TWM585446U - Output voltage regulator of switching power supply - Google Patents

Abstract

The output voltage regulator of the switchable power supply of the utility model comprises: a power converter, a power switch, a power detection unit, a comparator, and a PWM controller; the utility model detects the secondary of the power converter The voltage of the front end and the back end of an energy storage inductor on the side is compared with the voltage drop change of the voltage between the front end and the back end of the energy storage inductor and amplifies an adjustment signal sent from an output terminal as a feedback signal of the PWM controller. The controller then adjusts the duty cycle of the switch driving signal output by the PWM controller according to the adjustment signal, so that when the load of the power supply increases, it can still provide stable output voltage and power output performance.

Description

Output voltage regulator of switching power supply

The utility model relates to a circuit structure of a power supply, in particular to a voltage compensation circuit of a switching power supply.

Low-power power supplies with multiple sets of outputs are widely used. Electronic devices such as monitors, personal computer hosts, notebook computers, optical disc drives, and graphics cards, or their peripherals often require outputs with different rated voltages. Therefore, when When the load increases, that is, the entire power supply needs to provide a larger output to meet, the output voltage on the output side of the power supply will appear a transient voltage drop (or voltage instability), so it is necessary to improve.

In the authorized Taiwan invention patent certificate number I 291283, a "output voltage regulator for power supply" was published to stabilize the power supply by eliminating the power bounce appearing on the output voltage of the switching power supply. Output voltage regulator for output voltage of switching power supply. The output voltage regulator mainly includes a voltage comparator, which compares a DC voltage with a reference voltage, and generates an output signal according to a comparison result, and a control switch, which is based on the voltage comparator. The output signal is biased, and a driving signal is provided to the power supply to stabilize the output voltage of the power supply according to an on / off state of one of the control switches.

After the authorized Taiwan invention patent certificate number I 317856 discloses a power supply regulator after the voltage regulator control circuit, it is mainly used in switching power supply for multiple sets of output The reactor uses a leading edge trigger to reset the sawtooth wave generator to generate a continuous sawtooth wave voltage signal, thereby achieving the purpose of stabilizing the output voltage of the power supply. The utility model uses a leading edge synchronization and on-time modulation control method, which detects the leading edge of the input voltage waveform of the secondary-side energy storage inductor, generates a reset signal, and resets a sawtooth wave generator to generate a stable signal. The continuous sawtooth wave voltage signal is compared with the voltage feedback signal to generate a power conduction signal corresponding to a stable output voltage. After the power conduction signal is cut off, flywheel conduction signals of opposite phases are generated. Each of the two different signals has an output terminal to drive the power switch on and the flywheel switch to operate. The utility model can be applied to various types of step-down voltage regulators whose input is AC or DC, and is used for voltage stabilization control of a plurality of sets of output switching power supplies with input and output isolation.

The technical problem to be solved by the utility model is to provide a voltage compensation circuit of a switching power supply.

An embodiment structure of the voltage compensation circuit of the switching power supply of the present utility model includes: a power converter, a power switch, a power detection unit, a comparator, and a PWM controller; wherein the primary side of the power converter Connected to a power switch. The power converter is used to convert the input voltage on the primary side of the power converter to the output voltage on the secondary side of the power converter. The power detection unit is electrically connected to an energy storage inductor on the secondary side of the power converter. The front end and the back end are used to obtain the voltage change of the front end and the back end of the energy storage inductor; the input end of the comparator is electrically connected to the power detection unit to compare the voltage drop of the front end and the back end of the energy storage inductor and After amplification, an adjustment signal is sent from an output terminal; a feedback terminal (FB pin) of the PWM controller is connected to the output terminal (FB1 pin) of the comparator, and the PWM controller generates a corresponding duty cycle according to the adjustment signal. The ratio of the switch driving signal is used to control the switching action of the power switch.

As a preferred embodiment of the comparator, the front-end sampling voltage (point B) of the energy storage inductor is input to the non-inverting input terminal of an operational amplifier of the comparator, and the back-end sampling voltage (point A) of the energy storage inductor is input to the comparator. An inverting input of an operational amplifier.

The beneficial effect of the voltage compensation circuit of the switching power supply of the utility model is that by detecting the voltage of the front end and the back end of the energy storage inductor on the secondary side of the power converter, the voltage of the front end and the back end of the energy storage inductor is compared. The voltage drop changes and amplifies an adjustment signal sent from an output terminal as a feedback signal of the PWM controller, and then adjusts the duty cycle of the switch driving signal output by the PWM controller according to the adjustment signal, thereby increasing the load of the power supply. It still can provide stable output voltage and power output performance.

10‧‧‧ main circuit

11‧‧‧ Power Converter

12‧‧‧Power Switch

20‧‧‧Power detection unit

30‧‧‧ Comparator

31‧‧‧ Computing Amplifier

40‧‧‧PWM controller

A‧‧‧ backend

B‧‧‧Front

C1, C2‧‧‧ output pins

D7‧‧‧Diode

FB‧‧‧Feedback

L1‧‧‧energy storage inductor

FB1‧‧‧ output

FIG. 1 is a functional block diagram of an embodiment of an output voltage regulator of a switching power supply of the present invention.

FIG. 2 is a partial circuit configuration diagram of an embodiment of the output voltage regulator of the switching power supply of the present invention.

FIG. 3 is a partial circuit configuration diagram of an embodiment of the output voltage regulator of the switching power supply of the present invention.

Please refer to FIG. 1, which is a functional block diagram of an embodiment of a voltage compensation circuit of a switching power supply of the present invention. The switching power supply basically includes: a main circuit 10, a power detection unit 20, a comparator 30, and a PWM controller 40; the main circuit 10 is basically electrically connected to an external power source ( (Usually mains power), after step-down rectification To supply loads, such as motherboards, optical disc drives, display cards and various interface cards and other electronic devices or their peripheral equipment, to supply output voltages of different rated voltages that are usually required, the main circuit 10 includes at least a power converter 11 and a power Switch 12, in general, power converter 11 is a transformer. Power switch 12 is generally a MOS field effect transistor but is not limited to this. The primary side of power converter 11 is connected to power switch 12, and power converter 11 is used for The input voltage on the primary side of the power converter 11 is converted into the output voltage on the secondary side of the power converter 11 for use by a load.

The power detection unit 20 is electrically connected to the front end B and the rear end A of an energy storage inductor L1 on the secondary side of the power converter 11 (see FIG. 2), and is used to obtain the front end B and the rear end of the energy storage inductor L1. The voltage of A is shown in FIG. 2 in a preferred embodiment. The voltage of the front end B and the back end A of the energy storage inductor L1 is obtained through a capacitor voltage divider.

The input end of the comparator 30 is electrically connected to the power detection unit 20, and is used to compare the voltage drop of the front end B and the back end A of the energy storage inductor L1 and amplify to send an adjustment signal from an output end.

In a preferred embodiment shown in FIG. 2, the comparator 30 has an operational amplifier 31. The sampling voltage of the front end B of the energy storage inductor L1 is input to the non-inverting input terminal (+) of the operational amplifier 31. The sampling voltage at the terminal A is input to the inverting input terminal (-) of the operational amplifier 31. The operational amplifier 31 compares the voltage drop of the front end B and the back end A of the energy storage inductor L1 and amplifies and sends an adjustment signal from an output terminal. As a feedback signal of the PWM controller 40, the circuit structure shown in FIG. 2 is shown. A feedback terminal (FB pin) of the PWM controller 40 is connected to the output terminal (FB1 pin) of the comparator 30. The controller 40 then adjusts the duty cycle of the switch driving signal output by the PWM controller 40 according to the adjustment signal, so as to control the switching action of the power switch 12, so that it can still provide stable power when the load of the power supply increases. Output voltage and power output performance. A preferred implementation of the circuit structure is shown in FIG. 3, wherein the PWM controller 40 is electrically connected to the power switch 12 through output pins C1 and C2, and is used to drive power through the switch driving signal. The switch 12 operates.

Please refer to FIG. 3, which is a partial circuit configuration diagram of an embodiment of the output voltage regulator of the switching power supply of the present invention. A preferred embodiment of the PWM controller 40 is to use a PWM control chip. FIG. 2 shows an exemplary circuit structure. The PWM control chip used is CG8010, but this is only implemented as the present invention. The exemplary configuration of the modes is not intended to limit the implementation of the PWM controller 40. When the output power of the main circuit 10 of the entire power supply increases, the current flowing through the transformer (that is, the power converter 11) will increase, thereby increasing the magnetic field of the transformer, and the voltage rectified by the diode (D7) will follow As the load increases, it increases. The utility model uses the feedback signal output from the comparator 30 to adjust the oscillation frequency of the RT pin of the PWM controller 40, thereby changing the operating frequency and the duty cycle of the entire main circuit 10, so as to adjust / compensate the switching power supply. The purpose of the output voltage; for example, when the oscillation frequency is small, the on-time of the power switch 12 is short, and the voltage output is low. When the oscillation frequency is large, the on-time of the power switch 12 is long, and the voltage output is high.

The operation mode of the utility model is that the feedback signal is fed from the FB pin of the PWM controller 40, adjusted by the PWM controller 40 and controlled by the change of the oscillation frequency of the RT pin, and adjusted throughout the control unit. It is connected to the output of 12V, 5V (3.3V is output by 5V step-down, so it is also counted as the output of 5V). When the aforementioned individual output (such as 12V, 5V, 3.3V) is increased when the load is increased, The utility model is used to achieve an ideal adjustment, so that the output voltage is the rated voltage without attenuation, and the voltage output is stabilized.

Although the present invention has been disclosed as above through the above embodiments, it is not To limit the utility model, those skilled in the art can make some modifications and retouching without departing from the spirit and scope of the utility model. Therefore, the scope of patent protection of the utility model shall be determined by the claims of the present application. Defined shall prevail.

Claims (2)

An output voltage regulator of a switching power supply is characterized by comprising: a power converter, a power switch, a power detection unit, a comparator, and a PWM controller. The primary side of the power converter is connected to the power. A switch, the power converter is used to convert the input voltage on the primary side of the power converter to the output voltage on the secondary side of the power converter, and the power detection unit is electrically connected to a storage on the secondary side of the power converter The front end and the back end of the energy storage inductor are used to obtain the voltage of the front end and the back end of the energy storage inductor; the input end of the comparator is electrically connected to the power detection unit to compare the voltages of the front end and the back end of the energy storage inductor. After the voltage drop and amplification, an adjustment signal is sent from an output terminal; a feedback terminal (FB pin) of the PWM controller is connected to the output terminal (FB1 pin) of the comparator, and the PWM controller according to the adjustment The signal generates a switch driving signal with a corresponding duty ratio to control the switching action of the power switch. The output voltage regulator of the switching power supply according to claim 1, wherein the front-end sampling voltage (point B) of the energy storage inductor is input to a non-inverting input terminal of an operational amplifier of the comparator, and the energy storage inductor The back-end sampling voltage (point A) is input to the inverting input terminal of an operational amplifier of the comparator.