TW201732482A - Voltage control circuit and constant-current driving device using the same - Google Patents

Abstract

A voltage control circuit for a constant-current driving device is disclosed. The constant-current driving device comprises a first resistance component and a voltage control component which are electrically connected with an input power. The voltage control circuit comprises a first voltage dividing component which is electrically connected with the first resistance component, a second voltage dividing component which is electrically connected with the first voltage dividing component and a grounding terminal, and a current control component. A control terminal of the current control component is electrically connected between the first voltage dividing component and the second voltage dividing component. A current input terminal of the current control component is electrically connected with the first voltage dividing component and a gate terminal of the voltage control component. A current output terminal of the voltage control component is electrically connected with the grounding terminal. Wherein according to the comparison result of the voltage of the control terminal and the threshold voltage of the current control component, the current control component processes an on-off operation to control the voltage of gate terminal of the voltage control component for generating a stable current.

Description

Voltage control circuit and its suitable constant current driving device

The present invention relates to a voltage control circuit, and more particularly to a voltage control circuit capable of saving cost and capable of controlling the current output and improving the service life, and a constant current driving device suitable for the same.

In recent years, due to the breakthrough of the light-emitting diode (LED) manufacturing technology, the luminance and luminous efficiency of the light-emitting diode have been greatly improved, so that the light-emitting diode gradually replaces the traditional light tube and becomes a new illumination. Components are widely used in lighting applications such as home lighting devices, automotive lighting devices, hand-held lighting devices, liquid crystal panel backlights, traffic sign lights, indicator boards, and the like.

The characteristic of the light-emitting diode is to generate stable brightness by receiving a stable current. However, when the light-emitting diode is in some cases, for example, the voltage supplied to the light-emitting diode becomes large, etc., the light-emitting diode is caused. When the received current is correspondingly large, the brightness of the light-emitting diode is unstable and easily damaged. Therefore, when the light-emitting diode is applied to the illumination device, the current received by the light-emitting diode is often changed by the current driving device. When the current is fixed or limited to a certain range, in addition to maintaining a stable brightness of the light-emitting diode, the life of the light-emitting diode can be prolonged.

However, the conventional constant current driving device needs to use a relatively complicated circuit such as a controller to perform constant current control, so the cost of the conventional constant current driving device is high. In addition, although some conventional constant current driving devices are used as simple circuits for constant current control, the internal components of such a relatively simple circuit use a plurality of voltage control elements, such as a MOS field effect transistor. (Metal Oxide Semiconductor Field Effect Transistor, MOSFET), etc., thereby controlling the current flowing through the LED, and since the voltage control element is a voltage-controlled component, when the constant current driving device operates, the constant current driving device The voltage control element is easily damaged by the excessive input voltage received by the constant current driving device, so the conventional constant current driving device using a plurality of voltage control elements has a relatively short service life.

In view of this, how to develop a voltage control circuit capable of improving the above-mentioned conventional technology and its suitable constant current driving device is an urgent problem to be solved by those skilled in the related art.

The purpose of the present invention is to provide a voltage control circuit and a constant current driving device thereof, which are controlled by a current control component of a voltage control circuit, a first voltage dividing component and a second voltage dividing component to control a constant current driving device. The voltage of the gate of the voltage control element is controlled, and the constant current driving device controls the constant current by the voltage control circuit, the voltage control component, the first impedance component and the second impedance component, and solves the conventional constant current driving. The device has a high cost, or the conventional constant current driving device has a short life span due to the easy damage of the voltage control element.

In order to achieve the above object, a preferred embodiment of the present invention provides a voltage control circuit for a constant current driving device, wherein the constant current driving device has a first impedance component and a voltage control component electrically connected to an input source. The voltage control circuit includes: a first voltage dividing component, one end of the first voltage dividing component is electrically connected to the first impedance component; and the second voltage dividing component, one end of the second voltage dividing component and the other end of the first voltage dividing component Electrically connected, the other end of the second voltage dividing component is electrically connected to the grounding terminal; and the current control component has a current input end, a control end and a current output end, and the control end is electrically connected to the other end of the first voltage dividing component And one end of the second voltage dividing component, the current input end is electrically connected to one end of the first voltage dividing component and the gate terminal of the voltage control component, and the current output terminal is electrically connected to the ground terminal, wherein the current control component is controlled according to the control The switching between the voltage of the terminal and the threshold voltage of the current control component is turned on or off to control the voltage of the gate terminal of the voltage control component to make the power Driving means for generating a constant current.

In order to achieve the above object, another preferred embodiment of the present invention provides a constant current driving device, comprising: a first impedance component, one end of the first impedance component is electrically connected to the input source; and the voltage control component has a defect. The extreme, the gate terminal and the source terminal are electrically connected to the other end of the first impedance element, and the 汲 extreme system is electrically connected to one end of the first impedance element and the input source respectively; the second impedance element is electrically connected to the source terminal And a voltage control circuit, comprising: a first voltage dividing component, one end of the first voltage dividing component is electrically connected to the first impedance component; and the second voltage dividing component is one end of the second voltage dividing component Electrically connected to the other end of the first voltage dividing component, the other end of the second voltage dividing component is electrically connected to the grounding terminal; and the current control component has a current input terminal, a control terminal and a current output terminal, and the control terminal is electrically connected Between the other end of the first voltage dividing component and one end of the second voltage dividing component, the current input terminal is electrically connected between one end of the first voltage dividing component and the gate terminal of the voltage control component, and the current The output terminal is electrically connected to the ground terminal, wherein the current control component is switched on or off according to the comparison between the voltage of the control terminal and the threshold voltage of the current control component to control the voltage of the gate terminal of the voltage control component to make a constant current The drive produces a steady current.

Some exemplary embodiments embodying the features and advantages of the present invention are described in detail in the following description. It is to be understood that the present invention is capable of various modifications in the various aspects of the present invention, and the description and drawings are intended to be illustrative and not limiting.

Please refer to FIG. 1 , which is a schematic diagram of the circuit structure of the constant current driving device according to the preferred embodiment of the present invention. As shown in FIG. 1, the constant current driving device 1 of the present embodiment is electrically connected to an input source 2, such as an alternating current power source or a direct current power source, to receive an input voltage Vin provided by the input source 2, and includes a voltage control element 11 The first impedance element 13, the second impedance element 14, and the voltage control circuit 3. The first impedance element 13 can be a resistive element or a variable resistive element. In the embodiment, the first impedance element 13 is used as a resistive element, but is not limited thereto. One end of the first impedance element 13 is electrically connected to the input source 2 to receive the input voltage Vin.

The voltage control element 11 has a 汲 terminal 11a, a gate terminal 11b and a source terminal 11c, wherein the gate terminal 11b is electrically connected to the other end of the first impedance element 13, and the 汲 terminal 11a is respectively connected to one end of the first impedance element 13 and an input source. 2 is electrically connected, and receives the input voltage Vin, and the source terminal 11c outputs a stable current according to the voltage between the gate terminal 11b and the source terminal 11c.

In some embodiments, as shown in FIG. 1, the voltage control element 11 can be formed by a MOS field effect transistor, such as an NMOS transistor, but not limited thereto, or a PMOS transistor.

One end of the second impedance element 14 is electrically connected to the source terminal 11c of the voltage control element 11, and the other end of the second impedance element 14 is electrically connected to the ground terminal G, that is, the second impedance element 14 is electrically connected to the source terminal 11c. And between the ground terminal G. When the voltage control element 11 is turned on and the 汲 terminal 11a receives the input voltage Vin, a first current I1 is formed and flows into the second impedance element 14 via the 汲 terminal 11a, the source terminal 11c, and the first impedance element 14 is generated. Voltage V1.

In some embodiments, the second impedance element 14 can be, for example, a resistive element as shown in FIG. 1 , but is not limited thereto, and is also a variable resistive element. In addition, the second impedance element 14 can be used to detect current, for example, to detect the magnitude of the first current I1. Moreover, the user can adjust the resistance value of the second impedance element 14 according to the requirement, and then adjust the magnitude of the first voltage V1 (ie, the magnitude of the voltage drop on the second impedance element 14).

The voltage control circuit 3 is electrically connected to the other end of the first impedance element 13, the gate terminal 11b of the voltage control element 11, and the ground terminal G for controlling the voltage of the gate terminal 11b of the voltage control element 11 and has current control. The component 12, the first voltage dividing component 15 and the second voltage dividing component 16, wherein one end of the first voltage dividing component 15 is electrically connected to the other end of the first impedance component 13 and the gate terminal 11b of the voltage control component 11, and One end of the two voltage dividing element 16 is electrically connected to the other end of the first voltage dividing element 15, and the other end of the second voltage dividing element 16 is electrically connected to the grounding end G. In the above embodiment, the first voltage dividing element 15 and the second voltage dividing element 16 may be formed of, for example, a resistive element as shown in FIG. 1 , but not limited thereto, and are also composed of a variable resistive element.

The current control element 12 has a current input terminal 12a, a control terminal 12b, and a current output terminal 12c. The control terminal 12b is electrically connected between the other end of the first voltage dividing component 15 and one end of the second voltage dividing component 16, and the current input terminal 12a is connected to the other end of the first impedance component 13 and the first voltage dividing component. One end of the 15 is electrically connected to the gate terminal 11b of the voltage control element 11, and the current output terminal 12c is electrically connected between the other end of the second voltage dividing element 16 and the ground terminal G. When the first impedance element 13 receives the input voltage Vin of the input source 2, a second current I2 is formed to flow through the first impedance element 13 and flow into the voltage control circuit 3, wherein when the second current I2 flows into the voltage control circuit 3, A second voltage V2 is formed on the control terminal 12b of the current control element 12 via the first voltage dividing element 15 and the second voltage dividing element 16.

In some embodiments, as shown in FIG. 1, the current control element 12 can be formed by an NPN bipolar junction transistor, so the current input terminal 12a, the control terminal 12b, and the current output terminal 12c are Corresponding to the set extreme, base and emitter extremes of the NPN bipolar junction transistor, the current control component 12 is not limited to the NPN dual carrier junction transistor, but may also be connected by a PNP dual carrier. The surface is composed of a transistor.

The current control element 12 performs an operation of turning on or off according to a comparison between a second voltage V2 and a threshold voltage of the current control element 12 itself, and generates a stable voltage to correspond to the gate of the control voltage control element 11. The voltage of the terminal 11b is substantially stable to a certain value, further illustrating that the current control element 12 compares the second voltage V2 received by the control terminal 12b with a threshold voltage (e.g., the threshold voltage of the current control element 12 is 0.7 volt). As a result, when the second voltage V2 is greater than the threshold voltage, the current control element 12 will be in an on state and generate an internal resistance until the second voltage V2 is less than the threshold voltage, the current control element 12 will be changed to the off state, so the current The control element 12 performs the switching operation of turning on or off in the above case, and after a nanosecond operation, the voltage flowing through the current controlling element 12 tends to be stable and generates a fixed voltage, and then the voltage controlling element 11 is controlled. The voltage of the gate terminal 11b tends to be stable, so that the voltage control element 11 limits the first current I1 flowing through the voltage control element 11, The effect is to achieve constant current.

In addition, the constant current driving device 1 of the present embodiment is applied to a device or device (ie, a load) of a certain current, that is, the input source 2 (ie, the power source) of the constant current driving device 1 is connected in series with a load (not shown) The load system can be a light-emitting diode (not shown) for outputting a stable current through the constant current driving device 1 to maintain a certain brightness of the light-emitting diode, but not limited thereto; In the actual implementation of the invention, the load may also be selected as a light-emitting diode device (for example, a light-emitting diode lamp), a charger, and a power supply, but not limited thereto.

The operation of the current driving device 1 of the present invention will be further explained below. During normal operation, the anode terminal 11a of the voltage control element 11 and one end of the first impedance element 13 receive the input voltage Vin of the input source 2, and the first current I1 flows into the second impedance via the 汲 terminal 11a and the source terminal 11c. The element 14 is configured to form a first voltage V1 on the second impedance element 14, and the input source 2 of the constant current driving device 1 can be connected in series, so that the load operates by receiving the first current I1, and the second current I2 flows through the first An impedance element 13 flows into the voltage control circuit 3, and a second voltage V2 is formed at the control terminal 12b of the current control element 12, and the current control element 12 is compared according to the comparison of the threshold voltage of the second voltage V2 and the current control element 12. The switching operation of the on or off is performed, and after the operation of the nanosecond time, the voltage flowing through the current control element 12 tends to be stable, and the voltage control element is stabilized even if the voltage of the gate terminal 11b of the voltage control element 11 is stable. 11 can limit the first current I1 flowing through the voltage control element 11 to achieve the effect of constant current.

As can be seen from the above, compared with the conventional constant current driving device, the current driving device 1 of the present invention only needs to utilize the voltage control element 11, the current control element 12, the first impedance element 13, the second impedance element 14, and the first voltage dividing element. The mutual matching between the 15 and the second voltage dividing element 16 can maintain the first current I1 at a stable current value, so that it is no longer necessary to set a complicated circuit such as a controller to perform constant current control, so the current driving in the present case The production cost of the device can be reduced. In addition, the current driving device 1 of the present invention actually achieves the effect of constant current by the mutual matching of the voltage control element 11 and the current control element 12 of the voltage control circuit 3, and the current control element 12 of the voltage control circuit 3 is The current-controlled component is not easily damaged by the change of the input voltage Vin, and the current control component 12 of the present invention can limit the received current by the first voltage-dividing component 15 and the second voltage-dividing component 16, so The current control element 12 does not cause damage due to the excessive current received by the voltage control circuit 3. Therefore, compared with some conventional constant current driving devices, a plurality of voltage control elements are used for constant current control, and the current driving device 1 of the present invention The voltage control circuit 3 has a long service life due to the use of the less susceptible current control element 12.

In addition, when the input voltage Vin of the input source 2 suddenly changes sharply, for example, when the user mistakenly connects the input voltage Vin of the constant current driving device 1 to 110v to the input voltage Vin of 220v, the constant current driving device will be enabled. 1 The received input voltage Vin is pulled up instantaneously, which causes the voltage control element 11 of the constant current driving device 1 to be easily damaged. Therefore, in order to protect the voltage control element 11 from being damaged due to the sudden rise of the input voltage Vin, in some embodiments. As shown in FIG. 2, the voltage control circuit 3 of the constant current driving device 1 further includes a fifth impedance element 17, a sixth impedance element 18, and a diode D. The cathode end of the diode D is electrically connected to the other end of the first voltage dividing element 15, the one end of the second voltage dividing element 16, and the control end 12b. One end of the fifth impedance element 17 is electrically connected to one end of the first impedance element 13 and the input source 2, and receives the input voltage Vin of the input source 2. One end of the sixth impedance element 18 is electrically connected to the anode end of the diode D and the other end of the fifth impedance element 17, and the other end of the sixth impedance element 18 is electrically connected to the ground terminal G. With the above circuit structure, when the input voltage Vin of the input source 2 is suddenly pulled up, the fifth impedance element 17 and the sixth impedance element 18 form a voltage dividing circuit and receive the input voltage Vin of the input source 2, and Since the pole body D is turned on, the current control element 12 is turned on by the input voltage Vin and forms a short circuit, so that the voltage of the gate terminal 11b of the voltage control element 11 is reduced to zero voltage, and thus the voltage control element 11 is turned off. The constant current driving device 1 is prevented from being damaged due to excessive electric energy.

In summary, the present invention provides a voltage control circuit and a suitable constant current driving device thereof, which control the constant current by matching the current control component, the first voltage dividing component and the second voltage dividing component of the voltage control circuit. The voltage of the gate terminal of the voltage control element of the driving device, and the constant current driving device controls the constant current by the voltage control circuit, the voltage control element, the first impedance element and the second impedance element, so that compared with The conventional constant current driving device needs to set a complicated circuit such as a controller to perform constant current control, and the production cost of the current driving device in the present case can be reduced. In addition, the current driving device of the present invention actually achieves the effect of constant current control by the mutual matching of the voltage control component and the current control component of the voltage control circuit, so that multiple voltage control is used compared to the conventional constant current driving device. The component is used for constant current control. The current drive device and voltage control circuit of this case are not easily damaged and have a long service life. The voltage control circuit of this case and its applicable constant current drive device are of great industrial value, and the application is made according to law.

This case has been modified by people who are familiar with the technology, but it is not intended to be protected by the scope of the patent application.

1‧‧‧Constant current drive
2‧‧‧ input source
Vin‧‧‧Input voltage
11‧‧‧Voltage control components
11a‧‧‧汲 Extreme
11b‧‧‧ gate extreme
11c‧‧‧ source extreme
13‧‧‧First impedance element
14‧‧‧Second impedance element
3‧‧‧Voltage control circuit
G‧‧‧ Grounding terminal
I1‧‧‧First current
I2‧‧‧second current
V1‧‧‧ first voltage
V2‧‧‧second voltage
12‧‧‧ Current control components
12a‧‧‧current input
12b‧‧‧Control end
12c‧‧‧current output
15‧‧‧First voltage dividing element
16‧‧‧Separate voltage component
17‧‧‧ fifth impedance element
18‧‧‧ sixth impedance element
D‧‧‧ diode

FIG. 1 is a schematic diagram showing the circuit structure of a constant current driving device according to a preferred embodiment of the present invention. FIG. 2 is a schematic diagram showing the circuit structure of a constant current driving device according to another preferred embodiment of the present invention.

1‧‧‧Constant current drive

2‧‧‧ input source

Vin‧‧‧Input voltage

11‧‧‧Voltage control components

11a‧‧‧汲 Extreme

11b‧‧‧ gate extreme

11c‧‧‧ source extreme

13‧‧‧First impedance element

14‧‧‧Second impedance element

3‧‧‧Voltage control circuit

G‧‧‧ Grounding terminal

I1‧‧‧First current

I2‧‧‧second current

V1‧‧‧ first voltage

V2‧‧‧second voltage

12‧‧‧ Current control components

12a‧‧‧current input

12b‧‧‧Control end

12c‧‧‧current output

15‧‧‧First voltage dividing element

16‧‧‧Separate voltage component

Claims (5)

A voltage control circuit is applied to a constant current driving device, wherein the constant current driving device has a first impedance component and a voltage control component electrically connected to an input source, and the voltage control circuit comprises: a first voltage divider An end of the first voltage dividing component is electrically connected to the first impedance component; a second voltage dividing component, one end of the second voltage dividing component is electrically connected to the other end of the first voltage dividing component, The other end of the second voltage dividing component is electrically connected to a grounding terminal; and a current control component has a current input terminal, a control terminal and a current output terminal, wherein the control terminal is electrically connected to the first partial voltage Between the other end of the component and the one end of the second voltage dividing component, the current input terminal is electrically connected to the one end of the first voltage dividing component and one gate terminal of the voltage control component, and the current output terminal is Electrically connected to the grounding terminal, wherein the current control component is switched on or off according to a comparison between a voltage of the control terminal and a threshold voltage of the current control component. , The control voltage for controlling the gate terminal voltage of the element, so that the constant current drive means for generating a constant current. The voltage control circuit of claim 1, wherein the current control element is an NPN bipolar junction transistor. The voltage control circuit of claim 2, wherein the current input terminal, the control terminal and the current output terminal of the current control component are respectively a set terminal of the NPN bipolar junction transistor. One base extreme and one extreme. The voltage control circuit of claim 1, further comprising a fifth impedance component, a sixth impedance component and a diode, wherein the cathode end of the diode is opposite to the first voltage component The other end, the one end of the second voltage dividing component and the control end are electrically connected, and one end of the fifth impedance component is electrically connected to the first impedance component and the input source, and one end of the sixth impedance component is The anode end of the diode and the other end of the fifth impedance element are electrically connected, and the other end of the sixth impedance element is electrically connected to the ground. A constant current driving device includes: a first impedance component, one end of the first impedance component is electrically connected to an input source; and a voltage control component has a 汲 extreme, a gate terminal and a source terminal, The gate terminal is electrically connected to the other end of the first impedance element, and the gate terminal is electrically connected to the one end of the first impedance element and the input source respectively; a second impedance element is electrically connected to the source terminal and And a voltage control circuit, comprising: a first voltage dividing component, one end of the first voltage dividing component is electrically connected to the first impedance component; a second voltage dividing component, the second One end of the voltage dividing element is electrically connected to the other end of the first voltage dividing element, the other end of the second voltage dividing element is electrically connected to a ground end; and a current control element has a current input end, a control terminal and a current output terminal, the control terminal is electrically connected between the other end of the first voltage dividing component and the one end of the second voltage dividing component, the current The input end is electrically connected between the one end of the first voltage dividing element and the gate end of the voltage control element, and the current output end is electrically connected to the ground end, wherein the current control element is based on the voltage of the control end A switching operation of turning on or off is performed in comparison with a threshold voltage of the current control element to control a voltage of the gate terminal of the voltage control element to cause a steady current to be generated by the constant current driving device.