LED backlight driving chip and ESD protection method

Abstract

The invention discloses an LED (Light Emitting Diode) backlight driving chip. The LED backlight driving chip comprises an LED pin, a high-voltage MOS (Metal Oxide Semiconductor) switch tube M1 and a driving operational circuit, the high-voltage MOS switch tube is an NMOS (N-channel Metal Oxide Semiconductor) or PMOS (P-channel Metal Oxide Semiconductor) switch tube, a drain electrode of the NMOS or PMOS switch tube is connected with the LED pin, a grid electrode of the NMOS or PMOS switch tube is controlled by a PWM (Pulse Width Modulation) signal, and the NMOS or PMOS switch tube is controlled to be switched on or switched off by the PWM signal; the source electrode of the NMOS or PMOS switch tube is connected with the driving operation circuit; the LED backlight driving chip further comprises a high-voltage ESD unit and a low-voltage ESD unit, the high-voltage ESD unit is connected between the LED pin and the ground in parallel, and the low-voltage ESD unit is connected between the source electrode of the NMOS or PMOS switch tube and the ground or a power supply in parallel.

Description

Technical Field

[0001] The present invention relates to the technical field of LED backlight, and in particular to an LED backlight driver chip and an ESD protection method. Background Art

[0002] Liquid crystal display (LCD) is the largest screen display application in modern display panels. The liquid crystal material used in LCD panels cannot emit light by itself and needs to be provided by a backlight source. LED backlight sources have the advantages of energy saving, environmental protection, and high performance and are widely used in LCD display panels. The performance of LED backlight driver chips is crucial to LCD display panels.

[0003] like Figure 1 As shown, the LED driver chip in the prior art is provided with an LED pin for connecting an LED light string. When the LED light string is composed of multiple LED lamp beads connected in series, the voltage on the LED pin is usually high, for example, 40V. Therefore, the ESD (Electro-Static discharge) unit in the prior art is generally provided between the LED pin and the ground. Since the LED pin is in a high voltage state, the corresponding ESD unit also needs to use a high voltage device. The LED pin is connected to the high voltage switch tube M1 inside the LED driver chip and the low voltage drive operation circuit. Since the high voltage switch tube M1 is directly connected to the high voltage at the LED pin, a high voltage device is selected, and the drive operation circuit is used to realize the dimming control drive and operation of the LED, so a low voltage device with faster operating response speed and higher precision is adopted, for example, an operating voltage of 3 to 5V. However, in this structure, when ESD current comes, the snapback of the ESD device is used to quickly conduct and discharge, which can effectively protect the high-voltage switch tube M1, but it cannot effectively ensure that a part of the current enters the driving operation circuit. Therefore, when the ESD device is triggered to turn on, there will still be charges coupled into the driving operation circuit through the drain and source parasitic capacitance of the high-voltage switch tube M1, which will cause damage to the devices in the driving operation circuit to a certain extent.

[0004] It can be seen that a new ESD protection circuit for an LED backlight driver chip is needed in the art. The ESD protection circuit based on the new LED backlight driver chip can more effectively implement ESD protection for the driving operation circuit in the LED backlight driver chip. Summary of the invention

[0005] The present invention provides an LED backlight driver chip. The LED backlight driver chip realizes effective protection of high-voltage devices and low-voltage devices inside the chip by setting a two-level ESD protection circuit.

[0006] Based on the above technical purpose, the present invention provides an LED backlight driver chip, the LED backlight driver chip includes an LED pin, a high-voltage MOS switch tube M1 and a driving operation circuit;

[0007] The high-voltage MOS switch tube is an NMOS switch tube, the drain of the NMOS switch tube is connected to the LED pin, the gate of the NMOS switch tube is controlled by a PWM signal, and the PWM signal controls the NMOS switch tube to be turned on or off; the source of the NMOS switch tube is connected to the driving operation circuit;

[0008] The LED backlight driver chip further comprises a high voltage ESD unit and a low voltage ESD unit. The high voltage ESD unit is connected in parallel between the LED pin and the ground, and the low voltage ESD unit is connected in parallel between the source of the NMOS switch tube and the ground.

[0009] In one embodiment, the high-voltage ESD unit is a high-voltage GGNMOS device or an ESD circuit composed of a PNP transistor and an NPN transistor.

[0010] In one embodiment, the low voltage ESD unit adopts a low voltage GGNMOS device or an ESD circuit composed of a PNP transistor and an NPN transistor.

[0011] The present invention also provides another LED backlight driver chip, the LED backlight driver chip comprises an LED pin, a high-voltage MOS switch tube M1 and a driving operation circuit;

[0012] The high-voltage MOS switch tube is a PMOS switch tube, the drain of the PMOS switch tube is connected to the LED pin, the gate of the PMOS switch tube is controlled by a PWM signal, and the PWM signal controls the PMOS switch tube to be turned on or off; the source of the PMOS switch tube is connected to the driving operation circuit;

[0013] The LED backlight driver chip also includes a high-voltage ESD unit and a low-voltage ESD unit. The high-voltage ESD unit is connected in parallel between the LED pin and an external driving power supply, and the low-voltage ESD unit is connected in parallel between the source of the PMOS switch tube and the external driving power supply.

[0014] In one embodiment, the high-voltage ESD unit is a high-voltage GGNMOS device or an ESD circuit composed of a PNP transistor and an NPN transistor.

[0015] In one embodiment, the low voltage ESD unit adopts a low voltage GGNMOS device or an ESD circuit composed of a PNP transistor and an NPN transistor.

[0016] Compared with the prior art, one or more embodiments of the present invention may have the following advantages:

[0017] The LED backlight driver chip of the present invention realizes effective protection of high-voltage devices and low-voltage devices inside the chip by setting up a two-level ESD protection circuit, thereby avoiding the existing technology of only implementing ESD protection for high-voltage devices, which causes damage to the low-voltage device area due to part of the current of the high-voltage device entering the low-voltage device area when the high-voltage device performs ESD discharge.

[0018] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0020] Figure 1 It is a schematic diagram of the ESD unit structure in the LED backlight driver chip in the prior art;

[0021] Figure 2 is a schematic structural diagram of an LED backlight driver chip according to a first embodiment of the present invention;

[0022] Figure 3 It is a schematic diagram of the structure of the LED backlight driver chip according to the second embodiment of the present invention. DETAILED DESCRIPTION

[0023] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings.

[0024] It should be understood that when an element or layer is referred to as "on ...", "adjacent to ...", "connected to" or "coupled to" other elements or layers, it can be directly on, adjacent to, connected to or coupled to other elements or layers, or there can be intervening elements or layers. On the contrary, when an element is referred to as "directly on ...", "directly adjacent to ...", "directly connected to" or "directly coupled to" other elements or layers, there is no intervening element or layer. It should be understood that although the terms first, second, third, etc. can be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present invention, the first element, component, region, layer or part discussed below can be represented as the second element, component, region, layer or part. And when the second element, component, region, layer or part is discussed, it does not indicate that the present invention necessarily has the first element, component, region, layer or part.

[0025] Spatially relative terms such as "under", "beneath", "below", "under", "above", "above", etc., may be used here for convenience of description to describe the relationship between an element or feature shown in the figure and other elements or features. It should be understood that in addition to the orientation shown in the figure, the spatial relationship terms are intended to also include different orientations of the device in use and operation. For example, if the device in the accompanying drawings is turned over, then the elements or features described as "under other elements" or "under it" or "under it" will be oriented as "on" other elements or features. Therefore, the exemplary terms "under" and "under" may include both upper and lower orientations. The device can be oriented otherwise (rotated 90 degrees or other orientations) and the spatial descriptors used herein are interpreted accordingly.

[0026] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be limiting of the present invention. When used herein, the singular forms "one", "an" and "said / the" are also intended to include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0027] Example 1

[0028] like Figure 2The structure diagram of the LED backlight driver chip in the first embodiment of the present invention is shown, and the LED backlight driver chip includes an LED pin, a high-voltage MOS switch tube M1 and a driving operation circuit.

[0029] The high-voltage MOS switch tube is an NMOS switch tube, the drain of the NMOS switch tube is connected to the LED pin, the gate of the NMOS switch tube is controlled by a PWM signal, and the PWM signal controls the NMOS switch tube to be turned on or off; the source of the NMOS switch tube is connected to the driving operation circuit.

[0030] The LED backlight driver chip further comprises a high voltage ESD unit and a low voltage ESD unit. The high voltage ESD unit is connected in parallel between the LED pin and the ground, and the low voltage ESD unit is connected in parallel between the source of the NMOS switch tube and the ground.

[0031] The high-voltage ESD unit may be a high-voltage GGNMOS device or an ESD circuit composed of a PNP transistor and an NPN transistor.

[0032] The low-voltage ESD unit adopts a low-voltage GGNMOS device or an ESD circuit composed of a PNP transistor and an NPN transistor.

[0033] Example 2

[0034] like Figure 3 The structure diagram of the LED backlight driver chip in the second embodiment of the present invention is shown, and the LED backlight driver chip includes an LED pin, a high-voltage MOS switch tube M1 and a driving operation circuit.

[0035] The high-voltage MOS switch tube is a PMOS switch tube, the drain of the PMOS switch tube is connected to the LED pin, the gate of the PMOS switch tube is controlled by a PWM signal, and the PWM signal controls the PMOS switch tube to be turned on or off; the source of the PMOS switch tube is connected to the drive operation circuit.

[0036] The LED backlight driver chip also includes a high-voltage ESD unit and a low-voltage ESD unit. The high-voltage ESD unit is connected in parallel between the LED pin and an external driving power supply, and the low-voltage ESD unit is connected in parallel between the source of the PMOS switch tube and the external driving power supply.

[0037] The high-voltage ESD unit may be a high-voltage GGPMOS device or an ESD circuit composed of a PNP transistor and an NPN transistor.

[0038] The low-voltage ESD unit adopts a low-voltage GGPMOS device or an ESD circuit composed of a PNP transistor and an NPN transistor.

[0039] As described above, the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. An LED backlight driver chip, characterized in that: The LED backlight driver chip includes an LED pin, a high-voltage MOS switch tube M1 and a driving operation circuit; The high-voltage MOS switch tube is an NMOS switch tube, the drain of the NMOS switch tube is connected to the LED pin, the gate of the NMOS switch tube is controlled by a PWM signal, and the PWM signal controls the NMOS switch tube to be turned on or off; the source of the NMOS switch tube is connected to the driving operation circuit; The LED backlight driver chip further comprises a high voltage ESD unit and a low voltage ESD unit. The high voltage ESD unit is connected in parallel between the LED pin and the ground, and the low voltage ESD unit is connected in parallel between the source of the NMOS switch tube and the ground.

2. The LED backlight driver chip according to claim 1, characterized in that: The high-voltage ESD unit is a high-voltage GGNMOS device or an ESD circuit composed of a PNP transistor and an NPN transistor.

3. The LED backlight driver chip according to claim 1, characterized in that: The low-voltage ESD unit adopts a low-voltage GGNMOS device or an ESD circuit composed of a PNP transistor and an NPN transistor.

4. An LED backlight driver chip, characterized in that: The LED backlight driver chip includes an LED pin, a high-voltage MOS switch tube M1 and a drive operation circuit; The high-voltage MOS switch tube is a PMOS switch tube, the drain of the PMOS switch tube is connected to the LED pin, the gate of the PMOS switch tube is controlled by a PWM signal, and the PWM signal controls the PMOS switch tube to be turned on or off; the source of the PMOS switch tube is connected to the driving operation circuit; The LED backlight driver chip also includes a high-voltage ESD unit and a low-voltage ESD unit. The high-voltage ESD unit is connected in parallel between the LED pin and an external driving power supply, and the low-voltage ESD unit is connected in parallel between the source of the PMOS switch tube and the external driving power supply.

5. The LED backlight driver chip according to claim 4, characterized in that: The high-voltage ESD unit is a high-voltage GGNMOS device or an ESD circuit composed of a PNP transistor and an NPN transistor.

6. The LED backlight driver chip according to claim 4, characterized in that: The low-voltage ESD unit adopts a low-voltage GGNMOS device or an ESD circuit composed of a PNP transistor and an NPN transistor.

7. An LED backlight panel, wherein the LED backlight panel uses the LED backlight driver chip according to any one of claims 1 to 6 to drive LED light-emitting elements to emit light.

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