KR101583024B1 - Control apparatus of Switching Mode Power Supply - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a switching mode power supply control apparatus, and more particularly, to a switching mode power supply control apparatus using a voltage generated internally instead of an external power supply as a power source to improve the complexity and yield. The present invention can provide a stable operation voltage by having a start section for stably operating in a low voltage state at the time of initial start, and can provide a stable operation voltage by operating a voltage The SMPS control device operates at a low voltage by transforming the input voltage to a low voltage and using it as an internal voltage source to minimize the withstand voltage characteristics and heat generation characteristics of various circuit elements constituting the SMPS It is possible to reduce the size of the circuit element and reduce the cost, thereby maximizing the yield, and there is no need to add a separate circuit structure for enduring the high voltage as in the conventional method, thereby greatly reducing the circuit complexity.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a switching mode power supply control apparatus,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a switching mode power supply control apparatus, and more particularly, to a switching mode power supply control apparatus using a voltage generated internally instead of an external power supply as a power source to improve the complexity and yield.

A control apparatus in a conventional switching mode power supply (SMPS) uses an external power supply as a power supply source for operation of an internal circuit at the start of power supply.

Accordingly, the control device of the SMPS uses the external voltage supplied at the start of operation as it is as an operation voltage, and converts the supplied external voltage into a voltage capable of operating the internal circuit by reducing the internal voltage of the chip.

The voltage supply of such a flow is used only at the starting point, but if it is left unchanged, the current in the standby mode becomes high and the current consumption increases.

In order to solve this problem, the external voltage is used as the operating voltage only at the start of the power supply, and after the internal control circuit starts to operate, the voltage supplied from the transformer is used as the power supply of the internal control circuit to cut off the external voltage supply flow . In this case, the current flow to the pin supplied with the external voltage is interrupted, and the high voltage of the external voltage is supplied to the corresponding pin, so a semiconductor process which can withstand the high voltage has to be used.

As a result, the high voltage applied through the input power source must be used as the voltage for control. Therefore, the complexity of the semiconductor manufacturing process of the control circuit constituting the SMPS and the area ratio of the corresponding portion are increased, And chip safety operations.

Accordingly, there is an increasing demand for development of a control device for an SMPS for improving the complexity and lowering the component cost by using the low voltage for the semiconductor manufacturing process while ensuring stable operation by lowering the voltage at the initial start-up.

Korean Patent No. 10-0314000

The present invention provides an SMPS controller capable of operating at a low voltage by using a voltage generated in the SMPS rather than an input voltage as an internal voltage source, thereby improving the circuit complexity and providing stable voltage to the load The present invention relates to an SMPS control apparatus.

A switching mode power supply controller according to an exemplary embodiment of the present invention includes a reference voltage generator connected to an input power source and a first power switch to adjust the input power source to a reference voltage and apply the same to the first power switch, An internal power generator for receiving the start voltage through the applied first power switch and providing the operating voltage after a delay time for reaching generation of a preset operating voltage; A control unit for generating a pulse signal and providing the pulse signal to a second power switch having one end connected in series to the first power switch and the other end connected to the ground and the first resistance element, The input voltage applied through the input power source is changed to a voltage required by the load in accordance with opening and closing of the second power switch And a transformer for transforming the voltage supplied to the load to provide the voltage to the internal power generator to maintain the operating voltage of the controller during the opening and closing operation of the second power switch according to the pulse signal can do.

As an example related to the present invention, the first and second power switches may be constituted by transistor elements.

The reference voltage generating unit may include a second resistive element having one end connected to the input power source, one end connected to the other end of the second resistive element, and the other end grounded, And a second terminal connected to the other end of the second resistor, and a second terminal connected to the other end of the second resistor, the second terminal being connected to the gate terminal of the first power switch when the second power switch is short- And a first capacitor to provide a voltage to short-circuit the first power switch

As an example related to the present invention, the Zener diode may be replaced by a general diode.

In one embodiment of the present invention, a first diode connected between the internal power generating unit and the gate terminal of the first power switch, one end grounded and the other end connected to the first diode, And a second capacitor for providing a charging voltage to the gate terminal of the first power switch through the first diode at the time of a short-circuit.

As an example related to the present invention, a buffer connected between the second resistance element and the gate terminal of the first power switch to prevent the reference voltage from falling may be further included.

In one embodiment of the present invention, the transformer has one end connected to the input power source and the other end connected to the drain terminal of the first power switch, and the input voltage is applied to the first and second power switches when the first and second power switches are short- And a second winding portion for transforming the input voltage applied to the first winding portion to a voltage required by the load, and one end of the second winding portion are grounded. In the opening and closing operation of the second power switch according to the pulse signal, And a third winding portion for transforming the voltage induced in the second winding portion to maintain the operation of the power generating portion and providing the transformed voltage to the internal power generating portion.

According to an embodiment of the present invention, the control unit may include a pulse signal generator for generating a pulse signal according to the operation voltage and providing the pulse signal to the second power switch, and a voltage generator for generating a voltage between a plurality of resistors connected in series to the other end of the third coil unit And a voltage measuring unit for providing the measured result to the pulse signal generating unit and varying the period of the pulse signal according to the result.

As an example related to the present invention, the power supply unit may include a second diode connected between the internal power generating unit and the third winding unit to block a reverse current flowing from the internal power generating unit to the third winding unit .

In one embodiment of the present invention, power is supplied from the first winding portion to the internal power generating portion while being connected between the internal power generating portion and the drain terminal of the second power switch, And a third diode for blocking a reverse current flowing to the terminal.

The present invention can provide a stable operation voltage by having a start section for stably operating in a low voltage state at the time of initial start, and can provide a stable operation voltage by operating a voltage The SMPS control device operates at a low voltage by transforming the input voltage to a low voltage and using it as an internal voltage source to minimize the withstand voltage characteristics and heat generation characteristics of various circuit elements constituting the SMPS It is possible to reduce the size of the circuit element and reduce the cost, thereby maximizing the yield, and there is no need to add a separate circuit structure for enduring the high voltage as in the conventional method, thereby greatly reducing the circuit complexity.

1 is a circuit diagram of a switching mode power supply control apparatus according to an embodiment of the present invention;
2 is a circuit diagram showing a detailed configuration of a reference voltage generator in a circuit diagram according to the embodiment of FIG.
3 is a timing diagram of a switching mode power supply control apparatus according to the configuration of FIG.
FIG. 4 is a circuit diagram showing another embodiment of the configuration of the switching mode power supply control apparatus according to the configuration of FIG. 2. FIG.
5 is a timing chart of the switching mode power supply control apparatus according to the configuration of FIG.
FIG. 6 is a circuit diagram showing another embodiment of the switching mode power supply control device according to the configuration of FIG. 2; FIG.

Hereinafter, detailed embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a circuit diagram of a switching-mode power supply control apparatus according to an embodiment of the present invention. The switching-mode power supply apparatus is configured in a switching mode power supply (SMPS) have.

As shown in the figure, the SMPS controller includes a reference voltage generator 10, an internal power generator 20, a controller 30, a transformer 40, a first power switch TR1, and a second power switch TR2 ).

The reference voltage generating unit 10 is connected to the input power source and the first power switch TR1 and adjusts the input voltage supplied from the input power source VIN to the reference voltage Vz, TR1).

The reference voltage generating unit 10 stably supplies the reference voltage Vz to the first power switch TR1 and the first power switch TR1 is stable from the reference voltage generating unit 10 Voltage is supplied to maintain the short-circuit state, thereby connecting the input power source and the internal power generator 20 to thereby provide a start voltage Vcc for starting the internal power generator 20.

The internal power generator 20 generates a start voltage Vcc through the first power switch TR1 in accordance with the short circuit of the first power switch TR1 and the opening of the second power switch TR2, And may provide the operating voltage Vdd to the controller 30 during a startup period for providing a preset stable operating voltage Vdd.

At this time, the controller 30 receives the operation voltage Vdd generated from the internal power generator 20 to which the start voltage Vcc is applied, and enters the operation phase after finishing the startup phase after a predetermined delay time.

Accordingly, the controller 30 starts operation after the start of the operation period according to the input of the operation voltage Vdd and the delay time to generate the pulse signal Vg, and outputs the pulse signal Vg to the second power switch (TR2).

Accordingly, the second power switch TR2, one end of which is connected in series to the first power switch TR1 and the other end of which is connected to the ground and the first resistor R1, is turned on and off according to the period of the pulse signal Vg. And an input voltage corresponding to the input power supply VIN may be applied to the transforming unit 40 when the second power switch TR2 is short-circuited.

The transformer 40 may convert the input voltage into a voltage required for the load 100 according to a short circuit between the first and second power switches TR1 and TR2 and provide the transformed voltage to the load 100 . At this time, a diode D and a capacitor C may be connected between the load 100 and the transforming unit 40 for stable voltage supply.

In this configuration, when the second power switch TR2 is opened or closed (switched) according to the pulse signal, the transforming unit 40 applies the load 100 (FIG. 1) to maintain the operation voltage Vdd of the control unit 30 Can be transformed to a low voltage required by the internal power generator 20 and supplied to the internal power generator 20.

Accordingly, the internal power generating unit 20 can stably operate in a low voltage state and can stably provide the operating voltage Vdd for the operation of the controller 30. [

In the above-described configuration, the first and second power switches TR1 and TR2 may be composed of transistor elements, and more preferably, a MOSFET.

As described above, the SMPS control apparatus according to the embodiment of the present invention includes a start-up section for down-converting an input voltage to a low voltage at a start-up and providing a stable operation voltage, Voltage is used as an internal voltage source for the operation of the control unit 30 and a high voltage provided from the input power supply VIN is not used as an internal voltage source to reduce the withstand voltage or heat generation characteristics of various circuit elements constituting the SMPS The size and cost of the circuit element can be reduced, and the heat generated in the configuration using the high voltage as it is can be greatly reduced.

2, detailed operation of each constituent unit will be described with reference to the detailed configuration of the reference voltage generator 10 and the reference voltage generator 10, A power supply VIN and a gate terminal of the first power switch TR1 are connected to the gate terminal of the first power switch TR1 to adjust an input voltage supplied from the input power supply VIN to a reference voltage Vz, As shown in FIG.

The reference voltage generating unit 10 includes a second resistor R2 having one end connected to the input power supply VIN and one end connected to the other end of the second resistor R2 and the first power switch TR1 And a zener diode ZD1 connected to the gate terminal of the first switch SW1 and grounded at the other end to adjust the input voltage applied from the input power supply VIN to a predetermined reference voltage Vz according to the zener voltage and output .

According to the above-described configuration, the reference voltage generator 10 can provide the stable reference voltage Vz to the gate terminal of the first power switch TR1 through the configuration of the Zener diode ZD1.

At this time, the Zener diode ZD1 may be replaced with a general diode.

The first power switch TR1 short-circuited according to the reference voltage Vz has a drain terminal connected to the input power supply VIN through the first winding part Tp of the transforming part 40, Is connected to the internal power generating unit 20 through a first diode D1 and connects the input power VIN and the internal power generating unit 20 when the reference voltage Vz is applied, And the voltage Vd applied to the first power switch TR1 through the power supply VIN may be supplied to the internal power generator 20 through the source terminal.

At this time, the first power switch TR1 can reduce the high voltage applied from the input power source VIN to the voltage Vd required by the internal power generator 20 operating at a low voltage.

A first diode D1 may be formed between the drain terminal of the second power switch TR2 and the internal power generating unit 20 and the first diode D1 may be connected between the drain terminal of the second power switch TR2 and the internal power generating unit 20, The power supplied through the first power switch TR1 from the power source VIN through the first winding part Tp of the transforming part 40 to the initial power source of the internal power generator 20, Generating unit 20 and prevents a reverse current generated from the internal power generating unit 20 from flowing to the second power switch TR2 in an operation period after the startup period to prevent malfunction.

The internal power generator 20 receives the start voltage Vcc from the first power switch TR1 through the first diode D1 and supplies the operation voltage Vdd to the controller 30, The control unit 30 completes the starting step and enters the operation step after the delay time is delayed by the previous delay time (starting period) until the operating voltage Vdd reaches the stable state.

Thereafter, the controller 30 starts operation when an operation voltage Vdd is applied from the internal power generator 20 to generate a pulse signal Vg, and outputs the pulse signal Vg to the second power switch (TR2).

The second power switch TR2 receives the pulse signal Vg through the gate terminal thereof and is opened or closed according to the period of the pulse signal Vg. The first resistor R1 and the ground are serially connected to the source terminal and the voltage provided through the input power supply VIN when the second power switch TR2 is short- May be configured to be applied to the transforming unit (40).

The transformer 40 is formed of first to third winding portions Tp, Ts and Ta, one end of the first winding portion Tp is connected to the input power source VIN, Is connected to the drain terminal of the first power switch (TR1), and a high voltage provided through the input power supply (VIN) is applied.

At this time, the second power switch TR2 is switched according to the pulse signal Vg to repeatedly open and short-circuit, and the current flowing in the first winding part Tp is controlled to stably maintain the voltage applied to the load do.

Accordingly, the second winding part Ts may transform the voltage applied to the first winding part Tp to the voltage required for the load 100 according to the induction of the magnetic field to provide the load 100 with the voltage.

Since the current flowing through the first power switch TR1 to the internal power generating unit 20 is substantially eliminated when the second power switch TR2 is short-circuited, A third winding part Ta for generating a voltage through the induction of a magnetic field can supply a voltage to the internal power generator 20. At this time, the third winding part Ta may have one end connected to the internal power generating part 20 and the other end connected to the ground.

In other words, the second power switch TR2 is switched in accordance with the pulse signal, and a current flows through the first winding part Tp when the second power switch TR2 is short-circuited, The energy stored in the first winding part Tp is transferred to the second winding part Ts and the current is supplied to the load 100 when the second power switch TR2 is opened.

At this time, the voltage of the second winding portion Ts is induced to the third winding portion Ta by the turns ratio of the second and third winding portions Ts and Ta, and the third winding portion Ta And supplies power (Vcc) to the internal power generator 20.

Accordingly, the internal power generating unit 20 operates in accordance with the voltage supplied from the third winding unit Ta to stably provide the operation voltage Vdd for the operation of the controller 30.

The internal power generating unit 20 is connected in series with the other end of the first capacitor C1 connected at one end to the ground and is connected between the internal power generating unit 20 and the third coil unit Ta 2 diode D2 may be connected and an additional resistor may be connected.

Accordingly, the first capacitor C1 can charge the voltage supplied from the third winding part Ta and supply the charging voltage to the internal power generating part 20, And the second diode D2 supplies a voltage Vcc provided from the third winding part Ta to the internal power generator 20, A reverse current generated from the first power supply unit 20 is prevented from flowing to the third coil unit Ta and the voltage is stably supplied to the internal power supply unit 20.

As described above, the SMPS controller provides stable voltage supply to the load 100 through the first and second winding portions Tp and Ts, and at the same time, supplies the voltage supplied to the load 100 to the inside The internal power supply for operating the power generating unit 20 and the control unit 30 can be used for down operation so that the voltage can be supplied to the load 100 stably while operating at a low voltage.

Accordingly, the present invention can be configured by minimizing the withstand voltage and heat generation characteristics of each circuit element compared to a conventional SMPS controller that applies a direct high voltage through the input power supply (VIN), and a separate additional circuit for preventing high voltage It is possible to greatly improve the ease of configuration and the complexity of the circuit element.

The control unit 30 includes a pulse signal generating unit 31 for generating the pulse signal Vg and a control unit 30 for controlling a voltage for measuring the voltages of the first and second winding units Tp and Ts And a measuring unit 32.

The pulse signal generator 31 generates a pulse signal Vg based on the operation voltage Vdd provided from the internal power generator 20 and supplies the pulse signal Vg to the gate terminal of the second power switch TR2, .

At this time, the pulse signal generator 31 may generate either a pulse width modulation (PWM) signal or a pulse frequency modulation (PFM) signal as a pulse signal.

On the other hand, the voltage measuring unit 32 can measure the voltage between the third and fourth resistance elements R3 and R4 connected in series with the third winding unit Ta, It is possible to measure the voltage applied to the first and second winding portions Tp and Ts according to the turns ratio of the third winding portions Tp, Ts and Ta and to supply the result to the pulse signal generating portion 31 have. At this time, one end of the fourth resistive element R4 may be connected to the ground.

The pulse signal generator 31 adjusts the period or width of the pulse signal Vg according to the result provided from the voltage measuring unit 32 and provides the gate signal to the gate terminal of the second power switch TR2 A current flowing in the first winding part Tp is controlled according to an opening and closing (switching) operation of the second power switch TR2 and a stable voltage is applied to the load 100 through the second winding part Ts .

The reference voltage generating unit 10 is supplied with a voltage from the input power supply VIN to the first and second power switches TR1 and TR2 when the second power switch TR2 is short- In order to prevent the reference voltage Vz from dropping in response to the drop of the voltage supplied to the voltage generating part 10, as shown in the figure, the other end of the second resistor R2 is connected in series, And may further include a second capacitor C2.

Accordingly, the second capacitor C2 charges the voltage adjusted through the Zener diode ZD1 when the second power switch TR2 is opened. When the second power switch TR2 is short-circuited, A charging voltage is provided to the gate terminal of the first power switch TR1 to compensate the reference voltage Vz and the first power switch TR1 is turned on while the voltage is being supplied to the load 100 through the transforming unit 40. [ Can be prevented from being opened.

That is, when the first power switch TR1 is continuously short-circuited when the second power switch TR2 is short-circuited, the input voltage supplied from the input power supply VIN is stably applied to the transforming unit 40 .

FIG. 3 is a timing diagram of the SMPS control apparatus according to the configuration of FIG. 2. As shown in FIG. 3, when the input voltage is applied from the initial input power supply VIN, the internal power generation unit 20 generates the reference voltage The internal power generating unit 20 can apply the operation voltage Vdd to the controller 30 when the start voltage Vcc is applied from the controller 10 to generate a stable operation voltage Vdd .

In this case, the input voltage (VIN) applies the input voltage to the DC 155V when the external voltage is AC 110V, and the input voltage can be applied to the DC 311V when the external voltage is 220V. When the external voltage is DC voltage, Applicable.

At this time, as shown in the drawing, the reference voltage Vz gradually increases with the input voltage from the input power supply VIN, and the first power switch TR1 is short-circuited according to the reference voltage Vz, The starting voltage Vcc provided to the unit 20 is gradually increased.

The first power switch TR1 supplies a constant voltage to the internal power generating unit 20 so as to stably generate a voltage.

The internal power generating unit 20 may supply the operating voltage to the controller 30 after a delay time (starting period) for reaching a state for supplying a stable voltage from the time when the starting voltage Vcc is supplied have.

When the operating voltage is supplied as described above, an operation section for providing a voltage to the load 100 is formed. In the operating period, the controller 30 provides a stable operating voltage Vdd from the internal power generating section 20 And generates and supplies a pulse signal Vg to the second power switch TR2.

At this time, the second power switch TR2 repeats opening and closing according to the pulse signal Vg. In this case, the transformer 40 is connected to the load 100 to maintain the operation of the controller 30. [ It is possible to convert the supplied voltage into a voltage Vcc required by the internal power generator 20 and provide the transformed voltage.

This allows the transformer 40 to continuously supply a voltage to the internal power generator 20 even during the switching operation of the second power switch TR2 according to the pulse signal Vg, Can be operated stably.

4, the first power switch TR1 is connected between the gate terminal and the drain terminal, and between the gate terminal and the source terminal, as shown in Fig. 4, Capacitors Cgd and Cgs are generated.

As a result, the voltage applied to the first power switch TR1 instantaneously drops as soon as the second power switch TR2 is short-circuited. Due to the influence of the parasitic capacitors Cgd and Cgs, The reference voltage Vz of the switch TR1 falls.

As a result, when the first power switch TR1 is opened, the current flow in the transforming unit 40 does not occur and the stable voltage can not be supplied to the load 100. [

In order to prevent this, the reference voltage generator 10 may include a third diode D3 connected between the internal power generator 20 and the gate terminal of the first power switch TR1, The third diode D3 can prevent the voltage applied to the first power switch TR1 from falling.

For example, the third diode D3 may provide a voltage Vcc to the gate terminal of the first power switch TR1 via the second diode D2 to the internal power generator 20 , The first capacitor C1 is connected to the first capacitor C1 so that the charge voltage can be supplied to the gate terminal of the first power switch TR1 to easily lower the reference voltage Vz .

It is preferable that the value of the first capacitor C1 is larger than the value of the parasitic capacitors Cgd and Cgs so that the charging voltage is stably supplied to the gate terminal of the first power switch TR1 can do.

FIG. 5 is a timing diagram according to the configuration of FIG. 4. As shown in FIG. 5, as the second power switch TR2 is short-circuited during the operation period in which the controller 30 operates, the effect of the parasitic capacitors Cgd and Cgs The third diode D3 is supplied with the voltage Vcc provided through the second diode D2 or the voltage Vcc supplied from the first capacitor C1 when the voltage applied to the first power switch TR1 is lowered The reference voltage Vz supplied to the gate terminal of the first power switch TR1 is prevented from falling below a predetermined voltage by providing the charging voltage to the gate terminal of the first power switch TR1, .

6 is a circuit diagram showing another embodiment of the SMPS controller according to the configuration of FIG. 2. In order to prevent the lowering of the reference voltage Vz shown in FIG. 4, the second resistance element R2) and the gate terminal of the first power switch (TR1).

Accordingly, even when the reference voltage Vz falls due to the opening of the second power switch TR2, the buffer U2 prevents the reference voltage Vz from dropping and stably supplies the reference voltage Vz .

In order to provide a stable voltage, the SMPS controller according to the above-described configuration provides a starting period for the internal power generator 20 to reach a state for stable operation voltage to minimize the influence of the initial high voltage application, The internal power generating unit 20 can be operated at a low voltage by using the internal power generated in the operation period in which the voltage is applied to the internal power generating unit 20.

Accordingly, it is not necessary to consider the withstand voltage characteristic of the circuit element, so that the size of the circuit element can be reduced, and the configuration of the high voltage prevention circuit or the like is not required, and the circuit complexity can be greatly improved.

The foregoing and other objects, features and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. However, the present invention is not limited to the above-described embodiments, and various changes and modifications may be made by those skilled in the art without departing from the scope of the present invention. .

10: reference voltage generator 20: internal power generator
30: control unit 31: pulse signal generating unit
32: voltage measuring unit 40:

Claims (10)

A reference voltage generator connected to the input power source and the first power switch to adjust the input power source to a reference voltage and apply the adjusted reference voltage to the first power switch;
An internal power supply generating unit for applying the initial start voltage through the first power switch in the start period and providing the operation voltage after a delay time for reaching generation of a predetermined operation voltage;
The pulse signal is supplied to the second power switch, one end of which is connected in series to the first power switch, and the other end of which is connected to the ground and the first resistance element, ; And
Wherein the second power switch is turned on and off according to the pulse signal to convert the input voltage applied through the input power supply to a voltage required by the load to provide the load with the load, And a transformer for transforming a voltage supplied to the load to maintain the operating voltage of the controller during operation and providing the transformed voltage to the internal power generator,
The reference voltage generator
A second resistive element whose one end is connected to the input power supply;
A Zener diode having one end connected to the other end of the second resistor and the other end grounded to adjust the applied input voltage to the reference voltage according to a Zener voltage and output; And
One end of which is connected in series to the other end of the second resistive element and the other end of which is grounded to provide a charging voltage to the gate terminal of the first power switch when the second power switch is short- And a capacitor,
The transformer
A first winding part having one end connected to the input power source and the other end connected to the drain terminal of the first power switch, and the input voltage being applied when the first and second power switches are short-circuited;
A second winding portion for transforming the input voltage applied to the first winding portion to a voltage required for the load; And
And a second coil connected to the first coil and the second coil, the first coil being connected to the first coil and the second coil, ≪ / RTI >
Wherein the first power switch down-converts the input power applied through the first winding section to a low voltage to provide the initial start voltage to the internal power generation section.
The method according to claim 1,
Wherein the first and second power switches are comprised of transistor elements.
delete The method according to claim 1,
Wherein the Zener diode is replaced by a general diode. ≪ Desc / Clms Page number 13 >
The method according to claim 1,
A third diode connected between the internal power generating unit and the gate terminal of the first power switch; And
A first capacitor connected to the third diode and having a first end connected to the third diode and providing a charging voltage to the gate terminal of the first power switch via the third diode when the second power switch is short-
Further comprising a control unit for controlling the switching power supply.
The method according to claim 1,
A buffer connected between the second resistor and the gate terminal of the first power switch to prevent the reference voltage from dropping;
Further comprising a control unit for controlling the switching power supply.
delete The method according to claim 1,
The control unit
A pulse signal generator for generating a pulse signal according to the operating voltage and providing the pulse signal to the second power switch; And
And a voltage measurement unit for providing a result of measuring a voltage between a plurality of resistors connected in series to the other end of the third winding unit to the pulse signal generator to vary the period of the pulse signal according to the result,
And a control unit for controlling the switching mode power supply.
The method according to claim 1,
And a second diode connected between the internal power generating unit and the third winding unit to block a reverse current flowing from the internal power generating unit to the third winding unit.
The method according to claim 1,
A second power switch connected between the internal power generating unit and the drain terminal of the second power switch for supplying power from the first winding unit to the internal power generating unit and for blocking reverse current flowing to the drain terminal of the second power switch And a first diode connected between the power supply and the power supply.

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