Start control circuit of power tube, row driving circuit and LED display device

Abstract

The invention provides a starting control circuit of a power tube, a row driving circuit and an LED display device. The starting control circuit of the power tube comprises a first starting branch which provides a first starting signal for the power tube when being started; the second starting branch provides a second starting signal for the power tube when being started; the first starting control circuit is used for controlling the first starting branch circuit to be started in at least a first starting stage in the effective time period of the input signal, and the power tube starts to be conducted when the first starting signal enables the driving voltage of the power tube to reach a starting threshold value; and the second starting control circuit receives the input signal and the driving voltage and controls the second starting branch circuit to be started at a second starting stage in the effective time period of the input signal, and the second starting signal enables the power tube to be completely conducted. Therefore, the power tube is in a weak opening state in the first starting stage, charges of parasitic capacitance of the output node are released, and the power tube is completely conducted in the second starting stage, so that current overshoot at the opening moment is avoided.

Description

Technical Field

[0001] The present application relates to the field of display drive technology, and in particular to a power tube startup control circuit, a row drive circuit and an LED display device. Background Art

[0002] LED display devices usually include an LED light source array and a display driver chip. The LED light source array includes a plurality of LED lamp beads arranged in rows and columns. The display driver chip is divided into a row driver chip and a column driver chip. For the row driver chip, it is connected to the same end of the LED lamp beads in the same row to realize common anode drive or common cathode drive. The row driver chip is responsible for providing driving current to all LED lamp beads on the row when the row is turned on. Therefore, the size of the MOS tube of the output stage in the row driver chip is required to be larger to ensure that sufficient driving current is provided to the LED lamp beads.

[0003] Figure 1 FIG. 4 shows a schematic diagram of a driving circuit of a large-size power tube in the prior art. Figure 1 As shown, the output stage MOS tube M0 of the row driver chip is a large-sized NMOS tube, which is connected to the cathode of the same row of LED lamp beads (D1, D2...Dm). When the MOS tube M0 is turned on, a path is formed, and current flows through the LED lamp beads. The input signal IN of the row driver chip needs to pass through a driver chain composed of a series of inverters to increase the driving ability of the inverter step by step to achieve the driving of the output stage large MOS tube M0. At the moment when the output stage MOS tube M0 is turned on, the parasitic capacitance Cs of the circuit output node will discharge through the MOS tube M0. Since the on-resistance of the MOS tube M0 is very small, a large transient current will be generated on the power supply / ground, causing voltage fluctuations on the power supply / ground, thereby affecting the working state of the circuit. Summary of the invention

[0004] In order to solve the above technical problems, the present application provides a power tube startup control circuit, a row drive circuit, a display driver chip, an LED display device and a terminal electronic device.

[0005] According to one aspect of the present invention, a startup control circuit for a power tube is provided, comprising: a first startup branch, which provides a first startup signal to the control end of the power tube when it is turned on; a second startup branch, which provides a second startup signal to the control end of the power tube when it is turned on; a first startup control circuit, which receives an input signal, controls the first startup branch to be turned on in at least a first startup phase within an effective period of the input signal, and the power tube starts to conduct when the first startup signal causes the driving voltage of the power tube to reach a turn-on threshold; and a second startup control circuit, which receives an input signal and a driving voltage, controls the second startup branch to be turned on in a second startup phase within an effective period of the input signal, and the second startup signal causes the power tube to be fully turned on, wherein the effective period of the input signal includes adjacent first startup phase and second startup phase.

[0006] Optionally, the first startup branch is continuously turned on during the effective period of the input signal, and in a time period outside the first startup phase in each working cycle, the second startup control circuit controls the startup state of the second startup branch to follow the startup state of the first startup branch.

[0007] Optionally, the second start-up control circuit includes: a driving state characterization circuit, which receives the driving voltage to output a characterization signal characterizing the voltage state of the driving voltage; and a following control circuit, which controls the connectivity between the control end of the first start-up branch and the control end of the second start-up branch according to the input signal and the characterization signal, and when a connection path is established between the control end of the first start-up branch and the control end of the second start-up branch, the start-up state of the second start-up branch follows the start-up state of the first start-up branch.

[0008] Optionally, the level state of the characterization signal changes when the driving voltage reaches a turn-on threshold of the power tube and reaches a turn-off threshold of the power tube.

[0009] Optionally, the follower control circuit disconnects the connection path between the control end of the first start branch and the control end of the second start branch when the input signal becomes valid, and starts to enter the first start phase; the follower control circuit also establishes a connection path between the control end of the first start branch and the control end of the second start branch when the characterization signal indicates that the driving voltage reaches the start-up threshold of the power tube, and starts to enter the second start phase.

[0010] Optionally, the startup control circuit of the power tube further includes: a shutdown branch, which is turned on when the input signal is invalid, and provides a shutdown signal to the control end of the power tube, wherein the shutdown signal shuts down the power tube when the driving voltage reaches a shutdown threshold.

[0011] Optionally, the first startup control circuit includes a plurality of inverters connected in series, which perform signal enhancement and phase adjustment processing on the input signal to provide an input control signal to the control end of the first startup branch.

[0012] Optionally, the first startup branch includes a first MOS tube, the second startup branch includes a second MOS tube, and the shutdown branch includes a third MOS tube; the driving state characterization circuit includes a current source and a fourth MOS tube connected in series, the control end of the fourth MOS tube receives the driving voltage, and the characterization signal is provided from the connection node between the current source and the fourth MOS tube; the follower control circuit includes a NAND gate, a switch unit and a fifth MOS tube, the input end of the NAND gate receives the input signal and the characterization signal, and the output end generates a switch signal, and the switch signal controls the conduction state of the switch unit and the fifth MOS tube.

[0013] Optionally, the switch unit connects the control end of the first MOS tube and the control end of the second MOS tube, and the switch unit includes a transmission gate, a switch tube or a switch; the fifth MOS tube is connected to the control end of the second MOS tube, and receives the switch signal when the fifth MOS tube is a PMOS tube, and receives an inverted signal of the switch signal when the fifth MOS tube is an NMOS tube.

[0014] Optionally, when the power tube is an NMOS tube, the first MOS tube and the second MOS tube are PMOS tubes, the third MOS tube and the fourth MOS tube are NMOS tubes, and the first startup control circuit includes an odd number of inverters; when the power tube is a PMOS tube, the first MOS tube and the second MOS tube are NMOS tubes, the third MOS tube and the fourth MOS tube are PMOS tubes, and the first startup control circuit includes an even number of inverters.

[0015] According to another aspect of the present invention, there is provided a row driving circuit connected to the same end of a row of LED lamp beads, wherein the row driving circuit comprises: a power tube, serving as the output stage of the row driving circuit; and a start-up control circuit of the power tube, wherein the start-up control circuit of the power tube is used to control the conduction state of the power tube, so that a stable drive current flows through the row of LED lamp beads when the power tube is turned on.

[0016] According to another aspect of the present invention, there is provided a display driver chip, comprising: a power supply; and a plurality of row driver circuits, each row driver circuit being connected to the same end of the same row of LED lamp beads, wherein the row driver circuit comprises a power tube as an output stage and a start-up control circuit of the power tube.

[0017] According to another aspect of the present invention, there is provided an LED display device, comprising: an LED array, the LED array comprising a plurality of LED lamp beads arranged in an array; and a plurality of row drive circuits, each of the row drive circuits correspondingly controlling a row of LED lamp beads, and each of the row drive circuits comprising a power tube and a start-up control circuit for the power tube.

[0018] According to another aspect of the present invention, there is provided a terminal electronic device, comprising: a power tube and a start-up control circuit of the power tube.

[0019] The beneficial effects of this application include at least:

[0020] The embodiment of the present application provides a startup control circuit of a power tube, a row drive circuit, a display driver chip, an LED display device and a terminal electronic device, and two startup branches are set at the control end of the power tube of the output stage. In the first startup stage when the input signal is valid, the first startup branch first changes the driving voltage of the power tube, and the driving voltage reaches the turn-on threshold value to put the power tube in a weak turn-on state, and the charge on the parasitic capacitor of the output node is slowly released through the power tube to avoid the formation of a large transient current. Afterwards, in the second startup stage when the input signal is valid, the second startup branch is turned on to make the power tube fully turned on, providing a current path for the LED lamp beads. Through the cooperation of the two startup branches, the charge on the parasitic capacitor is well discharged, and the normal working state of the circuit is not affected. A stable current path can also be provided for the LED lamp beads to ensure the stability of the picture of the LED display device.

[0021] Furthermore, the first startup control circuit enables the first startup branch to remain on during the entire period when the input signal is valid, and the second startup control circuit enables the second startup branch to follow the on state of the first startup branch during the period outside the first startup phase. Specifically, the connection state between the control end of the first startup branch and the control end of the second startup branch can be controlled according to the input signal and the characterization signal of the driving voltage, so that the working state of the second startup branch can be accurately controlled to accurately control the start-up timing of the power tube and stabilize the working state of the circuit.

[0022] It should be noted that the above general description and the following detailed description are merely exemplary and explanatory and do not limit the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic diagram of a driving circuit for a large-size power tube in the prior art is shown;

[0024] Figure 2 A schematic circuit diagram of a power tube startup control circuit and a part of a row drive circuit according to a first embodiment of the present invention is shown;

[0025] Figure 3 Shows Figure 2 A schematic diagram of waveforms of various signals in a startup control circuit of a power tube;

[0026] Figure 4 A schematic circuit diagram of a power tube startup control circuit and a part of a row drive circuit according to a second embodiment of the present invention is shown;

[0027] Figure 5 A partial structural schematic diagram of an LED display device according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0028] In order to facilitate understanding of the present application, the present application will be described more comprehensively below with reference to the relevant drawings. The drawings provide preferred embodiments of the present application. However, the present application can be implemented in different forms and is not limited to the embodiments described herein.

[0029] References to "one embodiment" or "some embodiments" etc. described in this specification mean that a particular feature, structure or characteristic described in conjunction with the embodiment is included in one or more embodiments of the present application. Thus, the statements "in one embodiment", "in some embodiments", "in some other embodiments", etc. that appear in different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in another way. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in another way. "Multiple" means two or more than two.

[0030] In addition, the same figure marks in the figures represent the same or similar structures, and thus their repeated description will be omitted. That is, the various parts in this specification are described in a combination of parallel and progressive manners, and each part focuses on the differences from other parts. The same or similar parts between the various parts can be referenced to each other.

[0031] Figure 2 FIG. 4 shows a schematic circuit diagram of a power tube startup control circuit and a part of a row drive circuit according to a first embodiment of the present invention. Figure 3 Shows Figure 2 Schematic diagram of the waveforms of various signals in the startup control circuit of the power tube.

[0032] and Figure 1 Similarly, the row driving circuit of this embodiment is connected to the same end of a row of LED lamp beads. When the output stage power tube of the row driving circuit is NMOS, the cathodes of a row of LED lamp beads are connected together and connected to the drain of the power tube M0. Figure 2As shown, the row driving circuit of this embodiment includes a power tube M0 and a start-up control circuit 100 of the power tube (other circuit structures and LED lamp beads are not shown). The power tube M0 serves as the output stage of the row driving circuit and provides an output signal OUT from the drain. The start-up control circuit 100 of the power tube is used to control the conduction state of the power tube M0 so that a stable drive current flows through a row of LED lamp beads when the power tube M0 is turned on.

[0033] The power tube startup control circuit 100 of this embodiment includes a first startup branch 110, a second startup branch 120, a first startup control circuit 130 and a second startup control circuit 140. The output end of the first startup branch 110 is connected to the control end of the power tube M0. When the first startup branch 110 is turned on, it provides a first startup signal to the control end of the power tube M0. The first startup signal can slowly increase the driving voltage NGATE of the power tube M0. The output end of the second startup branch 120 is connected to the control end of the power tube M0. When the second startup branch 120 is turned on, it provides a second startup signal to the control end of the power tube M0. The second startup signal can quickly increase the driving voltage of the power tube M0. The input end of the first startup control circuit 130 receives the input signal IN, and the output end is connected to the control end of the first startup branch 110. When the input signal IN is valid, the first startup branch 110 is controlled to be turned on. In a working cycle, the effective period of the input signal IN includes the adjacent first startup stage and the second startup stage. The first startup control circuit 130 controls the first startup branch 110 to turn on at least in the first startup phase, and the first startup signal causes the driving voltage NGATE of the power tube to rise, and the power tube M0 starts to conduct when the driving voltage NGATE reaches the turn-on threshold. The turn-on threshold mentioned here refers to the voltage required for the power tube M0 to just start conducting. The second startup control circuit 140 receives the input signal IN and the driving voltage NGATE, and controls the second startup branch 120 to turn on in the second startup phase within the effective period of the input signal IN. The second startup signal causes the driving voltage of the power tube M0 to rise rapidly, and the power tube M0 is fully turned on. Thus, in the first startup phase, the first startup branch 110 causes the power tube M0 to start conducting and is in a weakly turned-on state, so that the charge on the parasitic capacitor Cs can be slowly released to avoid the large transient current caused by the discharge of the parasitic capacitor when the power tube is turned on. Then in the second startup phase, the power tube is fully turned on and enters a normal working state, so that the LED lamp beads can form a current path.

[0034] Further, the first startup control circuit 130 can also control the first startup branch 110 to remain turned on during the entire effective period of the input signal. Then, in the time period outside the first startup phase in each working cycle, the second startup control circuit 140 can control the second startup branch 120 to follow the first startup branch 110. Specifically, the first startup control circuit 130, for example, includes a plurality of inverters connected in series, and performs signal enhancement and phase adjustment processing on the input signal IN to provide an input control signal X to the control end of the first startup branch 110. In this embodiment, the power tube M0 is an NMOS tube, and the first startup control circuit 130 includes an odd number of inverters, for example, including 3 inverters connected end to end. That is, the input signal IN is output after passing through the inverter O1, the inverter O2 and the inverter O3, and the obtained input control signal X is opposite in phase to the input signal IN. Correspondingly, the first startup branch 110, for example, includes a first MOS tube P1, and the power tube M0 is an NMOS, then the first MOS tube P1 can be a PMOS tube. The source of the first MOS transistor P1 receives the V1 voltage, the drain of the first MOS transistor P1 is connected to the control end of the power transistor M0, and the gate of the first MOS transistor P1 is connected to the output end of the inverter O3. When the input signal IN is valid, the first MOS transistor P1 is turned on during the period when the input control signal X is at a low level. Similarly, the second startup branch 120 includes, for example, a second MOS transistor P2, and if the power transistor M0 is an NMOS, then the second MOS transistor P2 is a PMOS transistor, the source of the second MOS transistor P2 receives the V2 voltage, the drain of the second MOS transistor P2 is connected to the control end of the power transistor M0, and the gate of the second MOS transistor P2 is connected to the output end of the second startup control circuit 140 to receive the follower control signal Y.

[0035] In one embodiment, the second startup control circuit 140 specifically includes a driving state characterization circuit 141 and a follower control circuit 142. The driving state characterization circuit 141 receives the driving voltage NGATE to output a characterization signal CTRL that characterizes the voltage state of the driving voltage NGATE. The level state of the characterization signal CTRL changes when the driving voltage NGATE reaches the turn-on threshold of the power tube M0 and reaches the turn-off threshold of the power tube. The follower control circuit 142 controls the connection state between the control end of the first startup branch 110 and the control end of the second startup branch 120 according to the input signal IN and the characterization signal CTRL. When a connection path is established between the control end of the first startup branch 110 and the control end of the second startup branch 120, the turn-on state of the second startup branch 120 follows the turn-on state of the first startup branch 110. That is, the follower control circuit 142 can control the connection path between the control end of the first MOS tube P1 and the control end of the second MOS tube P2. When the connection path is established, the control end of the second MOS tube P2 is connected to the control end of the first MOS tube P1, and the follower control signal Y changes with the input control signal X. Moreover, the size of the first MOS transistor P1 is smaller than that of the second MOS transistor P2 , so that in the first startup phase, the driving voltage NGATE rises slowly, while in the second startup phase, the power transistor M0 can be fully turned on.

[0036] When the circuit is working, the follower control circuit 142 disconnects the connection path between the control end of the first start-up branch and the control end of the second start-up branch when the input signal IN becomes effective, and starts to enter the first start-up phase. That is, in the first start-up phase, the control end of the second MOS transistor P2 is disconnected from the control end of the first MOS transistor P1, and the follower control signal Y has nothing to do with the input control signal X. The follower control signal Y generated by the follower control circuit 142 turns off the second MOS transistor P2. Then, the follower control circuit 142 also establishes a connection path between the control end of the first start-up branch and the control end of the second start-up branch when the characterization signal CTRL characterizes that the driving voltage NGATE reaches the turn-on threshold of the power transistor M0, and starts to enter the second start-up phase. Therefore, after the driving voltage NGATE reaches the turn-on threshold of the power transistor M0, the characterization signal CTRL flips the level, the control end of the second MOS transistor P2 is connected to the control end of the first MOS transistor P1, and the follower control signal Y follows the level state of the input control signal X. Since the input control signal X is maintained at a low level during the effective period of the input signal, the follower control signal Y is also output as a low level in the second start-up phase, so that the second MOS transistor P2 is turned on.

[0037] Further, the startup control circuit 100 of the power tube also includes a shutoff branch 150, which is turned on when the input signal IN is invalid, and provides a shutoff signal to the control end of the power tube M0, and the shutoff signal turns off the power tube M0 when the driving voltage NGATE reaches the shutoff threshold. The shutoff branch includes a third MOS tube N1, and when the power tube is an NMOS tube, the third MOS tube N1 is an NMOS tube. The source of the third MOS tube N1 is grounded, and the drain is connected to the drain of the first MOS tube P1 and the drain of the second MOS tube P2. The control end of the third MOS tube N1 receives the input control signal X. Therefore, the working state of the third MOS tube N1 is opposite to the working state of the first MOS tube P1.

[0038] Continue to see Figure 2 , the driving state characterization circuit 141 includes a current source A1 and a fourth MOS tube N2 connected in series, the control end of the fourth MOS tube N2 receives the driving voltage NGATE, and provides a characterization signal CTRL from the connection node between the current source A1 and the fourth MOS tube N2. When the power tube is an NMOS tube, the fourth MOS tube N2 is an NMOS tube, the source of the fourth MOS tube N2 is grounded, and the drain is connected to the current source A1. The driving state characterization circuit 141 may also include an inverter chain, such as an inverter O5 and an inverter O6 connected in series. The input end of the inverter O5 is connected to the common node of the fourth MOS tube N2 and the current source A1, and the characterization signal CTRL is provided from the output end of the inverter O6, so the level state of the characterization signal CTRL is opposite to that of the driving voltage NGATE. The follower control circuit 142, for example, includes a NAND gate U1, a switch unit and a fifth MOS tube P3. The two input ends of the NAND gate U1 receive the input signal IN and the characterization signal CTRL respectively, and the output end generates a switch signal swn. The switch signal swn is used to control the conduction state of the switch unit and the fifth MOS tube P3. The switch unit connects the control end of the first MOS tube P1 and the control end of the second MOS tube P2. The switch unit includes, for example, a transmission gate, a switch tube or a switch. In this embodiment, the switch unit takes the transmission gate K1 as an example, then the output end of the NAND gate U1 is also connected to the inverter O4, and the output end of the inverter provides the inverted signal swp of the switch signal. The transmission gate K1 is connected between the control end of the first MOS tube P1 and the control end of the second MOS tube P2, and receives the switch signal swn and the inverted signal swp of the switch signal. Then, when the switch unit does not use the transmission gate K1, an inverter O4 can be omitted. The fifth MOS tube P3 is connected to the control end of the second MOS tube P2, which can be an NMOS tube or a PMOS tube. As Figure 2When the fifth MOS transistor P3 is a PMOS transistor, its source receives the voltage V3, its gate is connected to the output end of the NAND gate U1, receives the switch signal swn, and its drain is connected to the control end of the second MOS transistor P2. When the transmission gate K1 is turned on, the fifth MOS transistor P3 is turned off, and the following control signal Y is the same as the input control signal X; when the transmission gate K1 is turned off, the fifth MOS transistor P3 is turned on, and the following control signal Y is a high level. When the fifth MOS transistor is an NMOS transistor, its control end or gate receives the inverted signal swp of the switch signal.

[0039] The following combination Figure 3 Introduce the working principle of the above circuit, such as Figure 3 As shown, before time t1, the input signal IN is in an invalid state, for example, a low level. Then the input control signal X is a high level, the first MOS transistor P1 is turned off, the third MOS transistor N1 is turned on, and the driving voltage NGATE is a low level; the characterization signal CTRL is a high level, so the switch signal swn output by the NAND gate U1 is a high level, the transmission gate K1 is turned on, and the fifth MOS transistor P3 is turned off; the follower control signal Y follows the input control signal X and is a high level, and the second MOS transistor P2 is turned off. At time t1, the input signal IN starts to be effective and enters the first startup stage, then the input control signal X is a low level, the first MOS transistor P1 is turned on, the third MOS transistor N1 is turned off, and the driving voltage NGATE starts to rise slowly; before the driving voltage reaches the start-up threshold, the characterization signal CTRL maintains a high level, so the switch signal swn output by the NAND gate U1 is a low level, the transmission gate K1 is turned off, and the fifth MOS transistor P3 is turned on; the follower control signal Y is a high level, and the second MOS transistor P2 is turned off. The time period t1-t2 is the first startup phase, during which the first MOS transistor P1 is turned on and the second MOS transistor P2 is turned off. At t2, the drive voltage NGATE reaches the turn-on threshold, the characterization signal CTRL flips to a low level, the switch signal swn output by the NAND gate U1 is a high level, the transmission gate K1 is turned on, and the fifth MOS transistor P3 is turned off; the follower control signal Y follows the input control signal X and is a low level, the second MOS transistor P2 is turned on, the drive voltage NGATE rises rapidly, and then stabilizes, and the power tube M0 is fully turned on. That is, the second startup phase begins from t2, during which both the first MOS transistor P1 and the second MOS transistor P2 are turned on.

[0040] At t3, the input signal IN starts to be invalid, and the second startup phase ends, so the t2-t3 time period is the second startup phase. At t3, the input control signal X flips to a high level, the first MOS tube P1 is turned off, and the third MOS tube N1 is turned on; so that the driving voltage GATE drops to zero, and the power tube M0 is turned off; then the level state of the characterization signal CTRL flips, the switch signal swn output by the NAND gate U1 is still at a high level, the transmission gate K1 is turned on, the fifth MOS tube P3 is turned off, and the follower control signal Y follows the input control signal X and flips to a high level. Due to the delay in signal transmission, the follower control signal Y flips to a high level after a period of time after t3, and the second MOS tube P2 is also turned off. Then at t4, the input signal IN becomes valid again and enters a new working cycle, so from t4 onwards, the state of the working cycle t1-t4 begins to repeat.

[0041] The power tube M0 in the above embodiment is an NMOS tube. In fact, the power tube M0 may also be a PMOS tube. In this case, the output end of the power tube M0 is connected to the anodes of a row of LED lamp beads, that is, common anode driving is realized.

[0042] Figure 4 A schematic circuit diagram of a power tube startup control circuit and a part of a row drive circuit according to a second embodiment of the present invention is shown.

[0043] like Figure 4 As shown, when the output stage MOS tube of the LED display row driving circuit is PMOS, it is necessary to control the pull-down speed of the driving voltage PGATE at the control end of the power tube to realize the segmented opening of the PMOS tube. In this embodiment, the row driving circuit still includes the power tube M0 and the start-up control circuit 100 of the power tube. The start-up control circuit 100 includes a first start-up branch 110, a second start-up branch 120, a first start-up control circuit 130, a second start-up control circuit 140 and a shut-down branch 150. Figure 2 Similar to the embodiment, the first startup branch 110 includes a first MOS transistor N1, the second startup branch 120 includes a second MOS transistor N3, and the shutdown branch 150 includes a third MOS transistor P1, that is, the first MOS transistor N1 and the second MOS transistor N3 are both NMOS transistors, and the third MOS transistor P1 is a PMOS transistor. Correspondingly, the first startup control circuit 130 includes an even number of inverters connected in series, for example, including inverter O1 and inverter O2, then the input control signal X is in phase with the input signal IN. The second startup control circuit 140 also includes a driving state characterization circuit 141 and a follower control circuit 142, and the circuit elements included in the driving state characterization circuit 141 and the follower control circuit 142 are the same as Figure 2The embodiment is the same as the embodiment. The difference is that in this embodiment, the fourth MOS transistor P4 in the follower control circuit 142 is a PMOS transistor, so the characterization signal CTRL is in phase with the driving voltage PGATE. Figure 4 In the embodiment, the fifth MOS transistor P3 can also be replaced by an NMOS transistor, and its control end is controlled by the inverted signal swp of the switch signal.

[0044] This embodiment and Figure 2 The similarities of the circuit structure and the working principle are not repeated here, and it can realize that at least in the first startup phase, the first MOS tube N1 is turned on, and in the second startup phase, the second MOS tube N3 is turned on.

[0045] Of course, the present invention also provides a display driver chip, which is used to drive a display panel, such as an LED panel. The display driver chip may include multiple row driver circuits, each row driver circuit is connected to the same end of the same row of LED lamp beads. The display driver chip may also include a power supply and other circuit structures, such as a discharge circuit, a timing controller, etc.

[0046] Figure 5 A partial structural schematic diagram of an LED display device according to an embodiment of the present invention is shown.

[0047] like Figure 5 As shown, this embodiment also provides an LED display device 300, which includes an LED array 320 and a plurality of row drive circuits 310. The LED array 320 includes a plurality of LED lamp beads (D1, D2, Dm, etc.) arranged in an array. Each row drive circuit 310 controls a row of LED lamp beads, and each row drive circuit 310 includes a power tube M0 and a start-up control circuit 100 of the power tube of the above embodiment.

[0048] Furthermore, the present invention may also provide a terminal electronic device, which may include the power tube and the power tube startup control circuit of any of the above embodiments. For example, the terminal electronic device may include Figure 5 The LED display device described herein, the terminal electronic device may be a mobile phone, a tablet computer, an electronic watch, etc., but is not limited thereto.

[0049] The power tube startup control circuit of the embodiment of the present invention and the row drive circuit, display driver chip, LED display device and terminal electronic device using the same are provided with two startup branches at the control end of the power tube of the output stage. In the first startup stage when the input signal is valid, the first startup branch first changes the driving voltage of the power tube, and the driving voltage reaches the turn-on threshold value to put the power tube in a weak turn-on state, and slowly releases the charge on the parasitic capacitor of the output node through the power tube to avoid the formation of a large transient current. Afterwards, in the second startup stage when the input signal is valid, the second startup branch is turned on to make the power tube fully turned on, providing a current path for the LED lamp beads. Through the cooperation of the two startup branches, the charge on the parasitic capacitor is well discharged without affecting the normal working state of the circuit, and a stable current path can be provided for the LED lamp beads to ensure the stability of the picture of the LED display device.

[0050] Finally, it should be noted that: Obviously, the above embodiments are only examples for clearly explaining the present application, and are not intended to limit the implementation methods. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from this are still within the scope of protection of the present application.

Claims

1. A startup control circuit for a power tube, comprising: A first start-up branch circuit provides a first start-up signal to the control end of the power tube when it is turned on; A second start-up branch circuit provides a second start-up signal to the control end of the power tube when it is turned on; A first startup control circuit receives an input signal, controls the first startup branch to be turned on in at least a first startup phase within an effective period of the input signal, and the power tube starts to be turned on when the driving voltage of the power tube reaches a start threshold value due to the first startup signal; as well as The second startup control circuit receives an input signal and a driving voltage, and controls the second startup branch to be turned on in a second startup phase within the effective period of the input signal, wherein the second startup signal causes the power tube to be fully turned on. The effective period of the input signal includes the adjacent first startup phase and the second startup phase.

2. The power tube startup control circuit according to claim 1, wherein: The first startup branch is continuously turned on during the effective period of the input signal, and in the time period outside the first startup phase in each working cycle, the second startup control circuit controls the opening state of the second startup branch to follow the opening state of the first startup branch.

3. The power tube startup control circuit according to claim 2, wherein: The second startup control circuit comprises: A driving state characterization circuit receives the driving voltage to output a characterization signal characterizing a voltage state of the driving voltage; A follower control circuit controls the connection state between the control end of the first start branch and the control end of the second start branch according to the input signal and the characterization signal, When a connection path is established between the control end of the first start-up branch and the control end of the second start-up branch, the start-up state of the second start-up branch follows the start-up state of the first start-up branch.

4. The power tube startup control circuit according to claim 3, wherein: The level state of the characterization signal changes when the driving voltage reaches a turn-on threshold of the power tube and reaches a turn-off threshold of the power tube.

5. The power tube startup control circuit according to claim 3, wherein: When the input signal starts to be effective, the follower control circuit disconnects the connection path between the control end of the first start-up branch and the control end of the second start-up branch, and starts to enter the first start-up phase; The follower control circuit also establishes a connection path between the control end of the first start-up branch and the control end of the second start-up branch when the characterization signal indicates that the drive voltage reaches the start-up threshold of the power tube, and starts to enter the second start-up stage.

6. The power tube startup control circuit according to claim 1, further comprising: The shutoff branch is turned on when the input signal is invalid, and provides a shutoff signal to the control end of the power tube. The shutoff signal shuts off the power tube when the driving voltage reaches a shutoff threshold.

7. The power tube startup control circuit according to claim 1, wherein: The first startup control circuit includes a plurality of inverters connected in series, which perform signal enhancement and phase adjustment processing on the input signal to provide an input control signal to the control end of the first startup branch.

8. The power tube startup control circuit according to claim 3, wherein: The first startup branch includes a first MOS transistor, the second startup branch includes a second MOS transistor, and the shutdown branch includes a third MOS transistor; The driving state characterization circuit comprises a current source and a fourth MOS transistor connected in series, the control end of the fourth MOS transistor receives the driving voltage, and the characterization signal is provided from a connection node between the current source and the fourth MOS transistor; The follower control circuit includes a NAND gate, a switch unit and a fifth MOS tube. The input end of the NAND gate receives the input signal and the characterization signal, and the output end generates a switch signal. The switch signal controls the conduction state of the switch unit and the fifth MOS tube.

9. The power tube startup control circuit according to claim 8, wherein: The switch unit connects the control end of the first MOS tube and the control end of the second MOS tube, and the switch unit includes a transmission gate, a switch tube or a switch; the fifth MOS tube is connected to the control end of the second MOS tube, and receives the switch signal when the fifth MOS tube is a PMOS tube, and receives an inverted signal of the switch signal when the fifth MOS tube is an NMOS tube.

10. The power tube startup control circuit according to claim 8, wherein: When the power tube is an NMOS tube, the first MOS tube and the second MOS tube are PMOS tubes, the third MOS tube and the fourth MOS tube are NMOS tubes, and the first startup control circuit includes an odd number of inverters; when the power tube is a PMOS tube, the first MOS tube and the second MOS tube are NMOS tubes, the third MOS tube and the fourth MOS tube are PMOS tubes, and the first startup control circuit includes an even number of inverters.

11. A row drive circuit, connected to the same end of a row of LED lamp beads, wherein: The row driving circuit comprises: A power tube, serving as an output stage of the row driving circuit; and According to the startup control circuit of the power tube according to any one of claims 1-10, the startup control circuit of the power tube is used to control the conduction state of the power tube, so that a stable driving current flows through the row of LED lamp beads when the power tube is turned on.

12. A display driver chip, comprising: power supply; as well as Multiple row drive circuits, each row drive circuit is connected to the same end of the same row of LED lamp beads, Wherein, the row driving circuit comprises a power tube as an output stage and a start-up control circuit of the power tube according to any one of claims 1-10.

13. An LED display device, comprising: An LED array, wherein the LED array includes a plurality of LED lamp beads arranged in an array; as well as A plurality of row drive circuits, each of which controls a row of LED lamp beads, and each of which comprises a power tube and a start-up control circuit of the power tube according to any one of claims 1-10.

14. A terminal electronic device, comprising: A power tube and a startup control circuit for the power tube according to any one of claims 1 to 10.

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