CN112366952A - Isolated voltage conversion circuit, control circuit thereof and power supply method - Google Patents
Isolated voltage conversion circuit, control circuit thereof and power supply method Download PDFInfo
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- CN112366952A CN112366952A CN202011273190.6A CN202011273190A CN112366952A CN 112366952 A CN112366952 A CN 112366952A CN 202011273190 A CN202011273190 A CN 202011273190A CN 112366952 A CN112366952 A CN 112366952A
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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
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/3353—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having at least two simultaneously operating switches on the input side, e.g. "double forward" or "double (switched) flyback" converter
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/10—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers
- H02H7/12—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers
- H02H7/1213—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers for DC-DC converters
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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
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/33561—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having more than one ouput with independent control
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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
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
- H02M3/33576—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
- H02M3/33592—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer having a synchronous rectifier circuit or a synchronous freewheeling circuit at the secondary side of an isolation transformer
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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
- H02M1/0045—Converters combining the concepts of switch-mode regulation and linear regulation, e.g. linear pre-regulator to switching converter, linear and switching converter in parallel, same converter or same transistor operating either in linear or switching mode
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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
- H02M1/0048—Circuits or arrangements for reducing losses
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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 secondary side control circuit for an isolated voltage conversion circuit, the isolated voltage conversion circuit, an electronic package and a method for providing multi-path output voltage. The secondary side of the isolated voltage conversion circuit comprises a first output circuit, the first output circuit comprises a switching tube, the first end of the switching tube is coupled with the secondary side winding, the second end of the switching tube is coupled with a linear device, the second end of the linear device is used for driving a load, and the secondary side control circuit is used for controlling the switching tube and the linear device. The secondary side control circuit, the isolated voltage conversion circuit, the electronic packaging part and the power supply method provided by the invention can provide multi-path output voltage at the secondary side, have better load regulation rate, and have higher efficiency while providing accurate load driving voltage.
Description
Technical Field
The invention relates to the field of electronics, in particular but not exclusively to an isolated voltage conversion circuit, a secondary side control circuit thereof, an electronic packaging part and a method for providing multi-path output voltage.
Background
In an electronic power supply system, it is often necessary to provide different power supply sources for different loads in the system. In the field of home appliances, for example, different power supplies are required for different components, such as motors, processing units, etc. One conventional method is to provide independent power supplies for different loads, but this method has a low integration level and a high system power cost. In order to improve the integration degree of a power supply system and reduce the cost of a power supply source, the requirement for a multi-output power supply system is provided.
A power supply method is to arrange two output circuits on the secondary side of an isolated power supply. Fig. 1 shows an isolated two-way output power supply system. The power supply system comprises a first output circuit providing a first output voltage V1 and a second output circuit providing a second output voltage V2, wherein the voltage V2 is fed back to a primary side control primary side switch through an optical coupler and the like to control the second output voltage V2. The voltage V1 is regulated by the linear device LDO to achieve higher output control accuracy. However, in such a circuit, the output range of the voltage V1 is very limited, and must be close to the second output voltage V2, otherwise the efficiency of the LDO will be greatly reduced. Meanwhile, the linear device is not suitable for being used in a large output current occasion or under the condition of short circuit, and when the LDO has overlarge working current and works for a long time, the reliability and the efficiency of the system are greatly reduced.
In view of the above, there is a need to provide a new structure or control method to solve at least some of the above problems.
Disclosure of Invention
The invention provides an isolated voltage conversion circuit, a secondary side control circuit thereof, an electronic package and a method for providing multi-path output voltage.
According to an aspect of the present invention, a secondary side control circuit for an isolated voltage converting circuit is provided, wherein the secondary side of the isolated voltage converting circuit includes a first output circuit, the first output circuit includes a switching tube having a first end, a second end and a control end, the first end of the switching tube is coupled to a secondary side winding, the second end of the switching tube provides a first output voltage, and the secondary side control circuit includes: the switch tube control circuit is coupled with the control end of the switch tube and is used for controlling the on-off state of the switch tube; and the output end of the linear control circuit is coupled with the control end of the linear device, the first end of the linear device is coupled with the second end of the switch tube, and the second end of the linear device provides a load driving voltage for driving a load.
In one embodiment, the secondary side of the isolated voltage conversion circuit further comprises a second output circuit coupled to the secondary side winding, the second output circuit providing a second output voltage for driving a second load.
In one embodiment, the secondary side control circuit further comprises a precision voltage regulator, wherein a first end of the precision voltage regulator is coupled to a light emitter of the optical coupler, the light emitter of the optical coupler is coupled to the second output voltage, a light receiver of the optical coupler is coupled to a primary side control circuit of the isolated voltage conversion circuit and used for adjusting energy transmitted to the secondary side, and the switch tube control circuit is coupled to the first voltage output end and controls the switch tube based on the first output voltage.
In one embodiment, the linear control circuit includes an over-current/short-circuit protection circuit that outputs a valid over-current protection signal when a signal indicative of over-current/short-circuit of the linear device is acquired, the linear control circuit controlling the linear device to turn off based on the valid over-current protection signal.
In one embodiment, the linear control circuit further comprises a self-recovery timing circuit, when the overcurrent/short-circuit protection circuit outputs a valid overcurrent protection signal, the self-recovery timing circuit is triggered to start timing, and when a preset time length passes, the self-recovery timing circuit controls the overcurrent/short-circuit protection circuit to stop overcurrent protection.
In one embodiment, the linear control circuit includes an over-current/short-circuit protection circuit, the over-current/short-circuit protection circuit including: a comparison circuit for comparing a sampling signal indicative of the current flowing through the linear device with a threshold signal, the comparison circuit providing an effective comparison signal when the sampling signal is greater than the threshold signal; and the continuous timing circuit is used for timing when the comparison signal is in an effective state, if the effective state duration of the comparison signal exceeds the preset duration, the overcurrent/short-circuit protection circuit outputs an effective overcurrent protection signal, and the linear control circuit controls the linear device to be switched off based on the effective overcurrent protection signal.
In one embodiment, the linear control circuit further comprises a self-recovery timing circuit, when the overcurrent protection signal is switched from an inactive state to an active state, the self-recovery timing circuit is triggered to start timing, and when a preset time length passes, the self-recovery timing circuit controls the overcurrent/short circuit protection circuit to stop overcurrent protection.
In one embodiment, the secondary side control circuit further comprises said linear device.
According to another aspect of the present invention, an isolated voltage converting circuit includes: a primary side circuit including a primary side switch; the transformer comprises a primary winding and a secondary winding, wherein the primary winding is coupled with a primary switch; the first output circuit comprises a switching tube, wherein the switching tube is provided with a first end, a second end and a control end, the first end of the switching tube is coupled with the secondary winding, and the second end of the switching tube provides a first output voltage; and a secondary side control circuit as described in any of the above embodiments.
In one embodiment, the secondary side control circuit further comprises said linear device.
In one embodiment, the isolated voltage converting circuit further comprises a second output circuit comprising a diode, an anode terminal of the diode being coupled to the secondary winding, a cathode terminal of the diode providing the second output voltage for driving the second load.
According to yet another aspect of the present invention, an electronic package for a secondary side of an isolated voltage converting circuit has an input pin and a load driving pin, the electronic package internally including: the switch chip is provided with a first end, a second end and a control end, wherein the first end of the switch chip is coupled with the secondary winding through the input pin; and a control chip including an LDO device having a first end and a second end, wherein the first end of the LDO device is coupled to the second end of the switch chip, the second end of the LDO device is coupled to the load driving pin, the control chip further having a switch control output coupled to the control end of the switch chip.
In one embodiment, the electronic package further has: the first voltage output pin is coupled with the second end of the switch chip; the power supply pin is internally coupled with a power supply end of the secondary side control chip and externally coupled with a second voltage output end of the isolated voltage conversion circuit; and the grounding pin is coupled with the secondary side reference ground.
In one embodiment, the electronic package further comprises a first voltage output pin coupled to the second terminal of the switch chip; the power supply pin is internally coupled with a power supply end of the secondary side control chip and externally coupled with a second voltage output end of the isolated voltage conversion circuit; and a grounding pin coupled with the secondary reference ground; the feedback pin is internally coupled with a feedback end of the secondary side control chip and externally coupled with the first voltage output end through the sampling circuit; the optical coupler connecting pin is internally coupled with a controllable voltage stabilizing source in the secondary side control chip and externally coupled with a first end of the optical coupler, wherein a second end of the optical coupler is coupled with a second voltage output end; and the reference pin is internally coupled with a reference end of a controllable voltage stabilizing source in the secondary side control chip.
According to yet another aspect of the present invention, a method of providing multiple output voltages in an isolated voltage conversion circuit comprises: providing a first output voltage at a first voltage output end through a switching tube at a secondary side; providing a second output voltage at a second voltage output terminal of the secondary side; and coupling a first terminal of the linear device to the first voltage output terminal, providing a load driving voltage at a second terminal of the linear device, and controlling the conduction degree of the linear device based on the load driving voltage.
In one embodiment, the method further comprises activating protection for the linear device when the linear device is over-current for a predetermined time duration.
In one embodiment, the method further comprises stopping the protection of the linear device after a second preset time period has elapsed after the protection mechanism is initiated.
In one embodiment, the first output voltage is adjusted by controlling the switching tube, and thus the load driving voltage is adjusted.
The secondary side control circuit for the isolated voltage conversion circuit, the electronic packaging part and the method for providing the multi-path output voltage can provide the multi-path output voltage at the secondary side, have better load regulation rate, provide accurate load driving voltage and have higher efficiency.
Drawings
Fig. 1 shows an isolated two-way output power supply system;
FIG. 2 is a schematic diagram of an isolated voltage conversion circuit according to an embodiment of the present invention;
FIG. 3 illustrates an isolated voltage conversion circuit according to an embodiment of the present invention;
FIG. 4 shows a schematic diagram of an over-current/short-circuit protection circuit according to an embodiment of the invention;
FIG. 5 shows a schematic diagram of an over-current/short-circuit protection circuit according to another embodiment of the invention;
figure 6 shows a schematic diagram of an electronic package according to an embodiment of the invention;
FIG. 7 is a schematic diagram of an isolated voltage conversion circuit according to an embodiment of the present invention; and
fig. 8 is a flowchart illustrating a method for providing multiple output voltages in an isolated voltage converting circuit according to an embodiment of the present 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 circuits or components such as signal amplification circuits, follower circuits, etc. "plurality" or "plurality" means two or more.
Fig. 2 shows a schematic diagram of an isolated voltage converting circuit according to an embodiment of the invention. The isolated voltage conversion circuit comprises a primary side circuit, a transformer T1 and a secondary side circuit. Wherein the primary circuit includes a primary switch Qp. The transformer T1 includes a primary winding L1 and a secondary winding L2, wherein the primary winding L1 is coupled to a primary switch Qp. The secondary side circuit includes a first output circuit, a second output circuit, and a secondary side control circuit 20. Wherein the first output circuit comprises a diode D1 and a switching tube Q1. The switching transistor Q1 has a first terminal, a second terminal and a control terminal, wherein the first terminal of the switching transistor Q1 is coupled to the secondary winding L1 through a diode D1, and the second terminal of the switching transistor Q1 provides the first output voltage V1. In another embodiment, diode D1 may not be included. The second output circuit and the first output circuit are connected in parallel and then coupled to the secondary winding L2. In another embodiment, the first output circuit and the second output circuit may each couple the first secondary winding and the second secondary winding. The second output circuit comprises a diode D2 for providing a second output voltage V2.
The secondary side control circuit 20 includes a linear device 21, a switching tube control circuit 22, and a linear control circuit 23. The linear device 21 is also referred to as LDO device 21. The first terminal of the LDO device 21 is coupled to the second terminal of the switching tube Q1 for receiving the first output voltage V1, the control terminal voltage of the LDO device 21 is controlled by the linear control circuit 23, and the second terminal of the LDO device 21 provides the load driving voltage V3 for driving the load.
The switch control circuit 22 is coupled to the control terminal of the switch Q1, and provides a switch control signal Ctrl1 for controlling the on and off states of the switch Q1. In one embodiment, the switching tube control circuit 22 is configured to control the switching tube Q1 based on the first output voltage V1, for example, when the primary side switch Qp is turned off, the switching tube Q1 is controlled to be in an off state, the secondary side winding L2 first provides a follow current to the second output circuit, when the first output voltage V1 is lower than a preset threshold, the switching tube control circuit 22 turns on the switching tube Q1 to supply power to the first output circuit, so as to adjust the first output voltage V1, and at the same time, the second output voltage V2 is fed back to the primary side through an isolation feedback circuit such as an optocoupler, and the energy transferred to the secondary side is controlled by controlling the primary side switch Qp to adjust the second output voltage V2. In another embodiment, the switching tube control circuit 22 controls the switching tube Q1 based on the second output voltage V2, when the secondary side starts freewheeling, the switching tube Q1 is in a conducting state to supply power to the first output circuit first, when the second output voltage V2 of the second output circuit is lower than a preset threshold, the switching tube Q1 is disconnected to supply energy to the second output circuit to adjust the voltage of the second output voltage V2, and simultaneously, the first output voltage V1 is fed back to the primary side through the isolation feedback circuit, and the adjustment is realized by controlling the primary side switch Qp. The switch tube control circuit 22 may also have other control modes. The output terminal of the linear control circuit 23 provides a second control signal Ctrl2 to the control terminal of the linear device 21 for controlling the conduction degree of the linear device 21. Preferably, the linear control circuit 23 is coupled to the second terminal of the LDO device 21 for obtaining the load driving voltage V3, and adjusting the second control signal Ctrl2 based on the load driving voltage V3. In one embodiment, the linear control circuit 23 comprises an error amplifying circuit, a first output terminal of which receives the load driving voltage V3, a second terminal of which is coupled to the reference voltage, and an output terminal of which provides the second control signal Ctrl 2. In one embodiment, the reference voltage is adjustable.
In this way, by controlling the on and off of the switching tube Q1, the first output voltage V1 can be adjusted to a voltage different from the second output voltage V2, and at the same time, the load driving voltage V3 which is precisely adapted to the use of a specific component can be provided to the load by adjusting the linear device 21 based on the first output voltage V1. The second output voltage V2 and the precisely controlled load drive voltage V3 may be powered for different components in the same appliance. By such a topology, accurate control of the load drive voltage can be achieved. Meanwhile, since the first output voltage V1 is adjustable, such as by setting the sampling resistor shown in fig. 3, the voltage difference between the load driving voltage V3 output by the LDO device 21 and the input voltage V1 thereof can be controlled at a lower level, so that the loss is low and the system has higher efficiency. The low power consumption linear device is easy to integrate in the control chip 20, further simplifying the architecture of the system.
In the embodiment shown in fig. 2, the secondary side of the isolated voltage translation circuit includes a first output circuit that provides voltage V1 and a second output circuit that provides voltage V2. In another embodiment, the isolated voltage converting circuit includes the switching tube Q1 and the LDO device 21, but does not include a second output circuit providing a second output voltage V2. Wherein the LDO device 21 generates the load driving voltage V3 based on the first output voltage V1 provided by the switching tube Q1 to provide an accurate driving voltage to the load. In another embodiment, the secondary side of the isolated voltage converting circuit may further include other output circuits, besides the first output circuit and the second output circuit, for coupling the secondary winding to provide a more multiplexed output voltage. Wherein the first output voltage V1 can also be used to power a load and is suitable for driving larger loads.
In the embodiment shown in fig. 2, the secondary control circuit 20 is fabricated on a semiconductor substrate to form a chip, wherein the secondary control circuit chip includes the linear device 21. In another embodiment, secondary control circuit 20 may not include LDO device 21, for example, secondary control circuit 20 is fabricated on a semiconductor substrate, and LDO device 21 is a discrete device.
In the embodiment shown in fig. 2, the isolated voltage converter circuit comprises a flyback voltage converter circuit. In other embodiments, the isolated voltage translation circuit may have other topologies, such as may include a forward voltage translation circuit.
In the embodiment shown in fig. 2, transformer T1 includes a secondary winding L2. In another embodiment, the transformer T2 may also include two secondary windings, with the dotted terminals coupled to the anode of the diode D1 of the first output circuit and the anode of the diode D2 of the second output circuit, respectively, and the different-dotted terminals coupled to the secondary ground.
Fig. 3 shows an isolated voltage conversion circuit according to an embodiment of the invention. The isolated voltage conversion circuit comprises a primary side circuit, a transformer T1 and a secondary side circuit. The primary circuit includes a primary switch Qp and a primary control circuit 31 that controls the primary switch Qp. The transformer T1 includes a primary winding L1 and a secondary winding L2, wherein a first end (a different name end) of the primary winding L1 is coupled to an input end of the isolated voltage converting circuit for receiving a dc input voltage source, another end (a same name end) of the primary winding L1 is coupled to a first end of a primary switch Qp, and another end of the primary switch Qp is coupled to a primary ground. A first end (a dotted end) of the secondary winding L2 is coupled to an anode of the diode D1 of the first output circuit and an anode of the diode D2 of the second output circuit, and a second end (a dotted end) of the secondary winding is connected to the secondary ground. The secondary side circuit comprises a first output circuit, a second output circuit, a secondary side control circuit 30, an isolation feedback loop, a sampling circuit and the like. The first output circuit comprises a diode D1, a switching tube Q1 and a first output capacitor C1. The second output circuit includes a diode D2 and a second output capacitor C2. The isolation feedback circuit comprises an optical coupler and an auxiliary resistor and an auxiliary capacitor, wherein the optical coupler comprises a light emitter positioned on the secondary side and a light receiver positioned on the primary side. The first output capacitor C1 is coupled to the second terminal of the switch Q1. The second output capacitor C2 is coupled to the cathode of the diode D2. The third output capacitor C3 is coupled to the second terminal of the LDO device 32 in the secondary side control circuit 30 for providing a load driving circuit. The other end of each of the capacitors C1, C2 and C3 is coupled to the secondary ground for filtering the first output voltage V1, the second output voltage V2 and the load driving voltage V3, respectively. In further embodiments, the capacitors C1 and C2 may also be included in the load driven by the voltages V1, V2, and V3, respectively.
The first output circuit includes a switch Q1, a first terminal of the switch Q1 is coupled to the secondary winding through a diode D1, a second terminal of the switch Q1 provides a first output voltage V1, and a control terminal of the switch Q1 is coupled to a switch control output terminal GATE of the secondary control circuit 30. In the illustrated embodiment, the switching transistor Q1 comprises a Metal Oxide Semiconductor Field Effect Transistor (MOSFET), wherein the drain terminal of the switching transistor Q1 is coupled to the cathode of the diode D1 to further couple the secondary winding L2, and the source terminal of the switching transistor Q1 provides the first output voltage V1. The second output circuit includes a diode D2 coupled to the secondary winding L2, and provides a second output voltage V2 for driving the second load. When the primary side switch Qp is turned off, if the switching tube Q1 is in a conducting state, the secondary side freewheeling current charges the first output capacitor C1 through the diode D1 and the switching tube Q1, and the first output voltage V1 rises. When the switching tube Q1 is turned off, the secondary freewheeling current charges the second output capacitor C2 through the diode D2.
The protection circuit 37 is used for controlling the linear control circuit 35 to pull down the voltage at the control terminal of the LDO device 32 for turning off the LDO device 32 when the abnormal state is detected. Preferably, the protection circuit includes an overcurrent/short-circuit protection function, and is an overcurrent/short-circuit protection circuit, when a second end of the LDO device, i.e., the load driving output terminal V3, is shorted or an overcurrent event occurs, the overcurrent/short-circuit protection circuit 37 obtains a signal indicating an overcurrent/short circuit of the linear device 32, the overcurrent/short-circuit protection circuit 37 outputs an effective overcurrent protection signal PT, and the linear control circuit 37 controls the LDO device 32 to turn off based on the effective overcurrent protection signal PT. In one embodiment, when detecting a sudden drop in the voltage at the second terminal of LDO device 32, over/short protection circuit 37 outputs a valid over-current protection signal PT. Therefore, the system can protect the LDO device 32, avoid the LDO device 32 from working for a long time under the condition of overlarge current, avoid the LDO device 32 from having higher power consumption, and improve the reliability of the system. The protection circuit 37 can also realize over-voltage protection or over-temperature protection of the LDO device 32. Preferably, the LDO device 32 is integrated inside the secondary control chip, so the system can achieve multi-aspect protection without providing an additional pin outside the control chip, and has a higher system integration level.
The switch tube control circuit 35 is coupled to the control terminal of the switch tube Q1 through a switch control output terminal GATE, and is used for controlling the on and off states of the switch tube Q1. In the embodiment shown in fig. 3, the switching tube control circuit 35 includes a comparing circuit CP, a non-inverting input of which receives the second reference voltage Vref2, and an inverting input of which is coupled to an output of the sampling circuit via a feedback terminal FB, wherein the sampling circuit is coupled to the first voltage output terminal V1. When the feedback voltage of the first output voltage V1 is lower than the reference voltage Vref2, the switching tube control circuit 35 controls the switching tube Q1 to be turned on. In another embodiment, the sampling circuit is coupled to the second voltage output terminal, and when the second output voltage V2 is lower than the threshold voltage, the switching tube control circuit 35 controls the switching tube Q1 to turn off.
Preferably, the supply voltage terminal VDD of the secondary control circuit 30 is coupled to the second voltage output terminal, and the second output voltage V2 is used for supplying power to the secondary control circuit 30.
Preferably, the secondary control circuit 30 further includes a precision voltage regulator 34. The precise voltage-stabilizing source 34 and the optical coupler constitute an isolation feedback circuit for feeding back the voltage signal of the secondary side to the primary side and controlling the primary side switch Qp to further control the energy transmitted from the primary side to the secondary side. In one embodiment, precision voltage regulator 34 is a TL431 device. As shown in the figure, the first end of the precision voltage regulator 34 is coupled to the first end of the light emitter of the optical coupler, the second end of the light emitter of the optical coupler is coupled to the second output voltage V2, and the light receiver of the optical coupler is coupled to the primary side control circuit 31 of the isolated voltage conversion circuit for regulating the energy transmitted to the secondary side. Meanwhile, the first switch tube control circuit 36 is coupled to the first voltage output terminal and controls the switch tube Q1 based on the first output voltage V1. Thus, the first output voltage V1 is controlled primarily by the control loop in the secondary control circuit 30, and the second output voltage V2 is controlled primarily by the isolated feedback circuit. In another embodiment, the first voltage output terminal is coupled to the light emitter of the optocoupler, and the second voltage output terminal is coupled to the input terminal of the switching tube control circuit 36, so that the first output voltage V1 is mainly controlled by the isolated feedback circuit, and the second output voltage V2 is mainly controlled by the control loop of the secondary control circuit 30.
Fig. 4 shows a schematic diagram of an overcurrent/short-circuit protection circuit according to an embodiment of the invention. Wherein the over-current/short-circuit protection circuit comprises a comparison circuit 41 for comparing a sampling signal CS indicative of the current flowing through the linear device with a threshold voltage Vref3, the comparison circuit 41 providing an active comparison signal to provide an active protection signal PT when the sampling signal CS is greater than the threshold signal Vref 3. The over-current/short circuit protection circuit further includes a self-recovery timing circuit 43 for timing off the protection state so that the system can automatically recover to the normal state when the fault condition is removed, enabling the LDO device to start up. When the comparison result is that the overcurrent protection signal PT is switched from the invalid state to the valid state, the self-recovery timing circuit 43 starts timing, and when the preset time length passes, the self-recovery timing circuit 43 controls the overcurrent/short-circuit protection circuit to stop overcurrent protection, the linear control circuit adjusts the conduction state of the linear device, and the linear device enters a normal working mode. In the illustrated embodiment, the over-current/short-circuit protection circuit further includes a trigger circuit 42 having a set input coupled to the output of the comparator circuit 41, a reset input coupled to the output of the self-recovery timer circuit 43, and an output providing the over-current protection signal PT. When the comparison circuit 41 indicates that the current flowing through the linear device is overcurrent, the comparison signal is switched to an active state, the trigger circuit 42 is set, and the overcurrent protection signal PT is in an active state. When the self-recovery timing circuit 43 overflows, the trigger circuit 42 is reset, the overcurrent protection signal PT is switched to an invalid state for stopping protection and maintaining for a period of time, at this time, if the current flowing through the linear device recovers to a normal value, the trigger circuit 42 is not set any more, the linear device enters a normal working state, and if a short-circuit condition exists continuously, the comparison circuit 41 sets the trigger circuit 42 again, and turns off the linear device. Of course, the flip-flop circuit 42 may be replaced with other logic circuits.
Fig. 5 shows a schematic diagram of an overcurrent/short-circuit protection circuit according to another embodiment of the invention. In contrast to the embodiment of fig. 4, the over-current/short-circuit protection circuit of fig. 5 further includes a continuous timing circuit 54. An input terminal of the continuous timing circuit 54 is coupled to the output terminal of the comparison circuit 51, and an output terminal of the continuous timing circuit 54 is coupled to the set input terminal of the trigger circuit 52. When the comparison signal output by the comparison circuit 41 is in an active state, the timer circuit 54 keeps timing, and if the active state duration of the comparison signal exceeds a preset duration, the overcurrent/short-circuit protection circuit outputs an active overcurrent protection signal PT for performing protection and turning off the linear device. Thus, by providing the continuous timing circuit 54, it is possible to prevent the false entry into the protection mode due to the interference signal.
In one embodiment, the over-current/short-circuit protection circuit may not include the self-recovery timing circuit 53 and the trigger circuit 52, and the output terminal of the continuous timing circuit 54 provides the protection signal PT. The system is restarted by another restart signal.
Figure 6 shows a schematic diagram of an electronic package according to an embodiment of the invention. The electronic package may be used for the secondary side of an isolated voltage conversion circuit. The secondary side electronic package internally includes a switch chip 61 and a control chip 62, and the electronic package externally has an input pin 631 and a load driving pin 632. In which a switching tube Q1 as shown in fig. 2 or 3 is fabricated on the switching chip 61. The sub-side control chip 62 is formed with the sub-side control circuit 20 shown in fig. 2 or the sub-side control circuit 30 shown in fig. 3. The connection relationship between the switch chip 61 and the secondary control chip 62 will be described with reference to fig. 2 or fig. 3. The switch chip 61 has a first terminal, a second terminal and a control terminal, wherein the first terminal of the switch chip 61 is coupled to the secondary winding L2 of the isolated voltage converting circuit through the input pin 631 (DRAIN). In the illustrated embodiment, a first end of the switch chip 61 is disposed on a back side of the switch chip 61, and is electrically coupled to the lead frame 64 and further coupled to an input pin 631(DRAIN) of the electronic package by a conductive material such as a conductive adhesive. In one embodiment, the lead frame 64 includes at least a portion of the input pin 631, i.e., the lead frame 64 and the input pin 631 are integral, for increased current carrying capability. The second terminal of the switch chip 61 provides a first output voltage V1 and is coupled to the first terminal of the LDO device in the control chip 62. The control terminal of the switch chip 61 is coupled to the switch control output terminal of the control chip 62 for receiving the switch tube control signal Ctrl 1. The switch tube control signal Ctrl1 may be provided by a switch tube control circuit in the control chip 62. The first terminal of the switch chip 61 may be the drain of the MOSFET Q1 shown in fig. 3, the second terminal of the switch chip 61 may be the source of the MOSFET Q1 shown in fig. 3, and the control terminal of the switch chip 61 may be the gate of the MOSFET Q1 shown in fig. 3. The control chip 62 includes an LDO device 621, wherein a first end of the LDO device 621 is coupled to the second end of the switch chip 61 for receiving the first output voltage V1, and a second end of the LDO device 621 is coupled to the load driving pin 632 for providing the load driving voltage V3. The control terminal of LDO device 621 may be coupled to the linear control circuit via the internal interconnect of control chip 62. By such a package, the system structure is simplified, and the method can be suitable for realizing multi-path output of different voltages on the secondary side of the isolated voltage conversion circuit by a simple device, and simultaneously provides a precisely regulated load driving voltage V3.
Fig. 7 shows a schematic diagram of an isolated voltage conversion circuit according to an embodiment of the invention. The secondary side of the isolated voltage translation circuit includes an electronics package 70. The electronic package 70 includes a switch chip and a control chip as shown in fig. 6, wherein the switch chip may include a switch tube Q1 as shown in fig. 3, and the control chip may include a secondary control circuit 30 as shown in fig. 3. The exterior of electronic package 70 has 8 pins as shown, and in addition to input pin DRAIN and load drive pin V3, electronic package 70 further has a first voltage output pin V1, a power supply pin VDD, a feedback pin FB, an optical coupling pin COMP, a reference pin REF, and a ground pin GND. As shown in fig. 6, the first voltage output pin V1 is coupled to the second terminal of the switch chip 61 internally and provides the first output voltage externally. The first output voltage V1 may also be used to drive a load. A sampling circuit may be disposed between the first voltage output pin V1 and the feedback pin FB for obtaining a sampling signal of the first output voltage. The power supply pin VDD is internally coupled to a power supply terminal of the secondary control chip, that is, corresponding to the power supply terminal VDD of the secondary control circuit 30 shown in fig. 3, and externally coupled to a second voltage output terminal V2 of the isolated voltage converting circuit, and supplies power to the secondary control chip by using a second output voltage V2. The feedback pin FB is internally coupled to a feedback terminal of the secondary control chip, and externally coupled to the first voltage output terminal V1 through a sampling circuit, for obtaining a sampling signal of the first output voltage V1. In another embodiment, the electronic package 70 does not include the feedback pin FB, and the feedback terminal of the secondary control chip is directly coupled to the first voltage output terminal V1 inside the electronic package 70. The optical coupling connection pin COMP is internally coupled to a controllable voltage stabilizing source in the secondary side control chip and externally coupled to a first end of the optical coupler 72. The second end of the optocoupler 72 is coupled to the second voltage output end V2, so that the primary side switch Qp is controlled based on the second output voltage V2, and further the energy output to the secondary side is controlled to realize the adjustment of the second output voltage V2. The reference pin VREF is internally coupled with a reference end of a controllable voltage stabilizing source in the secondary side control chip and is externally coupled with a divider resistor. The controllable voltage-stabilizing source is integrated in the secondary side control chip, so that the system integration level is improved. In another embodiment, where the controllable voltage supply employs an external discrete device, such as TL431, electronic package 70 does not include optically coupled pins COMP and reference pin VREF. The ground pin GND is coupled to the secondary reference ground.
Fig. 8 is a flowchart illustrating a method for providing multiple output voltages in an isolated voltage converting circuit according to an embodiment of the present invention. The method includes coupling a first terminal of a switching tube to a secondary winding of the isolated voltage converting circuit at a secondary side of the isolated voltage converting circuit and providing a first output voltage at a second terminal of the switching tube, wherein the second terminal of the switching tube serves as a first voltage output terminal of the isolated voltage converting circuit at step 801. The method includes providing a second output voltage at a secondary side of the isolated voltage conversion circuit, where the second output voltage is obtainable by coupling a rectifier to the secondary winding and at an output of the rectifier, at step 802. The method further includes coupling a linear device to the first voltage output terminal to provide a precisely controlled load driving voltage at step 803, and in particular, a first terminal of the linear device may be coupled to the first voltage output terminal and a second terminal of the linear device provides the load driving voltage to provide the precisely controlled load driving voltage by adjusting a conduction level of the linear device. The method may further include turning off the linear device and starting the protection mechanism when the linear device is detected to be over-current for a predetermined duration. In one embodiment, after the protection mechanism is started, when a second preset time passes, the protection of the linear device is stopped, so that the system can be automatically recovered. In one embodiment, the method further comprises adjusting the first output voltage through the switching tube based on the need of adjusting the load driving voltage, and making the on-resistance of the linear device to be a lower level while accurately controlling the load driving voltage, so as to keep the power consumption of the system to be a lower state and improve the efficiency of the system. In one embodiment, the method further comprises error amplifying the load driving voltage with a timing sampling signal of the first output voltage and further controlling the linear device such that the load driving voltage is adjusted by adjusting a resistance value of a sampling resistor coupled to the first voltage output terminal while maintaining the stability and low power of the load driving voltage.
Those skilled in the art should understand that the logic controls such as "high" and "low", "set" and "reset", "and gate" and "or gate", "non-inverting input" and "inverting input" in the logic controls referred to in the specification or the drawings may be exchanged or changed, and the subsequent logic controls may be adjusted to achieve the same functions or purposes as the above-mentioned embodiments.
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 secondary side control circuit for an isolated voltage conversion circuit, wherein a secondary side of the isolated voltage conversion circuit includes a first output circuit, wherein the first output circuit includes a switching tube having a first end, a second end, and a control end, the first end of the switching tube being coupled to a secondary winding, the second end of the switching tube providing a first output voltage, the secondary side control circuit comprising:
the switch tube control circuit is coupled with the control end of the switch tube and is used for controlling the on-off state of the switch tube; and
and the output end of the linear control circuit is coupled with the control end of the linear device, the first end of the linear device is coupled with the second end of the switch tube, and the second end of the linear device provides a load driving voltage for driving a load.
2. The secondary-side control circuit of claim 1 wherein the secondary side of the isolated voltage translation circuit further comprises a second output circuit coupled to the secondary-side winding, the second output circuit providing a second output voltage for driving a second load.
3. The secondary side control circuit of claim 2 further comprising a precision voltage regulator, wherein a first terminal of the precision voltage regulator is coupled to a light emitter of the optocoupler, the light emitter of the optocoupler is coupled to the second output voltage, a light receiver of the optocoupler is coupled to a primary side control circuit of the isolated voltage conversion circuit for regulating the energy transmitted to the secondary side, and the switch tube control circuit is coupled to the first voltage output terminal and controls the switch tube based on the first output voltage.
4. The secondary-side control circuit of claim 1 further comprising the linear device.
5. The secondary-side control circuit of claim 1 wherein the linear control circuit includes an over-current/short-circuit protection circuit that outputs an active over-current protection signal when a signal indicative of over-current/short-circuit of the linear device is acquired, the linear control circuit controlling the linear device to turn off based on the active over-current protection signal.
6. The secondary control circuit of claim 1 wherein the linear control circuit comprises an over-current/short-circuit protection circuit comprising:
a comparison circuit for comparing a sampling signal indicative of the current flowing through the linear device with a threshold signal, the comparison circuit providing an effective comparison signal when the sampling signal is greater than the threshold signal; and
and the continuous timing circuit is used for timing when the comparison signal is in an effective state, and outputting an effective overcurrent protection signal by the overcurrent/short circuit protection circuit if the effective state duration of the comparison signal exceeds a preset duration, and the linear control circuit is used for controlling the linear device to be turned off based on the effective overcurrent protection signal.
7. The secondary side control circuit as claimed in claim 5 or 6, wherein the linear control circuit further comprises a self-recovery timing circuit, the self-recovery timing circuit is triggered to start timing when the overcurrent protection signal is switched from the inactive state to the active state, and the self-recovery timing circuit controls the overcurrent/short-circuit protection circuit to stop overcurrent protection when a preset time length elapses.
8. An isolated voltage conversion circuit comprising:
a primary side circuit including a primary side switch;
the transformer comprises a primary winding and a secondary winding, wherein the primary winding is coupled with a primary switch;
the first output circuit comprises a switching tube, wherein the switching tube is provided with a first end, a second end and a control end, the first end of the switching tube is coupled with the secondary winding, and the second end of the switching tube provides a first output voltage; and
the secondary side control circuit of any of claims 1-6.
9. An isolated voltage conversion circuit as claimed in claim 8, further comprising a second output circuit comprising a diode, an anode terminal of the diode being coupled to the secondary winding, a cathode terminal of the diode providing a second output voltage for driving a second load.
10. An electronic package for a secondary side of an isolated voltage conversion circuit having an input pin and a load drive pin, the electronic package comprising:
the switch chip is provided with a first end, a second end and a control end, wherein the first end of the switch chip is coupled with the secondary winding through the input pin; and
and the control chip comprises an LDO device, the LDO device is provided with a first end and a second end, the first end of the LDO device is coupled with the second end of the switch chip, the second end of the LDO device is coupled with the load driving pin, and the control chip is further provided with a switch control output end which is coupled with the control end of the switch chip.
11. The electronic package of claim 10, further comprising:
the first voltage output pin is coupled with the second end of the switch chip;
the power supply pin is internally coupled with a power supply end of the secondary side control chip and externally coupled with a second voltage output end of the isolated voltage conversion circuit; and
and the grounding pin is coupled with the secondary reference ground.
12. The electronic package according to claim 11, further comprising:
the feedback pin is internally coupled with a feedback end of the secondary side control chip and externally coupled with the first voltage output end through the sampling circuit;
the optical coupler connecting pin is internally coupled with a controllable voltage stabilizing source in the secondary side control chip and externally coupled with a first end of the optical coupler, wherein a second end of the optical coupler is coupled with a second voltage output end; and
and the reference pin is internally coupled with a reference end of the controllable voltage-stabilizing source.
13. A method of providing multiple output voltages in an isolated voltage conversion circuit, comprising:
providing a first output voltage at a first voltage output end through a switching tube at a secondary side;
providing a second output voltage at a second voltage output terminal of the secondary side; and
the first end of the linear device is coupled with the first voltage output end, the load driving voltage is provided at the second end of the linear device, and the conduction degree of the linear device is controlled based on the load driving voltage.
14. The method of claim 13, further comprising turning off the linear device to start protection when the linear device is detected to be over-current for a preset time period, and stopping protection of the linear device after a second preset time period has elapsed.
15. The method of claim 13, further comprising adjusting the load drive voltage by adjusting a resistance of a sampling resistor coupled to the first voltage output.
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