CN114094854A - Power supply conversion system and control chip and power supply control circuit thereof - Google Patents
Power supply conversion system and control chip and power supply control circuit thereof Download PDFInfo
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- CN114094854A CN114094854A CN202111317466.0A CN202111317466A CN114094854A CN 114094854 A CN114094854 A CN 114094854A CN 202111317466 A CN202111317466 A CN 202111317466A CN 114094854 A CN114094854 A CN 114094854A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
- H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
- H02M7/12—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/21—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/217—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/32—Means for protecting converters other than automatic disconnection
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
- H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
- H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
- H02M3/158—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load
- H02M3/1582—Buck-boost converters
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Dc-Dc Converters (AREA)
Abstract
The invention provides a power supply conversion system, a power supply control circuit and a control chip thereof. The power supply control circuit is used for supplying power for the control drive circuit, the control drive circuit is used for controlling a power device of the power supply conversion system, the power supply control circuit obtains power supply input voltage through an auxiliary winding coupled with the power supply conversion system, the power supply control circuit comprises a switch circuit and a linear circuit, and the output end of the switch circuit and the output end of the linear circuit are combined and provide power supply voltage for supplying power for the control drive circuit. The power supply conversion system, the control chip and the power supply control circuit thereof provided by the invention can expand the output range of the output voltage, have reliable power supply and lower standby loss, and have higher power density and power supply efficiency.
Description
Technical Field
The invention relates to the field of electronics, in particular but not limited to a power conversion system, a control chip thereof and a power supply control circuit.
Background
Power converters are indispensable components in electronic systems. As is well known, power converters include two main types, namely, a linear converter and a switching power converter, and can be divided into two types, namely, an isolated type and a non-isolated type in terms of conversion mode. In the case of a switching power supply, the isolated converter is widely applied, because the isolated converter can protect a load from being impacted and damaged by high voltage of an input bus, and the isolated converter has wide application in telecommunication wireless networks, automobiles and medical equipment. Among various topologies of the isolated Converter, the Flyback Converter topology does not need to output a filter inductor, so that the circuit has the advantages of simple structure, isolated output and low cost, and occupies a high proportion in the application of terminal equipment. The isolated power conversion system is used in the power adapter of the USB-PD quick-charging protocol due to the advantages.
Fig. 1 shows a schematic diagram of an isolated flyback converter applied to a medium-small power adapter, where the architecture is controlled by a secondary feedback ssr (secondary Side regulation), which is a mainstream control architecture of the medium-small power adapter at present. Fig. 1 shows a widely used flyback power conversion system for converting Alternating Current (AC) to Direct Current (DC). The system comprises: the power supply comprises a full bridge rectifier, a power controller, a transformer, a primary side power MOS switch, a current detection resistor, a secondary side rectifier filter and an isolation feedback compensation network. The power controller is used for controlling a power device MOS of the driving power supply conversion system so as to regulate the output voltage Vout. In a starting stage of the flyback conversion system, generally, power is taken from a bus through a starting resistor Rst (as shown in fig. 1) or a high-voltage starting Junction Field Effect Transistor (JFET) tube built in a chip, and the power is used for supplying power to a circuit in a power controller. After the start-up is finished, the auxiliary winding La (shown in fig. 1) continuously supplies power to the power controller chip. However, the voltage of the auxiliary winding La is limited by the variation of the output voltage Vout, which causes the supply voltage VDD of the flyback converter system to vary, approximately equal to (Na/Ns) × Vout, where Na is the number of auxiliary winding turns and Ns is the number of secondary winding turns.
However, in the PD fast charging situation, the output voltage Vout required by the load provided by the power conversion system has a large variation range, for example, for PD3.0, the output voltage Vout varies from 3V to 21V, which requires that the operating range of the power supply voltage VDD also varies greatly. For example, when the minimum operating voltage of the supply voltage VDD is 10V, which means that the supply voltage VDD needs to provide a supply voltage of 10V even when the output voltage Vout is low, for example, when the voltage is 3V, and accordingly, when the output voltage Vout is 21V, the supply voltage VDD may be as high as 70V, but a high supply voltage means that the withstand voltage requirement on the supply voltage pin VDD is high, and when the supply voltage VDD is high, the loss of the supply control circuit inside the chip is large, and the heat generation is a big problem. In addition, in many cases, such as gan drive, the supply voltage is required to be a value that varies only slightly or is fixed and does not vary with the voltage of the auxiliary winding.
In view of the above, it is desirable to provide a new power supply control circuit for supplying power to the interior of the control chip of the power conversion system, so as to be capable of adapting to a larger output voltage Vout variation range in the PD fast charging situation.
Disclosure of Invention
At least in view of one or more problems in the background art, the present invention provides a power conversion system, a control chip and a power supply control circuit thereof.
According to an aspect of the present invention, a control chip for a power conversion system has a first pin and a second pin, wherein the first pin is externally used for coupling a first end of an inductor, a second end of the inductor is used for coupling a first capacitor and coupling an auxiliary winding through a diode, and the second pin is used for coupling a second capacitor, the control chip includes: the switch circuit comprises a switch, wherein the first end of the switch is coupled with the first pin, the second end of the switch is coupled with the first end of the rectifier tube, and the second end of the rectifier tube is coupled with the second pin; the linear circuit comprises a linear device, wherein a first end of the linear device is coupled with the first pin, and a second end of the linear device is coupled with the second pin; the selection control circuit controls the enabling switch circuit or the linear circuit based on the voltage of the second end of the inductor or the voltage of the second pin; and the control driving circuit is provided with a power supply end and a signal output end, wherein the power supply end is coupled with the second pin, and the signal output end is used for driving a power device of the power supply conversion system.
In one embodiment, the inductor, the switch and the rectifier tube form a boost circuit, and the duty ratio of the boost circuit is preset and fixed.
In one embodiment, the control chip further has a third pin for externally coupling a control terminal of the power device, wherein the signal output terminal is coupled to the third pin.
According to another aspect of the present invention, a control chip for a power conversion system has a first pin and a second pin, wherein the first pin is externally coupled to a first capacitor and coupled to an auxiliary winding through a diode, and the second pin is coupled to a second capacitor, the control chip includes: the switch circuit comprises an inductor and a switch, wherein the first end of the inductor is coupled with the first end of the switch, the second end of the inductor is coupled with the first pin, the second end of the switch is coupled with the first end of the rectifier tube, and the second end of the rectifier tube is coupled with the second pin; the linear circuit comprises a linear device, wherein a first end of the linear device is coupled with a first pin or a first end of an inductor, and a second end of the linear device is coupled with a second pin; the selection control circuit controls the enabling switch circuit or the linear circuit based on the voltage of the second end of the inductor; and the control driving circuit is provided with a power supply end and a signal output end, wherein the power supply end is coupled with the second pin, and the signal output end is used for driving a power device of the power conversion circuit.
According to another aspect of the present invention, a power supply control circuit for a power conversion system is provided, the power supply control circuit is configured to supply power to a control driving circuit, the control driving circuit is configured to control a power device of the power conversion system, the power supply control circuit obtains a power supply input voltage by coupling to an auxiliary winding of the power conversion system, the power supply control circuit includes a switching circuit and a linear circuit, and an output terminal of the switching circuit and an output terminal of the linear circuit are combined and provide a power supply voltage for supplying power to the control driving circuit.
In one embodiment, the power supply control circuit further comprises a selection control circuit that selectively switches between the switching circuit and the linear circuit based on the power supply input voltage for enabling the switching circuit or the linear circuit.
In one embodiment, the switch circuit is a boost circuit, the boost circuit comprises an inductor, a switch and a rectifier tube, wherein a first end of the inductor is coupled with a first end of the switch and a first end of the rectifier tube, a second end of the inductor is coupled with the auxiliary winding through a diode, a second end of the switch is grounded, a second end of the rectifier tube is an output end of the switch circuit, when the power supply input voltage is lower than a preset threshold value, the control circuit is selected to enable the boost circuit, the switch and the rectifier tube are alternately switched on, and a linear device in the linear circuit is switched off; when the power supply input voltage is higher than the preset threshold value, the selection control circuit enables the linear circuit, the booster circuit stops working, and the linear device is conducted.
In one embodiment, the boost circuit operates at a fixed duty cycle.
In one embodiment, the selection control circuit calculates a supply input voltage Vin based on the supply voltage VDD, Vin being VDD + Doff, where Doff is a duty cycle of the boost circuit, and selectively switches between the boost circuit and the linear circuit for enabling the boost circuit or the linear circuit based on the calculated supply input voltage.
In one embodiment, the selection control circuit includes: the voltage detection circuit is used for detecting the power supply voltage and providing a voltage detection signal; the computing circuit receives the voltage detection signal and the duty ratio signal and computes a computing signal representing the power supply input voltage; a comparison circuit that compares the calculation signal with a threshold signal; and a switching control circuit that enables the switching circuit or the linear circuit based on a comparison result of the comparison circuit.
In one embodiment, a rectifier tube in the switching circuit and a linear device in the linear circuit are multiplexed with the same switching device, and the switching device is selectively controlled to work in a switching state or a linear state according to the power supply input voltage.
According to a further aspect of the present invention, a power conversion system is provided, which includes the control chip or the power supply control circuit as described in any of the above embodiments.
In one embodiment, the power conversion system is used in a power adapter of a PD fast charging protocol.
The power supply conversion system, the control chip and the power supply control circuit thereof provided by the invention can expand the output range of the output voltage, have reliable power supply and lower standby loss, and have higher power density and power supply efficiency.
Drawings
The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention.
Fig. 1 shows an isolated flyback converter schematic;
FIG. 2 illustrates a schematic diagram of a power conversion system according to an embodiment of the invention;
FIG. 3 is a schematic diagram of a control chip for a power conversion system according to an embodiment of the invention;
FIG. 4 shows a schematic diagram of a power supply control circuit according to an embodiment of the invention;
FIG. 5 illustrates a linear circuit embodiment according to an embodiment of the present invention;
FIG. 6 shows a control chip schematic according to an embodiment of the invention;
FIG. 7 shows a power supply control circuit schematic according to an embodiment of the invention.
Detailed Description
For a further understanding of the invention, reference will now be made to the preferred embodiments of the invention by way of example, and it is to be understood that the description is intended to further illustrate features and advantages of the invention, and not to limit the scope of the claims.
The description in this section is for several exemplary embodiments only, and the present invention is not limited only to the scope of the embodiments described. Combinations of different embodiments, and substitutions of features from different embodiments, or similar prior art means may be substituted for or substituted for features of the embodiments shown and described.
The term "coupled" or "connected" in this specification includes both direct and indirect connections. An indirect connection is a connection made through an intermediate medium, such as a conductor, wherein the electrically conductive medium may contain parasitic inductance or parasitic capacitance, or through an intermediate circuit or component as described in the embodiments in the specification; indirect connections may also include connections through other active or passive devices that perform the same or similar function, such as connections through switches, signal amplification circuits, follower circuits, and so on. "plurality" or "plurality" means two or more.
Fig. 2 shows a schematic diagram of a power conversion system according to an embodiment of the invention. In the illustrated embodiment, the power conversion system is an isolated flyback power conversion system, and includes a primary circuit and a secondary circuit, which are isolated by a transformer, wherein the primary circuit has a primary winding Lp and a power device Q1. The power device Q1 may be any suitable power device for performing a switching action or regulating the output voltage Vout of the power conversion system via a controlled conduction level. In one embodiment, the power device Q1 includes a Metal Oxide Semiconductor Field Effect Transistor (MOSFET). In another embodiment, the power device Q1 includes a power transistor. In one embodiment, power device Q1 includes a gallium nitride (GaN) power tube. The secondary circuit has a secondary winding Ls and a rectifier Do. Based on the control of the power device Q1, the power conversion system converts the input bus voltage Vbus of the input primary circuit into the output voltage Vout of the output end of the secondary circuit, for driving the load. In one embodiment, the output voltage Vout is a voltage source satisfying the USB-PD fast charge protocol, and the power conversion system is used in a PD fast charge power adapter. The power conversion system further comprises an auxiliary winding La, a first capacitor C1, a second capacitor C2, a diode D1, a control drive circuit 22 for controlling the power device Q1, and a power supply control circuit 21 for supplying power to the control drive circuit 22. The supply control circuit 21 obtains a supply input voltage Vin by coupling the auxiliary winding La. Wherein the first terminal of the auxiliary winding La is coupled to the anode of the first diode D1, the second terminal of the auxiliary winding La is grounded GND, the cathode of the diode D1 is coupled to the power input terminal of the power control circuit 21 and the first terminal of the first capacitor C1, and the second terminal of the first capacitor C1 is grounded GND. The voltage Vin across the first capacitor C1 is the supply input voltage provided by the auxiliary winding La for providing a voltage source to the supply control circuit 21. The voltage Vin may also be used as a feedback signal for control input to the control drive circuit 22. The second capacitor C2 has one end coupled to the output end of the power control circuit 21 and the other end grounded, and the second capacitor C2 is used for providing the power voltage VDD.
The power supply control circuit 21 includes a switching circuit 211 and a linear circuit 212. Wherein the switching circuit 211 comprises a switch K and an inductor L1. Preferably, the switch circuit 211 comprises a Boost (Boost) circuit, including an inductor L1 coupled to the auxiliary winding La through a diode D1, a switch K coupled to a first terminal of the inductor L1, and a rectifying tube coupled to a first terminal of the inductor L1 and the switch K, and the other terminal of the rectifying tube is used as an output terminal of the switch circuit 211. In other embodiments, the switch circuit 211 may also include a Buck-boost (Buck-boost) circuit or other types of switch circuits. The linear circuit 212 comprises a linear device, wherein a first terminal of the linear device is also coupled to the auxiliary winding La through a diode D1. The output of the switching circuit 211 and the output of the linear circuit 212 are combined to provide the supply voltage VDD. The output terminal of the switch circuit 211 may be directly coupled to the output terminal of the linear circuit 212 at the first terminal of the second capacitor C2 for providing the supply voltage VDD. The output of the switching circuit 211 and the output of the linear circuit 212 may also each be coupled to the composite circuit and provide the supply voltage VDD through the output of the composite circuit. In one embodiment, the composite circuit includes two switching tubes, wherein input terminals of the two switching tubes are respectively coupled to the output terminal of the linear circuit and the output terminal of the switching circuit, output terminals of the two switching tubes are coupled to the output terminal of the power supply control circuit, and control terminals of the two switching tubes are respectively coupled to the output terminal of the selection control circuit. When the output voltage Vout is low, the power supply input voltage Vin is also low, and at this time, the selection switch boosting circuit 211 operates to make the power supply voltage VDD higher than the power supply input voltage Vin, and supplies power to the control driving circuit 22 after boosting. When the output voltage Vout is high, the power supply input voltage Vin is also high, and the enable linear circuit 212 is selected to enable the power supply voltage VDD to be lower than the power supply input voltage Vin, and to supply power to the control driving circuit 22 after voltage reduction. Therefore, no matter how the output voltage Vout changes, the supply voltage VDD can be limited in a reasonable range, and the output range of the output voltage Vout can be expanded.
In one embodiment, the power supply control circuit 21 and the control driving circuit 22 are fabricated in a control chip 20, and the control chip 20 is integrated as an electronic package through a packaging process. In another embodiment, the inductor L1 is fabricated outside the control chip as a peripheral circuit, and other components of the power supply control circuit 21 and the control driving circuit 22 are fabricated in the same control chip. In one embodiment, the power device Q1 is also integrated in the control chip.
The control drive circuit 22 is supplied with power from the power supply voltage VDD supplied from the power supply control circuit 21. The control drive circuit 22 outputs a control drive signal GATE for controlling the power device Q1 to regulate the output voltage Vout of the power conversion system.
The illustrated power conversion system is a flyback voltage converter structure, and in other embodiments, the power conversion system may also adopt other topologies, such as a forward voltage converter, a Buck voltage converter, and the like, for example, an auxiliary winding obtains an auxiliary voltage source through inductive coupling of a transformer and a Buck circuit.
Fig. 3 shows a schematic diagram of a control chip 30 for a power conversion system according to an embodiment of the invention. The control chip 30 is externally coupled to an inductor L1, and is coupled to the first capacitor C1, the diode D1 and the auxiliary winding La through an inductor L1. The auxiliary winding La is rectified by a diode D1 and filtered by a capacitor C1 to provide a power supply input voltage Vin, which is further coupled to the SW port of the chip 30 through an inductor L1. The control chip 30 includes a power supply control circuit 31 and a control drive circuit 32, the auxiliary winding La supplies power to the power supply control circuit 31, and the power supply control circuit 31 generates a power supply voltage VDD for supplying power to the control drive circuit 32 based on the power supply input voltage Vin. The power supply control circuit 31 includes a voltage boost circuit 311, a linear circuit (LDO)312, and a selection control circuit 313, where the selection control circuit 313 selects one of the voltage boost circuit 311 and the linear circuit 312 to operate according to the power supply input voltage Vin, that is, whether the power supply voltage VDD is in the boost control power supply mode or the linear circuit power supply mode is determined by the power supply input voltage Vin. The chip 30 performs combined power supply control of the switch type boost control power supply and the linear circuit power supply to the power supply voltage VDD through the external inductor L1. In the illustrated embodiment, the boost circuit 311 operates with a fixed duty ratio Doff, and the selection control circuit 313 detects the supply voltage VDD, calculates the supply input voltage Vin based on the supply voltage VDD, where Vin is VDD Doff, and enables the boost circuit 311 or the linear circuit 312 according to the calculated supply input voltage Vin. In one embodiment, the duty cycle of the boost circuit is preset fixed, with a value following a preset curve, with a determined functional relationship between the supply input voltage Vin and the supply voltage VDD, which may be a non-linear relationship. In the linear circuit operating state, the selection control circuit 313 can switch to the boost mode when the supply voltage VDD is smaller than a predetermined threshold, and the boost circuit 311 operates. In another embodiment, the selection control circuit 313 directly obtains the value of the power supply input voltage Vin, and selects one of the voltage boosting circuit 311 and the linear circuit 312 to operate based on the directly detected power supply input voltage Vin, so as to realize the switching control of the switch circuit 311 and the linear circuit 312. The power supply input voltage Vin obtained by rectifying and filtering the auxiliary winding La is obtained in a mode of presetting the duty ratio or directly detected, the power supply input voltage Vin is used for effectively controlling the working range of the boosting mode, normal work can be guaranteed under the condition that the power supply input voltage Vin provided by the auxiliary winding La is low, such as no load and the like, and the circuit is simple to control, so that the standby loss is reduced. The control driving circuit 32 has a power supply terminal and a signal output terminal, wherein the power supply terminal is coupled to the output terminal of the power supply control circuit 31 and the pin VDD, so that the power supply control circuit 31 supplies power to the control driving circuit 32. The signal output terminal provides an output driving signal GATE. Specifically, the control drive circuit 32 includes a control circuit for generating a pulse width modulation signal PWM and a drive circuit for amplifying the PWM signal to output a drive signal GATE to drive the power device. The control circuit and the drive circuit are powered by a supply voltage VDD supplied by a supply control circuit 31. By selecting the switch circuit 311 or the linear circuit 312 to operate under different power supply input voltages Vin, the power supply voltage VDD can be limited within a reasonable range under a wider range of the power supply input voltage Vin, so as to provide a suitable power supply voltage VDD for the control driving circuit 32, thereby realizing effective driving of the power device and realizing a wider range of output voltage regulation of the power conversion system. Meanwhile, the control chip 30 has fewer external peripheral elements, simple circuit, low standby loss, and high power density and power efficiency.
In the illustrated embodiment, the control chip 30 has a first pin SW, a second pin VDD, a third pin GATE, and a ground pin GND. Of course, the control chip 30 may also have other pins, such as a feedback pin for receiving a current feedback signal or other feedback signals. The first pin SW is coupled to a first terminal of the inductor L1, and a second terminal of the inductor L1 is coupled to a first terminal of the capacitor C1 and a cathode of the diode D1. An anode of the diode D1 is coupled to a first end of the auxiliary winding La. The second terminal of the auxiliary winding La and the second terminal of the capacitor C1 are connected to ground GND. The first pin SW is coupled to the power supply control circuit 31. Of course, the inductor L1 may also be part of the power supply control circuit, or part of the switch circuit 311 in the power supply control circuit. The first pin SW is for receiving a supply input voltage source from the auxiliary winding La. The second pin VDD is coupled to the second capacitor C2 externally, and coupled to the output terminal of the power supply control circuit 31 internally for providing the power supply voltage for controlling the driving circuit. The third pin GATE is used to drive the power device. In one embodiment, the control chip 30 is fabricated in an electronic package, which may have one or more dies therein. In another embodiment, the control chip 30 is fabricated on a semiconductor substrate.
In another embodiment, the power device may also be integrated inside the control chip 30.
Fig. 4 shows a schematic diagram of a power supply control circuit according to an embodiment of the invention. The power supply control circuit comprises a switch circuit 41 and a linear circuit 42, wherein the switch circuit 41 comprises a switch K, a rectifier switch T1 and an inductor L1 which form a booster circuit. The switch K and the rectifier T1 may be MOSFETs or transistors. The rectifier T1 may be replaced by a diode. The first terminal of the inductor L1 is coupled to the first terminal of the switch K and the first terminal of the rectifier switch T1, the second terminal of the inductor L1 is coupled to the auxiliary winding La through the diode D1, the second terminal of the switch K is grounded GND, and the second terminal of the rectifier switch T1 is used as the output terminal of the switch circuit 41. When K is turned on, the first terminal SW of the inductor L1 is pulled to ground, the inductor L1 charges, when K is turned off, the rectifier T1 is turned on, the inductor L1 charges the second capacitor C2, and assuming that the boost circuit control operates in Continuous Current Mode (CCM) or critical conduction mode (BCM), there are:
Vin*Ton/L＝(VDD-Vin)*Toff/L
the method comprises the following steps: vin ═ 1-Don ═ VDD ═ Doff ═ VDD
Where L is the inductance of the external inductor L1, and Ton and Toff are the on and off times, respectively, of the boost-controlled switch K. Doff is the duty cycle of the boost switch OFF time OFF. In a preferred embodiment, Doff is a fixed value. The value of Vin may be obtained by detecting the supply voltage VDD. By setting a fixed duty ratio, the switching circuit does not need a feedback and compensation loop, thereby greatly simplifying system control and reducing standby power consumption.
The linear circuit 42 includes a linear device T3, and the linear device T3 may also be a MOSFET or a transistor, and operate in a linear region. In the illustrated embodiment, a first terminal of the linear device T3 is coupled to the node SW, i.e., a first terminal of the inductor L1, and a second terminal of the linear device T3 is coupled together as an output terminal of the linear circuit 42 and an output terminal of the switch circuit 41, and is commonly coupled to a first terminal of the second capacitor C2 for providing the supply voltage VDD for controlling the driving circuit. When the selection control circuit enables the linear circuit 42 and simultaneously disables the switch circuit 41, the inductor L1 may be regarded as a conducting wire for transferring the rectified and filtered supply input voltage Vin transferred by the auxiliary winding La to the linear circuit 42, and after being converted by the linear circuit 42, the supply voltage VDD is provided at the first end of the second capacitor C2.
The power supply control circuit further includes a voltage detection circuit 43, a calculation circuit 44, a comparison circuit 45, and a switching control circuit 46. Wherein the voltage detection circuit 43 comprises a voltage divider circuit composed of resistors R1 and R2, the voltage detection circuit providing a voltage detection signal indicative of the supply voltage VDD. The calculation circuit 44 receives the voltage detection signal and the duty ratio signal Doff, and calculates a calculation signal V1 representing the power supply input voltage Vin based on the duty ratio Doff and the voltage detection signal. The comparison circuit 45 compares the calculated calculation signal V1 with a threshold signal Vref1, and controls the switching control circuit 46 according to the comparison result to enable the switch circuit 41 or the linear circuit 42. When the calculated power supply input voltage Vin is lower than a certain value, the calculated signal V1 is lower than a threshold signal Vref1, and the selection control circuit enables the booster circuit to control the switch K and the rectifier tube T1 to work in an alternate switching state. The supply voltage is boosted to be greater than the supply input voltage Vin. When Vin is calculated to be higher than a certain value, a calculation signal V1 is higher than a threshold signal Vref1, the LDO power supply mode is switched to, the linear circuit is enabled, the linear control circuit 47 works, the booster circuit stops working, and the linear device is conducted. The linear control circuit 47 may be a closed-loop negative feedback control circuit including voltage dividing resistors R3 and R4, and an error amplifier EA for error amplifying the divided voltage of VDD and the reference signal Vref 2. In another embodiment, the linear circuit 42 may also employ a voltage regulator clamp control as shown in fig. 5.
By the control, the range of the power supply voltage can be effectively controlled, so that the standby loss in no-load is reduced, and the range of the output voltage of the power supply conversion system is expanded.
Fig. 5 shows a linear circuit embodiment according to an embodiment of the invention. A linear device in the linear circuit adopts a triode and a voltage regulator tube to realize the control of the power supply voltage VDD.
FIG. 6 shows a schematic diagram of a control chip 60 according to an embodiment of the invention. In this embodiment, the inductor L1 coupled between the cathode of the diode D1 and the first capacitor C1 is fabricated inside the control chip 60. In contrast to the embodiment of fig. 3, the first pin Vin of the control chip 60 is directly coupled to the cathode of the diode D1. The connection manner of the inductor L1 and other components of the power supply control circuit may be the connection manner shown in fig. 4, wherein a first terminal of the inductor L1 is coupled to the first terminal of the switch K and the first terminal of the linear device T2, and a second terminal of the inductor L1 is coupled to the cathode of the diode D1. In another embodiment, the first terminal of the inductor L1 is coupled to the first terminal of the switch K, and the second terminal of the inductor L1 is coupled to the cathode of the diode D1 externally and coupled to the first terminal of the linear device internally. By arranging the inductor L1 in the control chip 60, reasonable power supply voltage can be provided under the condition of meeting the requirement of outputting voltage in a large range, the power consumption of the system is reduced, peripheral devices of the power conversion system are reduced, the volume of the system is reduced, and the integration level of the system is improved.
Fig. 7 shows a schematic diagram of the power supply control circuit 70 according to an embodiment of the invention. In this embodiment, the switch circuit and the linear circuit of the power supply control circuit 70 share a switch device T3, so that when the selection control circuit 71 detects that the power supply input voltage Vin is low (during the first time period), the switch enable signal EN1 is asserted, the switch K and the rectifier T3 are controlled by the switch signal CT1, the switch device T3 operates in the switch state, the switch K and the switch device T3 are alternately turned on, and the inductor L1, the switch K and the switch device T3 form a voltage boost circuit for making the power supply voltage VDD higher than the power supply input voltage Vin. The switching signal CT1 may be a square wave signal with alternating positive and negative levels. When the selection control circuit 71 detects that the power supply input voltage Vin is higher (at a second time period), the second enable signal EN2 is asserted, the control signal CT2 controls the switching device T3 to operate in a linear state, the switch K is turned off, the inductor L1 is degenerated into a wire function, and the power supply voltage VDD is lower than the power supply input voltage Vin by controlling the conduction degree of the linear device T3. CT2 may be the signal provided by linear control circuit 47 in fig. 4. Therefore, the output range of the power supply voltage VDD is limited in a larger output voltage range, the control driving circuit in the control chip can be prevented from being powered by a higher power supply voltage when the power supply conversion system is at a high output voltage, so that the loss is lower, the efficiency of the power supply conversion system is improved, and meanwhile, the control driving circuit has enough power supply voltage to realize driving when the output voltage is low.
The description and applications of the invention herein are illustrative and are not intended to limit the scope of the invention to the embodiments described above. The descriptions related to the effects or advantages in the specification may not be reflected in practical experimental examples due to uncertainty of specific condition parameters or influence of other factors, and the descriptions related to the effects or advantages are not used for limiting the scope of the invention. Variations and modifications of the embodiments disclosed herein are possible, and alternative and equivalent various components of the embodiments will be apparent to those skilled in the art. It will be clear to those skilled in the art that the present invention may be embodied in other forms, structures, arrangements, proportions, and with other components, materials, and parts, without departing from the spirit or essential characteristics thereof. Other variations and modifications of the embodiments disclosed herein may be made without departing from the scope and spirit of the invention.
Claims (15)
1. A control chip for a power conversion system, having a first pin and a second pin, wherein the first pin is externally used for coupling a first end of an inductor, a second end of the inductor is used for coupling a first capacitor and coupling an auxiliary winding through a diode, and the second pin is used for coupling a second capacitor, the control chip comprising:
the switch circuit comprises a switch and a rectifying tube, wherein the first end of the switch is coupled with the first pin, the second end of the switch is coupled with the first end of the rectifying tube, and the second end of the rectifying tube is coupled with the second pin;
the linear circuit comprises a linear device, wherein a first end of the linear device is coupled with the first pin, and a second end of the linear device is coupled with the second pin;
the selection control circuit controls the enabling switch circuit or the linear circuit based on the voltage of the second end of the inductor or the voltage of the second pin; and
and the control driving circuit is provided with a power supply end and a signal output end, wherein the power supply end is coupled with the second pin, and the signal output end is used for driving a power device of the power supply conversion system.
2. The control chip of claim 1, wherein the inductor, the switch and the rectifier constitute a boost circuit, and a duty ratio of the boost circuit is preset and fixed.
3. The control chip of claim 1, further comprising a third pin for externally coupling a control terminal of the power device, wherein the signal output terminal of the control driving circuit is coupled to the third pin.
4. A control chip for a power conversion system is provided with a first pin and a second pin, wherein the first pin is externally used for being coupled with a first capacitor and being coupled with an auxiliary winding through a diode, the second pin is used for being coupled with a second capacitor, and the control chip comprises:
the switch circuit comprises an inductor, a switch and a rectifying tube, wherein the first end of the inductor is coupled with the first end of the switch, the second end of the inductor is coupled with a first pin, the second end of the switch is coupled with the first end of the rectifying tube, and the second end of the rectifying tube is coupled with a second pin;
the linear circuit comprises a linear device, wherein a first end of the linear device is coupled with a first pin or a first end of an inductor, and a second end of the linear device is coupled with a second pin;
the selection control circuit controls the enabling switch circuit or the linear circuit based on the voltage of the second end of the inductor; and
and the control driving circuit is provided with a power supply end and a signal output end, wherein the power supply end of the control driving circuit is coupled with the second pin, and the signal output end of the control driving circuit is used for driving a power device of the power conversion circuit.
5. The control chip of any one of claims 1-4, wherein the rectifier and the linear device share the same switching device, and in the first time period, the selection control circuit enables the switching circuit, the switching device operates in a switching state, the switching device and the switching device are alternately turned on, and the inductor, the switching device and the switching device form a voltage boosting circuit; in a second time phase, the selection control circuit enables the linear circuit, the switch device works in a linear state, and the switch is turned off.
6. A power conversion system comprising the control chip of any one of claims 1-4.
7. A power supply control circuit for a power conversion system is provided, wherein the power supply control circuit is used for supplying power for a control drive circuit, the control drive circuit is used for controlling a power device of the power conversion system, the power supply control circuit obtains power supply input voltage by being coupled with an auxiliary winding of the power conversion system, the power supply control circuit comprises a switch circuit and a linear circuit, and the output end of the switch circuit and the output end of the linear circuit are combined and provide power supply voltage for supplying power for the control drive circuit.
8. The power supply control circuit of claim 7, further comprising a selection control circuit that selectively switches between the switching circuit and the linear circuit based on the power supply input voltage for enabling the switching circuit or the linear circuit.
9. The power supply control circuit of claim 7, wherein the switch circuit is a boost circuit, the boost circuit includes an inductor, a switch and a rectifier, wherein a first terminal of the inductor is coupled to a first terminal of the switch and a first terminal of the rectifier, a second terminal of the inductor is coupled to the auxiliary winding through a diode, a second terminal of the switch is grounded, a second terminal of the rectifier is an output terminal of the switch circuit, when the power supply input voltage is lower than a preset threshold, the selection control circuit enables the boost circuit, the switch and the rectifier are alternately turned on, and a linear device in the linear circuit is turned off; when the power supply input voltage is higher than the preset threshold value, the selection control circuit enables the linear circuit, the booster circuit stops working, and the linear device is conducted.
10. The power supply control circuit of claim 9, wherein the boost circuit operates at a fixed duty cycle.
11. The power supply control circuit of claim 10, wherein the selection control circuit calculates a supply input voltage Vin based on a supply voltage VDD, Vin-VDD + Doff, where Doff is a duty cycle of the boost circuit, the selection control circuit selectively switching between the boost circuit and the linear circuit for enabling the boost circuit or the linear circuit based on the calculated supply input voltage.
12. The power supply control circuit of claim 8, wherein the selection control circuit comprises:
the voltage detection circuit is used for detecting the power supply voltage and providing a voltage detection signal;
the computing circuit receives the voltage detection signal and the duty ratio signal and computes a computing signal representing the power supply input voltage;
a comparison circuit that compares the calculation signal with a threshold signal; and
and a switching control circuit for enabling the switching circuit or the linear circuit based on the comparison result of the comparison circuit.
13. The power supply control circuit of claim 7, wherein the rectifier in the switching circuit and the linear device in the linear circuit are multiplexed with the same switching device, and the switching device is selectively controlled to operate in a switching state or a linear state according to the power supply input voltage.
14. A power conversion system comprising a supply control circuit as claimed in any one of claims 7 to 13, a power device and an auxiliary winding.
15. The power conversion system of claim 14, used in a power adapter for a PD fast charge protocol.
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| CN202111317466.0A CN114094854B (en) | 2021-11-09 | 2021-11-09 | Power conversion system, control chip thereof and power supply control circuit |
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| CN114094854B (en) | 2023-07-18 |
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