LED backlight driving chip and BV protection method for driving pin

Abstract

The application discloses an LED backlight driving chip, which comprises an LED pin, a high-voltage MOS switch tube M1 and a driving operation circuit; the high-voltage MOS switch tube is an NMOS or PMOS switch tube, the drain of the NMOS or PMOS switch tube is connected with the LED pin, the gate of the NMOS or PMOS switch tube is controlled by a PWM signal, the PWM signal controls the NMOS or PMOS switch tube to be turned on or turned off, the source of the NMOS or PMOS switch tube is connected with the driving operation circuit; the LED backlight driving chip further comprises a low-voltage ESD unit, and the low-voltage ESD unit is connected in parallel to both ends of the operation circuit. Another low-voltage ESD unit connected in series between the LED pin and the ground or the power supply is used to replace a traditional high-voltage ESD unit.

Description

Technical Field

[0001] This invention relates to the field of LED backlight technology, and in particular to a BV protection method for an LED backlight driver chip and its driver pins. Background Technology

[0002] Liquid crystal displays (LCDs) are the most prevalent type of display panel in modern applications. The liquid crystal material used in LCD panels is not self-emissive and requires a backlight to provide illumination. LED backlights, with their advantages of energy saving, environmental friendliness, and high performance, are widely used in LCD display panels. The performance of the LED backlight driver chip is crucial to the LCD display panel's performance.

[0003] like Figure 1 As shown, the existing LED backlight driver chip includes: an LED pin, a high-voltage MOS switch M1, and a driving operation circuit. The LED pin is used to connect to an LED string. When the LED string is composed of multiple LEDs connected in series, the voltage on the LED pin is usually relatively high, such as 40V. The driving operation circuit is generally a low-voltage device to ensure calculation speed and accuracy.

[0004] In existing technologies, ESD (Electro-Static Discharge) units are generally located between the LED pin and ground. Since the LED pin is under high voltage, the corresponding ESD unit also needs to use high-voltage devices. An ESD unit is a structure where a high-voltage MOS is connected as a GGNMOS or a transistor is connected as a diode. The ESD unit is connected between the LED pin and GND to protect the device connected in parallel. When ESD current arrives, the ESD device's snapback function quickly conducts and discharges. In this circuit structure, the breakdown voltage (BV) on the LED pin is actually determined by the breakdown voltage of the ESD device. This is because the switching transistor M1 and the driving operation circuit are connected in series, and their sum of BV is greater than the BV of the ESD device.

[0005] Therefore, there is a need in this field for a new LED backlight driver chip that can more effectively improve the breakdown voltage performance of LED pins. Summary of the Invention

[0006] This invention proposes an LED backlight driver chip, which improves the breakdown voltage of the LED pins by changing the ESD unit settings of the LED pins, thereby improving the breakdown voltage performance of the LED pins.

[0007] Based on the above technical objectives, the present invention provides an LED backlight driver chip, the LED backlight driver chip comprising: LED pins, a high-voltage MOS switch M1 and a driving operation circuit;

[0008] The high-voltage MOS switch is an NMOS switch, the drain of the NMOS switch is connected to the LED pin, the gate of the NMOS switch is controlled by a PWM signal, and the PWM signal controls the NMOS switch to be turned on or off; the source of the NMOS switch is connected to the driving operation circuit.

[0009] The LED backlight driver chip also includes a low-voltage ESD unit, which is connected in parallel across the driver operation circuit.

[0010] The present invention also provides another LED backlight driver chip, which includes: LED pins, a high-voltage MOS switch M1 and a driving operation circuit.

[0011] The high-voltage MOS switch is a PMOS switch, the drain of the PMOS switch is connected to the LED pin, the gate of the PMOS switch is controlled by a PWM signal, and the PWM signal controls the PMOS switch to be turned on or off; the source of the PMOS switch is connected to the driving operation circuit.

[0012] The LED backlight driver chip also includes a low-voltage ESD unit, which is connected in parallel across the driver operation circuit.

[0013] The present invention also provides another LED backlight driver chip, which includes: LED pins, a high-voltage MOS switch M1 and a driving operation circuit.

[0014] The high-voltage MOS switch is an NMOS switch, the drain of the NMOS switch is connected to the LED pin, the gate of the NMOS switch is controlled by a PWM signal, and the PWM signal controls the NMOS switch to be turned on or off; the source of the NMOS switch is connected to the driving operation circuit.

[0015] The LED backlight driver chip also includes multiple low-voltage ESD units, which are connected in series and then connected in parallel between the LED pin and ground.

[0016] The present invention also provides another LED backlight driver chip, which includes: LED pins, a high-voltage MOS switch M1 and a driving operation circuit.

[0017] The high-voltage MOS switch is a PMOS switch, the drain of the PMOS switch is connected to the LED pin, the gate of the PMOS switch is controlled by a PWM signal, and the PWM signal controls the PMOS switch to be turned on or off; the source of the PMOS switch is connected to the driving operation circuit.

[0018] The LED backlight driver chip also includes multiple low-voltage ESD units, which are connected in series and then connected in parallel between the LED pin and the external power supply.

[0019] Compared with the prior art, one or more embodiments of the present invention may have the following advantages:

[0020] The LED backlight driver chip of the present invention improves the breakdown voltage of the LED pins by changing the ESD unit settings of the LED pins, thereby improving the breakdown voltage performance of the LED pins.

[0021] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the description, claims and drawings. Attached Figure Description

[0022] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with the embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0023] Figure 1 This is a schematic diagram of the circuit structure of an existing LED backlight driver chip.

[0024] Figure 2 This is a schematic diagram of the circuit structure of the LED backlight driver chip according to the first embodiment of the present invention;

[0025] Figure 3 This is a schematic diagram of the circuit structure of the LED backlight driver chip according to the second embodiment of the present invention;

[0026] Figure 4 This is a schematic diagram of the circuit structure of the LED backlight driver chip according to the third embodiment of the present invention;

[0027] Figure 5 This is a schematic diagram of the circuit structure of the LED backlight driver chip according to the fourth embodiment of the present invention. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings.

[0029] 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 may be directly on, adjacent to, connected to, or coupled to other elements or layers, or there may be intervening elements or layers. Conversely, when an element is referred to as "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" other elements or layers, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc., may be used to describe various elements, components, areas, layers, and / or portions, these elements, components, areas, layers, and / or portions should not be limited by these terms. These terms are only used to distinguish one element, component, area, layer, or portion from another element, component, area, layer, or portion. Therefore, without departing from the teachings of this invention, the first element, component, area, layer, or portion discussed below may be referred to as a second element, component, area, layer, or portion. And when a second element, component, area, layer, or portion is discussed, it does not imply that the first element, component, area, layer, or portion necessarily exists in this invention.

[0030] Spatial relation terms such as “below,” “under,” “below,” “under,” “above,” “above,” etc., are used herein for convenience of description to describe the relationship between one 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, spatial relation terms are intended to also include different orientations of the device in use and operation. For example, if the device in the figure is flipped, then the element or feature described as “below,” “under,” or “below” other elements or features will be oriented “above” other elements or features. Therefore, the exemplary terms “below” and “under” can include both above and below orientations. The device may be otherwise oriented (rotated 90 degrees or otherwise) and the spatial descriptive terms used herein will be interpreted accordingly.

[0031] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. When used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising” and / or “including,” when used in this specification, identify the presence of the stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups. When used herein, the term “and / or” includes any and all combinations of the associated listed items.

[0032] Example 1

[0033] like Figure 2 As shown, the LED backlight driver chip in this embodiment includes: LED pins, a high-voltage MOS switch M1, and a driving operation circuit.

[0034] The high-voltage MOS switch is an NMOS switch, the drain of the NMOS switch is connected to the LED pin, the gate of the NMOS switch is controlled by a PWM signal, and the PWM signal controls the NMOS switch to be turned on or off; the source of the NMOS switch is connected to the driving operation circuit.

[0035] The LED backlight driver chip also includes a low-voltage ESD unit, which is connected in parallel between the source of the NMOS switch and ground.

[0036] In this embodiment, through integrated circuit design, the high-voltage MOS switch is designed to achieve self-ESD protection. When ESD charge arrives, the high-voltage MOS switch can self-conduct to discharge the ESD current to the high potential terminal of the driving operation circuit. The low-voltage ESD unit parallel to the driving operation circuit will be triggered to conduct, discharging the ESD current to GND, eliminating the need for a high-voltage ESD protection module from the LED pin to the ground terminal. The design feature of the high-voltage MOS switch is that it can use an LDMOS switch with multiple P-doped buried layers. The LDMOS switch with multiple P-doped buried layers includes a first P-doped buried layer on the silicon dioxide layer of the LDMOS. This first P-doped buried layer is used to form a high electric field at the interface between the silicon dioxide layer and the N-type drift region of the LDMOS to reduce the on-resistance of the LDMOS and facilitate rapid release of ESD charge. Meanwhile, a second P-doped buried layer and a third P-doped buried layer with different doping concentrations and lengths are provided in the N-type drift region of the LDMOS switch. The ends of the second P-doped buried layer and the third P-doped buried layer can generate a high electric field, thereby having a significant depletion effect, which further reduces the on-resistance of the LDMOS switch.

[0037] Alternatively, in this embodiment, a capacitor can be connected between the gate and drain of the high-voltage MOS switch to achieve rapid ESD charge release.

[0038] In this embodiment, since the high-voltage ESD unit in the prior art is omitted, the breakdown voltage of the LED pin is determined by the breakdown voltage of the high-voltage MOS switch and the equivalent breakdown voltage of the low-voltage ESD unit connected in parallel with the driving operation circuit. Therefore, the breakdown voltage of the LED pin is significantly improved compared with the breakdown voltage of the high-voltage ESD unit in the prior art.

[0039] Example 2

[0040] like Figure 3 As shown, the LED backlight driver chip in this embodiment includes: LED pins, a high-voltage MOS switch M1, and a driving operation circuit.

[0041] The high-voltage MOS switch is a PMOS switch, the drain of the PMOS switch is connected to the LED pin, the gate of the PMOS switch is controlled by a PWM signal, and the PWM signal controls the PMOS switch to be turned on or off; the source of the PMOS switch is connected to the driving operation circuit.

[0042] The LED backlight driver chip also includes a low-voltage ESD unit, which is connected in parallel across the driver operation circuit.

[0043] In this embodiment, through integrated circuit design, the high-voltage MOS switch is designed to achieve self-ESD protection. When ESD charge arrives, the high-voltage MOS switch can automatically conduct to discharge the ESD current to the high potential terminal of the drive operation circuit. The low-voltage ESD unit parallel to the drive operation circuit will be triggered to conduct, discharging the ESD current to the external power supply, thus eliminating the need for a high-voltage ESD protection module between the LED pin and the external power supply. The design of the high-voltage MOS switch is the same as in the aforementioned embodiment 1.

[0044] In this embodiment, since the high-voltage ESD unit provided in the prior art is omitted, the breakdown voltage of the LED pin is determined by the breakdown voltage of the high-voltage MOS switch and the equivalent breakdown voltage of the low-voltage ESD unit connected in parallel with the driving operation circuit. Therefore, the breakdown voltage of the LED pin is significantly improved compared with the breakdown voltage of the high-voltage ESD unit in the prior art.

[0045] Example 3

[0046] like Figure 4 As shown, the LED backlight driver chip in this embodiment includes: LED pins, a high-voltage MOS switch M1, and a driving operation circuit.

[0047] The high-voltage MOS switch is an NMOS switch, the drain of the NMOS switch is connected to the LED pin, the gate of the NMOS switch is controlled by a PWM signal, and the PWM signal controls the NMOS switch to be turned on or off; the source of the NMOS switch is connected to the driving operation circuit.

[0048] The LED backlight driver chip also includes multiple low-voltage ESD units, which are connected in series and then connected in parallel between the LED pin and ground.

[0049] In this embodiment, a high-voltage ESD unit in the prior art is replaced with multiple low-voltage ESD units connected in series, so that the breakdown voltage of the LED pin is determined by the sum of the breakdown voltages of the multiple low-voltage ESD units. Moreover, the sum of the breakdown voltages of the multiple low-voltage ESD units connected in series is also greater than the breakdown voltage of the high-voltage ESD unit in the prior art, thereby significantly improving the breakdown voltage of the LED pin.

[0050] Example 4

[0051] like Figure 5 As shown, the LED backlight driver chip in this embodiment includes: LED pins, a high-voltage MOS switch M1, and a driving operation circuit.

[0052] The high-voltage MOS switch is a PMOS switch, the drain of the PMOS switch is connected to the LED pin, the gate of the PMOS switch is controlled by a PWM signal, and the PWM signal controls the PMOS switch to be turned on or off; the source of the PMOS switch is connected to the driving operation circuit.

[0053] The LED backlight driver chip also includes multiple low-voltage ESD units, which are connected in series and then connected in parallel between the LED pin and the external power supply.

[0054] In this embodiment, a high-voltage ESD unit in the prior art is replaced with multiple low-voltage ESD units connected in series, so that the breakdown voltage of the LED pin is determined by the sum of the breakdown voltages of the multiple low-voltage ESD units. Moreover, the sum of the breakdown voltages of the multiple low-voltage ESD units connected in series is also greater than the breakdown voltage of the high-voltage ESD unit in the prior art, thereby significantly improving the breakdown voltage of the LED pin.

[0055] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. An LED backlight driver chip, characterized in that, The LED backlight driver chip includes: LED pins, a high-voltage MOS switch M1, and a driving operation circuit. The high-voltage MOS switch is an NMOS switch, the drain of the NMOS switch is connected to the LED pin, the gate of the NMOS switch is controlled by a PWM signal, and the PWM signal controls the NMOS switch to be turned on or off; the source of the NMOS switch is connected to the driving operation circuit. The LED backlight driver chip also includes a low-voltage ESD unit, which is connected in parallel across the driver operation circuit. The high-voltage MOS switch is an LDMOS switch with multiple P-doped buried layers. The LDMOS switch with multiple P-doped buried layers includes a first P-doped buried layer disposed on the silicon dioxide layer of the LDMOS. The first P-doped buried layer is used to form a high electric field at the junction between the silicon dioxide layer and the N-type drift region of the LDMOS to reduce the on-resistance of the LDMOS.

2. An LED backlight driver chip, characterized in that, The LED backlight driver chip includes: LED pins, high-voltage MOS switch M1, and driving operation circuit; The high-voltage MOS switch is a PMOS switch, the drain of the PMOS switch is connected to the LED pin, the gate of the PMOS switch is controlled by a PWM signal, and the PWM signal controls the PMOS switch to be turned on or off; the source of the PMOS switch is connected to the driving operation circuit. The LED backlight driver chip also includes a low-voltage ESD unit, which is connected in parallel across the driver operation circuit. The high-voltage MOS switch is an LDMOS switch with multiple P-doped buried layers. The LDMOS switch with multiple P-doped buried layers includes a first P-doped buried layer disposed on the silicon dioxide layer of the LDMOS. The first P-doped buried layer is used to form a high electric field at the junction between the silicon dioxide layer and the N-type drift region of the LDMOS to reduce the on-resistance of the LDMOS.

3. An LED backlight driver chip, characterized in that, The LED backlight driver chip includes: LED pins, high-voltage MOS switch M1, and driving operation circuit; The high-voltage MOS switch is an NMOS switch, the drain of the NMOS switch is connected to the LED pin, the gate of the NMOS switch is controlled by a PWM signal, and the PWM signal controls the NMOS switch to be turned on or off; the source of the NMOS switch is connected to the driving operation circuit. The LED backlight driver chip also includes multiple low-voltage ESD units, which are connected in series and then connected in parallel between the LED pin and ground. The high-voltage MOS switch is an LDMOS switch with multiple P-doped buried layers. The LDMOS switch with multiple P-doped buried layers includes a first P-doped buried layer disposed on the silicon dioxide layer of the LDMOS. The first P-doped buried layer is used to form a high electric field at the junction between the silicon dioxide layer and the N-type drift region of the LDMOS to reduce the on-resistance of the LDMOS.

4. An LED backlight driver chip, characterized in that, The LED backlight driver chip includes: LED pins, high-voltage MOS switch M1, and driving operation circuit; The high-voltage MOS switch is a PMOS switch, the drain of the PMOS switch is connected to the LED pin, the gate of the PMOS switch is controlled by a PWM signal, and the PWM signal controls the PMOS switch to be turned on or off; the source of the PMOS switch is connected to the driving operation circuit. The LED backlight driver chip also includes multiple low-voltage ESD units, which are connected in series and then connected in parallel between the LED pin and the external power supply. The high-voltage MOS switch is an LDMOS switch with multiple P-doped buried layers. The LDMOS switch with multiple P-doped buried layers includes a first P-doped buried layer disposed on the silicon dioxide layer of the LDMOS. The first P-doped buried layer is used to form a high electric field at the junction between the silicon dioxide layer and the N-type drift region of the LDMOS to reduce the on-resistance of the LDMOS.

5. An LED backlight panel, wherein the LED backlight panel uses an LED backlight driver chip as described in any one of claims 1-4 to drive LED light-emitting elements to emit light.

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