, at this time, the second voltage feedback signal FB2 is grounded, the first operational amplifier module 2 does not have a pull-down capability, and the output line compensation circuit does not work, so as to prevent the process of starting and rising the power supply from being considered as output overload, which causes the output voltage to be charged too high due to the compensation voltage, and is not beneficial to the stable operation of the load. When the power output is stable, the initialization signal PG is converted into a high level, the first switch K1 is turned on, the second switch K2 is turned off, and at this time, the control chip voltage VCC is low, after voltage division is performed by the second resistor R2, the third resistor R3 and the fourth resistor R4, the voltage on the fourth resistor R4, that is, the divided voltage signal VA is low, and the divided voltage signal VA and the reference voltage signal VREF are amplified by the second amplifier AMP2 to obtain the first voltage feedback signal FB 1. In order to prevent the voltage loss of the output line from being too large under the heavy load condition of the power output, the first voltage feedback signal FB1 is connected with the second voltage feedback signal FB2 through the first switch K1. Because the second voltage feedback signal FB2 is larger at this time, the pull-down current obtained after passing through the first operational amplifier module 2 is also larger, the voltage signal VB decreases accordingly, and is divided by the voltage dividing module 3 again, at this time, the divided voltage signal VA on the fourth resistor R4 decreases lower, the lower divided voltage signal VA and the reference voltage signal VREF are input to the second amplifier AMP2 and amplified to obtain the higher first voltage feedback signal FB1 to be transmitted to the pulse width modulation module PWM and the oscillation module OSC, the higher the first voltage feedback signal FB1 is input to the pulse width modulation module PWM and the oscillation module OSC to obtain the higher power output, thereby ensuring that the output line voltage under the heavy load is compensated by the output line compensation circuit, so that the load operates stably.

Referring to fig. 3, the output line compensation circuit without overcharge in the second embodiment of the present invention is substantially the same as the output line compensation circuit without overcharge in the first embodiment, except that: the complementary line control module 1 includes a first switch K1, a control end of the first switch K1 is connected to the initialization signal PG, the first switch K1 is connected in series to a drain of the field effect transistor Q2 in the first operational amplifier module 2, the complementary line control module 1 directly controls the operation of the first operational amplifier module 2, and a non-inverting input end of the first amplifier AMP1 is connected to the first voltage feedback signal FB1, so that the output line compensation circuit without overcharge is simpler, and the principle of the complementary line control module is the same as that of the embodiment, which is not described herein.

Referring to fig. 2, fig. 3 and fig. 4, the present invention further discloses an output line compensation method without overcharge, which adopts the output line compensation circuit without overcharge, and the method includes the following steps:

the line compensation control module 1 controls the pull-down current of the first operational amplifier module 2;

the voltage division module 3 is used for dividing the working voltage signal of the power control chip, outputting a voltage division signal VA and sending the voltage division signal VA to the second operational amplifier module 4;

the second operational amplifier module 4 is also connected to a reference voltage signal VREF, and the second operational amplifier module 4 performs differential amplification on the signal VA and the reference voltage signal VREF to output a first voltage feedback signal FB 1;

the first voltage feedback signal FB1 is input to other modules in the power control chip to adjust the power output to match the output voltage of the load.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.