CN110635702A - High-precision multi-output flyback switching power supply circuit and method - Google Patents
High-precision multi-output flyback switching power supply circuit and method Download PDFInfo
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- CN110635702A CN110635702A CN201911085710.8A CN201911085710A CN110635702A CN 110635702 A CN110635702 A CN 110635702A CN 201911085710 A CN201911085710 A CN 201911085710A CN 110635702 A CN110635702 A CN 110635702A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
- H02M7/30—Conversion of ac power input into dc power output without possibility of reversal by dynamic converters
- H02M7/32—Conversion of ac power input into dc power output without possibility of reversal by dynamic converters using mechanical contact-making and -breaking parts
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Abstract
The application relates to a high-precision multi-output flyback switching power supply circuit and a method, which comprises at least two power supply output circuits connected with a secondary coil of a power supply chip and a control chip used for controlling the at least two power supply output circuits, wherein the at least two power supply output circuits comprise a first power supply output circuit and a second power supply output circuit connected with the first power supply output circuit in parallel, the second power supply output circuit comprises a switch used for conducting the second power supply output circuit, and the control chip is connected with the switch; and a reference voltage value is preset in the control chip, and when the control chip detects that the output voltage value of the second power output circuit is smaller than the reference voltage value, the control chip controls the switch to be closed so as to enable the second power output circuit to be conducted. The control chip used for controlling the first power output circuit and the second power output circuit is arranged, the multiple output voltages are adjusted in an active control mode, and the effects of good load adjustment rate and high output voltage precision are achieved.
Description
Technical Field
The invention relates to a high-precision multi-output flyback switching power supply circuit and a method, and belongs to the technical field of switching power supplies.
Background
With the high-speed development of power electronic technology, the relationship between power electronic equipment and the work and life of people is increasingly close, the power electronic equipment can not be connected with a reliable power supply, the efficiency and the output precision of the power supply are two main performance indexes pursued by power supply researchers, the power supply generally adopts a switching power supply, the switching power supply is a power supply which utilizes the modern power electronic technology to control the time ratio of the connection and disconnection of a switching tube and maintain stable output voltage, and the flyback switching power supply is the simplest power supply in the switching power supply topology. The output transformer serves as an energy storage inductor, the whole power supply is small in size and simple in structure, and multiple paths of mutually isolated voltages can be output simultaneously, so that the power supply is widely applied. However, although the demand of the conventional multi-output switching power supply increases, the accuracy is relatively low and the load regulation rate is poor.
Disclosure of Invention
The invention aims to provide a high-precision multi-output flyback switching power supply circuit and a method, which can regulate multi-output voltage in an active control mode and achieve the effects of good load regulation rate and high output voltage precision.
In order to achieve the purpose, the invention provides the following technical scheme: a high-precision multi-output flyback switching power supply circuit comprises at least two power supply output circuits connected with a secondary coil of a power supply chip and a control chip used for controlling the at least two power supply output circuits, wherein the at least two power supply output circuits comprise a first power supply output circuit and a second power supply output circuit connected with the first power supply output circuit in parallel, the second power supply output circuit comprises a switch used for conducting the second power supply output circuit, and the control chip is connected with the switch; and when the control chip detects that the output voltage value of the second power output circuit is smaller than the reference voltage value, the control chip controls the switch to be closed so as to enable the second power output circuit to be conducted.
Furthermore, the first power output circuit includes a first diode, a first capacitor, and a first power output end connected to the first capacitor, a first end of the first diode is connected to the secondary coil, a second end of the first diode is connected to the first end of the first capacitor, and a second end of the first capacitor is grounded.
Further, the second power output circuit further includes a second diode, a second capacitor, and a second power output terminal connected to the second capacitor, a first end of the second diode is connected to the secondary coil and a first end of the first diode, a second end of the second diode is connected to the switch, a first end of the second capacitor is connected to the switch, and a second end of the second capacitor is grounded.
The invention also provides a high-precision multi-output flyback switching power supply circuit, which comprises at least two power supply output circuits connected with the secondary coil of a power supply chip, a control chip used for controlling the at least two power supply output circuits and a secondary feedback circuit, wherein the at least two power supply output circuits comprise a first power supply output circuit and a second power supply output circuit connected with the first power supply output circuit in parallel, the second power supply output circuit comprises a switch used for conducting the second power supply output circuit, and the control chip is connected with the switch; the output voltage of the first power output circuit is directly fed back to the power chip through the secondary feedback circuit, a reference voltage value is preset in the control chip, and when the control chip detects that the output voltage value of the second power output circuit is smaller than the reference voltage value, the control chip controls the switch to be closed so as to enable the second power output circuit to be conducted.
Further, the secondary feedback circuit comprises a secondary control chip and an optical coupler used for feeding back the output voltage of the first power output circuit to the power chip, and the optical coupler is connected with the secondary control chip; and the secondary side control chip and the control chip are integrated.
Further, the output voltage value of the first power output circuit is greater than the output voltage value of the second power output circuit.
The invention also provides a high-precision multi-output power supply method, which adopts the high-precision multi-output flyback switching power supply circuit, and comprises the following steps:
the switch of the second power output circuit is switched off, the second power output circuit is not conducted, and the current of the first power output circuit is equal to the current of the secondary coil;
and a reference voltage value is preset in the control chip, and after the control chip detects that the second output voltage value of the second power output circuit is smaller than the reference voltage value, the control chip controls the switch to be closed so as to enable the second power output circuit to be conducted, and at the moment, the current of the second power output circuit is equal to the current of the secondary coil.
Further, the method further comprises:
and when the second power output circuit is switched on, the first power output circuit is switched off.
Further, the method further comprises:
the output voltage value of the first power output circuit is larger than that of the second power output circuit, and the first power output circuit has the minimum on-time.
The invention has the beneficial effects that: the control chip for controlling the first power output circuit and the second power output circuit is arranged, so that the multi-output voltage is regulated in an active control mode, and the effects of good load regulation rate and high output voltage precision are achieved;
and a time division multiplexing working mode is adopted, so that at least two power output circuits are mutually independent and do not interfere with each other, and the working efficiency of the power supply is improved.
The foregoing description is only an overview of the technical solutions of the present invention, and in order to make the technical solutions of the present invention more clearly understood and to implement them in accordance with the contents of the description, the following detailed description is given with reference to the preferred embodiments of the present invention and the accompanying drawings.
Drawings
Fig. 1 is a block diagram of a high-precision multi-output flyback switching power supply circuit according to the present invention.
Fig. 2 is a schematic diagram of a high-precision multi-output flyback switching power supply circuit according to the present invention.
Fig. 3 is a schematic diagram of the waveforms of fig. 2.
Fig. 4 is a schematic diagram of a high-precision multi-output flyback switching power supply circuit including a secondary-side feedback circuit according to the present invention.
Fig. 5 is a flow chart of the high-precision multi-output power supply method of the present invention.
Detailed Description
The following detailed description of embodiments of the present invention is provided in connection with the accompanying drawings and examples. The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.
Referring to fig. 1 and 2, a high-precision multi-output flyback switching power supply circuit according to a preferred embodiment of the present invention includes at least two power output circuits connected to a secondary winding 1 of a power chip and a control chip 2 for controlling the at least two power output circuits, wherein the secondary winding 1 is mutually inductive with a primary auxiliary winding. In this embodiment, the switching power supply circuit includes two power output circuits, which are a first power output circuit 3 and a second power output circuit 4 connected in parallel with the first power output circuit 3, and indeed, in other embodiments, the number of the power output circuits may be other, which is not specifically limited herein and is determined according to the actual situation. The second power output circuit 4 includes a switch K1 for making it conductive, the out pin of the control chip 2 is connected to the switch, and the out pin of the control chip 2 outputs an SK control signal. A reference voltage value Vx is preset in the control chip 2, and when the control chip 2 detects that the output voltage value of the second power output circuit 4 is smaller than the reference voltage value Vx, the control chip 2 controls the switch to be closed so that the second power output circuit 4 is conducted.
It should be noted that in this embodiment, the output voltage value of the first power output circuit 3 is greater than the output voltage value of the second power output circuit 4, so that the purpose of the arrangement is that when the second power output circuit 4 is turned on, the first power output circuit 3 is turned off and does not interfere with each other.
The first power output circuit 3 includes a first diode D1, a first capacitor C1 and a first power output end, the first end of the first diode D1 is connected to the secondary winding 1, the second end of the first diode D1 is connected to the first end of the first capacitor C1, the second end of the first capacitor C1 is grounded, and the voltage on the first capacitor C1 is the first power output end voltage VOUT 1.
Second power output circuit 4 still includes second diode D2, second electric capacity C2 and second power output end, the first end of second diode D2 with secondary winding 1, the first end of first diode D1 are connected, the second end of second diode D2 with switch K1 and control chip 2's OUT foot are connected, the first end of second electric capacity C2 with the other end of switch K1 and control chip 2's IN foot are connected, the second end ground connection of second electric capacity C2, the voltage on second electric capacity C2 is the voltage VOUT2 of second power output end.
When the primary coil conducting switch Is switched off, the secondary coil 1 starts to have a current Is flowing through. Since the switch K1 Is not closed, the switch Is1 Is, only the first power output circuit 3 has current, and the first capacitor C1 starts to charge; when the control chip 2 detects that the voltage of the second power output end is lower than a certain reference voltage, the switch K1 is controlled to be closed, and meanwhile, the voltage of the first power output end is mutually inducted to the primary auxiliary coil through the secondary coil 1 to act on the power chip. After the switch K1 Is closed, since VOUT2< VOUT1, the first diode Is hard to conduct, so that Is2 Is, only the second power output circuit 4 has current, and the second capacitor C2 starts to charge until the current drops to 0.
In the control process, the voltage of the first power output end is mutually inducted to the primary auxiliary coil through the secondary coil 1 to act on the power chip, and the primary feedback mode is adopted. When the power supply chip detects that the output voltage of the first power supply output end is low, the peak current flowing through the secondary coil 1 is increased; if the output voltage of the first power supply output end is detected to be higher, the peak current flowing through the secondary coil 1 is reduced, and therefore the voltage of the multi-output power supply is accurately controlled.
Fig. 3 shows a waveform schematic diagram of a high-precision multi-output flyback switching power supply circuit, and it can be known from periods T1 and T2 that when a secondary coil 1 Is turned on, a current Is starts to flow, a switch K1 controls a signal SK to output a low-level signal, a switch K1 Is turned off, a current Is1 Is equal to Is in a first power output circuit 3, and an output voltage VOUT1 of the first power output terminal rises; when the control chip 2 detects that the output voltage VOUT2 of the second power output terminal Is less than Vx, the switch control signal SK outputs a high-level signal, the switch K1 Is closed, the current Is2 of the second power output circuit 4 Is equal to Is, and the output voltage VOUT2 of the second power output terminal rises. From the period T3, when the output voltage VOUT2 of the second power supply output terminal is greater than Vx in the entire period, the current in the secondary winding 1 always flows through the first power supply output circuit 3, and the output voltage VOUT1 of the first power supply output terminal rises. As can be seen from the period T4, VOUT1 has a minimum on-time (tmin), which ensures that the first capacitor C1 stores electricity first, and after tmin time delay, if VOUT2< Vx Is detected, the switch K1 Is closed, the current Is2 Is of the second power output circuit 4, and the output voltage VOUT2 of the second power output terminal rises.
Referring to fig. 4, unlike the high-precision multi-output flyback switching power supply circuit, the high-precision multi-output flyback switching power supply circuit in this embodiment further includes a secondary feedback circuit, and information is directly fed back to the power supply chip through the secondary feedback circuit, which is a secondary feedback manner. The power supply comprises at least two power supply output circuits connected with a secondary coil 1 of a power supply chip, a control chip 2 used for controlling the at least two power supply output circuits and a secondary feedback circuit, wherein the at least two power supply output circuits comprise a first power supply output circuit 3 and a second power supply output circuit 4 connected with the first power supply output circuit 3 in parallel, the second power supply output circuit 4 comprises a switch used for conducting the second power supply output circuit, and the control chip 2 is connected with the switch; the output voltage of the first power output circuit 3 is fed back to the power chip through the secondary feedback circuit, a reference voltage value is preset in the control chip 2, and when the control chip detects that the output voltage value of the second power output circuit 4 is smaller than the reference voltage value, the control chip 2 controls the switch to be closed so that the second power output circuit is conducted.
The secondary feedback circuit comprises a secondary control chip and an optocoupler used for feeding back the output voltage of the first power output circuit 3 to the power chip, the secondary feedback circuit and the control chip 2 are integrally arranged or separately and independently arranged, in the embodiment, the secondary feedback circuit and the control chip 2 are integrally arranged, namely the secondary control chip and the control chip 2 are integrated together, and the secondary control chip is TL 431. Indeed, in other embodiments, the secondary control chip may be other, and is not limited specifically herein according to the actual situation. The opto-coupler with the OUT1 pin of control chip 2 is connected, the second power output end with the second input IN2 of control chip 2 is connected, the second output end of control chip 2 the control end of first switch K1 is connected.
Referring to fig. 5, the present invention further provides a high-precision multi-output power supply method, which adopts the above-mentioned high-precision multi-output flyback switching power supply circuit, and the method includes:
the switch K1 of the second power output circuit 4 is turned off, and at this time, the current of the first power output circuit 3 is equal to the current of the secondary coil 1, the first output voltage value of the first power output circuit 3 is fed back to the power chip through the secondary coil 1 or the secondary feedback circuit, and the power chip outputs a pulse width modulation signal according to the level of the first output voltage value;
a reference voltage value is preset in the control chip 2, after the control chip 2 detects that the output voltage value of the second power output circuit 4 is smaller than the reference voltage value, the control chip 2 controls the switch to be closed so as to enable the second power output circuit 4 to be conducted, and at the moment, the current of the second power output circuit 4 is equal to the current of the secondary coil 1.
The method further comprises the following steps:
when the second power output circuit 4 is turned on, the first power output circuit 3 is turned off. The output voltage value of the first power output circuit 3 is greater than the output voltage value of the second power output circuit 4, and the first power output circuit 3 has the minimum on-time, so that the first capacitor C1 is ensured to store electricity first.
In summary, the following steps: the control chip 2 for controlling the first power output circuit 3 and the second power output circuit 4 is arranged, so that the multi-output voltage is regulated in an active control mode, and the effects of good load regulation rate and high output voltage precision are achieved;
and a time division multiplexing working mode is adopted, so that at least two power output circuits are mutually independent and do not interfere with each other, and the working efficiency of the power supply is improved.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (9)
1. A high-precision multi-output flyback switching power supply circuit is characterized by comprising at least two power supply output circuits connected with a secondary coil of a power supply chip and a control chip used for controlling the at least two power supply output circuits, wherein the at least two power supply output circuits comprise a first power supply output circuit and a second power supply output circuit connected with the first power supply output circuit in parallel, the second power supply output circuit comprises a switch used for conducting the second power supply output circuit, and the control chip is connected with the switch; and when the control chip detects that the output voltage value of the second power output circuit is smaller than the reference voltage value, the control chip controls the switch to be closed so as to enable the second power output circuit to be conducted.
2. The high accuracy multi-output flyback switching power supply circuit as in claim 1, wherein the first power output circuit comprises a first diode, a first capacitor and a first power output terminal connected to the first capacitor, a first terminal of the first diode is connected to the secondary winding, a second terminal of the first diode is connected to a first terminal of the first capacitor, and a second terminal of the first capacitor is connected to ground.
3. The high-precision multi-output flyback switching power supply circuit as claimed in claim 1, wherein said second power output circuit further comprises a second diode, a second capacitor and a second power output terminal connected to said second capacitor, a first end of said second diode is connected to said secondary winding and a first end of said first diode, a second end of said second diode is connected to said switch, a first end of said second capacitor is connected to said switch, and a second end of said second capacitor is connected to ground.
4. A high-precision multi-output flyback switching power supply circuit is characterized by comprising at least two power supply output circuits, a control chip and a secondary feedback circuit, wherein the at least two power supply output circuits are connected with a secondary coil of a power supply chip; the output voltage of the first power output circuit is directly fed back to the power chip through the secondary feedback circuit, a reference voltage value is preset in the control chip, and when the control chip detects that the output voltage value of the second power output circuit is smaller than the reference voltage value, the control chip controls the switch to be closed so as to enable the second power output circuit to be conducted.
5. The high-precision multi-output flyback switching power supply circuit of claim 4, wherein the secondary feedback circuit comprises a secondary control chip, an optical coupler for feeding back the output voltage of the first power output circuit to the power chip, and the optical coupler is connected with the secondary control chip; and the secondary side control chip and the control chip are integrated.
6. The high precision multi-output flyback switching power supply circuit of any of claims 1-3 or 4-5, wherein an output voltage value of the first power output circuit is greater than an output voltage value of the second power output circuit.
7. A high-precision multi-output power supply method, wherein the high-precision multi-output flyback switching power supply circuit according to any one of claims 1 to 3 or 4 to 5 is adopted, and the method comprises the following steps:
the switch of the second power output circuit is switched off, the second power output circuit is not conducted, and the current of the first power output circuit is equal to the current of the secondary coil;
and a reference voltage value is preset in the control chip, and after the control chip detects that the second output voltage value of the second power output circuit is smaller than the reference voltage value, the control chip controls the switch to be closed so as to enable the second power output circuit to be conducted, and at the moment, the current of the second power output circuit is equal to the current of the secondary coil.
8. A high accuracy multiple output power supply method according to claim 7, said method further comprising:
and when the second power output circuit is switched on, the first power output circuit is switched off.
9. A high accuracy multiple output power supply method according to claim 7, said method further comprising:
the output voltage value of the first power output circuit is larger than that of the second power output circuit, and the first power output circuit has the minimum on-time.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201911085710.8A CN110635702A (en) | 2019-11-08 | 2019-11-08 | High-precision multi-output flyback switching power supply circuit and method |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201911085710.8A CN110635702A (en) | 2019-11-08 | 2019-11-08 | High-precision multi-output flyback switching power supply circuit and method |
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| CN110635702A true CN110635702A (en) | 2019-12-31 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113098265A (en) * | 2021-04-13 | 2021-07-09 | 苏州力生美半导体有限公司 | Single-inductor double-output BUCK switching power supply and charge-discharge control method thereof |
-
2019
- 2019-11-08 CN CN201911085710.8A patent/CN110635702A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113098265A (en) * | 2021-04-13 | 2021-07-09 | 苏州力生美半导体有限公司 | Single-inductor double-output BUCK switching power supply and charge-discharge control method thereof |
| CN113098265B (en) * | 2021-04-13 | 2022-02-08 | 苏州力生美半导体有限公司 | Single-inductor double-output BUCK switching power supply and charge-discharge control method thereof |
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