CN118589814A - Multi-channel output switching power supply and its control circuit - Google Patents
Multi-channel output switching power supply and its control circuit Download PDFInfo
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- CN118589814A CN118589814A CN202410705653.3A CN202410705653A CN118589814A CN 118589814 A CN118589814 A CN 118589814A CN 202410705653 A CN202410705653 A CN 202410705653A CN 118589814 A CN118589814 A CN 118589814A
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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
- H02M1/0083—Converters characterised by their input or output configuration
- H02M1/009—Converters characterised by their input or output configuration having two or more independently controlled outputs
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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
- H02M1/0003—Details of control, feedback or regulation circuits
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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
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Abstract
本发明提供了一种多路输出开关电源及其控制电路，其中，该多路输出开关电源包括变压器和第一至第n路开关管，该控制电路被配置为：在第m路系统输出电压与第一路系统输出电压分享变压器的退磁能量的情况下，基于系统输出反馈信号和第m路输出反馈逻辑信号生成动态增强使能信号，基于动态增强使能信号生成用于控制第m路开关管处于导通状态的退磁电流分配控制信号或动态增强控制信号，并且基于退磁电流分配控制信号或动态增强控制信号生成用于控制第m路开关管的导通与关断的第m路开关控制信号，其中，系统输出反馈信号是通过对第一至第n路输出反馈逻辑信号执行逻辑运算生成的，n是大于等于2的整数，m是大于等于2且小于等于n的整数。
The present invention provides a multi-channel output switching power supply and a control circuit thereof, wherein the multi-channel output switching power supply includes a transformer and first to n-th switching tubes, and the control circuit is configured to: when the m-th system output voltage and the first system output voltage share the demagnetization energy of the transformer, generate a dynamic enhancement enable signal based on a system output feedback signal and an m-th output feedback logic signal, generate a demagnetization current distribution control signal or a dynamic enhancement control signal for controlling the m-th switching tube to be in a conducting state based on the dynamic enhancement enable signal, and generate an m-th switch control signal for controlling the conduction and shutdown of the m-th switching tube based on the demagnetization current distribution control signal or the dynamic enhancement control signal, wherein the system output feedback signal is generated by performing a logical operation on the first to n-th output feedback logic signals, n is an integer greater than or equal to 2, and m is an integer greater than or equal to 2 and less than or equal to n.
Description
Technical Field
The invention relates to the field of circuits, in particular to a multi-output switching power supply and a control circuit thereof.
Background
The switching power supply is also called a switching power supply and a switching converter, and is one type of power supply. The function of the switching power supply is to convert a dc or ac voltage into a voltage or current required by the user terminal through different types of architectures (e.g., flyback (fly-back) architecture, buck (buck) architecture, boost (boost) architecture, etc.).
Disclosure of Invention
According to an embodiment of the present invention, a control circuit for a multiple-output switching power supply, wherein the multiple-output switching power supply includes a transformer and first to nth switching transistors, and in each demagnetization cycle of the transformer, only one of second to nth system output voltages of the multiple-output switching power supply shares demagnetization energy of the transformer with a first system output voltage of the multiple-output switching power supply, the control circuit is configured to: and generating a dynamic enhancement enable signal based on the system output feedback signal and the mth output feedback logic signal under the condition that the mth system output voltage in the second to nth system output voltages shares the demagnetization energy of the transformer with the first system output voltage, generating a demagnetization current distribution control signal or a dynamic enhancement control signal for controlling the mth switching tube in a conducting state in the first to nth switching tubes based on the dynamic enhancement enable signal, and generating an mth switching control signal for controlling the on and off of the mth switching tube based on the demagnetization current distribution control signal or the dynamic enhancement control signal, wherein the system output feedback signal is generated by performing a logic operation on the first to nth output feedback logic signals, the second to nth output feedback logic signals are generated by comparing second to nth output feedback divided voltages with corresponding threshold voltages respectively, and the second to nth output feedback divided voltages are generated by dividing the second to nth system output voltages respectively, and n is an integer greater than or equal to 2 and less than or equal to 2.
The multi-output switching power supply according to the embodiment of the invention comprises the control circuit.
Drawings
The invention will be better understood from the following description of specific embodiments thereof, taken in conjunction with the accompanying drawings, in which:
fig. 1 is a schematic diagram showing the logic structure of a conventional multiple-output switching power supply.
Fig. 2 is a schematic diagram showing a logic structure of the demagnetizing current distribution unit shown in fig. 1.
Fig. 3 shows a timing diagram of a plurality of signals related to the demagnetization current distribution shown in fig. 1.
Fig. 4 shows a timing diagram of a plurality of signals associated with the dynamic load switching shown in fig. 1.
Fig. 5 shows a schematic diagram of the logic structure of a multi-output switching power supply according to an embodiment of the invention.
FIG. 6 illustrates an example logical structure diagram of the dynamic enhancement control module shown in FIG. 5.
Fig. 7 shows a timing diagram of a plurality of signals associated with the dynamic enhancement control module shown in fig. 6.
FIG. 8 illustrates another logical structure diagram of the dynamic enhancement control module illustrated in FIG. 5.
FIG. 9 illustrates yet another logical architecture diagram of the dynamic enhancement control module illustrated in FIG. 5.
Detailed Description
Features and exemplary embodiments of various aspects of the invention are described in detail below. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the invention by showing examples of the invention. The present invention is in no way limited to any particular configuration and algorithm set forth below, but rather covers any modification, substitution, and improvement of elements, components, and algorithms without departing from the spirit of the invention. In the drawings and the following description, well-known structures and techniques have not been shown in order to avoid unnecessarily obscuring the present invention. In addition, the term "a and B connected" as used herein may mean "a and B directly connected" or "a and B indirectly connected via one or more other elements".
Fig. 1 is a schematic diagram showing the logic structure of a conventional multiple-output switching power supply. In the multiple output switching power supply 100 shown in fig. 1, an ac rectifying circuit 102 and an input capacitor Cin rectify and filter an ac input voltage vin_ac to generate a dc input voltage vin_rec; the primary winding of the transformer T1 stores energy when the first path switching tube S1 is in a conducting state, and transmits energy to the secondary side of the transformer T1 through a mutual inductance effect when the first path switching tube S1 is in a switching-off state to generate a multi-path system output voltage CV1 … CVn (n is equal to or greater than 2), wherein the first path system output voltage CV1 is connected with a capacitive load or an LED lamp string load; Based on a special transformer transformation ratio design, the conduction voltage drop Vd of the first path secondary winding voltage Vaux1 minus the diode D1 corresponding to the first path system output voltage CV1 satisfies Vaux1-Vd < CV1, and the logic operation is carried out on the output feedback logic signals corresponding to the path system output voltages, so that: in each demagnetization cycle of the transformer T1, only one of the second to nth system output voltages CV2 to CVn (i.e., the mth system output voltage CVm, m is any integer of 2 or more and n or less) shares the demagnetization energy of the transformer T1 with the first system output voltage CV1, when the m-th switching tube Sm is in a conducting state, part of the demagnetizing energy stored in the transformer T1 is distributed to the m-th system output voltage CVm, and when the m-th switching tube Sm is in a switching-off state, part of the demagnetizing energy stored in the transformer T1 is distributed to the first-path system output voltage CV1; The output voltage dividing networks 104-1 to 104-n divide the first to nth system output voltages CV1 … CVn to generate first to nth output feedback divided voltages VFB1 … VFBn, respectively; the comparator network 106 compares the first-n-th output feedback divided voltages VFB1 … VFBn with respective threshold voltages to generate first-n-th output feedback logic signals fb1_req-fbn_req, respectively (e.g., the comparator network includes n comparators, each comparator comparing a respective output feedback divided voltage with a threshold voltage to generate a respective output feedback logic signal); the output feedback control unit 108 performs a logic operation on the first to nth output feedback logic signals fb1_req to fbn_req to generate a system output feedback signal fb_req; A feedback signal transmission unit (e.g., a capacitive coupling, magnetic coupling, or optically coupled isolated transmission unit, or non-isolated transmission unit) 110 generates a system output indication signal fb_rec based on the system output feedback signal fb_req; the feedback signal detection unit 112 generates a primary-side on trigger signal fb_tri for controlling the first-path switching tube S1 to change from an off state to an on state based on the system output indication signal fb_rec; the threshold signal generation unit 114 generates a primary threshold signal cs_pk based on the primary on trigger signal fb_tri; primary current detection unit 116 generates primary current characterization signal CS based on primary current Ics flowing through the primary winding of transformer T1; The comparator 118 compares the primary current characterization signal CS and the primary threshold signal cs_pk to generate a primary off trigger signal tri_off for controlling the first switching tube S1 to change from the on state to the off state; the primary side switch control unit 120 generates a primary side switch control signal PWM for controlling on and off of the first path switching tube S1 based on the primary side on trigger signal fb_tri and the primary side off trigger signal tri_off; the demagnetizing current distribution unit 122 generates a demagnetizing current distribution control signal Vcomp based on the second to nth output feedback logic signals fb2_req to fbn_req and the second to nth output feedback divided voltages VFB2 to VFBn; The demagnetizing pulse width detection unit 124 generates a demagnetizing pulse width characterization signal Demag based on the demagnetizing current characterization signal FWD that characterizes the demagnetizing current of the transformer T1; the secondary side switch control unit 126 generates second to nth switch control signals s2_ctrl to sn_ctrl for controlling on and off of the second to nth switch transistors S2 to Sn based on the demagnetizing current distribution control signal Vcomp and the demagnetizing pulse width characterization signal Demag.
Here, it should be noted that the demagnetization current distribution unit 122, the demagnetization pulse width detection unit 124, and the secondary side switch control unit 126 may be implemented as at least a part of a control circuit located on the secondary side of the transformer T1, wherein a core idea of implementing the demagnetization current distribution is to adaptively adjust pulse widths of the second to nth switch control signals s2_ctrl to sn_ctrl for controlling on and off of the second to nth switch transistors S2 to Sn according to a high-low comparison relationship between the second to nth output feedback divided voltages VFB2 to VFBn and the corresponding threshold voltages, thereby adaptively adjusting demagnetization energies distributed to the second to nth system output voltages CV1 to CVn, and implementing cross adjustment of multiplexing outputs.
Fig. 2 is a schematic diagram showing a logic structure of the demagnetizing current distribution unit shown in fig. 1. As shown in fig. 2, in the demagnetizing current distribution unit 122, the feedback voltage division selection module performs a logic operation on the second to nth output feedback logic signals fb2_req to fbn_req to generate a feedback voltage division selection signal, and selects one of the second to nth output feedback voltage division voltages VFB2 to VFBn as the selected output feedback voltage VFBX of the current one or more periods based on the feedback voltage division selection signal; the transconductance amplifier EA1 generates a feedback divided error amplified current based on the selected output feedback divided VFBX and the reference voltage Vref 1; the feedback divided error amplified current is integrated on the compensation capacitor Ccomp to obtain the demagnetized current distribution control signal Vcomp.
Fig. 3 shows a timing diagram of a plurality of signals related to the demagnetization current distribution shown in fig. 1. As shown in fig. 3, in the case where the mth system output voltage CVm of the second to nth system output voltages CV2 to CVn shares the demagnetization energy of the transformer T1 with the first system output voltage CV 1: when the demagnetizing pulse width characterization signal Demag changes from low level to high level, the mth switching tube Sm changes from off state to on state, the mth system output voltage CVm is firstly distributed to the demagnetizing energy of the transformer T1, and the first system output voltage CV1 is not distributed to the demagnetizing energy of the transformer T1; after the mth switching tube Sm is changed from the on state to the off state, the first system output voltage CV1 is distributed to the demagnetization energy of the transformer T1.
Fig. 4 shows a timing diagram of a plurality of signals associated with the dynamic load switching shown in fig. 1. As shown in fig. 4, in the case where the mth system output voltage CVm and the first system output voltage CV1 of the second to nth system output voltages CV2 to CVn share the demagnetization energy of the transformer T1, when the load of the mth system output voltage CVm is instantaneously switched from no load or very light load to heavy load, the mth system output voltage CVm drops from the preset voltage Vset to V1 substantially, and the difference voltage (Vset-V1) may reach 15% or more of the preset voltage Vset. In order to make the mth system output voltage CVm drop less during the dynamic fast switching of the load from light load to heavy load, it is necessary to make the on time of the mth switching tube Sm increase rapidly in several periods, so that the mth system output voltage CVm is distributed to more demagnetization energy from the transformer T1. The on time of the mth switching transistor Sm is determined by the magnitude of the signal amplitude of the demagnetizing current distribution control signal Vcomp. The need for the demagnetization current distribution control signal Vcomp to switch from a higher voltage to a lower voltage or from a lower voltage to a higher voltage in a very short time during the dynamic fast switching of the load, but the compensation capacitance Ccomp is usually larger due to the consideration of system stability, which results in that the demagnetization current distribution control signal Vcomp changes slowly with the load of the mth system output voltage CVm and may require N (for example, N >10 cycles for changing from the lower voltage to the higher voltage), which results in that the mth system output voltage CVm cannot distribute more demagnetization energy to the transformer T1 in a short time during the dynamic fast switching of the load thereof from light load to heavy load, and thus drops more, resulting in a relatively poor dynamic load adjustment rate of the system.
Fig. 5 shows a schematic diagram of the logic structure of a multi-output switching power supply according to an embodiment of the invention. As can be seen in conjunction with fig. 1 and 5, the multiple-output switching power supply 500 shown in fig. 5 is different from the multiple-output switching power supply 100 shown in fig. 1 in that a dynamic enhancement control unit 128 is added to cooperate with the secondary side switching control unit 126 or the demagnetizing current distribution unit 122 to improve the dynamic characteristics of the entire multiple-output switching power supply system. Specifically, in the case where the mth system output voltage CVm of the second to nth system output voltages CV2 to CVn shares the demagnetization energy of the transformer T1 with the first system output voltage CV 1: the dynamic enhancement control unit 128 generates a dynamic enhancement enable signal dy_en based on the system output feedback signal fb_req and the mth output feedback logic signal FBm _req, and generates a dynamic enhancement control signal dy_ctrl for controlling the mth switching transistor Sm to be in an on state based on the dynamic enhancement enable signal dy_en, and the secondary side switching control unit 126 generates an mth switching control signal sm_ctrl for controlling the on and off of the mth switching transistor Sm based on the dynamic enhancement control signal dy_ctrl, the demagnetization pulse width characterization signal demag, and the demagnetization current allocation control signal Vcomp; or the dynamic enhancement control unit 128 generates the dynamic enhancement enable signal dy_en based on the system output feedback signal fb_req and the mth output feedback logic signal FBm _req, the demagnetizing current distribution unit 122 generates the demagnetizing current distribution control signal Vcomp for controlling the mth switching tube Sm to be in the on state based on the dynamic enhancement enable signal dy_en, and the secondary side switching control unit 126 generates the mth switching control signal sm_ctrl for controlling the on and off of the mth switching tube Sm based on the demagnetizing current distribution control signal Vcomp and the demagnetizing pulse width characterization signal demag.
FIG. 6 illustrates an example logical structure diagram of the dynamic enhancement control module shown in FIG. 5. As shown in fig. 6, in the dynamic enhancement control unit 128-1, when the mth system output voltage CVm and the first system output voltage CV1 of the second to nth system output voltages CV2 to CVn share the demagnetizing energy of the transformer T1, the output feedback detection module generates an output feedback detection signal fb_det for representing the high-low contrast relationship between the mth system output voltage CVm and the preset voltage Vset based on the mth output feedback logic signal FBm _req; the multi-period counting module generates a dynamic enhancement enabling signal Dy_EN by performing multi-period counting on the system output feedback signal FB_m when the output feedback detection signal FB_det represents that the mth system output voltage CVm is lower than a preset voltage Vset; the dynamic enhancement determination module generates a dynamic enhancement control signal dy_ctrl based on the output feedback detection signal fb_det in response to the dynamic enhancement enable signal dy_en. At this time, the secondary side switch control unit 126 generates an mth switch control signal sm_ctrl for controlling on and off of the mth switch transistor Sm based on the dynamic enhancement control signal dy_ctrl, the demagnetizing current distribution control signal Vcomp, and the demagnetizing pulse width detection signal Demag.
Fig. 7 shows a timing diagram of a plurality of signals associated with the dynamic enhancement control module shown in fig. 6. As shown in fig. 7, in the case where the mth system output voltage CVm of the second to nth system output voltages CV2 to CVn shares the demagnetization energy of the transformer T1 with the first system output voltage CV 1: when the mth output feedback logic signal FBm _req changes from low level to high level, the output feedback detection signal fb_det changes from low level to high level (indicating that the mth system output voltage CVn is lower than the preset voltage Vset); when the output feedback detection signal fb_det is at a high level and the period count of the system output feedback signal fb_req is full of N (n+.3) periods, the dynamic enhancement enable signal dy_en changes from a low level to a high level, the dynamic enhancement control signal dy_ctrl changes from a low level to a high level, the mth switching control signal sm_ctrl changes from a low level to a high level, and the mth switching transistor Sm is continuously in an on state in a plurality of periods in which the dynamic enhancement control signal dy_ctrl is at a high level (i.e., the dynamic enhancement enable signal dy_en is at a high level). In addition, when the mth output feedback logic signal fbn_req changes from high level to low level, the output feedback detection signal fb_det changes from high level to low level (indicating that the mth system output voltage CVn exceeds the preset voltage Vset), the dynamic enhancement enable signal dy_en changes from high level to low level, the dynamic enhancement control signal dy_ctrl changes from high level to low level immediately or through N periods, the mth switching control signal sm_ctr changes from high level to low level, and the mth switching transistor Sm switches between on and off states in each period in which the dynamic enhancement control signal dy_ctrl is at low level (i.e., the dynamic enhancement enable signal dy_en is at low level). It can be seen that the mth switching tube Sm starts to change from the off state to the on state at the moment when the mth system output voltage CVm becomes lower than the preset voltage Vset and keeps the on state until the mth system output voltage CVm is restored to exceed the preset voltage Vset, so that all the demagnetized energy stored in the transformer T1 can be continuously and completely distributed to the mth system output voltage CVm during the period when the mth system output voltage CVm is lower than the preset voltage Vset, so that the mth system output voltage CVm cannot drop too much under the condition of dynamic rapid switching of the load from light load to heavy load, and the dynamic characteristics of the switching power supply system are improved.
FIG. 8 illustrates another logical structure diagram of the dynamic enhancement control module illustrated in FIG. 5. As shown in fig. 8, in the dynamic enhancement control unit 128-2, when the mth system output voltage CVm and the first system output voltage CV1 of the second to nth system output voltages CV2 to CVn share the demagnetizing energy of the transformer T1, the output feedback detection module generates an output feedback detection signal fb_det for representing the high-low contrast relationship between the mth system output voltage CVm and the preset voltage Vset based on the mth output feedback logic signal FBm _req; the multi-period counting module generates the dynamic enhancement enable signal dy1_en by multi-period counting the system output feedback signal fb_req when the output feedback detection signal fb_det characterizes the mth system output voltage CVm being lower than the preset voltage Vset (e.g., counting from a rising edge of the system output feedback signal fb_req, and changing the dynamic enhancement enable signal dy1_en from a low level to a high level when the duration of the output feedback detection signal fb_det at a high level reaches N periods (n+.3)). Accordingly, in the demagnetizing current distribution unit 122-1, the dynamic enhancement switch S11 is turned on and off under the control of the dynamic enhancement enable signal dy1_en; when the dynamic enhancement switch S11 is in a conducting state, a transconductance amplifying unit formed by a transconductance amplifier EA1 and a transconductance amplifier EA2 is utilized to generate a demagnetizing current distribution control signal Vcomp based on an mth output feedback voltage divider VFBm and a reference voltage Vref 1; when the dynamic enhancement switch S11 is in the off state, the demagnetizing current distribution control signal Vcomp is generated based on the mth output feedback voltage division VFBm and the reference voltage Vref1 using only the transconductance amplifier EA 1. For example, when the dynamic enhancement enable signal dy1_en is at a high level, the dynamic enhancement switch S11 is in a conductive state under the control of the dynamic enhancement enable signal dy1_en, the transconductance amplifier EA1 and the transconductance amplifier EA2 constitute a transconductance amplifying unit whose closed-loop control transconductance Gm is equal to the sum of the transconductance Gm1 of the transconductance amplifier EA1 and the transconductance Gm2 of the transconductance amplifier EA2, so that a larger feedback divided error amplification current can be obtained based on the difference between the mth output feedback divided voltage CVm and the reference voltage Vref1, which can make the demagnetized current distribution control signal Vcomp obtained by integrating the feedback divided error amplification current on the compensation capacitor Ccomp change from a low voltage to a high level more rapidly; Since the change speed of the demagnetizing current distribution control signal Vcomp from low level to high level is greatly accelerated, the time for changing the pulse width of the mth switching control signal sm_ctrl from narrower to wider is also greatly shortened, so that the mth system output voltage CVm can obtain more demagnetizing energy of the transformer T1 in a short time, and the mth system output voltage CVm drops less when the load thereof is dynamically and rapidly switched. In addition, when the mth system output voltage CVm continuously increases such that the mth output feedback logic signal FBm _req changes from the high level to the low level, the dynamic enhancement enable signal dy1_en may continuously maintain the high level m (m+.1) for a period of time without immediately changing from the high level to the low level. The output voltage CVm of the mth system can not drop too much due to the dynamic rapid switching of the load from light load to heavy load by the dynamic enhancement control method, so that the dynamic characteristic of the switching power supply system can be improved.
FIG. 9 illustrates yet another logical architecture diagram of the dynamic enhancement control module illustrated in FIG. 5. As shown in fig. 9, in the dynamic enhancement control unit 128-3, when the mth system output voltage CVm and the first system output voltage CV1 of the second to nth system output voltages CV2 to CVn share the demagnetizing energy of the transformer T1, the output feedback detection module generates an output feedback detection signal fb_det for representing the high-low contrast relationship between the mth system output voltage CVm and the preset voltage Vset based on the mth output feedback logic signal FBm _req; the multi-period counting module generates the dynamic enhancement enable signal dy2_en by multi-period counting the system output feedback signal fb_req when the output feedback detection signal fb_det characterizes the mth system output voltage CVm being lower than the preset voltage Vset (e.g., counting from a rising edge of the system output feedback signal fb_req, and changing the dynamic enhancement enable signal dy2_en from a low level to a high level when the duration of the output feedback detection signal fb_det being at a high level reaches N periods (n+.3)). Accordingly, in the demagnetizing current distribution unit 122-2, the dynamic enhancement switch S12 is turned on and off under the control of the dynamic enhancement enable signal dy2_en; when the dynamic enhancement switch S12 is in an on state, generating a demagnetized current distribution signal Vcomp by using a constant current i2 from a current source i2 and a feedback voltage division error amplified current generated by a transconductance amplifier EA1 based on an mth output feedback voltage division VFBm and a reference voltage Vref 1; when the dynamic enhancement switch S12 is in the off state, the demagnetizing current distribution control signal Vcomp is generated by amplifying the current with the transconductance amplifier EA1 based on the feedback division error generated by the mth output feedback division VFBm and the reference voltage Vref 1. For example, when the dynamic enhancement enable signal Dy2_EN is at a high level, the dynamic enhancement switch S12 is in a conducting state under the control of the dynamic enhancement enable signal Dy2_EN, the constant current i2 provided by the current source i2 flows to the compensation capacitor Ccomp via the dynamic enhancement switch S12, the transconductance amplifier EA1 also flows to the compensation capacitor Ccomp based on the feedback divided voltage error amplified current i1 generated by the mth output feedback divided voltage VFBm and the reference voltage Vref1, the integrated current i obtained on the compensation capacitor Ccomp is equal to the sum of the currents i1 and i2, which greatly accelerates the changing speed of the demagnetizing current distribution control signal Vcomp from a low level to a high level, The time for the pulse width of the mth switching control signal sm_ctrl to change from narrower to wider is also greatly shortened, so that the mth system output voltage CVm can be distributed to more demagnetizing energy from the transformer T1 in a short time, and the mth system output voltage CVm drops less when the load thereof is dynamically and rapidly switched. In addition, when the system output logic signal fb_req changes from high level to low level, the dynamic enhancement enable signal dy2_en may not immediately change from high level to low level but may continue to maintain the high level m (m Σ1) for a period of time before changing to low level. The output voltage CVm of the mth system can not drop too much due to the dynamic rapid switching of the load from light load to heavy load by the dynamic enhancement control method, so that the dynamic characteristic of the switching power supply system can be improved.
It should be appreciated that the dynamic enhancement control scheme above is also applicable to various circuit topologies such as buck, boost, buck-boost, fly-back, forward, asymmetric half-bridge, etc., and is not limited to the circuit topologies described herein in connection with the accompanying figures.
The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. For example, the algorithms described in particular embodiments may be modified without departing from the basic spirit of the invention. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
Claims (11)
1. A control circuit for use in a multiple output switching power supply, wherein the multiple output switching power supply comprises a transformer and first through n-th switching transistors, and wherein only one of the second through n-th system output voltages of the multiple output switching power supply shares demagnetization energy of the transformer with a first system output voltage of the multiple output switching power supply during each demagnetization cycle of the transformer, the control circuit configured to:
Generating a dynamic enhancement enable signal based on a system output feedback signal and an mth output feedback logic signal, generating a demagnetizing current distribution control signal or a dynamic enhancement control signal for controlling an mth switching tube in an on state of the first to nth switching tubes based on the dynamic enhancement enable signal, and generating an mth switching control signal for controlling on and off of the mth switching tube based on the demagnetizing current distribution control signal or the dynamic enhancement control signal, in the case that an mth system output voltage of the second to nth system output voltages shares the demagnetizing energy of the transformer with the first system output voltage, wherein
The system output feedback signals are generated by performing logic operation on first to nth output feedback logic signals, the second to nth output feedback logic signals are generated by respectively comparing second to nth output feedback divided voltages with corresponding threshold voltages, the second to nth output feedback divided voltages are generated by respectively dividing the second to nth system output voltages, n is an integer greater than or equal to 2, and m is an integer greater than or equal to 2 and less than or equal to n.
2. The control circuit of claim 1, further configured to:
Generating an output feedback detection signal representing a high-low comparison relation between the mth path system output voltage and a preset voltage based on the mth path output feedback logic signal, and generating the dynamic enhancement enabling signal by performing multi-cycle counting on the system output feedback signal when the output feedback detection signal represents that the mth path system output voltage is lower than the preset voltage.
3. The control circuit of claim 2, wherein the output feedback detection signal changes from low to high when the mth output feedback logic signal changes from low to high, and the dynamic enhancement enable signal changes from low to high when the output feedback detection signal is at high and the cycle count of the system output feedback signal reaches a predetermined cycle count.
4. The control circuit according to claim 3, wherein when the dynamic enhancement enable signal changes from a low level to a high level, the dynamic enhancement control signal changes from a low level to a high level, and the mth switching tube is continuously in an on state in a plurality of periods in which the dynamic enhancement control signal is at a high level.
5. The control circuit according to claim 4, wherein when the mth output feedback logic signal changes from a high level to a low level, the output feedback detection signal changes from a high level to a low level, the dynamic enhancement enable signal changes from a high level to a low level, the dynamic enhancement control signal changes from a high level to a low level immediately or with a delay of N cycles, the mth switching tube switches between an on state and an off state in each cycle in which the dynamic enhancement control signal is at a low level, N is an integer of 1 or more.
6. The control circuit of claim 3, further configured to:
the demagnetizing current distribution control signal is generated based on the mth output feedback voltage, the reference voltage, and the dynamic enhancement enable signal.
7. The control circuit of claim 6, further configured to:
controlling the on and off of the dynamic enhancement switch by using the dynamic enhancement enabling signal;
when the dynamic enhancement switch is in a conducting state, generating the demagnetizing current distribution control signal by using a transconductance amplifying unit consisting of a first transconductance amplifier and a second transconductance amplifier based on the mth output feedback voltage and the reference voltage; and
And when the dynamic enhancement switch is in an off state, generating the demagnetizing current distribution control signal by using the first transconductance amplifier based on the mth output feedback voltage division and the reference voltage.
8. The control circuit of claim 7, further configured to:
And generating feedback partial pressure error amplification current by utilizing the transconductance amplifying unit or the first transconductance amplifier based on the mth output feedback partial pressure and the reference voltage, so that the feedback partial pressure error amplification current is integrated on a compensation capacitor to obtain the demagnetizing current distribution control signal.
9. The control circuit of claim 6, further configured to:
controlling the on and off of the dynamic enhancement switch by using the dynamic enhancement enabling signal;
Generating the demagnetizing current distribution control signal by using a constant current from a constant current source and a transconductance amplifier based on the mth output feedback voltage division and a feedback voltage division error amplification current generated by the reference voltage when the dynamic enhancement switch is in a conducting state; and
And when the dynamic enhancement switch is in an off state, generating the demagnetizing current distribution control signal by using the transconductance amplifier based on the feedback voltage division error amplification current generated by the mth output feedback voltage division and the reference voltage.
10. The control circuit of claim 9, further configured to:
And integrating the feedback partial pressure error amplification current and the constant current or the feedback partial pressure error amplification current on a compensation capacitor to obtain the demagnetizing current distribution control signal.
11. A multiple output switching power supply comprising a control circuit as claimed in any one of claims 1 to 10 for use in a multiple output switching power supply.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202410705653.3A CN118589814A (en) | 2024-05-31 | 2024-05-31 | Multi-channel output switching power supply and its control circuit |
| TW113127193A TWI880823B (en) | 2024-05-31 | 2024-07-19 | Multi-channel output switching power supply and its control circuit |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202410705653.3A CN118589814A (en) | 2024-05-31 | 2024-05-31 | Multi-channel output switching power supply and its control circuit |
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| CN118589814A true CN118589814A (en) | 2024-09-03 |
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| CN202410705653.3A Pending CN118589814A (en) | 2024-05-31 | 2024-05-31 | Multi-channel output switching power supply and its control circuit |
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| US6504267B1 (en) * | 2001-12-14 | 2003-01-07 | Koninklijke Philips Electronics N.V. | Flyback power converter with secondary-side control and primary-side soft switching |
| FR2884074B1 (en) * | 2005-04-01 | 2007-07-06 | Alcatel Converters Sa | MULTI-CHANNEL CONVERTER WITH CASCADE CUTTING AND CURRENT LIMITATION |
| US8829949B2 (en) * | 2012-01-17 | 2014-09-09 | Franc Zajc | Method and apparatus for driving a voltage controlled power switch device |
| TWI548196B (en) * | 2012-05-14 | 2016-09-01 | 全漢企業股份有限公司 | Forward-based power supply apparatus and fan driving method thereof |
| US10914778B2 (en) * | 2015-01-13 | 2021-02-09 | Omicron Electronics Gmbh | Transformer testing device, and method for testing a transformer |
| CN108347173B (en) * | 2018-04-08 | 2019-12-27 | 昂宝电子（上海）有限公司 | Quasi-resonance flyback switching power supply system |
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