LED control chip, method and multi-channel backlight system

Abstract

Embodiments of the present invention disclose an LED control chip, method, and multi-channel backlight system. The LED control chip provided by the embodiments of the present invention is used to control the switching on and off of each channel in a multi-channel LED. The LED control chip includes multiple LED pins corresponding to the multi-channel LEDs. The LED control chip is configured to: after the LED control chip is powered on, charge each of the multiple LED pins using an internal reference current of the LED control chip; compare the voltage on each of the multiple LED pins with a preset voltage threshold to obtain multiple comparison results corresponding to each of the multiple LED pins; and determine whether each channel in the multi-channel LED should be switched on or off based on each of the multiple comparison results.

Description

Technical Field

[0001] The embodiments of the present invention generally relate to the field of integrated circuits, and more particularly to an LED control chip, method, and multi-channel backlight system. Background Art

[0002] In the LED (Light Emitting Diode) backlight application of switching power supply, multi-channel constant current backlight drive is a common system architecture. Its advantage is that the backlight distribution is more uniform. Compared with the single-string LED backlight system, the multi-string parallel LED backlight system can be evenly distributed under the screen, so that the brightness of each area of ​​the screen is consistent, without the problem of high brightness in the middle of the screen and low brightness in the four corners in the single-string LED backlight system.

[0003] However, in practice, it's necessary to disable one or more LED channels to match different screen requirements. Traditional solutions typically shut down unused LED channels through LED short-circuit protection or LED short-circuit protection. This shutdown occurs after the chip has begun normal operation, which can easily lead to a series of problems, including output voltage overshoot and chip protection errors. Summary of the Invention

[0004] In a first aspect, an embodiment of the present invention provides an LED control chip for controlling the turning on and off of each channel of a multi-channel LED, including multiple LED pins corresponding to the multi-channel LED. The LED control chip is configured to: after the LED control chip is powered on, charge each of the multiple LED pins using an internal reference current of the LED control chip; compare the voltage on each of the multiple LED pins with a preset voltage threshold to obtain multiple comparison results corresponding to each of the multiple LED pins; and determine whether each channel of the multi-channel LED needs to be turned off or on based on each of the multiple comparison results.

[0005] In a second aspect, an embodiment of the present invention further provides an LED control chip and a multi-channel LED as described in the first aspect, wherein each channel of the multi-channel LED is respectively connected to each LED pin of a plurality of LED pins of the LED control chip.

[0006] In a third aspect, an embodiment of the present invention further provides a control method executed by an LED control chip, for controlling the turning off and on of each channel in a multi-channel LED, wherein the LED control chip includes a plurality of LED pins corresponding to the multi-channel LED, and the method includes: after the LED control chip is powered on, charging each of the plurality of LED pins using an internal reference current of the LED control chip; comparing the voltage on each of the plurality of LED pins with a preset voltage threshold to obtain a plurality of comparison results corresponding to each of the plurality of LED pins; and determining whether each channel in the multi-channel LED needs to be turned off or on based on each of the plurality of comparison results.

[0007] The embodiments of the present invention provide an LED control chip, method, and multi-channel backlight system, which can detect whether each channel in a multi-channel LED needs to be turned off or on, and then turn off unused channels before the LED control chip operates normally, thereby preventing a series of problems such as output voltage overshoot and chip misprotection caused by turning off certain channels. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0009] Figure 1 A schematic diagram of the structure of a multi-channel backlight system with a traditional boost architecture is shown;

[0010] Figure 2 A schematic structural diagram of an LED control chip provided by an embodiment of the present invention is shown;

[0011] Figure 3 Shows a schematic structural diagram of the channel control module of the normal use channel;

[0012] Figure 4 Shown Figure 3 Schematic diagram of waveforms of corresponding signals in the channel control module of a normally used channel shown;

[0013] Figure 5 A schematic diagram of the structure of a channel control module for shutting down a channel is shown;

[0014] Figure 6 Shown Figure 5 Schematic diagram of waveforms of corresponding signals in the channel control module of the shut-down channel shown;

[0015] Figure 7The figure shows a flow chart of the LED control method provided by the embodiment of the present invention. DETAILED DESCRIPTION

[0016] The features and exemplary embodiments of various aspects of the present invention will be described in detail below. In order to make the objects, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only configured to explain the present invention and are not configured to limit the present invention. For those skilled in the art, the present invention can be implemented without the need for some of these specific details. The following description of the embodiments is merely to provide a better understanding of the present invention by illustrating examples of the present invention.

[0017] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, the elements defined by the phrase "comprising..." do not exclude the presence of other identical elements in the process, method, article, or device comprising the elements.

[0018] In order to better understand the technical solution provided by the embodiment of the present invention, the following first introduces the multi-channel backlight system of the traditional boost architecture. Figure 1 , Figure 1 The figure shows a schematic structural diagram of a multi-channel backlight system with a traditional boost architecture.

[0019] like Figure 1 As shown, the multi-channel backlight system of the boost architecture may include an LED control chip 100, multi-channel LEDs (including channels LED1...LEDX), an input capacitor C1, an inductor L1, a transistor M1, a resistor R1, a freewheeling diode D1, and an output capacitor C2, etc., wherein each channel of the multi-channel LED may include an LED light string.

[0020] The LED control chip 100 may include a low dropout regulator (LDO) 102, an under voltage lockout (UVLO) module 104, a reference voltage and reference current generation module 106, a driver 108, an oscillator 110, a comparator 112, a control logic 114, an amplifier 116, an error amplifier 118, a feedback control module 120, an operational amplifier 122, and a constant current unit 124.

[0021] Among them, VIN is the input voltage of the LED control chip 100 and the entire system. When the gate drive signal Gate is at a high level, the transistor M1 (for example, an NMOS transistor) is turned on, and the input voltage VIN is stored through the inductor L1. When the gate drive signal Gate is at a low level, the transistor M1 is turned off, and the energy on the inductor L1 is superimposed on the input voltage VIN and charges the output capacitor C2 through the freewheeling diode D1, so that the output voltage Vout of the system gradually increases. When the output voltage Vout increases to a certain voltage, the LED lamp string of the channel is turned on.

[0022] As an example, constant current control of the LED string is performed via the constant current unit 124 in the LED control chip 100. The feedback control module 120 can detect the lowest voltage DHC among the multi-channels LED1 to LEDX and input this lowest voltage DHC to the first input of the error amplifier 118. The second input of the error amplifier 118 can receive the error reference voltage EA_ref from the reference voltage and reference current generation module 106. The error amplifier 118 can be used to amplify the error between the error reference voltage EA_ref and the lowest voltage DHC and generate a compensation signal CMP. The comparator 112 can be used to compare the CMP signal with the internally generated Ramp signal and generate a gate drive signal Gate for controlling the turn-off of the transistor M1. The gate drive signal Gate for controlling the turn-on of the transistor M1 can be generated by the CLK signal. Ultimately, when the error reference voltage EA_ref is equal to the minimum voltage DHC generated by the feedback control module 120, a suitable output voltage Vout can be generated, that is, the output voltage required by the LED light string output is satisfied (due to the differences between the on-state voltages of the various LED light strings, the output voltage Vout needs to satisfy the requirements of the LED light string with the maximum on-state voltage) while minimizing the loss of the chip.

[0023] In order to solve one or more of the problems in the prior art, the embodiments of the present invention provide an LED control chip, method and multi-channel backlight system.

[0024] Figure 2 A schematic structural diagram of an LED control chip provided by an embodiment of the present invention is shown. Figure 1 and Figure 2 The same or similar components are marked with the same reference numerals. To simplify the description, they are not repeated here. The following mainly introduces the differences between the two.

[0025] Specifically, Figure 2 The LED control chip 200 shown is Figure 1 The main difference between the LED control chip 100 shown is that, compared to Figure 1 The LED control chip 100 shown, Figure 2 The LED control chip 200 shown mainly adds a channel control module 126. The main functions of the channel control module 126 may include determining the status of the multi-channel LED settings by detecting the voltage of the multi-channel LED1 to LEDX. Based on the determined status of each channel in the multi-channel LED, before the LED control chip 200 operates normally, the channel enable signals Channel_en1 to Channel_enx corresponding to the multi-channel LED1 to LEDX are generated, and the channel enable signals Channel_en1 to Channel_enx are provided to the constant current unit 124 to control the operating status of the multi-channel LED1 to LEDX. For example, the channel enable signal Channel_en1 can be used to control the operating status of the channel LED1, and the channel enable signal Channel_enx can be used to control the operating status of the channel LEDX.

[0026] As an example, Figure 2 The LED control chip 200 shown can be configured to charge each of the multiple LED pins using the internal reference current Iref of the LED control chip after the LED control chip is powered on; compare the voltage on each of the multiple LED pins with a preset voltage threshold Vth_1 to obtain multiple comparison results corresponding to each of the multiple LED pins; and determine whether each channel of the multi-channel LED needs to be turned off or on based on each of the multiple comparison results.

[0027] Specifically, if Figure 3 and Figure 5 As shown, Figure 3 and Figure 5 FIG. 1 shows a schematic structural diagram of the channel control module 126 and the constant current unit 124 in the LED control chip 200 provided in an embodiment of the present invention. Specifically, Figure 3 shows a schematic diagram of the structure of the channel control module 126 of the normal use channel, and Figure 5 FIG. 1 shows a schematic structural diagram of a channel control module 126 for shutting down a channel.

[0028] As an example, see Figure 3 and Figure 5 After the LED control chip is powered on, the internal reference current Iref1 from the reference voltage and reference current generating module 106 is used to charge the LED1 pin. The voltage on the LED1 pin is compared with the preset voltage threshold Vth_1 using the comparison CMP1. Based on the comparison result, it is determined whether the corresponding LED channel needs to be turned off or on.

[0029] As an example, the LED control chip 200 can be further configured to charge each of the multiple LED pins using the internal reference current Iref during a preset period of time starting from the moment the LED control chip is powered on (corresponding to the period when the signal pg is at a high level and the signal pg_delay is at a low level); lock each of the multiple comparison results at a moment when the preset period of time starting from the moment the LED control chip is powered on (the signal pg_delay changes from a low level to a high level); and determine whether each channel of the multi-channel LED needs to be turned off or turned on based on each of the locked multiple comparison results.

[0030] Specifically, if Figure 4 and Figure 6 As shown, Figure 4 Shown Figure 3 FIG. 1 is a waveform diagram of corresponding signals in the channel control module 126 of a normally used channel. Figure 6 Shown Figure 5 The waveform diagram of the corresponding signal in the channel control module 126 of the shut-down channel is shown.

[0031] As an example, during a preset period of time (corresponding to a period when the signal pg is high and the signal pg_delay is low) starting from the moment the LED control chip is powered on, the internal reference current Iref is used to charge the LED pin, for example, Figure 4 In the waveform shown, the voltage on the LED pin is charged until it rises to a value greater than the preset voltage threshold Vth_1. At this time, the output signal CMP1_out of the comparator is flipped (from a low level to a high level). When the signal pg_delay changes from a low level to a high level, the internal reference current Iref is turned off to stop charging the LED pin, causing the voltage on the LED pin to drop below the preset voltage threshold Vth_1. At this time, the output signal CMP1_out of the comparator is flipped (from a high level to a low level). Figure 6In the waveform shown, the voltage on the LED pin remains lower than the preset voltage threshold Vth_1 during charging, and the output signal CMP1_out of the comparator remains at a low level and does not flip. When the signal pg_delay changes from a low level to a high level, the output signal CMP1_out of the comparator is locked. Based on the locked comparison result, it is determined whether the corresponding channel needs to be turned off or on. For example, Figure 4 In the waveform shown in FIG. 1 , the locked comparison result indicates that the voltage on the LED pin is greater than the preset voltage threshold Vth_1, and it is determined that the LED channel corresponding to the LED pin needs to be turned on. Figure 6 In the waveform diagram shown, the locked comparison result indicates that the voltage on the LED pin is less than the preset voltage threshold Vth_1, and it is determined that the LED channel corresponding to the LED pin needs to be turned off.

[0032] As an example, the LED control chip can be further configured to turn off the internal reference current Iref after a preset period of time from the moment the LED control chip is powered on (when the signal pg_delay changes from a low level to a high level) to prevent affecting the normal operation of subsequent channels.

[0033] As an example, the LED control chip can be further configured to, during a preset period of time (corresponding to the period when the signal pg is at a high level and the signal pg_delay is at a low level) starting from the moment the LED control chip is powered on, if it is detected that the voltage on a first LED pin among the multiple LED pins rises to be greater than a preset voltage threshold Vth_1, determine that a first LED channel corresponding to the first LED pin in the multi-channel LED needs to be turned on, and control the turning on of the first LED channel, wherein the first LED pin may include one or more LED pins.

[0034] For example, in Figure 3 and Figure 4 In the illustrated embodiment, during a period when the signal pg is at a high level and the signal pg_delay is at a low level (corresponding to a period when the internal reference current Iref is at a high level), the comparator CMP1 can detect a moment when the voltage on the first LED pin is greater than a preset voltage threshold Vth_1, and can then determine that the first LED channel corresponding to the first LED pin needs to be turned on. It can be understood that the "first" in the first LED pin is merely used to distinguish different pins, and does not have a restrictive meaning, and may include one or more LED pins that need to be turned on.

[0035] As an example, the LED control chip can be further configured to, during a preset period of time (corresponding to the period when the signal pg is at a high level and the signal pg_delay is at a low level) starting from the moment the LED control chip is powered on, if it is detected that the voltage on a second LED pin among the multiple LED pins remains less than a preset voltage threshold, determine that a second LED channel corresponding to the second LED pin in the multi-channel LED needs to be turned off, and control the shutdown of the second LED channel, wherein the second LED pin may include one or more LED pins.

[0036] For example, in Figure 5 and Figure 6 In the illustrated embodiment, during a preset period of time (corresponding to a period in which the signal pg is high and the signal pg_delay is low) starting from the moment the LED control chip is powered on, the comparator CMP1 can detect that the voltage on the second LED pin remains less than a preset voltage threshold Vth_1, and it can be determined that the second LED channel corresponding to the second LED pin needs to be turned off. It can also be understood that the "second" in the second LED pin is merely used to distinguish different pins and does not have a restrictive meaning. It can include one or more LED pins.

[0037] The following Figure 3 and Figure 5 The channel control module 126 shown is described in detail, and it should be noted that it is provided as an example only and should not be construed as limiting.

[0038] As an example, Figure 3As shown, when the first channel corresponding to the LED1 pin needs to be turned on, the channel control module 126 may include a first transistor PM1, a first comparator CMP1, and a first trigger, wherein a first terminal of the first transistor PM1 may receive an internal reference current Iref1, a second terminal may receive a signal pg_delay, and a third terminal may be connected to the LED1 pin; a first terminal of the first comparator CMP1 may be connected to the LED1 pin, and a second terminal may receive a preset voltage threshold Vth_1; a first terminal of the first trigger may be connected to the third terminal of the first comparator CMP1, a second terminal may receive the signal pg_delay, and a third terminal may output a first channel enable signal channel_en1 for controlling the turning on of the first channel corresponding to the LED1 pin; wherein the signal pg_delay may be used to control the turning on of the first transistor PM1 when the LED control chip is powered on, and to control the first trigger to output the first channel enable signal channel_en1 from a low level to a high level at a moment when a preset period has passed since the LED control chip was powered on (corresponding to the moment when the signal pg_delay changes from a low level to a high level), so as to control the turning on of the first channel corresponding to the first LED pin.

[0039] Figure 3 The circuit structure diagram of the channel control module 126 of the normal use channel is shown. Figure 3 and Figure 4 , LED1 pin is in floating state, C1 is the parasitic capacitance from LED1 pin to ground, after the LED control chip is powered on, the signal pg_delay is low level, the first transistor PM1 is turned on, the signal pg_delay_b (the inverse signal of pg_delay) is high level, the transistor NM2 is turned on, and the internal reference current Iref1 is used to charge the LED1 pin through the first transistor PM1. Since the parasitic capacitance C1 is small at this time, the voltage on the LED1 pin is charged to the VDD voltage in a very short time. When the LED1 is detected After the voltage on the pin rises to a value greater than the preset voltage threshold VTh1, the output signal CMP1_out of the comparator CMP1 flips (from a low level to a high level). When the signal pg_delay changes from a low level to a high level, the output signal CMP1_out of the comparator CMP1 is locked and a high-level channel enable signal channel_en1 is output, so that the corresponding channel can operate normally. When the signal pg_delay changes from a low level to a high level, the internal reference current Iref1 is turned off to prevent affecting the normal operation of subsequent channels.

[0040] As a further example, each of the plurality of channel control modules 126 may further include a delay unit connected between the comparator CMP1 and the trigger. The delay unit may be used to shield interference signals appearing on the LED pin to prevent the channel from being shut down by mistake.

[0041] Among them, the signal pg, signal pg_delay and signal pg_delay_b are pre-set in the LED control chip, wherein the signal pg_delay_b is the inverse signal of the signal pg_delay, and generates an internal reference current Iref1. As described above, the internal reference current Iref1 is used to charge the LED1 pin. When the signal pg is at a high level and the signal pg_delay is at a low level, if it is detected that the voltage on the LED1 pin rises to be greater than the preset voltage threshold Vth_1, the output signal CMP1_out of the comparator CMP1 flips from a low level to a high level. When the signal pg_delay changes from a low level to a high level, the output signal CMP1_out of the comparator CMP1 is locked and output as a high-level channel enable signal channel_en1, so that the corresponding channel can operate normally.

[0042] As an example, Figure 3 As shown, the LED control chip may further include a plurality of constant current units corresponding to the plurality of LED pins, and each of the plurality of constant current units is turned off when the LED control chip is powered on.

[0043] As an example, Figure 3 As shown, the constant current unit 124 may include an operational amplifier OP1, a second resistor Rc, a third transistor NM1, and a fourth transistor NM2. The first end of the operational amplifier OP1 may receive an internal reference voltage Vref1 of the LED control chip; the first end of the third transistor NM1 may be connected to one of the multiple LED pins, and the second end and the third end may be connected to the second end and the third end of the operational amplifier OP1, respectively; the first end of the second resistor Rc may be connected to the third end of the third transistor NM1, and the second end may be grounded; the first end of the fourth transistor NM2 may be connected to the second end of the third transistor NM1, the second end may receive a third control signal pg_delay_b, and the third end may be grounded, wherein the third control signal pg_delay_b may be used to control the conduction of the fourth transistor NM2 when the LED control chip is powered on, so as to control the turn-off of the third transistor NM1.

[0044] Specifically, when the LED control chip is started, the signal pg_delay_b is at a high level, the fourth transistor NM2 is turned on, and the gate of the third transistor NM1 is pulled down by the fourth transistor NM2 , so that the third transistor NM1 is turned off to turn off the constant current unit 124 .

[0045] As an example, when the channel corresponding to the LED1 pin needs to be turned off, such as Figure 5 As shown, the channel control module 126 may include a second transistor PM1, a first resistor R1, a second comparator CMP1, and a second trigger, wherein a first end of the second transistor PM1 may receive an internal reference current Iref1, a second end may receive a signal Pg_delay, and a third end may be connected to the LED1 pin; a first end of the first resistor R1 may be connected to the LED1 pin, a second end may be grounded, and a resistance value of the first resistor R1 may be less than a preset resistance threshold; a first end of the second comparator CMP1 may be connected to the LED1 pin, and a second end may receive a preset voltage threshold Vth_1; a first end of the second trigger may be connected to the second comparator CM1. The third end of P1, the second end can receive the signal Pg_delay, and the third end can output the channel enable signal channel_en1 for controlling the shutdown of the first channel corresponding to the LED1 pin; wherein, the signal Pg_delay can be used to control the conduction of the second transistor PM1 when the LED control chip is powered on, and is used to control the second trigger to output the channel enable signal channel_en1 at a low level at a moment when a preset period of time has passed since the LED control chip was powered on (corresponding to the moment when the signal Pg_delay changes from a low level to a high level), so as to control the shutdown of the first channel corresponding to the LED1 pin.

[0046] Figure 5 The circuit structure diagram of the channel control module 126 for shutting down the channel is shown, combined with Figure 5 and Figure 6 , compared to Figure 3 The circuit shown, Figure 5The circuit shown adds a resistor R1 from the LED1 pin to ground. The resistance of the resistor R1 is set to be less than a preset resistance threshold, for example, zero ohms. After the LED control chip is powered on, the signal pg changes from a low level to a high level, the signal pg_delay is low, the second transistor PM1 is turned on, the signal pg_delay_b (the inverse signal of pg_delay) is high, the transistor NM2 is turned on, and the internal reference current Iref1 is used to charge the LED1 pin through the second transistor PM1. Since the resistance of the resistor R1 is small at this time, the voltage on the LED1 pin is very low. During the period when the signal pg is high and the signal pg_delay is low, the LED1 pin can be detected. The voltage on the D1 pin is always less than the preset voltage threshold Vth_1. The output signal CMP1_out of the comparator CMP1 does not flip and always remains at a low level. When the signal pg_delay changes from a low level to a high level, the output signal CMP1_out of the comparator CMP1 is locked and a low-level channel enable signal channel_en1 is output, so that the corresponding channel is turned off. When the signal pg_delay changes from a low level to a high level, the internal reference current Iref1 is turned off to prevent affecting the normal operation of subsequent channels.

[0047] As a further example, Figure 5 As shown, each of the multiple channel control modules 126 may further include a delay unit connected between the comparator CMP1 and the trigger. The delay unit may be used to shield interference signals appearing on the LED pin to prevent the problem of mistakenly shutting down the channel.

[0048] Among them, the signal pg, signal pg_delay and signal pg_delay_b are pre-set in the LED control chip, wherein the signal pg_delay_b is the inverse signal of the signal pg_delay, and generates an internal reference current Iref1. As described above, the internal reference current Iref1 is used to charge the LED1 pin. When the signal pg is at a high level and the signal pg_delay is at a low level, if it is detected that the voltage on the LED1 pin is always less than the preset voltage threshold Vth_1, the output signal CMP1_out of the comparator CMP1 always remains at a low level. When the signal pg_delay changes from a low level to a high level, the output signal CMP1_out of the comparator CMP1 is locked and outputs a low-level channel enable signal channel_en1, so that the corresponding channel is turned off.

[0049] As an example, Figure 5As shown, the LED control chip may further include a plurality of constant current units corresponding to the plurality of LED pins, and each of the plurality of constant current units is turned off when the LED control chip is powered on.

[0050] As an example, Figure 5 As shown, the constant current unit 124 may include an operational amplifier OP1, a second resistor Rc, a third transistor NM1 and a fourth transistor NM2, wherein the first end of the operational amplifier OP1 may receive an internal reference voltage Vref1 of the LED control chip; the first end of the third transistor NM1 may be connected to one of the multiple LED pins (for example, the LED1 pin), and the second end and the third end may be connected to the second end and the third end of the operational amplifier OP1, respectively; the first end of the second resistor Rc may be connected to the third end of the third transistor NM1, and the second end may be grounded; the first end of the fourth transistor NM2 may be connected to the second end of the third transistor NM1, the second end may receive the third control signal pg_delay_b, and the third end may be grounded, wherein the third control signal pg_delay_b may be used to control the conduction of the fourth transistor NM2 when the LED control chip is powered on, so as to control the turn-off of the third transistor NM1.

[0051] Specifically, when the LED control chip is started, the signal pg_delay_b is high, the fourth transistor NM2 is turned on, and the gate of the third transistor NM1 is pulled down by the fourth transistor NM2 , so that the third transistor NM1 is turned off to turn off the constant current unit 124 .

[0052] It should be noted that Figure 3 and Figure 5 The channel control module 126 shown is introduced by taking the LED1 pin as an example to be turned on and off, which should not be interpreted as limiting. Since the multi-channel backlight system includes multiple channels, a channel control module 126 and a constant current unit 124 corresponding to each of the multiple channels are provided, wherein Figure 3 and Figure 5 The channel control module 126 and the constant current unit 124 corresponding to one of the channels are shown. The channel control modules 126 and the constant current units 124 corresponding to the other channels are similar. Figure 3 and Figure 5 The circuit structure shown is not described here in detail for the sake of simplicity.

[0053] In addition, an embodiment of the present invention further provides a control method executed by the LED control chip as described above, referring to Figure 7 , Figure 7A flow chart of an LED control method 700 provided in an embodiment of the present invention is shown, which is used to control the turning on and off of each channel of a multi-channel LED. The LED control chip may include multiple LED pins corresponding to the multi-channel LEDs. The method 700 may include: S702, after the LED control chip is powered on, charging each of the multiple LED pins using an internal reference current of the LED control chip; S704, comparing the voltage on each of the multiple LED pins with a preset voltage threshold to obtain multiple comparison results corresponding to each of the multiple LED pins; and S706, determining whether each channel of the multi-channel LED should be turned off or on based on each of the multiple comparison results.

[0054] As an example, the method 700 may further include charging each of the multiple LED pins using an internal reference current Iref during a preset period starting from the moment the LED control chip is powered on; locking each of the multiple comparison results at a moment when the preset period has passed since the moment the LED control chip is powered on; and determining whether each channel of the multi-channel LED needs to be turned off or turned on based on each of the locked multiple comparison results.

[0055] As an example, the method 700 may further include turning off the internal reference current when a preset period of time has passed since the LED control chip was powered on.

[0056] As an example, the method 700 may further include, during a preset period starting from the moment the LED control chip is powered on, if it is detected that the voltage on a first LED pin among the multiple LED pins rises to be greater than a preset voltage threshold, determining that a first LED channel corresponding to the first LED pin in the multi-channel LED needs to be turned on and controlling the turning on of the first LED channel, wherein the first LED pin includes one or more LED pins.

[0057] As an example, the method 700 may further include, during a preset period starting from the moment the LED control chip is powered on, if it is detected that the voltage on a second LED pin among the plurality of LED pins remains less than a preset voltage threshold, determining that a second LED channel corresponding to the second LED pin in the multi-channel LED needs to be turned off and controlling the second LED channel to be turned off, wherein the second LED pin includes one or more LED pins.

[0058] It is understandable that the various steps and details of the LED control method provided in the embodiment of the present invention are consistent with the details described above with reference to the LED control chip, and therefore, they are not repeated here for simplicity of description.

[0059] Furthermore, embodiments of the present invention provide a multi-channel backlight system including the aforementioned LED control chip, which has an arbitrary channel selection function and can be used to control the on / off of any of the multiple channels. As an example, the multi-channel backlight system can be a multi-channel backlight system with a boost architecture, or a multi-channel backlight system with other suitable architectures, which is not limited by this application.

[0060] In summary, in traditional LED control chips, unused LED channels are usually shut down through LED lamp open circuit or LED lamp short circuit protection. The shutdown state is after the LED control chip has started normal operation, which can easily cause a series of problems such as output voltage overshoot and chip misprotection.

[0061] The LED control chip, method, and multi-channel backlight system provided by the embodiments of the present invention set a channel status detection mode when the control chip is working normally, configure the channels that need to be shut down through some peripheral settings, and then shut down the channels that are not needed before the control chip works normally to prevent problems such as output voltage overshoot and chip misprotection. At the same time, the embodiments of the present invention can set any unnecessary channels, so that convenient wiring can be performed when the user uses it.

[0062] It should be understood that the present invention is not limited to the specific configurations and processes described above and illustrated in the figures. For the sake of brevity, a detailed description of known methods is omitted. In the above embodiments, several specific steps are described and illustrated as examples. However, the method of the present invention is not limited to the specific steps described and illustrated. Those skilled in the art may make various changes, modifications, and additions, or change the order of the steps after understanding the spirit of the present invention.

[0063] The functional blocks shown in the above-described block diagram can be implemented as hardware, software, firmware or a combination thereof. When implemented in hardware, it can be, for example, an electronic circuit, an application specific integrated circuit (ASIC), appropriate firmware, a plug-in unit, a function card or the like. When implemented in software, the elements of the present invention are programs or code segments that are used to perform the required tasks. The program or code segment can be stored in a machine-readable medium, or transmitted on a transmission medium or a communication link by a data signal carried in a carrier wave. "Machine-readable medium" can include any medium capable of storing or transmitting information. Examples of machine-readable media include electronic circuits, semiconductor memory devices, ROMs, flash memories, erasable ROMs (EROMs), floppy disks, CD-ROMs, optical disks, hard disks, optical fiber media, radio frequency (RF) links, etc. The code segment can be downloaded via a computer network such as the Internet, an intranet, etc.

[0064] It should also be noted that the exemplary embodiments described herein describe methods or systems based on a series of steps or devices. However, the present invention is not limited to the order of the steps described above. In other words, the steps may be performed in the order described in the embodiments, or in a different order, or several steps may be performed simultaneously.

[0065] The above description is only a specific embodiment of the present invention. Those skilled in the art will clearly understand that for the convenience and brevity of description, the specific working processes of the systems, modules and units described above can refer to the corresponding processes in the aforementioned method embodiments, and will not be repeated here. It should be understood that the protection scope of the present invention is not limited to this. Any person skilled in the art can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention.

Claims

1. An LED control chip for controlling the switching on and off of each channel in a multi-channel LED, characterized in that: The LED control chip includes a plurality of LED pins corresponding to the multi-channel LEDs, and is configured as follows: After the LED control chip is powered on, charging each of the plurality of LED pins using an internal reference current of the LED control chip; comparing a voltage on each of the plurality of LED pins with a preset voltage threshold to obtain a plurality of comparison results corresponding to each of the plurality of LED pins; as well as Determining whether each channel of the multi-channel LED needs to be turned off or on according to each of the plurality of comparison results, and controlling the turning off or on of the corresponding channel of the multi-channel LED; The LED control chip also includes multiple channel control modules corresponding to the multiple LED pins, and multiple constant current units corresponding to the multiple LED pins. The multiple channel control modules include a channel control module for controlling the connection of corresponding channels in the multi-channel LED and a channel control module for controlling the disconnection of corresponding channels in the multi-channel LED. Each of the multiple constant current units is turned off when the LED control chip is powered on.

2. The LED control chip according to claim 1, characterized in that: The LED control chip is further configured as follows: During a preset period of time starting from the moment the LED control chip is powered on, charging each of the plurality of LED pins using the internal reference current; Locking each of the plurality of comparison results when the preset period of time has passed since the LED control chip was powered on; as well as According to each of the locked comparison results, it is determined whether each channel of the multi-channel LED needs to be turned off or turned on.

3. The LED control chip according to claim 2, characterized in that: The LED control chip is further configured as follows: When the preset period of time has passed since the LED control chip was powered on, the internal reference current is turned off.

4. The LED control chip according to claim 2, characterized in that: The LED control chip is further configured as follows: During the preset period starting from the moment the LED control chip is powered on and a voltage on a first LED pin among the plurality of LED pins is detected to rise to be greater than the preset voltage threshold, it is determined that a first LED channel corresponding to the first LED pin in the multi-channel LED needs to be turned on and the first LED channel is controlled to be turned on, wherein the first LED pin includes one or more LED pins.

5. The LED control chip according to claim 2, characterized in that: The LED control chip is further configured as follows: During the preset period starting from the moment the LED control chip is powered on and elapses, if it is detected that the voltage on a second LED pin among the plurality of LED pins remains less than the preset voltage threshold, it is determined that a second LED channel corresponding to the second LED pin in the multi-channel LED needs to be turned off, and the second LED channel is controlled to be turned off, wherein the second LED pin includes one or more LED pins.

6. The LED control chip according to claim 4, characterized in that: The channel control module for controlling the connection of the corresponding channel among the plurality of channel control modules includes: a first transistor, a first terminal receiving the internal reference current, a second terminal receiving a first control signal, and a third terminal connected to the first LED pin; a first comparator, a first terminal connected to the first LED pin, and a second terminal receiving the preset voltage threshold; and A first trigger, wherein the first terminal is connected to the third terminal of the first comparator, the second terminal receives the first control signal, and the third terminal outputs a first channel enable signal for controlling the first LED channel to be turned on; The first control signal is used to control the conduction of the first transistor when the LED control chip is powered on, and is used to control the first trigger to output the first channel enable signal from a low level to a high level when the preset period of time passes from the moment the LED control chip is powered on.

7. The LED control chip according to claim 6, characterized in that: Each of the plurality of channel control modules further comprises: The first delay unit is connected between the first comparator and the first trigger.

8. The LED control chip according to claim 5, characterized in that: The channel control module for controlling the shutoff of the corresponding channel among the plurality of channel control modules includes: a second transistor, a first terminal receiving the internal reference current, a second terminal receiving a second control signal, and a third terminal connected to the second LED pin; a first resistor, a first end of which is connected to the second LED pin, a second end of which is grounded, and a resistance value of the first resistor is less than a preset resistance threshold; a second comparator, a first terminal of which is connected to the second LED pin, and a second terminal of which receives the preset voltage threshold; and A second trigger, wherein the first terminal is connected to the third terminal of the second comparator, the second terminal receives the second control signal, and the third terminal outputs a second channel enable signal for controlling the shutdown of the second LED channel; The second control signal is used to control the conduction of the second transistor when the LED control chip is powered on, and is used to control the second trigger to output the second channel enable signal at a low level when the preset period of time has passed since the LED control chip was powered on.

9. The LED control chip according to claim 8, characterized in that: Each of the plurality of channel control modules further comprises: The second delay unit is connected between the second comparator and the second trigger.

10. The LED control chip according to claim 1, characterized in that: Each of the plurality of constant current units includes an operational amplifier, a second resistor, a third transistor, and a fourth transistor, wherein: The first end of the operational amplifier receives the internal reference voltage of the LED control chip; The first terminal of the third transistor is connected to one of the plurality of LED pins, and the second terminal and the third terminal are connected to the second terminal and the third terminal of the operational amplifier respectively; A first end of the second resistor is connected to the third end of the third transistor, and a second end thereof is grounded; The first terminal of the fourth transistor is connected to the second terminal of the third transistor, the second terminal receives the third control signal, and the third terminal is grounded; wherein, The third control signal is used to control the conduction of the fourth transistor when the LED control chip is powered on, so as to control the turn-off of the third transistor.

11. A multi-channel backlight system, comprising the LED control chip and multi-channel LEDs according to any one of claims 1 to 10, wherein: Each channel of the multi-channel LED is respectively connected to each LED pin of the plurality of LED pins of the LED control chip.

12. A control method executed by an LED control chip, for controlling the turning off and on of each channel in a multi-channel LED, characterized in that: The LED control chip includes a plurality of LED pins corresponding to the multi-channel LEDs, and the control method includes: After the LED control chip is powered on, charging each of the plurality of LED pins using an internal reference current of the LED control chip; Comparing the voltage on each of the plurality of LED pins with a preset voltage threshold to obtain a plurality of comparison results corresponding to each of the plurality of LED pins; and Determining whether each channel of the multi-channel LED needs to be turned off or on according to each of the plurality of comparison results, and controlling the turning off or on of the corresponding channel of the multi-channel LED; The LED control chip further includes a plurality of channel control modules corresponding to the plurality of LED pins, and a plurality of constant current units corresponding to the plurality of LED pins. The plurality of channel control modules include a channel control module for controlling the connection of corresponding channels in the multi-channel LED and a channel control module for controlling the disconnection of corresponding channels in the multi-channel LED. The control method further includes: Each of the plurality of constant current units is turned off when the LED control chip is powered on.

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