CN101976946B - Circuit and method for transforming negative voltage between direct currents - Google Patents

Abstract

The invention provides a negative voltage conversion circuit between direct currents, including a direct current power supply, a power supply controller, an inductor, a first diode, a first capacitor, a load, a soft start circuit and a voltage adjustment circuit, one end of the load leads to a negative voltage output end, and the other One end is the ground terminal; the positive pole of the DC power supply is connected to the reference ground, and the negative pole is connected to the power controller; the power controller is connected to the negative voltage output terminal and the first diode; the inductance is connected to the first diode, the first capacitor, and the voltage adjustment The circuit is connected to the negative voltage output terminal; the first diode is connected to the voltage adjustment circuit, the first capacitor, and the ground terminal of the load; the first capacitor is connected in parallel to the load; the soft start circuit is connected to the power controller, the negative pole of the DC power supply, and the reference ground ; The voltage adjustment circuit is connected to the reference ground, the DC power supply, the power controller, the negative voltage output terminal and the ground terminal of the load. The invention also provides a negative voltage conversion method between direct currents. The invention has stronger carrying capacity and higher efficiency.

Description

Direct current negative voltage conversion circuit and method

technical field

The invention belongs to the technical field of conversion circuits, and in particular relates to a DC-to-DC negative voltage conversion circuit and method (that is, a DC-DC negative voltage conversion circuit and method).

Background technique

With the rapid development of electronic technology, more and more electronic systems need to use negative power supply to work normally, such as operational amplifiers, modems, computer power supplies, etc. At the same time, in order to meet the development direction of modern power supply technology, the requirements of the system for the negative power supply are further improved, especially in the two aspects of the load capacity and efficiency of the negative power supply.

There are three commonly used negative voltage conversion circuits between direct currents (that is, DC-DC negative voltage conversion circuits):

1. Linear regulated power supply

As shown in Figure 1, the negative voltage conversion circuit includes a DC power supply 1, a filter capacitor 2, a filter capacitor 3, a load 4, and a negative voltage three-terminal regulator 5. The magnitude of the voltage is high. The negative voltage of the required output terminal 46 can be obtained by using a negative voltage three-terminal regulator 5, such as 7905, etc. This technique has a simple circuit, but low efficiency and high power consumption. It is generally only used in occasions where switching power supplies cannot be used, such as circuits that are sensitive to interference.

2. Charge pump

As shown in Figure 2, the negative voltage conversion circuit includes a DC power supply 7, an analog switch 8, an analog switch 9, an analog switch 11, an analog switch 12, an energy storage capacitor 10, an energy storage capacitor 13, a load 14, and a rectangular wave oscillator 6 And the inverter 15 , the rectangular wave drive signal output by the rectangular wave oscillator 6 directly controls the opening and closing of the analog switch 8 and the analog switch 9 . At the same time, the driving signal directly controls the analog switch 11 and the analog switch 12 to be turned on and off through the inverter 15 . When the rectangular wave oscillator 6 outputs a high level, the analog switch 8 and the analog switch 9 are turned on, the analog switch 11 and the analog switch 12 are turned off, and the DC power supply 7 will charge the energy storage capacitor 10 . When the rectangular wave oscillator 6 outputs a high level, the analog switch 8 and the analog switch 9 are turned off, the analog switch 11 and the analog switch 12 are turned on, and the energy storage capacitor 10 will charge the energy storage capacitor 13 and supply power to the load 14 . Since the high potential of the energy storage capacitor 13 is grounded, the negative voltage of the output terminal 47 can be obtained at this time. The biggest advantage of this solution is that it uses capacitors to store energy, and there are few external components, which can make the volume of the power supply small. However, its output characteristics are poor, and its load capacity is poor.

3. DC-DC voltage conversion (that is, voltage conversion between direct currents)

As shown in Figure 3, the DC-DC voltage conversion circuit includes a DC power supply 16, a switch tube 17, a diode 18, an inductor 19, a capacitor 20 and a load 21, and its basic working principle is: when the switch tube 17 is turned on, the inductor 19 To store energy, the capacitor 20 supplies power to the load 21 . When the switch tube 17 is turned off, the inductor 19 charges the capacitor 20 through the diode 18, and the unidirectional conduction characteristic of the diode 18 makes the output voltage of the output terminal 48 negative relative to the reference ground. The disadvantage of this circuit is that it cannot charge the capacitor while the inductor is storing energy, so the load capacity is weak.

Contents of the invention

The primary purpose of the present invention is to overcome the disadvantages and deficiencies of the above-mentioned prior art, and provide a DC-to-DC negative voltage conversion circuit with simple and reasonable structure, which can effectively reduce the ripple of the output voltage and increase its load capacity and efficiency.

Another object of the present invention is to provide a method for converting negative voltage between direct currents realized by the above circuit.

For reaching above-mentioned purpose, the present invention adopts following technical scheme:

Negative voltage conversion circuit between direct currents, including direct current power supply, power supply controller, inductor, first diode, first capacitor, load, soft start circuit and voltage adjustment circuit, said power supply controller includes power triode collector output pin , reference ground pin, feedback input pin, soft start input pin and power supply pin, one end of the load leads to a negative voltage output end, and the other end is a ground end connected to the reference ground; the positive pole of the DC power supply is connected to the reference ground, its negative pole is connected to the reference ground pin of the power controller; connected to the anode of the inductor; one end of the inductor is connected to the anode of the first diode, and the other end is respectively connected to one end of the first capacitor, the voltage adjustment circuit, one end of the load and the negative voltage output end; the first The cathode of the diode is respectively connected to the voltage adjustment circuit, the other end of the first capacitor and the ground terminal of the load; the two ends of the first capacitor are respectively connected to the two ends of the load; the soft start circuit is respectively connected to the soft The start input pin, the negative pole of the DC power supply, and the reference ground are connected; the voltage adjustment circuit is respectively connected with the reference ground, the negative pole of the DC power supply, the feedback input pin, the negative voltage output terminal, and the ground terminal of the load.

The soft-start circuit includes a second capacitor and a sixth resistor, both ends of the second capacitor are respectively connected to the negative pole of the DC power supply and the soft-start input pin of the power controller, and one end of the sixth resistor is connected to the reference ground , and the other end is connected to the soft-start input pin of the power controller.

The voltage adjustment circuit includes a fifth resistor, a fourth resistor, a triode, a three-terminal parallel type Zener diode, a first resistor, and a second resistor, and the set of the negative pole of the DC power supply, the fifth resistor, the fourth resistor, and the triode The electrodes are connected in sequence, the feedback input pin of the power controller is connected to the connection point of the fifth resistor and the fourth resistor; the emitter of the triode is connected to the reference ground, and its base is connected to the three-terminal parallel Zener diode The cathode of the three-terminal parallel connection type Zener diode is connected to the anode of the negative voltage output terminal and one end of the inductor respectively; the reference electrode of the three-terminal parallel connection type Zener diode is connected to one end of the second resistor, and the second resistor The other end of the first resistor is respectively connected to the cathode of the first diode and the grounding end of the load; the two ends of the first resistor are respectively connected to the reference electrode and the anode of the three-terminal parallel Zener diode.

The voltage adjustment circuit further includes a third resistor, one end of the third resistor is connected to the base of the triode, and the other end is respectively connected to the emitter of the triode and the reference ground.

The first diode is a Schottky diode.

The transistor is a PNP transistor.

The method for converting negative voltage between direct currents by the above circuit comprises the following steps:

(1) Soft start: Before the DC power is applied, the voltage on the second capacitor in the soft start circuit is zero. After the DC power is applied, the voltage on the second capacitor is the voltage on the soft start input pin of the power controller by Zero gradually increases; when the voltage on the second capacitor, that is, the voltage on the soft-start input pin of the power controller is greater than the startup voltage inside the power controller, the soft-start process is completed, and the soft-start time is determined by the soft-start The size of the sixth resistor and the second capacitor in the circuit is determined;

(2) Charging of the first capacitor: After the negative voltage conversion circuit between direct currents completes the soft start, when the power triode inside the power controller is turned on, the power transistor collector output pin of the power controller and the reference ground pin A low-impedance path is formed between them, and the DC power supply charges the inductor and the first capacitor; when the power transistor inside the power controller is turned off, the current in the inductor continues to charge the first capacitor through the first diode until it is in the inductor The stored energy is released or the power triode inside the power controller is turned on again; the first capacitor is charged in the process of storing and releasing energy in the inductor, so as to reduce the ripple of the output voltage and increase the DC current The load capacity and efficiency of the negative voltage conversion circuit between the two;

(3) Voltage adjustment:

(3-1) Boost adjustment: After the DC-to-DC negative voltage conversion circuit completes the soft start, in the voltage adjustment circuit, when the voltage amplitude of the negative voltage output terminal drops, the voltage is divided by the first resistor and the second resistor accordingly The voltage loaded between the reference pole and the anode of the three-terminal parallel Zener diode also drops, if the voltage between the reference pole and the anode of the three-terminal parallel Zener diode is divided by the first resistor and the second resistor If it is less than the internal reference voltage of the three-terminal parallel-connected Zener diode, the input current of the cathode of the three-terminal parallel-connected Zener diode decreases, and at the same time, the current of the collector of the triode decreases, and is loaded to the power controller through the fourth resistor and the fifth resistor. The voltage of the feedback input pin also drops, and the power controller increases the conduction time of the internal power transistor accordingly to reduce its off time, thereby increasing the charging current and charging time of the first capacitor, and increasing the voltage of the negative voltage output terminal ;

(3-2) Step-down adjustment: After the DC-to-DC negative voltage conversion circuit completes the soft start, in the voltage adjustment circuit, when the voltage amplitude of the negative voltage output terminal rises, the voltage is divided by the first resistor and the second resistor accordingly The voltage loaded between the reference pole and the anode of the three-terminal parallel Zener diode also rises, if the voltage between the reference pole and the anode of the three-terminal parallel Zener diode is divided by the first resistor and the second resistor If it is greater than the internal reference voltage of the three-terminal parallel Zener diode, the input current of the cathode of the three-terminal parallel Zener diode rises, and at the same time, the current of the collector of the triode rises, and is loaded to the power controller through the fourth resistor and the fifth resistor The voltage of the feedback input pin also rises, and the power controller correspondingly reduces the conduction time of the internal power transistor to increase its off time, thereby reducing the charging current and charging time of the first capacitor, and reducing the negative voltage output terminal voltage.

In the step (3), when the voltage adjustment circuit performs step-up adjustment or step-down adjustment, the third resistor realizes bypassing the leakage current of the three-terminal parallel-connected Zener diode to prevent leakage of the three-terminal parallel-connected Zener diode. The current adversely affects the feedback loop.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

(1) The DC-to-DC negative voltage conversion circuit of the present invention, compared with the existing DC-to-DC negative voltage conversion circuit, can charge the capacitor while storing energy in the inductance. It can output energy through the inductor, thereby reducing the ripple of the output voltage, increasing its load capacity and efficiency, and has a strong load capacity.

(2) The present invention is provided with a voltage adjustment circuit, which can adjust the conduction time of the internal power transistor of the power supply controller through the voltage adjustment circuit, thereby adjusting the voltage of the negative voltage output terminal, which has the advantages of high efficiency and flexibility.

Description of drawings

FIG. 1 is a schematic diagram of a first structure of a circuit in the prior art.

Fig. 2 is a second structure schematic diagram of the prior art circuit.

FIG. 3 is a schematic diagram of a third structure of a circuit in the prior art.

Fig. 4 is a structural schematic diagram of the circuit of the present invention.

Detailed ways

The present invention will be further described in detail below in conjunction with the embodiments and the accompanying drawings, but the embodiments of the present invention are not limited thereto.

Example

As shown in Figure 4, the negative voltage conversion circuit between direct currents includes a direct current power supply 36, a power supply controller 39, an inductor 31, a first diode 30, a first capacitor 29, a load 28, a soft start circuit and a voltage adjustment circuit, so The power controller 39 includes a power triode collector output pin 40, a reference ground pin 41, a feedback input pin 42, a soft start input pin 43 and a power supply pin 44, and one end of the load 28 leads to a negative voltage output terminal 45, the other end is the ground terminal connected to the reference ground; the anode of the DC power supply 36 is connected to the reference ground, and its negative pole is connected to the reference ground pin 41 of the power controller 39; the power pin 44 of the power controller 39 is connected to the reference ground. The negative voltage output terminal 45 is connected, and the power triode collector output pin 40 of the power controller 39 is connected with the anode of the first diode 30; one end of the inductor 31 is connected with the anode of the first diode 30, Its other end is respectively connected with one end of the first capacitor 29, the voltage adjustment circuit, one end of the load 28 and the negative voltage output terminal 45; the cathode of the first diode 30 is respectively connected with the voltage adjustment circuit, the first capacitor 29 The other end of the first capacitor 29 is connected to the ground terminal of the load 28; the two ends of the first capacitor 29 are respectively connected to the two ends of the load 28; the soft start circuit is respectively connected to the soft start input pin 43 of the power controller 39 and the The negative pole is connected to the reference ground; the voltage adjustment circuit is respectively connected to the reference ground, the negative pole of the DC power supply 36 , the feedback input pin 42 , the negative voltage output terminal 45 , and the ground terminal of the load 28 .

The soft start circuit includes a second capacitor 37 and a sixth resistor 38, the two ends of the second capacitor 37 are respectively connected to the negative pole of the DC power supply 36 and the soft start input pin 43 of the power controller 39, and the sixth resistor One end of the resistor 38 is connected to the reference ground, and the other end is connected to the soft start input pin 43 of the power controller 39 .

The voltage adjustment circuit includes a fifth resistor 35, a fourth resistor 34, a triode 33, a three-terminal parallel type Zener diode 22, a first resistor 27 and a second resistor 26, the negative pole of the DC power supply 36, the fifth resistor 35 , the fourth resistor 34, and the collector of the triode 33 are connected in turn, and the feedback input pin 42 of the power controller 39 is connected to the connection point of the fifth resistor 35 and the fourth resistor 34; the emitter of the triode 33 and The reference ground is connected, and its base is connected to the cathode 23 of the three-terminal parallel connection type Zener diode 22, and the anode 25 of the three-terminal parallel connection type Zener diode 22 is respectively connected to the negative voltage output terminal 45 and one end of the inductor 31; The reference pole 24 of the three-terminal parallel connection type Zener diode 22 is connected to one end of the second resistor 26, and the other end of the second resistor 26 is respectively connected to the cathode of the first diode 30 and the ground terminal of the load 28; the first Both ends of the resistor 27 are respectively connected to the reference pole 24 of the three-terminal parallel Zener diode 22 and the anode 25 of the three-terminal parallel Zener diode 22 .

The voltage adjustment circuit further includes a third resistor 32, one end of the third resistor 32 is connected to the base of the transistor 33, and the other end is respectively connected to the emitter of the transistor 33 and the reference ground.

The first diode 30 is a Schottky diode.

The transistor 33 is a PNP transistor.

The method for converting negative voltage between direct currents by the above circuit comprises the following steps:

(1) Soft start: before applying DC power supply 36, the voltage on the second capacitor 37 in the soft start circuit is zero, after applying DC power supply 36, the voltage on the second capacitor 37 is the soft start input lead of power controller 39 The voltage on the pin 43 gradually increases from zero; when the voltage on the second capacitor 37, that is, the voltage on the soft-start input pin 43 of the power controller 39, is greater than the internal startup voltage of the power controller 39, the soft start is completed process, the time of its soft start is determined by the size of the sixth resistor 38 and the second capacitor 37 in the soft start circuit;

(2) Charging of the first capacitor 29: after the negative voltage conversion circuit between direct currents completes the soft start, when the power transistor inside the power controller 39 is turned on, the power transistor collector output pin 40 of the power controller 39 is connected to the A low-impedance path is formed between the reference ground pins 41, and the DC power supply 36 charges the inductor 31 and the first capacitor 29; when the power transistor inside the power controller 39 is turned off, the current in the inductor 31 passes through the first diode instead. The tube 30 continues to charge the first capacitor 29 until the energy stored in the inductor 31 is released or the power triode inside the power controller 39 is turned on again; the first capacitor 29 is charged in the process of storing energy and releasing energy in the inductor 31 , to reduce the ripple of the output voltage and increase the load capacity and efficiency of the negative voltage conversion circuit between direct currents;

(3) Voltage adjustment:

(3-1) Boost adjustment: After the DC-to-DC negative voltage conversion circuit completes the soft start, in the voltage adjustment circuit, when the voltage amplitude of the negative voltage output terminal 45 drops, the first resistor 27 and the second The voltage between the reference electrode 24 and the anode 25 of the three-terminal parallel-connected Zener diode 22 is also dropped when the voltage is divided by the resistor 26. The voltage between the reference electrode 24 and the anode 25 of 22 is less than the internal reference voltage of the three-terminal parallel connection type Zener diode 22, then the input current of the cathode 23 of the three-terminal parallel connection type Zener diode 22 drops, and the current of the collector of the triode 33 drop, the voltage loaded to the feedback input pin 42 of the power controller 39 through the fourth resistor 34 and the fifth resistor 35 also drops, and the power controller 39 correspondingly increases the conduction time of the internal power triode to reduce its shutdown Time, thereby increasing the charging current and charging time to the first capacitor 29, and increasing the voltage of the negative voltage output terminal 45;

(3-2) Step-down adjustment: After the negative voltage conversion circuit between direct currents completes the soft start, in the voltage adjustment circuit, when the voltage amplitude of the negative voltage output terminal 45 rises, correspondingly through the first resistor 27 and the second The voltage between the reference pole 24 and the anode 25 of the three-terminal parallel connection type Zener diode 22 is also increased by the voltage division of the resistor 26. The voltage between the reference electrode 24 and the anode 25 of 22 is greater than the internal reference voltage of the three-terminal parallel connection type Zener diode 22, then the input current of the negative electrode 23 of the three-terminal parallel connection type Zener diode 22 rises, and the collector of the triode 33 simultaneously As the current rises, the voltage applied to the feedback input pin 42 of the power controller 39 through the fourth resistor 34 and the fifth resistor 35 also rises, and the power controller 39 correspondingly reduces the conduction time of the internal power triode to increase its turn-off time. Off time, thereby reducing the charging current and charging time of the first capacitor 29, and reducing the voltage of the negative voltage output terminal 45.

In the step (3), when the voltage adjustment circuit performs step-up adjustment or step-down adjustment, the third resistor 32 realizes bypassing the leakage current of the three-terminal parallel-connected Zener diode 22 to prevent the three-terminal parallel-connected Zener diode from 22 leakage current adversely affects the feedback loop.

The above-mentioned embodiment is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited by the above-mentioned embodiment, and any other changes, modifications, substitutions, combinations, Simplifications should be equivalent replacement methods, and all are included in the protection scope of the present invention.

Claims (7)

1. negative voltage translation circuit between direct current; It is characterized in that: comprise DC power supply, power-supply controller of electric, inductance, first diode, first electric capacity, load, soft starting circuit and voltage-regulating circuit; Said power-supply controller of electric comprises pliotron collector electrode output pin, reference ground pin, feedback input pin, soft start input pin and power pins; One end of said load is drawn the negative voltage output, and the other end is for connecting the earth terminal with reference to ground; The positive pole of said DC power supply connects with reference to ground, and its negative pole is connected with the reference ground pin of power-supply controller of electric; The power pins of said power-supply controller of electric is connected with the negative voltage output, and the pliotron collector electrode output pin of said power-supply controller of electric is connected with the anode of first diode; One end of said inductance is connected with the anode of first diode, and its other end is connected with an end and the negative voltage output of an end of first electric capacity, voltage-regulating circuit, said load respectively; The negative electrode of said first diode is connected with the other end of voltage-regulating circuit, first electric capacity and the earth terminal of load respectively; The two ends of first electric capacity are connected with the two ends of load respectively; Said soft starting circuit is connected with soft start input pin, the negative pole of DC power supply, the reference ground of power-supply controller of electric respectively; Said voltage-regulating circuit is connected with earth terminal with reference to the negative pole of ground, DC power supply, feedback input pin, negative voltage output, load respectively.

2. negative voltage translation circuit between direct current according to claim 1; It is characterized in that: said soft starting circuit comprises second electric capacity and the 6th resistance; The two ends of said second electric capacity are connected with the negative pole of DC power supply, the soft start input pin of power-supply controller of electric respectively; One end of said the 6th resistance connects with reference to ground, and the other end is connected with the soft start input pin of power-supply controller of electric.

3. negative voltage translation circuit between direct current according to claim 1; It is characterized in that: said voltage-regulating circuit comprises the 5th resistance, the 4th resistance, triode, three end parallel connection type voltage stabilizing didoes, first resistance and second resistance; The collector electrode of the negative pole of said DC power supply, the 5th resistance, the 4th resistance, triode connects successively, and the feedback input pin of said power-supply controller of electric is connected on the interface of the 5th resistance and the 4th resistance; The emitter of said triode is connected with reference ground, and its base stage is connected with the negative electrode of three end parallel connection type voltage stabilizing didoes, and the anode of said three end parallel connection type voltage stabilizing didoes is connected with an end of negative voltage output, inductance respectively; The reference utmost point of said three end parallel connection type voltage stabilizing didoes is connected with an end of second resistance, and the other end of second resistance is connected with the negative electrode of first diode, the earth terminal of load respectively; The two ends of said first resistance are connected with the reference utmost point, the anode of three end parallel connection type voltage stabilizing didoes respectively.

4. negative voltage translation circuit between direct current according to claim 3; It is characterized in that: said voltage-regulating circuit also comprises the 3rd resistance; One end of said the 3rd resistance is connected with the base stage of triode, and the other end is connected with emitter, the reference ground of triode respectively.

5. according to negative voltage translation circuit between each described direct current of claim 1～4, it is characterized in that: said first diode is a Schottky diode.

6. by negative voltage transform method between the direct current of each said circuit realization of claim 1～5, it is characterized in that, comprise the steps:

(1) soft start: before applying DC power supply, the voltage in the soft starting circuit on second electric capacity is zero, apply DC power supply after, the voltage on second electric capacity is that the voltage on the soft start input pin of power-supply controller of electric increases by zero gradually; When the voltage on second electric capacity is that voltage on the soft start input pin of power-supply controller of electric is during greater than the starting resistor of power-supply controller of electric inside; Then accomplished soft start-up process, the time of its soft start is confirmed by the size of the 6th resistance in the soft starting circuit and second electric capacity;

The charging of (2) first electric capacity: after the negative voltage translation circuit is accomplished soft start between said direct current; When the inner pliotron conducting of power-supply controller of electric; Form low impedance path between the pliotron collector electrode output pin of power-supply controller of electric and the reference ground pin, DC power supply is given inductance and the charging of first electric capacity; When the inner pliotron of power-supply controller of electric turn-offed, the electric current in the inductance changed by continuing through first diode to first electric capacity charging pliotron conducting once more that energy stored release finishes or power-supply controller of electric is inner in inductance; Realize that first electric capacity all obtains charging in inductance storage power and the process that releases energy;

(3) voltage adjustment:

(3-1) adjustment of boosting: after the negative voltage translation circuit is accomplished soft start between said direct current; In the voltage-regulating circuit; When the voltage magnitude of negative voltage output descends; Correspondingly be loaded into the reference utmost point of three end parallel connection type voltage stabilizing didoes and the voltage between the anode also descends through first resistance and second electric resistance partial pressure; If the reference utmost point and the voltage between the anode that are loaded into three end parallel connection type voltage stabilizing didoes through first resistance and second electric resistance partial pressure are less than the inner reference voltage of three end parallel connection type voltage stabilizing didoes; Then the input current of the negative electrode of three end parallel connection type voltage stabilizing didoes descends, and the electric current of transistor collector descends simultaneously, and the voltage that is loaded into the feedback input pin of power-supply controller of electric through the 4th resistance and the 5th resistance also descends; Power-supply controller of electric correspondingly increases the ON time of internal power triode, to reduce its turn-off time;

(3-2) step-down adjustment: after the negative voltage translation circuit is accomplished soft start between said direct current; In the voltage-regulating circuit; When the voltage magnitude of negative voltage output rises; Correspondingly be loaded into the reference utmost point of three end parallel connection type voltage stabilizing didoes and the voltage between the anode also rises through first resistance and second electric resistance partial pressure; If the reference utmost point and the voltage between the anode that are loaded into three end parallel connection type voltage stabilizing didoes through first resistance and second electric resistance partial pressure are greater than the inner reference voltage of three end parallel connection type voltage stabilizing didoes; Then the input current of the negative electrode of three end parallel connection type voltage stabilizing didoes rises, and the electric current of the collector electrode of triode rises simultaneously, and the voltage that is loaded into the feedback input pin of power-supply controller of electric through the 4th resistance and the 5th resistance also rises; Power-supply controller of electric correspondingly reduces the ON time of internal power triode, to increase its turn-off time.

7. according to negative voltage transform method between the direct current of the said circuit of claim 6; It is characterized in that: in the said step (3); Voltage-regulating circuit is when boosting adjustment or step-down adjustment, and the 3rd resistance is realized the leakage current bypass to three end parallel connection type voltage stabilizing didoes.

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