US-12628253-B2 - LED driving device and LED lighting device including the same

Abstract

The present disclosure relates to a light emitting diode (LED) driving device that may expand a usable range of LED current and battery voltage by reducing heat generation of an integrated circuit, and an LED lighting device including the same, which may include a current controller that constantly controls an LED current flowing through an LED string and an IC heat dissipation part connected to a node between the LED string and the current controller to dissipate IC heat of the current controller, wherein when a battery voltage supplied to the LED string increases, the IC heat dissipation part reduces a first LED current flowing from the LED string to the current controller and simultaneously increases a second LED current flowing from the LED string to the current controller via the IC heat dissipation part, thereby reducing the IC heat generation of the current controller.

Inventors

• Byung Jun SEO
• Ji Hwan Kim
• Young Jin Woo
• Jong Min Lee
• Ju Pyo Hong

Assignees

• LX SEMICON CO., LTD.

Dates

Publication Date

20260512

Application Date

20231101

Priority Date

20221101

Claims (20)

1. 1 . A light emitting diode (LED) driving device comprising: a current controller configured to constantly control an LED current flowing through an LED string; and an IC heat dissipation part connected to a node between the LED string and the current controller to dissipate IC heat of the current controller, wherein when a battery voltage supplied to the LED string increases, a first LED current flowing from the LED string to the current controller is decreased and simultaneously a second LED current flowing from the LED string to the current controller via the IC heat dissipation part is increased to dissipate IC heat generation of the current controller, wherein the current controller includes: a first switching part that has one side connected to a node between the LED string and the IC heat dissipation part to form a first path through which the first LED current flows; and a second switching part that has one side connected to the IC heat dissipation part to form a second path through which the second LED current flows, and wherein a first output voltage provided to the first switching part and a second output voltage provided to the second switching part are different from each other so as to adjust a resistance difference between the first switching part and the second switching part.
2. 2 . The LED driving device of claim 1 , wherein the first switching part has the other side connected to a ground to form the first path; and the second switching part has the other side connected to the ground to form the second path.
3. 3 . The LED driving device of claim 2 , wherein the current controller includes: a voltage regulator configured to provide a reference voltage; and an amplifier configured to provide an output voltage to each of the first switching part and the second switching part based on the reference voltage provided from the voltage regulator and a feedback voltage provided through a wire connected to a node between the first and second switching parts and the ground.
4. 4 . The LED driving device of claim 3 , wherein the first switching part includes a first transistor connected to a first output terminal of the amplifier, and when the first output voltage is input from the first output terminal of the amplifier, the first switching part is configured to control the first LED current flowing from the LED string to the current controller based on the first output voltage.
5. 5 . The LED driving device of claim 3 , wherein the second switching part includes one second transistor or a plurality of second transistors connected to a second output terminal of the amplifier, and when the second output voltage is input from the second output terminal of the amplifier, the second switching part is configured to control the second LED current flowing from the LED string to the current controller via the IC heat dissipation part based on the second output voltage.
6. 6 . The LED driving device of claim 1 , wherein the IC heat dissipation part includes a heat dissipation resistor that has one side connected to the first switching part of the current controller and the other side connected to the second switching part of the current controller.
7. 7 . The LED driving device of claim 6 , wherein the IC heat dissipation part includes one heat dissipation resistor when a first transistor included in the first switching part is one and the second transistor included in the second switching part is one.
8. 8 . The LED driving device of claim 6 , wherein the IC heat dissipation part includes a plurality of heat dissipation resistors when the first transistor included in the first switching part is one and a second transistor included in the second switching part is plural.
9. 9 . The LED driving device of claim 6 , wherein a resistance value of the heat dissipation resistor is determined according to at least one of LED current consumption of the LED string and a power capacity of a battery that provides the battery voltage.
10. 10 . The LED driving device of claim 6 , wherein a resistance value of the heat dissipation resistor is determined based on a resistance value of a resistor connected between the first and second switching parts and the ground.
11. 11 . The LED driving device of claim 6 , wherein a size of a resistance value of the heat dissipation resistor is directly proportional to a size of a battery voltage value corresponding to a current saturation point including a first time point when the first LED current is decreased and then becomes constant or a second time point when the second LED current is increased and then becomes constant.
12. 12 . The LED driving device of claim 11 , wherein when the battery voltage increases, the IC heat dissipation part gradually decreases the first LED current and maintains it constant at the current saturation point and gradually increases the second LED current and maintains it constant at the current saturation point to dissipate IC power of the current controller.
13. 13 . The LED driving device of claim 12 , wherein IC power before the current saturation point is calculated by Equation of P1_IC=(V LC ×ILED)−(V LC 2 /RHD) (where P1_IC is the IC power before the current saturation point, V LC is the LED voltage flowing from the LED string to the current controller, ILED is the LED current flowing from the LED string to the current controller, and RHD is the resistance of the heat dissipation resistor of the IC heat dissipation part).
14. 14 . The LED driving device of claim 12 , wherein IC power after the current saturation point is calculated by Equation of P2_IC=(V LC ×ILED)−(ILED 2 /RHD) (where P2_IC is the IC power after the current saturation point, V LC is the LED voltage flowing from the LED string to the current controller, ILED is the LED current flowing from the LED string to the current controller, and RHD is the resistance of the heat dissipation resistor of the IC heat dissipation part).
15. 15 . The LED driving device of claim 12 , wherein a voltage at the current saturation point is calculated by Equation of V LC =ILED×RHD (where V LC is the LED voltage flowing from the LED string to the current controller at the current saturation point, ILED is the LED current flowing from the LED string to the current controller, and RHD is the resistance of the heat dissipation resistor of the IC heat dissipation part).
16. 16 . The LED driving device of claim 1 , wherein the current controller includes: a voltage detector configured to detect an LED voltage flowing through the node between the LED string and the IC heat dissipation part; a current selector configured to select any one of the first LED current applied from the LED string and the second LED current applied from the IC heat dissipation part based on the detected LED voltage to output the selected LED current to the current controller; and a switching part that has one side connected to the current selector and the other side connected to a ground to control the first LED current or the second LED current.
17. 17 . The LED driving device of claim 16 , wherein the current selector includes: a first switch configured to electrically connect the LED string and the switching part according to a control signal of the voltage detector; and a second switch configured to electrically connect the IC heat dissipation part and the switching part according to the control signal of the voltage detector.
18. 18 . The LED driving device of claim 17 , wherein the second switch includes one switch or a plurality of switches according to the number of heat dissipation resistors of the IC heat dissipation part.
19. 19 . An LED driving method of an LED driving device in which an IC heat dissipation part is connected between an LED string and a current controller comprising: detecting an LED voltage from a node between the LED string and the IC heat dissipation part; checking whether the detected LED voltage increases; controlling an LED current such that the LED current of the LED string is switched from a first path flowing from the LED string to the current controller to a second path flowing from the LED string to the current controller via the IC heat dissipation part when the LED voltage increases; and reducing IC heat generation of the current controller when the LED current flows through the second path, wherein the current controller includes: a first switching part that has one side connected to a node between the LED string and the IC heat dissipation part to form the first path through which the first LED current flows; and a second switching part that has one side connected to the IC heat dissipation part to form the second path through which the second LED current flows, and wherein a first output voltage provided to the first switching part and a second output voltage provided to the second switching part are different from each other so as to adjust a resistance difference between the first switching part and the second switching part.
20. 20 . An LED lighting device comprising: an LED string to which a plurality of LEDs are connected; a battery configured to supply a voltage to the LED string; a current controller configured to constantly control an LED current flowing through the LED string; and an IC heat dissipation part connected to a node between the LED string and the current controller to dissipate IC heat of the current controller, wherein when the battery voltage supplied to the LED string increases, a first LED current flowing from the LED string to the current controller is decreased and simultaneously a second LED current flowing from the LED string to the current controller via the IC heat dissipation part is increased to reduce IC heat generation of the current controller, wherein the current controller includes: a first switching part that has one side connected to a node between the LED string and the IC heat dissipation part to form a first path through which the first LED current flows; and a second switching part that has one side connected to the IC heat dissipation part to form a second path through which the second LED current flows, and wherein a first output voltage provided to the first switching part and a second output voltage provided to the second switching part are different from each other so as to adjust a resistance difference between the first switching part and the second switching part.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to and the benefit of Korean Patent Application No. 10-2022-0143757, filed on Nov. 1, 2022, the disclosure of which is incorporated herein by reference in its entirety. TECHNICAL FIELD The present disclosure relates to a light emitting diode (LED) driving device that may expand a usable range of LED current and battery voltage by reducing heat generation of an integrated circuit, and an LED lighting device including the same. BACKGROUND In general, a vehicle may employ lighting devices for various uses inside or outside the vehicle. As an example, the lighting devices of the vehicle may include rear combination lamps installed on both sides of the rear of the vehicle. The rear combination lamps may include a turn signal lamp, a stop lamp, a tail lamp, a backup lamp, and the like and may be used to inform drivers of other vehicles following an ego vehicle of a driving intention and state of the ego vehicle. Recently, lighting devices using high-brightness light emitting diodes (LEDs) have been developed, and rear combination lamps using the LEDs have been developed as lighting devices for vehicles. Rear combination lamps that use LEDs as light sources have changed into various designs, and the number of LEDs used in rear combination lamps has tended to gradually increase according to the design change. As described above, the LED lighting devices need to operate stably without generating heat, save power, and be developed to be implemented with a small number of components. However, in the LED lighting devices, when a voltage supplied from a battery increases due to an external or internal environment, a voltage applied to a current controller switch of an LED driving device increases and integrated circuit power (IC Power) of the switch increases, so that heat generation in the integrated circuit increases and restrictions on the LED current and battery voltage occur. Therefore, it is necessary to develop an LED driving device capable of expand a usable range of LED current and battery voltage by reducing heat generation of an integrated circuit in the future. SUMMARY Technical Problem The present disclosure is directed to solving the above-described problems and other problems. The present disclosure is directed to providing a light emitting diode (LED) driving device capable of reducing IC heat generation of a current controller and expanding a usable range of LED current and battery voltage by distributing IC power according to an increase in a battery voltage using an IC heat dissipation part disposed between an LED string and the current controller, and an LED lighting device including the same. Technical Solution A light emitting diode (LED) driving device according to an embodiment of the present disclosure includes a current controller that constantly controls an LED current flowing through an LED string and an IC heat dissipation part connected to a node between the LED string and the current controller to dissipate IC heat of the current controller, wherein when a battery voltage supplied to the LED string increases, the IC heat dissipation part dissipates a first LED current flowing from the LED string to the current controller and simultaneously increases a second LED current flowing from the LED string to the current controller via the IC heat dissipation part, thereby reducing IC heat generation of the current controller. An LED driving method according to an embodiment of the present disclosure, which is an LED driving method of an LED driving device in which an IC heat dissipation part is connected between an LED string and a current controller, may include detecting an LED voltage from a node between the LED string and the IC heat dissipation part, checking whether the detected LED voltage increases, controlling an LED current such that the LED current of the LED string is switched from a first path flowing from the LED string to the current controller to a second path flowing from the LED string to the current controller via the IC heat dissipation part when the detected LED voltage increases, and reducing IC heat generation of the current controller when the LED current flows through the second path. An LED lighting device including an LED driving device according to an embodiment of the present disclosure may include an LED string to which a plurality of LEDs are connected, a battery that supplies voltage to the LED string, a current controller that constantly controls an LED current flowing through the LED string, and an IC heat dissipation part that is connected to a node between the LED string and the current controller to dissipate IC heat of the current controller, wherein when the battery voltage supplied to the LED string increases, the IC heat dissipation part dissipates a first LED current flowing from the LED string to the current controller and simultaneously increases a second LED current flowing from th