CN2783625Y - Small inductance boosting type DC converter - Google Patents

Abstract

A small inductance step-up DC converter is prepared as using multivibrator to generate square-wave signal with adjustable frequency and duty ratio to drive switch transistor to be switched on and off, connecting inductance current in collector loop of transistor in series to make relevant change along with switching on and off of transistor, generating instantaneous high voltage at one end of inductance when switching on and off according to self-inductance effect, obtaining stable high voltage and small current output by rectification and filtering. The utility model discloses be fit for providing the biasing high pressure for portable equipment, the advantage is light in weight, small.

Description

Small Inductor Boost DC Converter

technical field

The utility model relates to a DC converter, in particular to a small inductance step-up DC converter with high voltage and low current output, which is suitable for photoelectric conversion devices, sensor bias circuits and avalanche photodiode detectors in small portable products.

Background technique

With the development of microelectronics technology, electronic equipment is improving towards integration, portability and digitalization, which requires the modules in the system to be more and more miniaturized and low power consumption. Therefore, in addition to stability, reliability, and high efficiency, miniaturization and light weight are also very urgent needs among the technical requirements put forward by the electronic system for the power supply device.

At present, many electronic systems are directly powered by batteries or only by a basic voltage, but many detectors, sensors and modules require a bias voltage much higher than the basic voltage, and a simple three-terminal linear regulator cannot meet the requirements. Only Step-up switching power supply is adopted. However, the traditional step-up switching power supply design circuit is complex, bulky, its own power consumption and weight are relatively large, and cannot be used in portable products with strict requirements on volume, weight and power consumption. Although the existing integrated step-up DC/DC converters can be small and light in size and weight, it is difficult for the output voltage to reach the high voltage required by general bias circuits.

In the prior art, the step-up DC/DC conversion method usually uses an oscillator to chop the DC signal, and then rectifies and filters the voltage after being transformed by the step-up transformer to generate a high-voltage DC output. The circuit principle is shown in Figure 1 , using the 555 integrated timer to form a square wave generator, the square wave signal drives the switching transistor VT to flip between the on and off states, thereby driving the transformer T to work, the output of the transformer is rectified by the diode VD, and outputs DC high voltage. Usually, in order to obtain the required high-voltage output, a capacitor is used for voltage doubler rectification. Since this method uses a transformer as a step-up element, its volume and weight cannot be made very small.

Another DC conversion method is the pulse width modulation (PWM) switching converter widely used at present. The input DC voltage is chopped by a high-frequency power switch, and energy storage elements such as capacitors and inductors are used to obtain separated energy from the input voltage source. , temporarily store energy in an inductor in the form of a magnetic field, or store it in a capacitor in the form of an electric field, and then convert the energy to the load to realize DC/DC conversion. The PWM technology is used to control the duty factor of the switching pulse by the output feedback to stabilize the output voltage, and the physical size of the energy storage element can be reduced by increasing the switching frequency. Switching converters are favored by people because of their high stability, high efficiency, flexible positive and negative polarity, and step-up and step-down methods. However, their circuits are relatively complicated. When used as a boost converter, the energy storage element or Transformers and complex circuits will still limit miniaturization. Another is to integrate the power switch, synchronous flow controller and control circuit, and externally connect the energy storage inductor and input/output filter capacitor, thereby greatly reducing the volume and weight. However, the output voltage of this type of product is currently Still can't meet the requirement.

In a word, the step-up DC/DC conversion method in the prior art adopts components such as a step-up transformer, a voltage doubler capacitor, an energy storage capacitor, and an inductor, and the weight and volume of the transformer are relatively large. However, the method of integrating control circuits often cannot provide a higher output voltage.

Contents of the invention

The technical problem to be solved by the utility model is to overcome the deficiencies of the above-mentioned prior art, and provide a small inductance step-up DC converter to realize high voltage and small current output, while having the advantages of light weight and small volume.

The basic principle of the utility model is that the switching signal is generated by the square wave generator, and the high-voltage pulse is generated by the self-inductance characteristic of the inductance element, and then the required DC high voltage is output through rectification and filtering.

The technical solution of the utility model is as follows:

A small inductive step-up DC converter, using 555 integrated timer as a square wave generator, the first resistor and the second resistor are respectively connected between the 6th pin and the 7th pin of the 555 integrated timer and the 7th pin Between the 555 integrated timer and the power supply, the node between the 6th pin and the 2nd pin of the 555 integrated timer and the second resistor is grounded through the first capacitor, the 1st pin is grounded, the 5th pin is grounded through the capacitor, and the 4th and 8th pins are connected to the power supply , the third pin is connected to the control pole of the switching transistor, the collector of the switching transistor is connected to the power supply through a booster, the emitter of the switching transistor is grounded, and it is characterized in that the first resistor and the second resistor are adjustable resistors ; The booster is a boost inductor, the node of the boost inductor and the collector of the switching transistor is connected to the positive pole of a rectifier diode, the negative pole of the rectifier diode is grounded again through a high-voltage filter capacitor, the rectifier diode The node of the negative electrode and the high-voltage filter capacitor is used as the output terminal of the DC high voltage.

The switching transistor adopts a fast switching transistor MMBAT42 with high withstand voltage and reduced saturation tube voltage, which is beneficial to reduce power consumption.

The boost inductor 3 should try to use an inductor with small volume, large inductance and saturation current.

The high-voltage filter capacitor is a non-polar capacitor with a withstand voltage greater than 300V.

The advantages and characteristics of the utility model are:

(1) The frequency and duty cycle of the square wave generator of the utility model can be adjusted by adjusting the first variable resistor and the second variable resistor, so that the output voltage can be adjusted in a wide range.

(2) The utility model adopts the step-up inductor to directly boost the voltage, which has high conversion efficiency and greatly reduces volume and weight.

(3) The utility model is small in size and light in weight.

Description of drawings

Fig. 1 is a circuit schematic diagram of a step-up DC conversion method in the prior art

Fig. 2 is a schematic circuit diagram of a specific embodiment of an inductance step-up DC converter of the present invention

Detailed ways

Please refer to FIG. 2 . FIG. 2 is a schematic circuit diagram of a specific embodiment of the inductive step-up DC converter of the present invention. It can be seen from the figure that the small inductance step-up DC converter of the present invention adopts the 555 integrated timer as the square wave generator, and the first resistor R1 and the second resistor R2 are respectively connected between the 6th pin and the 7th pin of the 555 Between pin 7 and power supply Vcc, the node between pin 6 and pin 2 of the 555 integrated timer and the second resistor R2 is grounded through the first capacitor C1, pin 1 is grounded, and pin 5 is grounded through the second capacitor C2 Grounding, the 4th and 8th pins are connected to the power supply Vcc, the 3rd pin is connected to the control pole of the switching transistor T, the collector of the switching transistor T is connected to the power supply Vcc through a booster, and the emitter of the switching transistor T is grounded. The first resistor R1 and the second resistor R2 are adjustable resistors; the booster is a boost inductor L, and the node between the boost inductor L and the collector of the switching transistor T is connected to a rectifier diode D The positive poles of the rectifier diode D are connected to each other, and the negative pole of the rectifier diode D is grounded again through a high-voltage filter capacitor C3.

The switching transistor T is a fast switching transistor MMBAT42 with high withstand voltage and low saturation tube voltage. The inductance of the boost inductor L is 2.2MH.

The high-voltage filter capacitor C4 is a non-polar capacitor with a withstand voltage greater than 300V. The equivalent series resistance of the filter capacitor is the main factor causing the output wave, and it will also affect the conversion efficiency. A capacitor with a low equivalent series resistance should be selected.

A square wave generator with adjustable frequency and duty ratio is composed of 555 integrated timer and adjustable resistors R1 and R2. After voltage division, it drives the switching transistor T. When the input is high, the transistor T is turned on and connected in series. The boost inductor L in the electrode circuit is charged. When the low level comes, the triode T is cut off. At this time, due to the self-inductance effect of the boost inductor L, a high-voltage pulse is generated, and the output filter capacitor C4 is charged through the fast rectifier diode D, resulting in High voltage, low current DC output Vout.

To sum up, the inductive step-up DC converter of the present invention has the advantages of small size, light weight, high conversion efficiency and the ability to provide high voltage and low current output.

Claims (4)

1, a kind of small inductance boost type DC converter, adopt 555 integrated timers as square-wave generator (1), first resistance (R1) and second resistance (R2) are connected on respectively between 555 the 6th pin and the 7th pin and between the 7th pin and the power supply (Vcc), the node of the 6th pin of this 555 integrated timer and the 2nd pin and second resistance (R2) is by first electric capacity (C1) ground connection, the 1st pin ground connection, the 5th pin is by second electric capacity (C2) ground connection, the the 4th and the 8th pin connects power supply (Vcc), the 3rd pin connects the control utmost point of switch triode (T), the collector electrode of this switch triode (T) connects power supply (Vcc) by a stepup transformer, the grounded emitter of this switch triode (T) is characterized in that described first resistance (R1) and second resistance (R2) are adjustable resistance; Described stepup transformer is boost inductance (L), the node of this boost inductance (L) and the collector electrode of this switch triode (T) links to each other with the positive pole of rectifier diode (D), the negative pole of this rectifier diode (D) passes through a high-voltage filtering capacitor (C3) ground connection again, and the node of negative pole of this rectifier diode (D) and high-voltage filtering capacitor (C3) is made the output of high direct voltage.

2, small inductance boost type DC converter according to claim 1 is characterized in that described switch triode (T) employing withstand voltage height, the high-speed switch triode MMBAT42 that saturated tube voltage drop is low.

3, small inductance boost type DC converter according to claim 1, the inductance value that it is characterized in that described boost inductance (L) is 2.2MH.

4,, it is characterized in that described high-voltage filtering capacitor (C3) is the polarity free capacitor of withstand voltage greater than 300V according to each described small inductance boost type DC converter of claim 1 to 3.

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