Coupling compensation module and light emitting diode driver thereof

Abstract

The present application discloses a coupling compensation module for compensating a channel voltage of a channel output by a constant current circuit of a light-emitting diode driver. The coupling compensation module includes a detection circuit for detecting a voltage change in the channel voltage to generate a detection result; and a compensation circuit for compensating the voltage change in the channel voltage based on the detection result.

Description

Technical Field

[0001] The present application relates to a coupling compensation module and a light-emitting diode driver thereof, and in particular to a coupling compensation module and a light-emitting diode driver thereof that can compensate for voltage changes in each channel caused by capacitive coupling and drive the light-emitting diode pixels of a light-emitting diode panel to display desired brightness. Background Art

[0002] In the existing light emitting diode (LED) driving technology, there are passive matrix common cathode driving structure and passive matrix common anode driving structure. Figure 1 and Figure 2 . Figure 1 This is a schematic diagram of a passive matrix common cathode drive structure. Figure 2 This is a schematic diagram of a passive matrix common anode drive structure. Figure 1 As shown, the passive matrix common cathode drive structure connects the anodes of LED pixels in each column of the matrix to the channels of the constant current sources of the LED driver 10 via each pulse width modulation (PWM) switch, while connecting the cathodes of LED pixels in each row of the matrix (connected to each scan line) to a ground terminal via each scan switch. When a timing controller 100 turns on a specific column and a specific row, an LED pixel at the intersection can emit light.

[0003] Similarly, if Figure 2 As shown, the passive matrix common anode drive structure connects the cathodes of LED pixels in each column of the matrix to the channels of the constant current sources of the LED driver 20 via each channel switch, and connects the anodes of LED pixels in each row of the matrix (connected to each scan line) to a power supply voltage via each scan switch. When a timing controller 200 turns on a specific column and a specific row, an LED pixel at the intersection can emit light.

[0004] In a passive matrix driving structure, when a specific channel of the LED driver 10 or 20 is turned on, if another channel of the LED driver 10 or 20 is simultaneously switched from on to off or from off to on, a channel voltage of the specific channel will drop or rise due to capacitive coupling.

[0005] For example, see Figure 3 and Figure 4 . Figure 3is a schematic diagram of a light emitting diode display panel 30 having an assembled extension structure, Figure 4 yes Figure 3 FIG. 1 is a schematic diagram of an image displayed by the LED display panel 30. Figure 3 As shown, the LED display panel 30 includes LED drivers 300 and 302 for driving the left and right LED pixels, respectively. When scan lines S1 and SX1 are connected to a ground terminal via corresponding scan switches, channels ch1 to chX and chX+1 to ch2X are turned on in a pulse width modulation manner during their respective on-time intervals to drive the corresponding LED pixels in the first row to the desired brightness.

[0006] In this case, when a specific channel (e.g., channel chX) is turned on, if another channel (e.g., one of channels ch1-ch3) is simultaneously switched from on to off, a channel voltage of the specific channel will drop due to capacitive coupling. For example, when channel ch1 switches from on to off at time T1, the channel voltage of channel ch1 (connected to the anode of the LED capacitor in channel ch1) drops. Consequently, the voltage of scan lines S2-SY (connected to the cathode of the LED capacitor in channel ch1) drops due to voltage coupling from the LED capacitor in channel ch1. Since scan lines S2-SY are connected to the cathodes of the LED capacitors in channels ch2-chX, the channel voltage of channels ch2-chX (connected to the anode of the LED capacitor in channels ch2-chX) drops due to voltage coupling from the LED capacitor in channels ch2-chX. This causes the constant current sources of channels ch2-chX to supply current to charge the LED capacitors in scan lines S1 and S2-SY (as shown in channel chX). Similarly, the voltage changes of channels chX+1 to ch2X and scanning lines SX1 to SXY can be obtained.

[0007] Therefore, when channels ch1 to chX are simultaneously turned on and off according to their respective on-time intervals, since channel chX has the longest on-time interval, the channel voltage of channel chX will all drop when channels ch1 to chX-1 are switched from on to off. In this way, even if channels chX and chX+1 are configured to have the same on-time interval (i.e., pulse width) to display the same brightness, since the channel voltage of channel chX drops X-1 times when driven, while the channel voltage of channel chX1 does not drop when driven, the area displayed by channel chX is darker than the area displayed by channel chX+1, and thus there will be a difference between them. Figure 4 There is a discontinuity shown.

[0008] Similarly, please refer to Figure 5 , Figure 5 yes Figure 3 Another operational schematic diagram of the LED display panel 30 is shown. When a specific channel (e.g., channel chX) is turned on, if another channel (e.g., one of channels ch1-ch3) is simultaneously switched from off to on, a channel voltage of the specific channel will increase due to capacitive coupling. Therefore, when channels ch1-chX are simultaneously turned off and then turned on according to their respective on-time intervals, since channel chX has the longest on-time interval, the channel voltage of channel chX will increase when channels ch1-chX-1 are switched from off to on. As a result, even if channels chX and chX+1 are configured to have the same on-time interval (i.e., pulse width) to display the same brightness, the channel voltage of channel chX increases X-1 times during driving, while the channel voltage of channel chX1 does not increase during driving. Therefore, the area displayed by channel chX is brighter than the area displayed by channel chX+1, resulting in a discontinuity (not shown) between the two areas.

[0009] Therefore, the prior art needs to be improved. Summary of the Invention

[0010] Therefore, the main purpose of the present application is to provide a coupling compensation module and a LED driver thereof that can compensate for the voltage variation of each channel caused by capacitive coupling and drive the LED pixels of the LED panel to display desired brightness.

[0011] The present application discloses a coupling compensation module for compensating a channel voltage of a channel output by a constant current circuit of a light-emitting diode driver. The coupling compensation module includes a detection circuit for detecting a voltage change in the channel voltage to generate a detection result; and a compensation circuit for compensating the voltage change in the channel voltage based on the detection result.

[0012] The present application also discloses an LED driver for driving an LED panel. The LED driver includes a constant current circuit for outputting a channel voltage of a channel; and a coupling compensation module, which includes a detection circuit for detecting a voltage change of the channel voltage to generate a detection result; and a compensation circuit for compensating for the voltage change of the channel voltage based on the detection result. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of a passive matrix common cathode drive structure.

[0014] Figure 2 It is a schematic diagram of a passive matrix common anode drive structure.

[0015] Figure 3 It is a schematic diagram of a light emitting diode display panel with an assembled extension structure.

[0016] Figure 4 yes Figure 3 A schematic diagram of an image displayed on a light emitting diode display panel is shown.

[0017] Figure 5 yes Figure 3 Another operational schematic diagram of the light emitting diode display panel is shown.

[0018] Figure 6 It is a partial schematic diagram of a light emitting diode driver according to an embodiment of the present application.

[0019] Figure 7 This is an embodiment of the present application Figure 6 Shown is a detailed circuit diagram of a coupling compensation module.

[0020] Figure 8 This is an embodiment of the present application Figure 7 The operation diagram of the coupling compensation module is shown.

[0021] Figure 9 This is an embodiment of the present application Figure 7 Another operational schematic diagram of the coupling compensation module is shown.

[0022] Figure 10 FIG. 1 is a schematic diagram of a light emitting diode display panel with an assembly extension structure according to an embodiment of the present application.

[0023] The description of the accompanying drawings is as follows:

[0024] 10, 20, 300, 302, 60 LED drivers

[0025] 100, 200 timing controller

[0026] 30, 1000 LED display panels

[0027] S1~SXY scanning lines

[0028] ch1~chX、chX+1~ch2X channels

[0029] 600 Constant Current Circuit

[0030] 602 Coupling Compensation Module

[0031] 604 Detection Circuit

[0032] 606 compensation circuit

[0033] 608, 610 sampling circuit

[0034] 612, 614 Comparators

[0035] INV1~INV4 inverters

[0036] MPS, MPWM, MP, MN transistors

[0037] Vch, Vsu, Vso, Vch', VREF voltage

[0038] C1~C2 capacitors

[0039] SW1~SW4 switches

[0040] DU Undershoot Detection

[0041] DO overshoot detection

[0042] DES decoupling enable signal

[0043] OR1~OR2 OR gate

[0044] ΔVth threshold voltage difference DETAILED DESCRIPTION

[0045] Please refer to Figure 6 , Figure 6 FIG. 1 is a partial schematic diagram of a light emitting diode (LED) driver 60 according to an embodiment of the present application. Figure 6 As shown, the LED driver 60 is used to drive a LED panel and includes a constant current circuit 600 and a coupling compensation (CC) module 602. The constant current circuit 600 can be Figure 1 、 Figure 3 and Figure 5 Each pair of constant current sources and pulse width modulation (PWM) switches shown can output a channel voltage Vch (i.e., the turn-on voltage of the corresponding light-emitting diode) when a corresponding channel CH is turned on. The coupling compensation module 602 includes a detection circuit 604 and a compensation circuit 606. The detection circuit 604 detects a voltage change in the channel voltage Vch to generate a detection result. The compensation circuit 606 compensates for the voltage change in the channel voltage Vch based on the detection result (i.e., brightness compensation).

[0046] Specifically, when channel CH is turned on and another channel of the LED driver 60 simultaneously switches from on to off or from off to on, the channel voltage Vch of channel CH decreases or increases, respectively, due to capacitive coupling. In these cases, the detection result indicates a decrease or increase in channel voltage Vch, and the compensation circuit 606 increases or decreases channel voltage Vch, respectively. In this way, the present application can compensate for voltage variations in channel voltage Vch, thereby driving the LED pixels of the LED panel to display desired brightness.

[0047] Specifically, in constant current circuit 600, a constant current transistor MPS receives a fixed voltage at its gate to provide a constant channel current (i.e., a constant current source). A switch SW1 is coupled between a power supply voltage and a gate of a pulse-width modulation transistor MPWM and is controlled by an inverted signal of a pulse-width modulation signal SPWM. When the pulse-width modulation signal SPWM is at a low level, the gate of the pulse-width modulation transistor MPWM is controlled to be at a high level (e.g., at the power supply voltage) or off. Another switch SW2 is coupled between an output terminal of an amplifier and the gate of the pulse-width modulation transistor MPWM and is controlled by the pulse-width modulation signal SPWM. When the pulse-width modulation signal SPWM is at a high level, a negative feedback loop is formed to lock a source voltage of the pulse-width modulation transistor MPWM to a reference voltage VREF, causing the pulse-width modulation transistor MPWM to conduct and output a constant channel current to drive a corresponding light-emitting diode (LED) and generate a channel voltage Vch (i.e., the turn-on voltage of the LED).

[0048] Furthermore, the detection circuit 604 includes sampling circuits 608 and 610, comparators 612 and 614, and an inverter INV1. The compensation circuit 606 includes transistors MP and MN. Specifically, when the channel CH is on, the sampling circuit 608 samples and holds the channel voltage Vch to generate a sampled voltage Vsu. The comparator 612 compares the channel voltage Vch with the sampled voltage Vsu to generate a first comparison result indicating whether the channel voltage Vch is less than the sampled voltage Vsu by a first threshold voltage difference ΔVth (i.e., whether the channel voltage Vch is less than the sampled voltage Vsu by the first threshold voltage difference ΔVth). The inverter INV1 receives the first comparison result and generates a first inverted signal as an undershoot detection signal DU of the detection result. When the undershoot detection signal DU indicates that the channel voltage Vch is less than the sampled voltage Vsu by a threshold voltage difference ΔVth, the transistor MP supplies current to the channel CH to increase the channel voltage Vch. As such, the present application can increase the channel voltage Vch when the channel CH is turned on and the channel voltage Vch drops beyond the threshold voltage difference ΔVth (to avoid erroneous operation when there is no coupling from other channels).

[0049] On the other hand, when channel CH is on, sampling circuit 610 samples and holds channel voltage Vch to generate a sampled voltage Vso. Comparator 612 compares channel voltage Vch with sampled voltage Vso to generate a second comparison result, serving as an overshoot detection function (DO), indicating whether channel voltage Vch is greater than the second sampled voltage Vso by a second threshold voltage difference (for example, in this embodiment, the second threshold voltage difference is the same as the first threshold voltage difference ΔVth, but in other embodiments, the second threshold voltage difference may also be different from the first threshold voltage difference ΔVth). When overshoot detection function DO indicates that channel voltage Vch is greater than the second sampled voltage Vso by a threshold voltage difference ΔVth, transistor MN draws current from channel CH to reduce channel voltage Vch. In this way, the present application can reduce channel voltage Vch when channel CH is on and channel voltage Vch increases by more than the threshold voltage difference ΔVth.

[0050] For details, please refer to Figure 7 , Figure 7 This is an embodiment of the present application Figure 6 Detailed circuit diagram of coupling compensation module 602 is shown. Figure 7As shown, sampling circuit 608 includes an inverter INV2, an OR gate OR1, a switch SW3, and a capacitor C1. Inverter INV2 receives a decoupling enable signal DES to generate a second inverted signal. OR gate OR1 receives the second inverted signal and an overshoot detection signal DO to generate a first operation result. Switch SW3 is coupled between channel CH and a positive input terminal of comparator 612 and includes a control terminal for receiving the first operation result. Capacitor C1 is coupled between a ground terminal and the positive input terminal of comparator 612 to provide a sampling voltage Vsu.

[0051] On the other hand, sampling circuit 610 includes inverters INV3 and INV4, an OR gate OR2, a switch SW4, and a capacitor C2. Inverter INV3 receives a decoupling enable signal DES to generate a third inverted signal. Inverter INV4 receives an undershoot detection signal DU to generate a fourth inverted signal. OR gate OR2 receives the third inverted signal and the fourth inverted signal to generate a second operation result. Switch SW4 is coupled between channel CH and a negative input terminal of comparator 614 and includes a control terminal for receiving the second operation result. Capacitor C2 is coupled between a ground terminal and the negative input terminal of comparator 614 and provides a sampling voltage Vso.

[0052] Furthermore, comparator 614 or 612 can be implemented as the circuit shown in the dashed box and include a mismatched input pair, wherein the channel width of a transistor at the positive input terminal is smaller than the channel width of a transistor at the negative input terminal (e.g., 0.9 times versus 1 times). Therefore, comparator 614 or 612 outputs a high-level comparison result only when the voltage at the positive input terminal exceeds the voltage at the negative input terminal by a threshold voltage difference ΔVth. Furthermore, transistors MP and MN have adjustable drive capabilities, providing appropriate drive capabilities for different light-emitting diodes with varying characteristics.

[0053] In this structure, see Figure 8 , Figure 8 This is an embodiment of the present application Figure 7 The operation diagram of the coupling compensation module 602 is shown in FIG. Figure 7 and Figure 8As shown, when channel CH is turned on and another channel with a channel voltage Vch' is about to be turned off, a decoupling enable signal DES (provided by a timing controller) is triggered for a specific time interval. When the decoupling enable signal DES is high and the overshoot detection signal DO is low (details will be described later), the first operation result is low, causing switch SW3 to turn off, sampling the channel voltage Vch on capacitor C1 as the sampled voltage Vsu. Then, when the channel with channel voltage Vch' is turned off, the channel voltage Vch drops. When the channel voltage Vch drops by more than the threshold voltage difference ΔVth, comparator 612 outputs the first comparison result as high (comparator 612 delays and extends the high first comparison result to meet actual compensation requirements). Subsequently, because the undershoot detection signal DU is low in response to the high first comparison result, transistor MP supplies current to channel CH, increasing the channel voltage Vch. At the same time, the undershoot detection DU is at a low level, so the second operation result is a high level, making the sampling voltage Vso equal to the channel voltage Vch, thereby preventing the channel voltage Vch from rising beyond the sampling voltage Vso plus the threshold voltage difference ΔVth and falsely triggering the transistor MN.

[0054] On the other hand, see Figure 9 , Figure 9 This is an embodiment of the present application Figure 7 Another operation diagram of the coupling compensation module 602 is shown. Figure 7 and Figure 9 As shown, when channel CH is turned on and another channel with channel voltage Vch' is about to be turned on, the decoupling enable signal DES (provided by a timing controller) is triggered for a specific time interval. When the decoupling enable signal DES is high and the undershoot detection signal DU is high (details will be described later), the second operation result is low, causing switch SW4 to turn off, sampling the channel voltage Vch on capacitor C2 as the sampled voltage Vso. Then, when the channel with channel voltage Vch' is turned on, the channel voltage Vch rises. When the channel voltage Vch rises above the threshold voltage difference ΔVth, comparator 614 outputs an overshoot detection signal DO high. (Comparator 614 delays and extends the high overshoot detection signal DO to meet actual compensation requirements.) Since the overshoot detection signal DO is high, transistor MN then draws current from channel CH, reducing the channel voltage Vch. At the same time, the overshoot detection DO is high and thus the first operation result is high, making the sampling voltage Vsu equal to the channel voltage Vch, thereby preventing the channel voltage Vch from dropping more than the sampling voltage Vsu minus the threshold voltage difference ΔVth and falsely triggering the transistor MP.

[0055] Please refer to Figure 10 , Figure 10FIG2 is a schematic diagram of an LED display panel 1000 having an assembly extension structure according to an embodiment of the present application. LED display panel 1000 is similar to LED display panel 30, and therefore, components with similar functions are represented by the same symbols. The primary difference between LED display panel 1000 and LED display panel 30 is that each channel of LED display panel 1000 is implemented with a coupling compensation module 602. This module compensates for voltage variations within each channel by appropriately increasing the voltage of each channel, thereby driving the LED pixels of LED display panel 1000 to display a desired brightness. As a result, the area displayed by channel chX and the area displayed by channel chX+1 have approximately the same brightness, with a continuous pattern between them (not shown).

[0056] It is worth noting that in the above embodiment, the voltage variation of each channel due to capacitive coupling is compensated, thereby driving the LED pixels of the LED panel to display the desired brightness. Those skilled in the art may make corresponding modifications or changes accordingly. For example, Figure 5 Each channel of the LED display panel 30 can also be implemented with a coupling compensation module 602 to compensate for voltage variations in each channel by appropriately reducing the voltage of each channel, thereby driving the LED pixels of the LED display panel to display a desired brightness. Furthermore, the LED pixels in different channels can have the same color (e.g., all green channels) or different colors (e.g., sequentially and repeatedly configured with red, green, and blue channels).

[0057] Furthermore, in the above embodiment, the coupling compensation module 602 detects the voltage change of the channel voltage Vch in the passive matrix common cathode driving structure, wherein the channel voltage Vch is an anode voltage of an anode of an LED. In other embodiments, the coupling compensation module 602 may also be Figure 2 The passive matrix common anode driving structure detects a voltage change of a channel voltage, wherein the channel voltage is a cathode voltage of a cathode of a light emitting diode.

[0058] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A coupling compensation module for compensating a channel voltage of a channel output by a constant current circuit of a light emitting diode driver, characterized in that: include: a detection circuit for detecting a voltage change of the channel voltage to generate a detection result, Wherein, the detection circuit includes: a first sampling circuit, configured to sample and hold the channel voltage when the channel is turned on, so as to generate a first sampling voltage; a first comparator, coupled to the first sampling circuit, for comparing the channel voltage with the first sampling voltage to generate a first comparison result indicating whether the channel voltage is less than the first sampling voltage by a first threshold voltage difference; a first inverter, coupled to the first comparator, for receiving the first comparison result to generate a first inverted signal as a down-shoot detection of the detection result; a second sampling circuit, configured to sample and hold the channel voltage when the channel is turned on, so as to generate a second sampling voltage; and a second comparator, coupled to the second sampling circuit, for comparing the channel voltage with the second sampling voltage to generate a second comparison result as an overshoot detection of the detection result to indicate whether the channel voltage is greater than the second sampling voltage by a second threshold voltage difference; and a compensation circuit, configured to compensate for the voltage variation of the channel voltage according to the detection result, wherein the compensation circuit comprises: a first transistor coupled to the first inverter, configured to increase the channel voltage when the undershoot detection indicates that the channel voltage is less than the first sampling voltage by more than the first threshold voltage; and A second transistor is coupled to the second comparator and the first transistor, and is configured to reduce the channel voltage when the overshoot detection indicates that the channel voltage is greater than the second sampling voltage by more than the second threshold voltage difference.

2. The coupling compensation module according to claim 1, wherein: The first sampling circuit includes: a second inverter, configured to receive a decoupling enable signal to generate a second inverted signal; a first OR gate, configured to receive the second inverted signal and an overshoot detection signal to generate a first operation result; a first switch coupled between the channel and a positive input terminal of the first comparator, comprising a control terminal for receiving the first operation result; and A first capacitor is coupled between a ground terminal and the positive input terminal of the first comparator, and is used to provide the first sampling voltage.

3. The coupling compensation module according to claim 1, wherein: The first comparator includes an unmatched first input pair.

4. The coupling compensation module according to claim 1, wherein: The second sampling circuit includes: a third inverter, configured to receive a decoupling enable signal to generate a third inverted signal; a fourth inverter, configured to receive a down-shoot detection signal to generate a fourth inverted signal; a second OR gate, configured to receive the third inverted signal and the fourth inverted signal to generate a second operation result; a second switch coupled between the channel and a negative input terminal of the second comparator, comprising a control terminal for receiving the second operation result; and A second capacitor is coupled between a ground terminal and a negative input terminal of the second comparator, and is used to provide the second sampling voltage.

5. The coupling compensation module according to claim 1, wherein: The second comparator includes an unmatched second input pair.

6. The coupling compensation module according to claim 1, wherein: When the channel is turned on and another channel is to be turned on or off, a decoupling enable signal is triggered for a specific time interval.

7. The coupling compensation module according to claim 1, wherein: When the LED driver is implemented in a passive matrix common cathode driving structure, the channel voltage is an anode voltage. When the LED driver is implemented in a passive matrix common anode driving structure, the channel voltage is a cathode voltage.

8. A light emitting diode driver for driving a light emitting diode panel, characterized in that: include: a constant current circuit for outputting a channel voltage of a channel; as well as A coupling compensation module, comprising: a detection circuit for detecting a voltage change of the channel voltage to generate a detection result, wherein the detection circuit comprises: a first sampling circuit, configured to sample and hold the channel voltage when the channel is turned on, so as to generate a first sampling voltage; a first comparator, coupled to the first sampling circuit, for comparing the channel voltage with the first sampling voltage to generate a first comparison result indicating whether the channel voltage is less than the first sampling voltage by a first threshold voltage difference; a first inverter, coupled to the first comparator, for receiving the first comparison result to generate a first inverted signal as a down-shoot detection of the detection result; a second sampling circuit, configured to sample and hold the channel voltage when the channel is turned on, so as to generate a second sampling voltage; and a second comparator, coupled to the second sampling circuit, for comparing the channel voltage with the second sampling voltage to generate a second comparison result as an overshoot detection of the detection result to indicate whether the channel voltage is greater than the second sampling voltage by a second threshold voltage difference; and a compensation circuit, configured to compensate for the voltage variation of the channel voltage according to the detection result, wherein the compensation circuit comprises: a first transistor coupled to the first inverter, configured to increase the channel voltage when the undershoot detection indicates that the channel voltage is less than the first sampling voltage by more than the first threshold voltage; and A second transistor is coupled to the second comparator and the first transistor, and is configured to reduce the channel voltage when the overshoot detection indicates that the channel voltage is greater than the second sampling voltage by more than the second threshold voltage difference.

9. The light emitting diode driver according to claim 8, wherein: The first sampling circuit includes: a second inverter, configured to receive a decoupling enable signal to generate a second inverted signal; a first OR gate, configured to receive the second inverted signal and an overshoot detection signal to generate a first operation result; a first switch coupled between the channel and a positive input terminal of the first comparator, comprising a control terminal for receiving the first operation result; and A first capacitor is coupled between a ground terminal and the positive input terminal of the first comparator, and is used to provide the first sampling voltage.

10. The light emitting diode driver according to claim 8, wherein: The first comparator includes an unmatched first input pair.

11. The light emitting diode driver according to claim 8, wherein: The second sampling circuit includes: a third inverter, configured to receive a decoupling enable signal to generate a third inverted signal; a fourth inverter, configured to receive a down-shoot detection signal to generate a fourth inverted signal; a second OR gate, configured to receive the third inverted signal and the fourth inverted signal to generate a second operation result; a second switch coupled between the channel and a negative input terminal of the second comparator, comprising a control terminal for receiving the second operation result; and A second capacitor is coupled between a ground terminal and a negative input terminal of the second comparator, and is used to provide the second sampling voltage.

12. The light emitting diode driver according to claim 8, wherein: The second comparator includes an unmatched second input pair.

13. The light emitting diode driver according to claim 8, wherein: When the channel is turned on and another channel is to be turned on or off, a decoupling enable signal is triggered for a specific time interval.

14. The light emitting diode driver according to claim 8, wherein: When the LED driver is implemented in a passive matrix common cathode driving structure, the channel voltage is an anode voltage. When the LED driver is implemented in a passive matrix common anode driving structure, the channel voltage is a cathode voltage.

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