阅读说明：本技术 开关电源控制器、开关电源系统及开关电源系统供电方法 (Switching power supply controller, switching power supply system and power supply method of switching power supply system ) 是由 江儒龙 胡黎强 孙顺根 朱臻 郜小茹 陈一辉 张弘 卢鹏飞 于 2020-06-05 设计创作，主要内容包括：本发明提供了一种开关电源控制器、开关电源系统及开关电源系统供电方法,所述开关电源控制器包括位于同一封装体内的输出电压供电单元、内置储能单元和逻辑控制单,所述输出电压供电单元用于利用所述开关电源系统的输出电压对所述内置储能单元进行充电,所述内置储能单元用于向所述逻辑控制单元提供工作电压。由此既能省去外置储能电容,又能利用输出电压供电,以显著降低供电损耗,实现更低待机功耗。进一步地,所述开关电源控制器还包括高压供电单元,以实现由输出电压供电和高压供电组合的混合供电方式,进而在必须用到高压供电的开关电源系统中,充分利用输出电压供电的机会,尽量减少高压供电单元直接供电的比例,以实现更低待机功耗。(The invention provides a switching power supply controller, a switching power supply system and a power supply method of the switching power supply system. Therefore, an external energy storage capacitor can be omitted, and power can be supplied by using the output voltage, so that the power supply loss is obviously reduced, and lower standby power consumption is realized. Furthermore, the switching power supply controller also comprises a high-voltage power supply unit so as to realize a hybrid power supply mode combining output voltage power supply and high-voltage power supply, and further fully utilize the opportunity of output voltage power supply in a switching power supply system which must use high-voltage power supply, and reduce the proportion of direct power supply of the high-voltage power supply unit as much as possible so as to realize lower standby power consumption.)

1. A switching power supply controller for controlling an output voltage of a switching power supply system, the switching power supply controller comprising: the output voltage power supply unit, the built-in energy storage unit and the logic control unit are positioned in the same packaging body; wherein the content of the first and second substances,

one end of the output voltage power supply unit is connected with an output voltage feedback end of the switch power supply system, the other end of the output voltage power supply unit is connected with a power input end of the built-in energy storage unit, and the output voltage power supply unit is used for charging the built-in energy storage unit by utilizing the output voltage of the switch power supply system;

the power output end of the built-in energy storage unit is connected with the working power supply end of the logic control unit, and the built-in energy storage unit is used for providing working voltage for the logic control unit.

2. The switching power supply controller according to claim 1, wherein the output voltage power supply unit comprises a first electronic switch, a control terminal of the first electronic switch is connected to a corresponding output terminal of the logic control unit, one end of a path of the first electronic switch is connected to an output voltage feedback terminal of the switching power supply system, and the other end of the path of the first electronic switch is connected to a power input terminal of the built-in energy storage unit.

3. The switching power supply controller according to claim 1, wherein the built-in energy storage unit comprises an energy storage capacitor, one end of the energy storage capacitor is grounded, and the other end of the energy storage capacitor is a power input end of the built-in energy storage unit.

4. The switching power supply controller according to claim 1, further comprising a high voltage power supply unit located in the package, wherein one end of the high voltage power supply unit is connected to a bus dc voltage end of the switching power supply system, and the other end of the high voltage power supply unit is connected to a power input end of the built-in energy storage unit, and the high voltage power supply unit is configured to charge the built-in energy storage unit in a stage where the built-in energy storage unit is insufficient to provide an operating voltage to the logic control unit.

5. The switching power supply controller according to claim 4, wherein the phase in which the built-in energy storage unit is insufficient to provide the operating voltage to the logic control unit comprises: the switching power supply controller is started and outputs the stage before establishment, and the stage after the internal energy storage unit is lower than a preset threshold value after the demagnetization is finished to the next switching period and is started in a discontinuous conduction mode.

6. The switching power supply controller according to claim 4, wherein said built-in energy storage unit further comprises a zener diode and a linear regulator, a cathode of said zener diode and an input terminal of said linear regulator being connected to each other and connecting said built-in energy storage unit and one terminal of said output voltage power supply unit and said high voltage power supply unit to each other; the anode of the voltage stabilizing diode is grounded, the output end of the linear voltage stabilizer is used as the power output end of the built-in energy storage unit and is connected with the working voltage end of the logic control unit, the other input end of the linear voltage stabilizer is connected with a first reference voltage, and the linear voltage stabilizer is used for adjusting the voltage output by the built-in energy storage unit to the working voltage required by the logic control unit according to the first reference voltage.

7. The switching power supply controller according to claim 4, wherein said logic control unit is further configured to optimize a ratio of supply times of said output voltage supply unit and said high voltage supply unit; the output voltage power supply unit is used for charging the built-in energy storage unit within a partial or whole load range of the switching power supply system under the control of the logic control unit.

8. The switching power supply controller according to claim 1, further comprising a power switch tube sampling unit located in the package, wherein the power switch tube sampling unit is configured to sample a corresponding current and feed back a sampling result to the logic control unit, and the output voltage power supply unit is configured to charge the internal energy storage unit before and/or after the current is sampled by the power switch tube sampling unit according to control of the logic control unit.

9. The switching power supply controller according to claim 1 or 8, further comprising a demagnetization detecting unit located in the package, the demagnetization detecting unit being configured to detect a demagnetization point of the switching power supply system and feed back a demagnetization detection result to the logic control unit; and the output voltage power supply unit is used for charging the built-in energy storage unit in a corresponding demagnetization stage according to the control of the logic control unit.

10. The switching power supply controller according to claim 8, further comprising a shielding time detection unit located in the package, wherein the shielding time detection unit is connected to the logic control unit and the power switch tube sampling unit, and is configured to feed back a shielding time of current sampling of the power switch tube sampling unit to the logic control unit; the output voltage power supply unit is used for charging the built-in energy storage unit in a demagnetization stage when the power switch tube of the power switch tube sampling unit is turned off without current sampling under the control of the logic control unit.

11. The switching power supply controller according to claim 8, wherein the power switch tube sampling unit has a power switch tube, the switching power supply controller further comprises a driving unit, the driving unit is connected to the logic control unit and a control end of the power switch tube, and the driving unit is configured to drive the power switch tube to be turned on or off under the control of the logic control unit so as to adjust an output voltage of the switching power supply system; the output voltage power supply unit is used for charging the built-in energy storage unit according to the output voltage adjusted by the driving unit.

12. The switching power supply controller according to claim 11, further comprising a voltage detection unit located in the package, wherein one end of the voltage detection unit is connected to an output voltage feedback end of the switching power supply system, and the other end of the voltage detection unit is connected to a corresponding input end of the logic control unit, and the voltage detection unit is configured to perform voltage sampling and size judgment on the output voltage of the switching power supply system, so that the logic control unit controls a driving unit to drive the power switching tube to be turned on or off according to a result of the size judgment, and then adjusts the output voltage of the switching power supply system.

13. The switching power supply controller according to claim 12, wherein the voltage detection unit includes a voltage sampling module, a second electronic switch and a comparator, a sampling input terminal of the voltage sampling module is connected to the output voltage feedback terminal, a sampling output terminal of the voltage sampling module is connected to one end of a path of the second electronic switch, the other end of the path of the second electronic switch is connected to one input terminal of the comparator, a control terminal of the second electronic switch is connected to a corresponding output terminal of the logic control unit, the other input terminal of the comparator is connected to a second reference voltage, and an output terminal of the comparator is connected to the output compensation terminal of the logic control unit.

14. The switching power supply controller according to claim 13, wherein said voltage sampling module comprises two voltage sampling resistors connected in series between said output voltage feedback terminal and ground, a node at which said two voltage sampling resistors are connected to each other being a sampling output terminal of said voltage sampling module; the two voltage sampling resistors are arranged in the packaging body or arranged outside the packaging body.

15. The switching power supply controller according to claim 13 or 14, wherein said voltage detection unit further comprises an overload short-circuit protection module, an input terminal of said overload short-circuit protection module being connected to a terminal of said second electronic switch interconnected with said comparator, an output terminal of said overload short-circuit protection module being connected to a corresponding input terminal of said logic control unit.

16. A switching power supply system, comprising: an alternating current voltage source, a rectifying circuit connected with the alternating current voltage source, a bus capacitor connected with the rectifying circuit, a bus direct current voltage end connected with a common end of the bus capacitor and the rectifying circuit, and the switching power supply controller according to any one of claims 1-15; the switching power supply controller is connected between the bus direct-current voltage end and the output voltage end of the switching power supply.

17. The switching power supply system according to claim 16, wherein said switching power supply system is a buck switching power supply system.

18. A power supply method of a switching power supply system is characterized by comprising the following steps:

setting a switching power supply controller, wherein the switching power supply controller comprises a built-in energy storage unit, an output voltage power supply unit and a logic control unit which are positioned in the same packaging body;

after the output of the switching power supply controller is established, in demagnetization time except sampling time, the output voltage power supply unit supplies power to the built-in energy storage unit by utilizing the output voltage of the switching power supply system, so that the built-in energy storage unit provides working voltage for the switching power supply controller to ensure the normal work of the switching power supply controller.

19. The method according to claim 18, wherein when the switching power supply system operates in DCM, the switching power supply controller enters a standby mode during a period from a demagnetization end to a next switching cycle start-up.

20. The power supplying method of claim 18, wherein before the switching power supply controller starts and the output is established, a high voltage power supplying unit supplies power to the built-in energy storage unit, so that the built-in energy storage unit supplies operating voltage to the switching power supply controller to complete the starting and the output establishment of the switching power supply controller.

21. The method according to claim 20, wherein when the switching power supply system operates in DCM, the high voltage power supply unit supplies power to the internal energy storage unit during a period from a time when demagnetization ends to a time when a next switching period is started, and when the operating voltage provided by the internal energy storage unit is lower than a predetermined threshold.

22. The power supply method according to claim 18, wherein after the output of the switching power supply controller is established, the charging time of the internal energy storage unit by the output voltage power supply unit is before or after the sampling time in a demagnetization time, or one part of the charging time of the internal energy storage unit by the output voltage power supply unit is before the sampling time and the other part is after the sampling time.

Technical Field

The invention relates to the technical field of switching power supplies, in particular to a switching power supply controller, a switching power supply system and a power supply method of the switching power supply system.

Background

High-voltage buck (high-side buck) AC-DC switching power supply system is widely applied to the fields of household appliances, electric meters and the like, along with the progress of science and technology, the performance requirement of the industry on products is higher and higher, higher efficiency, lower standby power consumption, better EMI performance, better use flexibility and lower cost are required.

Fig. 1 shows a conventional high-side buck AC-DC switching power supply system. The AC side voltage of the power grid is rectified by a rectifier bridge consisting of diodes D1, D2, D3 and D4, and then is output as an output voltage DC OUT after being controlled by a control chip U0, wherein the DC OUT is a fixed value. The output voltage DC OUT supplies power to a subsequent load, and in the switching power supply system, when the switching power supply system stably operates, the operating voltage (i.e., the supply voltage) VCC of the control chip U0 is realized by the output voltage DC OUT through the diode D6 and the VCC sampling capacitor C3, and the VCC sampling capacitor C3 completes sampling of the output voltage DC OUT and supplying power to the control chip U0, that is, the power supply mode of the control chip U0 is the output voltage power supply mode, and the standby power consumption of the control chip is good, but because the VCC sampling capacitor C3 is needed and sampling of the output voltage DC OUT is not direct sampling, the load regulation rate, the dynamic characteristics, and the like of the output voltage DC OUT are poor.

In addition, in some other existing high side buck AC-DC switching power supply systems, a specially-designed High Voltage (HV) power supply unit supplies power to a control chip of the switching power supply system, so as to avoid using an output voltage to supply power to the control chip, and under the condition of the same current consumption, the power consumption of the control chip itself powered by the HV power supply unit is far greater than that of the control chip itself powered by the output voltage shown in fig. 1, and thus, the ultra-low standby power consumption of the whole switching power supply system is difficult to achieve.

Disclosure of Invention

The invention aims to provide a switching power supply controller, a switching power supply system and a power supply method of the switching power supply system, which can save an external capacitor for sampling an output voltage and reduce the standby power consumption of the system on the basis of supplying power to the switching power supply controller by adopting the output voltage.

To solve the above technical problem, the present invention provides a switching power supply controller for controlling an output voltage of a switching power supply system, the switching power supply controller including: the power supply device comprises an output voltage power supply unit, a built-in energy storage unit and a logic control unit; wherein the content of the first and second substances,

one end of the output voltage power supply unit is connected with an output voltage feedback end of the switch power supply system, the other end of the output voltage power supply unit is connected with a power input end of the built-in energy storage unit, and the output voltage power supply unit is used for charging the built-in energy storage unit by utilizing the output voltage of the switch power supply system;

the power output end of the built-in energy storage unit is connected with the working power supply end of the logic control unit, and the built-in energy storage unit is used for providing working voltage for the logic control unit.

The present invention also provides a switching power supply system, including: the switching power supply comprises an alternating current voltage source, a rectifying circuit connected with the alternating current voltage source, a bus capacitor connected with the rectifying circuit, a bus direct current voltage end connected with a common end of the bus capacitor and the rectifying circuit, and the switching power supply controller; the switching power supply controller is connected between the bus direct-current voltage end and the output voltage end of the switching power supply.

The invention also provides a power supply method of the switching power supply system, which comprises the following steps:

setting a switching power supply controller, wherein the switching power supply controller comprises a built-in energy storage unit, an output voltage power supply unit and a logic control unit which are positioned in the same packaging body;

after the output of the switching power supply controller is established, in demagnetization time except sampling time, the output voltage power supply unit supplies power to the built-in energy storage unit by utilizing the output voltage of the switching power supply system, so that the built-in energy storage unit provides working voltage for the switching power supply controller to ensure the normal work of the switching power supply controller.

Compared with the prior art, the technical scheme of the invention has one of the following beneficial effects:

1. the output voltage power supply unit, the built-in energy storage unit and the logic control unit of the switching power supply controller are integrated in the same packaging body (namely a chip), so that an external capacitor for sampling the output voltage can be omitted on the basis of supplying power to the logic control unit by adopting the output voltage, the load regulation rate and the dynamic characteristic of the output voltage are further improved, the whole system is simpler, the system cost is low, and the miniaturization and the simplification of a switching power supply system are facilitated.

2. The output voltage is mainly adopted to charge the built-in energy storage unit in most load ranges (such as no load and light load) of the whole switch power supply system, and then the required working voltage is provided for the logic control unit.

3. Under the condition that the built-in energy storage unit is not enough to supply power to the logic control unit, the high-voltage power supply unit supplies power to the built-in energy storage unit, so that a mixed power supply mode combining output voltage power supply and high-voltage power supply is realized, chip starting and output establishment of the switching power supply controller are realized, and the normal work of a system of the switching power supply controller can be maintained after the output is established. And the opportunity of supplying power to the built-in energy storage unit by the output voltage is further fully utilized, the proportion of the high-voltage power supply unit directly supplying power to the built-in energy storage unit is reduced as much as possible, and only a small part of electric quantity is required to be supplied by the high-voltage power supply unit, so that the standby power consumption and the light load efficiency of the switch power supply system can be ensured.

4. The technical scheme of the invention is suitable for application occasions with higher requirements on standby power consumption and the like, particularly for non-isolated auxiliary power supply applications.

Drawings

Fig. 1 is a schematic circuit diagram of a conventional high side buck AC-DC switching power supply system with an external VCC sampling capacitor.

Fig. 2 is a schematic circuit diagram of a switching power supply controller according to an embodiment of the present invention.

Fig. 3 is a specific example circuit schematic of the switching power supply controller shown in fig. 2.

Fig. 4 is a schematic structural diagram of a switching power supply system according to an embodiment of the invention.

Fig. 5 to 10 are timing chart examples of charging and sampling in a power supply method of a switching power supply system according to an embodiment of the present invention.

Fig. 11 is a schematic circuit diagram of a switching power supply controller according to another embodiment of the present invention.

Fig. 12 is a schematic structural diagram of a switching power supply system according to another embodiment of the present invention.

Detailed Description

The technical solution proposed by the present invention will be further described in detail with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention.

Referring to fig. 2 to 4, an embodiment of the invention provides a switching power supply controller U2 for controlling an output voltage DC OUT of a switching power supply system. The switching power supply controller U2 includes: the device comprises a logic control unit 10, a high-voltage power supply unit 11, an output voltage power supply unit 12, a built-in energy storage unit 13, a voltage detection unit 14, a driving unit 15, a power switch tube sampling unit 16, an over-temperature protection unit 17, a shielding time detection unit 18, an oscillator 19 and a demagnetization detection unit 20. And these units are all integrated in the same package (i.e., chip), so that the switching power controller of the present embodiment is a switching power controller chip. The output voltage supply unit 12 comprises a first electronic switch SW. The built-in energy storage unit 13 comprises an energy storage capacitor C0, a voltage regulator diode D0 and a linear regulator LDO. An Oscillator (OSC)19 is electrically connected to the logic control unit 10 for adjusting the operating frequency of the switching power supply system.

The output voltage power supply unit 12 is configured to charge the energy storage capacitor C0 with the output voltage DC OUT of the switching power supply system. The output voltage power supply unit 12 includes a first electronic switch SW, one end of a path of the first electronic switch SW is connected to the output voltage feedback terminal VFB of the switching power supply system, the other end of the path of the first electronic switch SW is connected to one end of the energy storage capacitor C0 and the cathode of the zener diode D0, a control terminal of the first electronic switch SW is connected to a corresponding signal output terminal of the logic control unit 10, the first electronic switch SW can be turned on or off under the control of the logic control unit 10, and when the first electronic switch SW is turned on, the output voltage DC OUT can be implemented to charge the energy storage capacitor C0. The first electronic switch SW may be a MOS transistor, a triode, or the like.

The built-in energy storage unit 13 is used for providing an operating voltage to the logic control unit 10, so that the switching power supply controller U2 can maintain a normal operating state, a standby state and the like. In the internal energy storage unit 13, one end of the energy storage capacitor C0 and the anode of the zener diode D0 are both grounded, the other end of the energy storage capacitor C0, the cathode of the zener diode D0 and one voltage input end of the linear regulator LDO form a power input end of the internal energy storage unit 13, a voltage output end of the linear regulator LDO is used as a power output end of the internal energy storage unit 13 and is connected to a working voltage end VCC of the logic control unit 10, the other voltage input end of the linear regulator LDO is connected to a first reference voltage REF, and the linear regulator LDO is configured to adjust the voltage output by the energy storage capacitor C0 to the working voltage VCC required by the logic control unit 10 according to the first reference voltage REF. The capacitance of the energy storage capacitor C0 may be 200pF, and the zener diode D0 may be a 10V zener diode.

The input end of the high-voltage power supply unit 11 is connected to a bus dc voltage terminal DRAIN (i.e., the DRAIN of the power switch Q0) of the switching power supply system, and the output end of the high-voltage power supply unit 11 is connected to the power input end of the built-in energy storage unit 13. The high voltage power supply unit 11 is configured to charge the energy storage capacitor C0 during a period when the energy storage capacitor C0 is not enough to provide the operating voltage to the logic control unit 10. The circuit design of the high voltage power supply unit 11 can refer to the previous patent application CN104124878A of the present applicant, and is not described herein again.

In addition, the stage in which the energy storage capacitor C0 is not enough to provide the operating voltage to the logic control unit 10, that is, the stage in which the high voltage power supply unit 11 charges the energy storage capacitor C0, includes: the method comprises a stage before the switching power supply controller is started and output is established, and a stage before demagnetization is finished to the next switching period of a power switch tube Q0 is started and after the voltage VCC of an energy storage capacitor C0 is lower than a preset threshold value in a Discontinuous Conduction (DCM) mode.

Specifically, before the switching power controller U2 chip is started and output is established, the high voltage power supply unit 11 charges the energy storage capacitor C0, that is, the switching power controller U2 is directly powered by the high voltage power supply unit 11, so that the switching power controller U2 can be quickly started. After the chip output of the switching power supply controller U2 is established, and after the power switch tube Q0 is turned off, in the demagnetization time, except the sampling time, the output voltage DC OUT is used for supplying power to the energy storage capacitor C0, so that the chip loss is reduced, and the system efficiency is improved. In CCM (continuous conduction) mode, the storage capacitor C0 is powered by the output voltage DCOUT during the demagnetization time, except for the sampling time. In the DCM mode, except for the sampling time, the output voltage DC OUT supplies power to the energy storage capacitor C0 during the demagnetization time, and when the demagnetization is finished until the next switching period of the power switch Q0 is turned on, the switching power supply controller U2 may enter the standby mode, close most of its internal circuits, reduce the quiescent current, and maintain the output of the energy storage capacitor C0 for as long as possible, and start the high voltage power supply unit 11 to charge the energy storage capacitor C0 until the voltage VCC of the energy storage capacitor C0 is lower than a certain preset threshold, thereby ensuring the normal operation of the switching power supply controller U2 chip.

As an example, the logic control unit 10 may be designed to optimize the power supply time ratio of the output voltage power supply unit 12 and the high voltage power supply unit 11, so that the output voltage power supply unit 12 can charge the internal energy storage unit 13 in most load ranges of the switching power supply system under the control of the logic control unit. Therefore, the output voltage DC OUT of the switch power supply system can be fully utilized by the output voltage power supply unit 12 to supply power to the energy storage capacitor C0, the proportion that the high-voltage power supply unit 11 directly supplies power to the energy storage capacitor C0 is reduced as much as possible, the power supply loss of the switch power supply controller can be obviously reduced, lower standby power consumption is realized, and the power supply requirement of the switch power supply system can be met by the small capacitor. In addition, the output voltage power supply unit 12 can mainly supply power to the energy storage capacitor C0 in most load ranges of the entire switching power supply system, for example, most of the power can be supplied by the output voltage power supply unit 12 during no-load and light-load, and only a small part of the power is supplied by the high voltage power supply unit 11, so that the standby power consumption and the light-load efficiency of the switching power supply system can be ensured.

Referring to fig. 3, the power switch tube sampling unit 16 includes a power switch tube Q0 and a sampling resistor Rcs, a DRAIN terminal of the power switch tube Q0 is connected to a bus dc voltage terminal DRAIN of the switching power supply system, a source terminal is connected to one end of the sampling resistor Rcs, a gate terminal is connected to the driving unit 15, and the other end of the sampling resistor Rcs is grounded. The work sampling resistor Rcs is used for sampling the current flowing through the power switch tube Q0 to reflect the load change of the switching power supply system. Therefore, the logic control unit 10 can control the output voltage power supply unit 12 according to the sampling result of the power switch tube sampling unit 16, so that the output voltage power supply unit 12 can charge the built-in energy storage unit 13 before and/or after the current sampling of the power switch tube sampling unit 16. Of course, in other embodiments of the present invention, the sampling resistor Rcs may also be replaced by other components such as a MOS transistor or a triode.

One input end of the driving unit 15 is connected to the logic control unit 10, the other input end of the driving unit 15 is connected to the over-temperature protection unit 17, the output end of the driving unit 15 is connected to the gate of the power switch Q0, and the driving unit 15 is configured to drive the power switch Q0 to be turned on or off under the control of the logic control unit 10, so as to adjust the output voltage DC OUT of the switching power supply system. After the power switch Q0 is turned off, the inductor L in fig. 2 starts the demagnetization process. The output voltage power supply unit 12 charges the internal energy storage unit 13 according to the output voltage DC OUT adjusted by the driving unit 15 under the control of the logic control unit 10.

The over-temperature protection unit 17 is used for detecting the chip temperature of the switching power supply controller, and when the chip temperature exceeds a preset temperature threshold, the driving unit 15 can be controlled to turn off the power switch tube Q0, so that the power switch tube Q0 is prevented from being out of work due to overhigh temperature, the output power of the switching power supply control system is reduced, and the chip temperature is reduced in time.

The shielding time detecting unit 18, also called Leading Edge Blanking (LEB) unit, its output end is connected the logic control unit 10, its input end is connected with the source electrode of the power switch tube Q0, the shielding time detecting unit 18 is used for feeding back to the logic control unit 10 the shielding time of the current sampling of the power switch tube sampling unit 16, therefore, the logic control unit 10 can control the output voltage power supply unit 12 to charge the built-in energy storage capacitor C0 in the demagnetization phase of the turn-off of the power switch tube Q0 and the non-sampling time according to the feedback result of the shielding time detecting unit 18.

The output end of the demagnetization detection unit 20 is connected to the logic control unit 10, and the input end is connected to the VFB end, so that during the turn-off period of the power switch Q0, the time from the turn-off of the power switch Q0 to the first time that the voltage of the VFB end drops to 0, that is, the demagnetization time of the switching power supply system, is detected and output to the logic control unit 10. That is, the demagnetization detecting unit 20 can be used to detect a demagnetization point of the switching power supply system and feed back a demagnetization detection result to the logic control unit 10. Therefore, the logic control unit 10 can control the output voltage power supply unit 12 to charge the energy storage capacitor C0 of the internal energy storage unit 13 in the corresponding demagnetization stage according to the feedback result of the demagnetization detecting unit 20.

The voltage detection unit 14 includes a voltage sampling module 141, a second electronic switch Ts, a filter capacitor Cs and a comparator Comp, the second electronic switch Ts may be an electronic component such as a MOS transistor or a triode, and the voltage sampling module 141 includes two voltage sampling resistors Rs1 and Rs2 connected in series between the output voltage feedback terminal VFB and ground. The node where the two voltage sampling resistors Rs1 and Rs2 are connected to each other is the sampling output terminal of the voltage sampling module 141, and is connected to one end of the path of the second electronic switch Ts. One end of the sampling resistor Rs1 connected to the output voltage feedback end VFB is a sampling input end of the voltage sampling module 141. In this embodiment, the two voltage sampling resistors Rs1 and Rs2 are embedded inside a chip of the switching power supply controller. The other end of the path of the second electronic switch Ts is connected to a filter capacitor Cs and an input end of a comparator Comp, a control end of the second electronic switch Ts is connected to a corresponding signal output end of the logic control unit 10, the other input end of the comparator Comp is connected to a second reference voltage Vref, and an output end of the comparator Comp is connected to an output compensation end Vcomp of the logic control unit 10. The second electronic switch Ts is turned on under the control of the logic control unit 10 to sample the output voltage DC OUT, so that the comparator Comp can compare the voltage obtained by voltage sampling with the second reference voltage Vref to output the voltage compensation signal Vcomp, the logic control unit 10 can generate a PWM (pulse width modulation) signal or a PFM (pulse frequency modulation) signal for controlling the driving unit 15 according to the Vcomp signal, and the driving unit 15 drives the power switch Q0 to be turned on or off to adjust the output voltage DC OUT of the switching power supply system.

Optionally, the voltage detecting unit 14 further includes an overload short-circuit protection module 142, an input end of the overload short-circuit protection module 142 is connected to one end of the second electronic switch Ts and the comparator Comp, and an output end of the overload short-circuit protection module 142 is connected to a corresponding input end of the logic control unit 10. The overload short-circuit protection module 142 is configured to control an output current flowing through the power switch Q0 and a load when the switching power supply system is short-circuited and/or overloaded, so as to protect the switching power supply system. The circuit design of the overload short-circuit protection module 142 can refer to the prior patent application CN105870896A of the present applicant, and is not described herein again.

Referring to fig. 2 to 4, the present embodiment further provides a switching power supply system, including: the switching power supply controller comprises an alternating current voltage source AC IN, a rectifying circuit connected with the alternating current voltage source AC IN, a bus capacitor C1 connected with the rectifying circuit, a bus direct current voltage end DRAIN connected with a common end of the bus capacitor C1 and the rectifying circuit, a switching power supply controller U2 of the embodiment, an inductor L, diodes D5, D6 and an output capacitor C2. The switching power supply controller U2 is connected between the bus DC voltage terminal DRAIN and the output voltage terminal DC OUT of the switching power supply system. The rectifying circuit comprises four diodes D1-D4. One end of the inductor L is connected with the cathode of the diode D5 and the ground end of the switching power supply controller U2, the other end of the inductor L is connected with one end of the output capacitor C2 and the anode of the diode D6, the other end of the output capacitor C2 and the anode of the diode D5 are both grounded, and the cathode of the diode D6 is connected with the output voltage feedback end VFB of the switching power supply controller U2. The alternating current voltage source AC IN is rectified by four diodes D1-D4 and filtered by a bus capacitor C1 to obtain direct current voltage Vbus. The power switch Q0, the inductor L, the diode D6 and the output capacitor C2 form a typical high-side buck switching power supply topology. The diode D6 can isolate the high voltage during the startup phase of the switching power supply controller U2, and the voltage sampling resistors Rs1 and Rs2 can be low-voltage resistors or high-voltage resistors. In other embodiments of the present invention, when the voltage sampling resistors Rs1 and Rs2 in the voltage detection unit 14 use high-voltage resistors, D6 may be omitted to further simplify the peripheral circuits.

Referring to fig. 2 to fig. 11, the present embodiment further provides a power supply method for a switching power supply system, which is suitable for the switching power supply system of the present embodiment, and the power supply method for the switching power supply system includes:

firstly, before a switching power supply controller U2 chip of a switching power supply system is started and output is established, an energy storage capacitor Co of a built-in energy storage unit 13 of the switching power supply controller is charged by a high-voltage power supply unit 11, so that the built-in energy storage unit 13 provides a working voltage VCC for the switching power supply controller to complete the starting and output establishment of the switching power supply controller. Specifically, when the switching power supply system is started, the VCC voltage on the energy storage capacitor Co is initially 0, the switching power supply system charges the energy storage capacitor C0 through the high-voltage power supply unit 11, and the VCC voltage on the energy storage capacitor Co gradually rises. When the VCC voltage is greater than or equal to a working voltage threshold, the logic control unit 10 controls the high-voltage power supply unit 11 to be turned off, and the system is started.

Then, after the chip output of the switching power supply controller U2 is established, and after the power switch Q0 is turned off, in the demagnetization time except the sampling time Ts, the output voltage DCOUT of the switching power supply system is utilized by the output voltage power supply unit 12 to charge the energy storage capacitor C0, so that the built-in energy storage unit 13 provides the working voltage VCC to the switching power supply controller U2 to ensure the normal operation of the switching power supply controller U2. Specifically, in each switching period of the power switch Q0, the switching power supply controller U2 samples the output voltage DC OUT through the voltage detection unit 14, when the power switch Q0 is turned off, when the inductor L is demagnetized and demagnetization is not yet completed, the first electronic switch SW is turned on, the output voltage DCOUT charges the energy storage capacitor C0 through the diode D6, the output voltage feedback terminal VFB, and the first electronic switch SW, and when sampling is needed and demagnetization is completed, the switch SW is turned off.

In the following, the power supply method of the switching power supply system of the present embodiment is further described with reference to the timing diagrams shown in fig. 5 to fig. 10, in each of the diagrams, the SW _ Charge curve is a timing curve of the on and off of the first electronic switch SW, and the high level indicates that the SW _ Charge is on. The VFB curve is a timing curve of the output voltage DCout, the TS curve is a timing curve of the on and off of the second electronic switch TS, the high level indicates that TS is on, and the TS curve also indicates a sampling time curve.

Referring to fig. 5, fig. 5 shows a charging and sampling timing sequence of the switching power supply system operating in the CCM mode, that is, after the output of the switching power supply controller U2 is established, except for the on-time of the power switch Q0, the system is all operating in the demagnetization process, during demagnetization, except for the sampling time Ts, other demagnetization times can Charge the internal energy storage capacitor C0 through the output voltage DCout, and the charging time (i.e., the time when SW _ Charge is high) is before the sampling time Ts (i.e., the time when Ts is high). In the CCM Mode, i.e., the continuous conduction Mode, the current of the inductor L never drops to 0 during one switching cycle of the power switch Q0. Or the inductor L never "resets", it means that the inductor L flux never returns to 0 during the switching period, and the inductor L coil still has current flowing through it when the power switch Q0 is closed.

Referring to fig. 6, fig. 6 shows a charging and sampling timing sequence of the switching power supply system operating in the DCM mode, that is, after the output of the switching power supply controller U2 is established and after the power switch Q0 is turned off, in the same demagnetization time, except for the sampling time Ts, the internal energy storage capacitor C0 is charged by the output voltage DCout through the first electronic switch SW during the demagnetization time, and the charging time (i.e., the time when SW _ Charge is high) is before the sampling time Ts (i.e., the time when Ts is high). In the DCM Mode, i.e. Discontinuous Conduction Mode, the current of the inductor L always drops to 0 in one switching period of the power switch Q0, which means that the inductor L is properly "reset", i.e. when the power switch Q0 is closed, the current of the inductor L is zero.

Fig. 7 is another charging and sampling timing sequence of the switching power supply system operating in the CCM mode, and fig. 8 is another charging and sampling timing sequence of the switching power supply system operating in the DCM mode, where both sampling times Ts are within a certain time period during demagnetization, and similarly, after the output of the switching power supply controller U2 is established, and after the power switch Q0 is turned off, the output voltage DCout charges the internal energy storage capacitor C0 through the first electronic switch SW during the demagnetization time which is not the sampling time. Accordingly, in both modes, the charging time (i.e., the time when SW _ Charge is high) is located before the sampling time Ts (i.e., the time when Ts is high) and is located after the sampling time Ts (i.e., the time when Ts is high).

Fig. 9 is another charging and sampling sequence of the switching power supply system operating in the CCM mode, and fig. 10 is another charging and sampling sequence of the switching power supply system operating in the DCM mode, in which after the output of the switching power supply controller U2 chip is established, and after the power switch Q0 is turned off, the output voltage DCout charges the internal energy storage capacitor C0 through the first electronic switch SW during the demagnetization time which is not the sampling time. Accordingly, in both modes, the charging time (i.e., the time when SW _ Charge is high) is after the sampling time Ts (i.e., the time when Ts is high).

It should be noted that, in the high side buck switching power supply system, most of the loads operate in the CCM mode, and at this time, the power supply of the switching power supply controller U2 can be completely provided by the output voltage DC OUT through the output voltage power supply unit and the internal energy storage unit, so that the chip loss of the switching power supply controller U2 itself is reduced, and the system efficiency is improved. When the switching power supply system works in the DCM mode, the output voltage DC OUT may charge the energy storage capacitor C0 except for the sampling time during demagnetization. When demagnetization is finished and the next switching period is started, the switching power supply controller U2 can enter a standby mode, most circuits inside the switching power supply controller U2 are closed, static current is reduced, the energy storage capacitor C0 supplies power to the logic control unit 10 for as long as possible, and when the voltage VCC of the energy storage capacitor C0 is lower than a certain value, the energy storage capacitor C0 is charged through the high-voltage power supply unit, so that the switching power supply controller U2 can work normally. Therefore, by optimizing parameters such as the power supply time of the output voltage power supply unit 12 and the high voltage power supply unit 11, the standby current of the switching power supply controller U2, and the voltage of the built-in energy storage capacitor C0, the working voltage required by the switching power supply controller U2 can be provided and maintained by the output voltage DC OUT through the output voltage power supply unit 12 and the energy storage capacitor C0 in most load ranges of the entire switching power supply system, most power can be provided by the output voltage DCOUT through the output voltage power supply unit 12 and the energy storage capacitor C0 in no-load and light-load conditions, and only a small part of power is supplied by the high voltage power supply unit 11, thereby ensuring the standby power consumption and the light-load efficiency of the system.

In the power supply method of the switching power supply system, the output voltage DC OUT is low, the duty ratio is small, the demagnetization time is long, the mixed power supply mode of the output voltage power supply unit and the high-voltage power supply unit is utilized, the opportunity of power supply of the output voltage DC OUT can be fully utilized, the proportion of direct power supply of the high-voltage power supply unit is reduced as much as possible, the power supply loss can be obviously reduced, lower standby power consumption is realized, and the light load efficiency is favorably improved.

In the above embodiments, the switching power supply controller, the switching power supply system, and the power supply method of the switching power supply system of the present invention have been described by taking "the logic control unit 10, the high voltage power supply unit 11, the output voltage power supply unit 12, the built-in energy storage unit 13, the voltage detection unit 14, the driving unit 15, the power switching tube sampling unit 16, the over-temperature protection unit 17, the shielding time detection unit 18, the oscillator 19, and the demagnetization detection unit 20" as examples, which are integrated in the same package (i.e., chip) and are individually used as a module. In other embodiments of the present invention, a part of or all of the structures of at least one of the logic control unit 10, the high voltage power supply unit 11, the output voltage power supply unit 12, the built-in energy storage unit 13, the voltage detection unit 14, the driving unit 15, the power switching tube sampling unit 16, the over-temperature protection unit 17, the shielding time detection unit 18, the oscillator 19, and the demagnetization detection unit 20, and other units may be integrated into one functional module, for example, the voltage detection unit 14 and the demagnetization detection unit 20 are integrated into a functional module having a complex function, which can detect the VFB terminal voltage to make the logic control unit 10 control the driving unit 15 to adjust the output voltage, can detect the demagnetization time, so that the logic control unit 10 can control the output voltage power supply unit 12 to charge the internal energy storage unit 13 in the demagnetization stage. In other embodiments of the present invention, a part of or all of the structure of at least one of the logic control unit 10, the high voltage power supply unit 11, the output voltage power supply unit 12, the built-in energy storage unit 13, the voltage detection unit 14, the driving unit 15, the power switching tube sampling unit 16, the over-temperature protection unit 17, the shielding time detection unit 18, the oscillator 19, and the demagnetization detection unit 20 may be externally disposed outside a chip of the switching power supply controller, and the rest of the structure may be integrated in the same chip to form a switching power supply control chip. For example, only the voltage sampling resistors Rs1 and Rs2 in the voltage sampling module 141 of the voltage detection unit 14 are externally disposed outside the switching power supply control chip, and the rest of the structure of the switching power supply controller is integrated in the switching power supply control chip.

Specifically, referring to fig. 11 and 12, another embodiment of the invention provides a switching power supply controller U2 for controlling an output voltage DC OUT of a switching power supply system. The switching power supply controller U2 includes: the device comprises a logic control unit 10, a high-voltage power supply unit 11, an output voltage power supply unit 12, a built-in energy storage unit 13, a voltage detection unit 14, a driving unit 15, a power switch tube sampling unit 16, an over-temperature protection unit 17, a shielding time detection unit 18 and an oscillator 19. And the output voltage power supply unit 12 includes a first electronic switch SW, the built-in energy storage unit 13 includes an energy storage capacitor C0, a zener diode D0 and a linear regulator LDO, the power switch tube sampling unit 16 includes a power switch tube Q0 and a sampling resistor Rcs, the voltage detection unit 14 includes a voltage sampling module 141, a second electronic switch Ts, a filter capacitor Cs and a comparator Comp, and the voltage sampling module 141 includes two voltage sampling resistors Rs1 and Rs2 connected in series between the output voltage feedback end VFB and ground.

The logic control unit 10, the high-voltage power supply unit 11, the output voltage power supply unit 12, the built-in energy storage unit 13, the second electronic switch Ts, the filter capacitor Cs, the comparator Comp, the driving unit 15, the power switch tube sampling unit 16, the over-temperature protection unit 17, the shielding time detection unit 18 and the oscillator 19 are integrated in the same chip to form a switching power supply control chip. The voltage sampling resistors Rs1 and Rs2 are arranged outside the control chip of the switching power supply, so that the output voltage DC OUT can be changed by changing the voltage sampling resistors Rs1 and Rs2, and the application is more flexible.

That is to say, compared with the switching power supply control chip corresponding to the switching power supply controller U2 shown in fig. 2, the switching power supply control chip corresponding to the switching power supply controller U2 of the present embodiment has no voltage sampling resistor in its internal voltage detection unit, but has an additional external input terminal VCS for voltage sampling, a replaceable external voltage sampling resistor Rs1 is connected between the VCS terminal and the output voltage feedback terminal VFB, and a replaceable external voltage sampling resistor Rs2 is connected between the VCS terminal and one end of the inductor L.

Referring to fig. 12, the present embodiment further provides a switching power supply system having a switching power supply controller chip corresponding to the switching power supply controller U2 shown in fig. 11. The switching power supply system further includes: the voltage sampling circuit comprises an alternating current voltage source AC IN, a rectifying circuit connected with the alternating current voltage source AC IN, a bus capacitor C1 connected with the rectifying circuit, a bus direct current voltage end DRAIN connected with a common end of the bus capacitor C1 and the rectifying circuit, a replaceable voltage sampling resistor Rs1 and a replaceable voltage sampling resistor Rs2, an inductor L, a diode D5 and an output capacitor C2. The voltage sampling resistor Rs1 is connected between the VCS terminal of the switching power supply controller chip and the output voltage feedback terminal VFB, and the voltage sampling resistor Rs2 is connected between the VCS terminal and one end of the inductor L. The power supply method of the switching power supply system of this embodiment is the same as the power supply method of the switching power supply system described in the previous embodiment, and is not described herein again.

In this embodiment, when the voltage sampling resistors Rs1 and Rs2 are low-voltage resistors, the diode D6 is further connected between the output voltage feedback terminal VFB and the output voltage DC OUT, and when the voltage sampling resistors Rs1 and Rs2 are high-voltage resistors, the diode D6 may be omitted to further simplify the circuit structure.

In the above embodiments, the energy storage elements in the built-in energy storage unit 13 are all exemplified by capacitors, but the technical solution of the present invention is not limited to this, and the energy storage elements in the built-in energy storage unit 13 may be replaced by inductors, or a combination of capacitors and inductors, or the like. In addition, in each of the above embodiments, the simplest structure of the output voltage power supply unit 12 is a first electronic switch SW, and the first electronic switch SW is an electronic component such as a MOS transistor or a triode, so as to simplify the structure of the switching power supply controller to the maximum extent and reduce the self power consumption of the switching power supply controller to the maximum extent, however, the technical solution of the present invention is not limited thereto, and the output voltage power supply unit 12 may also be any other suitable circuit capable of providing a current path for connecting the control terminal of the logic control unit and providing a current from the VFB terminal to one terminal of the storage capacitor C0 under the control of the logic control unit, and may be composed of a plurality of MOS transistors, and the more complicated the circuit composing the output voltage power supply unit 12, the larger the self power consumption of the switching power supply controller is caused.

It should be further noted that, in the above embodiments, although the output voltage power supply unit 12 and the high voltage power supply unit 11 are taken as an example for performing hybrid power supply, the technical solution of the present invention is not limited thereto. For example, in other embodiments of the present invention, for example, in a high side buck switching power supply system with a CCM mode, a switching power supply controller of the switching power supply system may be provided with a VCC external port or a Vin external port, a high voltage power supply unit may be replaced by a high voltage resistor (not shown) inside the switching power supply controller, and one end of the high voltage resistor may be connected to the VCC external port or the Vin external port to access a bus voltage, and the other end of the high voltage resistor is connected to an LDO, so that the high voltage power supply unit 11 in the switching power supply controller may be omitted, during a chip start and output setup phase of the switching power supply controller, the bus voltage Vbus of the switching power supply system supplies power to the logic control unit 10, and the power supply may be completely provided by the output voltage DC OUT through the output voltage power supply unit 12 and the built-in energy storage unit 13, thereby simplifying the structure of the switching power supply, and the chip loss of the switching power supply controller is reduced, and the system efficiency is improved.

In addition, the technical scheme of the invention is not only suitable for a high side buck switching power supply system, but also suitable for any switching power supply system with constant voltage output, the output voltage of the switching power supply systems can be periodically sampled by the voltage detection unit, and the logic control unit can quickly and accurately adjust the output voltage according to the sampling result, so that the dynamic response characteristic of the switching power supply system is improved, and the precision of the output voltage is improved.

The above description is only for the purpose of describing the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention, and any variations and modifications made by those skilled in the art based on the above disclosure are within the scope of the appended claims.