CN209982333U - Switching power supply start-up circuit - Google Patents
Switching power supply start-up circuit Download PDFInfo
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- CN209982333U CN209982333U CN201920772055.2U CN201920772055U CN209982333U CN 209982333 U CN209982333 U CN 209982333U CN 201920772055 U CN201920772055 U CN 201920772055U CN 209982333 U CN209982333 U CN 209982333U
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Abstract
The utility model discloses a switching power supply starting circuit, which comprises an input voltage sampling circuit, a switch control circuit and a voltage stabilizing circuit; the input voltage sampling circuit is used for sampling an input voltage signal of the switching power supply and outputting the voltage sampling signal to the control end of the switching control circuit, the switching control circuit controls the conduction or the cut-off of an internal switching tube under the driving of the sampling signal, and the voltage stabilizing circuit stabilizes the voltage of the control end of the chip under the control of the switching circuit. Compared with the prior art, the utility model discloses circuit structure is simple, realizes with low costs, only needs to increase the start area load ability that a small amount of components and parts can promote switching power supply.
Description
Technical Field
The patent of the utility model relates to a switching power supply's start-up circuit especially promotes switching power supply start-up and carries the circuit of ability.
Background
Fig. 1 is a conventional optocoupler feedback circuit, and when a switching power supply in the prior art adopts the circuit shown in fig. 1 to implement isolated feedback, due to different application environments, a load of a switching power supply product may be connected with a large capacitive load or a large inductive load, so that a normal power supply may have power-on protection or hiccup due to a large peak load current when being powered on, and thus cannot normally operate.
In view of the above, a circuit capable of improving the loading capability of a switching power supply under a large capacitive load or a large inductive load is needed.
SUMMERY OF THE UTILITY MODEL
The utility model provides a switching power supply start-up circuit aims at solving the relatively poor problem of present switching power supply start-up capacitive load or inductive load area load ability.
In order to achieve the above purpose, the technical scheme of the utility model is as follows:
a switch power supply start-up circuit is characterized in that: the circuit comprises an input voltage sampling circuit, a switch control circuit and a voltage stabilizing circuit; the input voltage sampling circuit is used for sampling an input voltage signal of the switching power supply and outputting the voltage sampling signal to the control end of the switching control circuit, the switching control circuit controls the conduction or the cut-off of an internal switching tube under the driving of the sampling signal, and the voltage stabilizing circuit stabilizes the voltage of the control end of the chip under the control of the switching circuit.
As a specific embodiment of the input voltage sampling circuit, the circuit is characterized in that: the voltage sampling circuit comprises a resistor R1 and a resistor R2, wherein one end of the resistor R1 is connected with the resistor R2 in series and is used for being connected with the input end of a switching power supply, the other end of the resistor R1 is grounded, and a voltage sampling signal is output from the connection point of the resistor R1 and the resistor R2.
As a first specific implementation mode of the switch control circuit and the voltage stabilizing circuit, the switch control circuit is characterized in that: the switch control circuit comprises a triode Q1, a resistor R3 and a controllable precise voltage-stabilizing source U2; the voltage stabilizing circuit comprises a voltage stabilizing diode D1; the control end of a controllable precise voltage-stabilizing source U2 is used for inputting a voltage sampling signal, the anode of the controllable precise voltage-stabilizing source U2 is grounded, the cathode of the controllable precise voltage-stabilizing source U2 is simultaneously connected with the base of a triode Q1 and one end of a resistor R3, the other end of the resistor R3 is used for inputting auxiliary power supply voltage, the emitting electrode of the triode Q1 is grounded, the collector of the triode Q1 is connected with the anode of a zener diode D1, and the cathode of the zener diode D1 is used for connecting the control end of a chip.
As a second specific implementation mode of the switch control circuit and the voltage stabilizing circuit, the switch control circuit is characterized in that: the switch control circuit comprises a triode Q1, a resistor R3 and a controllable precise voltage-stabilizing source U2; the voltage stabilizing circuit comprises a voltage stabilizing diode D1; the control end of a controllable precise voltage-stabilizing source U2 is used for inputting a voltage sampling signal, the anode of the controllable precise voltage-stabilizing source U2 is grounded, the cathode of the controllable precise voltage-stabilizing source U2 is simultaneously connected with the base of a triode Q1 and one end of a resistor R3, the other end of the resistor R3 is used for inputting auxiliary power supply voltage, the anode of a zener diode D1 is grounded, the cathode of the zener diode D1 is connected with the emitting electrode of the triode Q1, and the collector of the triode Q1 is used for connecting the control end of a chip.
As a third specific implementation mode of the switch control circuit and the voltage stabilizing circuit, the switch control circuit is characterized in that: the switch control circuit comprises an MOS (metal oxide semiconductor) tube, a resistor R3 and a controllable precise voltage-stabilizing source U2; the voltage stabilizing circuit comprises a voltage stabilizing diode D1; the control end of the controllable precise voltage-stabilizing source U2 is used for inputting a voltage sampling signal, the anode of the controllable precise voltage-stabilizing source U2 is grounded, the cathode of the controllable precise voltage-stabilizing source U2 is simultaneously connected with the grid of the MOS tube and one end of the resistor R3, the other end of the resistor R3 is used for inputting an auxiliary power supply voltage, the source of the MOS tube is grounded, the drain of the MOS tube is connected with the anode of the voltage-stabilizing diode D1, and the cathode of the voltage-stabilizing diode D1 is used for connecting the control end of the chip.
As a fourth specific implementation mode of the switch control circuit and the voltage stabilizing circuit, the switch control circuit is characterized in that: the switch control circuit comprises an MOS (metal oxide semiconductor) tube, a resistor R3 and a controllable precise voltage-stabilizing source U2; the voltage stabilizing circuit comprises a voltage stabilizing diode D1; the control end of the controllable precise voltage-stabilizing source U2 is used for inputting a voltage sampling signal, the anode of the controllable precise voltage-stabilizing source U2 is grounded, the cathode of the controllable precise voltage-stabilizing source U2 is simultaneously connected with the grid of the MOS tube and one end of the resistor R3, the other end of the resistor R3 is used for inputting an auxiliary power supply voltage, the anode of the voltage-stabilizing diode D1 is grounded, the cathode of the voltage-stabilizing diode D1 is connected with the source electrode of the MOS tube, and the drain electrode of the MOS tube is used for connecting the control end of the chip.
The working principle of the present invention will be described in detail with reference to the embodiments in the detailed description.
Compared with the prior art, the utility model discloses circuit structure is simple, realizes with low costs, only needs to increase the start area load ability that a small amount of components and parts can promote switching power supply.
Drawings
FIG. 1 is a conventional optocoupler feedback circuit;
fig. 2 is a block diagram of a starting circuit of a switching power supply of the present invention;
fig. 3 is a schematic diagram of a switching power supply start-up circuit of the present invention;
fig. 4 is a schematic diagram of a switching power supply start-up circuit of the present invention.
Detailed Description
The embodiments of the present invention will be further described with reference to the accompanying drawings:
as shown in fig. 2, for the utility model relates to a switching power supply start circuit structure block diagram, including input voltage sampling circuit, on-off control circuit and voltage stabilizing circuit, input voltage sampling circuit's input connection switching power supply's input V2, input voltage sampling circuit's output connection switching control circuit's control end, ground end GND is connected to input voltage sampling circuit's earthing terminal, switching control circuit's one end is connected switching power supply's chip control end FB behind voltage stabilizing circuit, ground end GND is connected to switching control circuit's the other end.
It should be noted that the purpose of the invention can also be achieved by moving the voltage stabilizing circuit in fig. 2 to a position between the other end of the switch control circuit and the ground GND.
A switching power supply starting circuit's a specific embodiment for example shown in fig. 3, input voltage sampling circuit includes resistance R1 and resistance R2, resistance R1 and resistance R2 establish ties back one end and are used for connecting switching power supply's input V2, other end ground connection, resistance R1 and resistance R2's tie point output voltage sampling signal. The switch control circuit comprises a triode Q1, a resistor R3 and a controllable precise voltage-stabilizing source U2; the voltage stabilizing circuit is a voltage stabilizing diode D1; the control end of a controllable precise voltage-stabilizing source U2 is used for inputting a voltage sampling signal, the anode of the controllable precise voltage-stabilizing source U2 is grounded, the cathode of the controllable precise voltage-stabilizing source U2 is simultaneously connected with the base of a triode Q1 and one end of a resistor R3, the other end of the resistor R3 is used for inputting an auxiliary power supply voltage V1, the emitting electrode of the triode Q1 is grounded, the collector of the triode Q1 is connected with the anode of a zener diode D1, and the cathode of the zener diode D1 is used for being connected with the control end of a chip.
The specific working process of the embodiment is as follows: when the input voltage of the power supply is lower, the output end of the input voltage sampling circuit outputs a low voltage sampling signal, the precision voltage stabilizing source U2 can be controlled to be cut off, the triode Q1 is conducted, the voltage of the chip control end FB is stabilized at a set value by the voltage stabilizing diode D1, and the chip control end FB is in a controlled state. When the power supply normally works, the output end of the sampling circuit outputs a high-voltage sampling signal, the precision voltage-stabilizing source U2 can be controlled to be switched on, the triode Q1 is switched off, the voltage-stabilizing diode D1 is switched off, and the optocoupler U1 normally works.
Fig. 4 is the utility model relates to a switching power supply start-up circuit schematic diagram two, with fig. 3 difference lie in with the positive pole ground connection of zener diode D1 in the circuit shown in fig. 3, triode Q1's projecting pole is connected to the negative pole, and triode Q1's collection is connection chip control end FB, and concrete working process is the same, no longer gives unnecessary details.
When switching power supply's application environment is great for capacitive load, increase the utility model discloses a behind the circuit, can improve switching power supply's capacitive load loading capacity. Because the switching power supply output end is influenced by a larger capacitive load, the output voltage is lower when the switching power supply is started, the voltage rises slowly, the switching power supply needs to charge the voltage of the output load to a certain voltage value within a certain time, otherwise, the switching power supply can restart and hiccup, and the switching power supply cannot be started normally. Increase the utility model discloses behind the circuit, because the establishment of input auxiliary power supply voltage V1 voltage when switching power supply starts, triode Q1 switches on, and chip control end FB is stabilized at a certain setting value by zener diode D1, and the power starts more easily this moment.
When the application environment of the switching power supply is larger for inductive load, the circuit of the utility model is added, and the inductive load carrying capacity of the switching power supply can be improved. Because the influence of the great inductive load of switching power supply output, output instantaneous current is great when switching power supply starts, leads to power overload protection easily to switching power supply restarts hiccup, unable normal start. Increase the utility model discloses afterwards, owing to the establishment of input auxiliary power supply voltage V1 voltage when switching power supply starts, triode Q1 switches on, and chip control end FB is stabilized at a certain setting value by zener diode D1, and the power starts more easily this moment.
The foregoing is a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, a plurality of equivalent substitutions, improvements and decorations can be made without departing from the principle of the present invention, such as replacing the transistor Q1 in fig. 3 and fig. 4 with a MOS transistor, and these improvements and decorations are also considered as the protection scope of the present invention.
Claims (6)
1. A switch power supply start-up circuit is characterized in that: the circuit comprises an input voltage sampling circuit, a switch control circuit and a voltage stabilizing circuit; the input voltage sampling circuit is used for sampling an input voltage signal of the switching power supply and outputting the voltage sampling signal to the control end of the switching control circuit, the switching control circuit controls the conduction or the cut-off of an internal switching tube under the driving of the sampling signal, and the voltage stabilizing circuit stabilizes the voltage of the control end of the chip under the control of the switching circuit.
2. The switching power supply boot-up circuit of claim 1, wherein: the input voltage sampling circuit comprises a resistor R1 and a resistor R2, wherein one end of the resistor R1 is connected with the resistor R2 in series and is used for being connected with the input end of the switching power supply, the other end of the resistor R1 is grounded, and a voltage sampling signal is output from the connection point of the resistor R1 and the resistor R2.
3. The switching power supply boot-up circuit of claim 1, wherein: the switch control circuit comprises a triode Q1, a resistor R3 and a controllable precise voltage-stabilizing source U2; the voltage stabilizing circuit comprises a voltage stabilizing diode D1; the control end of a controllable precise voltage-stabilizing source U2 is used for inputting a voltage sampling signal, the anode of the controllable precise voltage-stabilizing source U2 is grounded, the cathode of the controllable precise voltage-stabilizing source U2 is simultaneously connected with the base of a triode Q1 and one end of a resistor R3, the other end of the resistor R3 is used for inputting auxiliary power supply voltage, the emitting electrode of the triode Q1 is grounded, the collector of the triode Q1 is connected with the anode of a zener diode D1, and the cathode of the zener diode D1 is used for connecting the control end of a chip.
4. The switching power supply boot-up circuit of claim 1, wherein: the switch control circuit comprises a triode Q1, a resistor R3 and a controllable precise voltage-stabilizing source U2; the voltage stabilizing circuit comprises a voltage stabilizing diode D1; the control end of a controllable precise voltage-stabilizing source U2 is used for inputting a voltage sampling signal, the anode of the controllable precise voltage-stabilizing source U2 is grounded, the cathode of the controllable precise voltage-stabilizing source U2 is simultaneously connected with the base of a triode Q1 and one end of a resistor R3, the other end of the resistor R3 is used for inputting auxiliary power supply voltage, the anode of a zener diode D1 is grounded, the cathode of the zener diode D1 is connected with the emitting electrode of the triode Q1, and the collector of the triode Q1 is used for connecting the control end of a chip.
5. The switching power supply boot-up circuit of claim 1, wherein: the switch control circuit comprises an MOS (metal oxide semiconductor) tube, a resistor R3 and a controllable precise voltage-stabilizing source U2; the voltage stabilizing circuit comprises a voltage stabilizing diode D1; the control end of the controllable precise voltage-stabilizing source U2 is used for inputting a voltage sampling signal, the anode of the controllable precise voltage-stabilizing source U2 is grounded, the cathode of the controllable precise voltage-stabilizing source U2 is simultaneously connected with the grid of the MOS tube and one end of the resistor R3, the other end of the resistor R3 is used for inputting an auxiliary power supply voltage, the source of the MOS tube is grounded, the drain of the MOS tube is connected with the anode of the voltage-stabilizing diode D1, and the cathode of the voltage-stabilizing diode D1 is used for connecting the control end of the chip.
6. The switching power supply boot-up circuit of claim 1, wherein: the switch control circuit comprises an MOS (metal oxide semiconductor) tube, a resistor R3 and a controllable precise voltage-stabilizing source U2; the voltage stabilizing circuit comprises a voltage stabilizing diode D1; the control end of the controllable precise voltage-stabilizing source U2 is used for inputting a voltage sampling signal, the anode of the controllable precise voltage-stabilizing source U2 is grounded, the cathode of the controllable precise voltage-stabilizing source U2 is simultaneously connected with the grid of the MOS tube and one end of the resistor R3, the other end of the resistor R3 is used for inputting an auxiliary power supply voltage, the anode of the voltage-stabilizing diode D1 is grounded, the cathode of the voltage-stabilizing diode D1 is connected with the source electrode of the MOS tube, and the drain electrode of the MOS tube is used for connecting the control end of the chip.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201920772055.2U CN209982333U (en) | 2019-05-27 | 2019-05-27 | Switching power supply start-up circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201920772055.2U CN209982333U (en) | 2019-05-27 | 2019-05-27 | Switching power supply start-up circuit |
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| Publication Number | Publication Date |
|---|---|
| CN209982333U true CN209982333U (en) | 2020-01-21 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201920772055.2U Active CN209982333U (en) | 2019-05-27 | 2019-05-27 | Switching power supply start-up circuit |
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| Country | Link |
|---|---|
| CN (1) | CN209982333U (en) |
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- 2019-05-27 CN CN201920772055.2U patent/CN209982333U/en active Active
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