Direct current conversion circuit, display drive circuit, and display device

Abstract

The application provides a direct current conversion circuit, a display driving circuit and a display device. The direct current conversion circuit comprises a direct current conversion unit, a ring detection feedback unit and an impedance compensation unit. The ring detection feedback unit detects the ring amplitude voltage of the direct current conversion unit and outputs an impedance compensation signal when the ring amplitude voltage is greater than a preset amplitude voltage, so as to control the impedance compensation unit to output an impedance with a corresponding impedance value to the gate of a power switch tube, thereby increasing the gate resistance of the power switch tube, reducing the ring amplitude voltage, making the direct current conversion unit normally perform direct current conversion work, realizing boost, buck or buck-boost work, and improving the working reliability of the direct current conversion circuit.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of display panels, and particularly relates to a direct current conversion circuit, a display driving circuit and a display device. BACKGROUND

[0002] A direct current conversion circuit (DC / DC) is used to realize step-up and step-down conversion from a first direct current voltage to a second direct current voltage, and is used in multiple fields, for example, in the field of display panels, a backlight driving circuit and / or a power management integrated circuit, which are all provided with corresponding direct current conversion circuits for realizing step-up and step-down conversion and providing working voltages for backlights, display panels and the like. The direct current conversion circuit is usually composed of a power switch tube, an inductor and a freewheeling tube, and according to different combinations, corresponding step-up circuits, step-down circuits and step-up and step-down circuits are formed.

[0003] Usually, the ringing of high-frequency components affecting electromagnetic interference is generated only when the direct current conversion circuit is in an under-damped state. A square resistance Rg is generated in the manufacturing process of the gate of the power switch tube, and the resistance Rg has a large fluctuation range. When the process fluctuation of the power switch tube causes Rg to become very small, as shown in FIG. 1, the ringing becomes large, and in a serious case, the direct current conversion circuit does not work normally. Figure 1 SUMMARY

[0004] The application aims to provide a direct current conversion circuit, and aims to solve the problem of ringing in the conventional direct current conversion circuit.

[0005] A first aspect of the application embodiment provides a direct current conversion circuit, comprising:

[0006] A direct current conversion unit, which is an inductive DC / DC topology circuit composed of a power switch tube, an inductor and a freewheeling tube, and a first end or a second end of the power switch tube, a first end or a second end of the inductor and a first end or a second end of the freewheeling tube are connected in common;

[0007] A ringing detection feedback unit, which is connected with a common node of the power switch tube, the inductor and the freewheeling tube, detects a ringing amplitude voltage of the common node, and outputs an impedance compensation signal when the ringing amplitude voltage is greater than a preset amplitude voltage;

[0008] An impedance compensation unit, which is connected with the ringing detection feedback unit and a gate of the power switch tube, and outputs an impedance of a preset resistance value to the gate of the power switch tube triggered by the impedance compensation signal, and the resistance value of the impedance changes in positive correlation with the ringing amplitude voltage.

[0009] ​Optionally, the first end of the power switch tube constitutes the input end of the DC conversion unit, the second end of the power switch tube, the first end of the inductor and the second end of the freewheeling diode are connected in common, and the second end of the inductor constitutes the output end of the DC conversion unit, and the first end of the freewheeling diode is grounded.

[0010] Alternatively, the first end of the inductor constitutes the input end of the DC conversion unit, the second end of the inductor, the first end of the power switch tube and the first end of the freewheeling diode are connected in common, the second end of the freewheeling diode constitutes the output end of the DC conversion unit, and the second end of the power switch tube is grounded.

[0011] Alternatively, the first end of the power switch tube constitutes the input end of the DC conversion unit, the second end of the power switch tube, the first end of the inductor and the second end of the freewheeling diode are connected in common, and the second end of the inductor constitutes the output end of the DC conversion unit, and the first end of the freewheeling diode is grounded.

[0012] Optionally, the ring detection feedback unit comprises:

[0013] a comparison unit connected to the common node of the power switch tube, the inductor and the freewheeling diode, and comparing the ring amplitude voltage of the common node with the preset amplitude voltage and outputting a level signal;

[0014] a signal output unit connected to the comparison unit and the impedance compensation unit, for receiving the level signal representing the size of the ring amplitude voltage of the common node, and outputting an impedance compensation signal when the ring amplitude voltage is greater than the preset amplitude voltage.

[0015] Optionally, the impedance compensation unit comprises a potentiometer connected in series between the control end of the DC conversion circuit and the gate of the power switch tube, and the control end of the potentiometer is connected to the signal end of the ring detection feedback unit.

[0016] Optionally, the impedance compensation unit comprises a switching switch and a plurality of first resistors, and the switching switch comprises a first end and a plurality of second ends.

[0017] The plurality of second ends of the switching switch are respectively connected in series with the first ends of the plurality of first resistors, the first end of the switching switch is connected to the control end of the DC conversion circuit, the second ends of the plurality of first resistors are connected in common and connected to the gate of the power switch tube, and the control end of the switching switch is connected to the signal end of the ring detection feedback unit.

[0018] Alternatively, the impedance compensation unit comprises a plurality of parallel resistance units connected in series between the control end of the DC conversion circuit and the gate of the power switch tube, and each resistance unit comprises a switching switch and a first resistance connected in series, and the control end of each switching switch is connected to the signal end of the ring detection feedback unit.

[0019] Optionally, the DC conversion circuit further comprises:

[0020] a buffer circuit connected to the common node, the buffer circuit being configured to absorb and suppress the ring.

[0021] Optionally, the buffer circuit comprises a second resistance and a capacitor.

[0022] The first end of the second resistance is connected to the common node, the second end of the second resistance is connected to the first end of the capacitor, and the second end of the capacitor is grounded.

[0023] Optionally, the DC conversion circuit further comprises a filter capacitor and a load resistance.

[0024] The first end of the filter capacitor, the first end of the load resistance, and the output end of the DC conversion unit are connected, and the second end of the filter capacitor and the second end of the load resistance are grounded.

[0025] A second aspect of the embodiments of the present application provides a display driving circuit, which comprises an LED driving chip and a DC conversion circuit as described above, and the DC conversion circuit is connected to the LED driving chip and an LED backlight source respectively.

[0026] And / or, the display driving circuit comprises a power management integrated circuit, a timing controller, a gate driving circuit, and a source driving circuit, the power management integrated circuit comprises at least one DC conversion circuit as described above, the power management integrated circuit is connected to the timing controller, the gate driving circuit, and the source driving circuit respectively, the timing controller is further connected to the gate driving circuit and the source driving circuit respectively, and the gate driving circuit and the source driving circuit are connected to a display panel respectively.

[0027] A third aspect of the embodiments of the present application provides a display device, which comprises a display panel and at least one display driving circuit as described above, the display panel is arranged opposite to the display driving circuit, and / or the display panel is connected to the display driving circuit.

[0028] The beneficial effects of the embodiments of the present application compared with the prior art are that: the DC conversion circuit is composed of a DC conversion unit, a ring detection feedback unit and an impedance compensation unit, the ring detection feedback unit detects the ring amplitude voltage of the DC conversion unit, and outputs an impedance compensation signal when the ring amplitude voltage is greater than a preset amplitude voltage, so as to control the impedance compensation unit to output an impedance with a corresponding impedance value to the gate of the power switch tube, so that the gate resistance of the power switch tube is increased, the ring amplitude voltage is reduced, the DC conversion unit normally performs DC conversion work, the boost, buck or boost-buck work is realized, and the working reliability of the DC conversion circuit is improved. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 A ring waveform schematic diagram of a traditional DC conversion circuit;

[0030] Figure 2 A first structure schematic diagram of a DC conversion circuit provided by the embodiment one of the present application;

[0031] Figure 3 A second structure schematic diagram of a DC conversion circuit provided by the embodiment one of the present application;

[0032] Figure 4 A third structure schematic diagram of a DC conversion circuit provided by the embodiment one of the present application;

[0033] Figure 5 A ring waveform schematic diagram provided by the embodiment one of the present application;

[0034] Figure 6 A fourth structure schematic diagram of a DC conversion circuit provided by the embodiment one of the present application;

[0035] Figure 7 A structure schematic diagram of an impedance compensation unit and a buffer circuit provided by the embodiment two and the embodiment four of the present application;

[0036] Figure 8 A waveform schematic diagram of an impedance compensation signal provided by the embodiment two of the present application;

[0037] Figure 9 A first structure schematic diagram of an impedance compensation unit provided by the embodiment three of the present application;

[0038] Figure 10 A second structure schematic diagram of an impedance compensation unit provided by the embodiment three of the present application;

[0039] Figure 11 A structure schematic diagram of a DC conversion circuit provided by the embodiment four of the present application;

[0040] Figure 12A structure schematic diagram of a direct current conversion circuit provided for the embodiment five of the present application is shown in the figure;

[0041] Figure 13 A first structure schematic diagram of a display driving circuit and a display device provided for the embodiment five and the embodiment six of the present application is shown in the figure;

[0042] Figure 14 A second structure schematic diagram of a display driving circuit and a display device provided for the embodiment five and the embodiment six of the present application is shown in the figure.

[0043] In the figure, each reference sign represents:

[0044] 1, backlight driving circuit; 2, display panel driving circuit; 210, power management integrated circuit; 220, timing controller; 230, source driving circuit; 240, gate driving circuit; 300, display panel; 110, direct current conversion circuit; 120, LED driving chip; 10, direct current conversion unit; 20, ringing detection feedback unit; 30, impedance compensation unit; 40, buffer circuit; 21, comparison unit; 22, signal output unit; Q1, power switch tube; L1, inductor; D1, freewheeling diode; C1, capacitor; C2, filter capacitor; U1, potentiometer; K1, switching switch; R1, first resistor; R2, second resistor; R3, load resistor; Ctr, switching signal; VIN, input power supply; VOUT, output power supply. DETAILED DESCRIPTION

[0045] In order to make the technical problems, technical solutions and beneficial effects of the present application more clearly understood, the present application will be further described in detail below in combination with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application.

[0046] In addition, the terms "first" and "second" are only used for description purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first" and "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise specifically limited.

[0047] Embodiment one

[0048] A first aspect of the embodiments of the present application provides a direct current conversion circuit 110, which is used for realizing step-up / down conversion from a first direct current voltage to a second direct current voltage, and is used in various fields, for example, in the field of display panels 300, backlight driving circuits 1 and / or power management integrated circuits 210, each of which is provided with a corresponding direct current conversion circuit 110 for realizing step-up / down conversion and providing working voltage for a backlight 200, a display panel 300, etc.

[0049] In order to avoid excessive ringing of the direct current conversion circuit 110 and affect the normal operation of the direct current conversion circuit 110 and improve the working reliability, optionally, as shown in Figures 2 to 4 The direct current conversion circuit 110 includes a direct current conversion unit 10, which is an inductor L1 type DC / DC topology circuit composed of a power switch Q1, an inductor L1 and a freewheeling tube. The first end or the second end of the power switch Q1, the first end or the second end of the inductor L1 and the first end or the second end of the freewheeling tube are connected in common. The power switch Q1, the inductor L1 and the freewheeling tube correspond to different types of direct current conversion circuits 110, such as step-up circuits, step-down circuits and step-up / down circuits, according to different connection modes. The freewheeling tube can be a freewheeling switch or a freewheeling diode D1, which is used to form a freewheeling circuit with the inductor L1 and the load after the power switch Q1 is turned off, and provides working voltage for the load. In an optional embodiment, in order to simplify the control logic, the freewheeling tube is a freewheeling diode D1.

[0050] In the embodiment, the ringing problem caused by the change of the gate resistance of the power switch Q1 can exist in multiple circuits. In order to solve the ringing problem of different circuits, the direct current conversion circuit 110 is applicable to different direct current conversion units 10. In an optional embodiment, as shown in Figure 2 The first end of the power switch Q1 constitutes the input end of the direct current conversion unit 10, the second end of the power switch Q1, the first end of the inductor L1 and the second end of the freewheeling tube are connected in common, the second end of the inductor L1 constitutes the output end of the direct current conversion unit 10, and the first end of the freewheeling tube is grounded.

[0051] The power switch Q1, the inductor L1 and the freewheeling diode D1 constitute a BUCK step-down circuit. The working principle of the BUCK step-down circuit is as follows: in the first stage, the power switch Q1 is turned on, the freewheeling diode D1 is cut off, the input power VIN stores energy through the inductor L1; in the second stage, the power switch Q1 is turned off, the inductor L1 is discharged, and the freewheeling diode D1 is turned on to play a freewheeling role, realizing step-down conversion, and the voltage of the output power VOUT is less than the voltage of the input power VIN.

[0052] Alternatively, as shown in Figure 3As shown, in another optional embodiment, the first end of the inductor L1 constitutes the input terminal of the DC-DC converter 10, the second end of the inductor L1, the first end of the power switch Q1 and the first end of the freewheeling diode are connected together, the second end of the freewheeling diode constitutes the output terminal of the DC-DC converter 10, and the second end of the power switch Q1 is grounded.

[0053] The power switch Q1, inductor L1, and freewheeling diode D1 form a BOOST boost circuit. The working principle of the BOOST boost circuit is as follows: In the first stage, the power switch Q1 is turned on, the input power supply VIN charges the inductor L1, and the freewheeling diode D1 is turned off. In the second stage, the power switch Q1 is turned off, the freewheeling diode D1 is turned on, the input power supply VIN supplies power to the downstream load through the inductor L1, realizing the boost conversion. The voltage of the output power supply VOUT is greater than the voltage of the input power supply VIN.

[0054] Or, such as Figure 4 As shown, in another optional embodiment, the first end of the power switch Q1 constitutes the input terminal of the DC-DC converter 10, the second end of the power switch Q1, the first end of the inductor L1 and the second end of the freewheeling diode are connected together, the second end of the inductor L1 is grounded, and the first end of the freewheeling diode constitutes the output terminal of the DC-DC converter 10.

[0055] The power switch Q1, inductor L1, and freewheeling diode D1 form a BUCK-BOOST circuit. The working principle of the BUCK-BOOST circuit is as follows: In the first stage, the power switch Q1 is turned on, the input power supply VIN charges the inductor L1, and the freewheeling diode D1 is turned off. In the second stage, the current flows in reverse, and the voltage of the output power supply VOUT is out of phase with the voltage of the input power supply VIN. The magnitude of the output power supply VOUT voltage depends on the ratio of the on and off time of the power switch Q1. It can be greater than or less than the voltage of the input power supply VIN, thereby realizing the dual functions of boost and buck.

[0056] The control terminal of the DC-DC converter circuit 110 is connected to the gate of the power switch Q1. After receiving the corresponding PWM signal, the DC-DC converter circuit 110 outputs it to the gate of the power switch Q1, thereby controlling the power switch Q1 to periodically turn on and off, and outputting the corresponding voltage power supply VOUT.

[0057] Because the gate of the power switch Q1 itself generates a square crystal resistance Rg during the manufacturing process, and the resistance value of Rg fluctuates greatly, the process fluctuation of the power switch Q1 can cause Rg to become very small, resulting in increased ringing. If the process fluctuation of the power switch Q1 causes Rg to become very large, it will lead to a longer switching time on the power switch Q1, resulting in increased energy loss and temperature of the power switch Q1, thereby increasing the risk of burn-out of the power switch Q1. Therefore, when a set of fixed resistors is set based on the existing power switch Q1 parameters to improve ringing, it cannot be applied to power switches Q1 with different processes and DC-DC converter circuit 110, resulting in increased ringing or increased power consumption, affecting the working state of DC-DC converter circuit 110. In order to solve the ringing problem caused by the change of the gate resistance of the power switch Q1 in the boost circuit, buck circuit, and buck-boost circuit, DC-DC converter circuit 110 also includes a ringing detection feedback unit 20 and an impedance compensation unit 30.

[0058] The ringing detection feedback unit 20 is connected to the common node of the power switch Q1, inductor L1 and freewheeling diode, and detects the ringing amplitude voltage of the common node. When the ringing amplitude voltage is greater than the preset amplitude voltage, it outputs an impedance compensation signal.

[0059] The impedance compensation unit 30 is connected to the ringing detection feedback unit 20 and the gate of the power switch Q1. The impedance compensation unit 30 is triggered by the impedance compensation signal to output an impedance of a preset value to the gate of the power switch Q1. The value of the impedance changes positively with the ringing amplitude voltage.

[0060] Impedance compensation unit 30 is connected in series between the control terminal of DC-DC converter circuit 110 and the gate of power switch Q1. After DC-DC converter 10 is manufactured or during operation, ringing detection feedback unit 20 detects the ringing amplitude voltage of DC-DC converter 10 by detecting the voltage of the common node. When the ringing amplitude voltage is less than or equal to the preset amplitude voltage, it indicates that the current ringing is small and DC-DC converter 10 can perform buck-boost conversion normally. At this time, ringing detection feedback unit 20 does not output impedance compensation signal. After the impedance compensation unit 30 does not receive the impedance compensation signal, it outputs 0 ohms impedance or maintains the current resistance value. The gate resistance of power switch Q1 maintains the original resistance value. The PWM signal continues to be output to power switch Q1 through impedance compensation unit 30 with unchanged resistance value, maintaining the current working state.

[0061] When the ring amplitude voltage is detected to be greater than the preset amplitude voltage, it indicates that the current ring is too large, and there is a possibility to affect the normal operation of the DC conversion unit 10. Therefore, the ring detection feedback unit 20 outputs a corresponding variable impedance compensation signal according to the ring amplitude, and at the same time, the impedance compensation unit 30 receives the variable impedance compensation signal and outputs a variable compensation impedance to the gate of the power switch tube Q1, thereby increasing the gate resistance of the power switch tube Q1, reducing the ring, and making the DC conversion unit 10 in a stable working environment, which will not cause the ring due to the process of the power switch tube Q1 or the difference of the external load, thereby maintaining a good electromagnetic environment.

[0062] The impedance output by the impedance compensation unit 30 changes synchronously according to the ring size generated by the process of the power switch tube Q1. When the preset amplitude voltage is exceeded, the larger the ring, the larger the impedance value output, and the smaller the ring, the smaller the impedance output. As shown in Figure 5 The amplitude voltage of the ring is limited below the preset amplitude voltage by outputting the preset impedance value according to the ring change, thereby improving the reliability of the DC conversion unit 10, and meeting the power switch tube Q1 of different processes and different types of DC conversion circuit 110.

[0063] The ring detection feedback unit 20 can adopt corresponding detection circuits, controllers, etc. Optionally, as shown in Figure 6 The ring detection feedback unit 20 includes:

[0064] The comparison unit 21 is connected with the common node of the power switch tube Q1, the inductor L1 and the freewheeling tube, and compares the ring amplitude voltage of the common node with the preset amplitude voltage and outputs a level signal.

[0065] The signal output unit 22 is connected with the comparison unit 21 and the impedance compensation unit 30, and is used for receiving the level signal representing the ring amplitude voltage of the common node, and outputting an impedance compensation signal when the ring amplitude voltage is greater than the preset amplitude voltage.

[0066] After the DC conversion unit 10 is made or during operation, the comparison unit 21 detects the ringing amplitude voltage of the DC conversion unit 10 by detecting and comparing the voltage of the common node, and when the ringing amplitude voltage is less than or equal to the preset amplitude voltage, it indicates that the current ringing is small, and the current DC conversion unit 10 can normally perform step-up / down conversion. At this time, the comparison unit 21 outputs a first level signal, and the signal output unit 22 does not output an impedance compensation signal after receiving the first level signal. The impedance compensation unit 30 outputs an impedance of 0 ohms or maintains the current impedance value without receiving the impedance compensation signal, and the gate resistance of the power switch tube Q1 maintains the original impedance value. The PWM signal continues to be output to the power switch tube Q1 through the impedance compensation unit 30 with unchanged impedance, and the current working state is maintained.

[0067] When the ringing amplitude voltage is detected to be greater than the preset amplitude voltage, it indicates that the current ringing is too large, and there is a possibility of affecting the normal operation of the DC conversion unit 10. At this time, the comparison unit 21 outputs a second level signal, and the ringing detection feedback unit 20 outputs a corresponding variable impedance compensation signal according to the second level signal. At the same time, the impedance compensation unit 30 outputs a variable compensation impedance to the gate of the power switch tube Q1 after receiving the variable impedance compensation signal, thereby increasing the gate resistance of the power switch tube Q1 and reducing the ringing, so that the DC conversion unit 10 is in a stable working environment and will not be affected by the process variation of the power switch tube Q1 or the change of the external load, thereby maintaining a good electromagnetic environment.

[0068] In order to realize separate comparison and detection of the positive and negative ringing amplitudes and improve the accuracy of ringing amplitude detection, the comparison unit 21 can be realized by using an inverter and a comparator in series. The negative amplitude is converted into a positive amplitude voltage by inversion, and then unified comparison is performed. The comparison unit 21 can also use an integrated chip structure, and the specific structure of the comparison unit 21 can be selected according to requirements.

[0069] The signal output unit 22 can be realized by using corresponding signal generators, controllers, processors and the like. The specific structure is not limited.

[0070] At the same time, in order to simplify the structure, the comparison unit 21 and the signal output unit 22 can also be integrated into a chip structure, and the specific structure can be set according to requirements.

[0071] The impedance compensation unit 30 can be realized by using corresponding resistors, capacitors C1 and inductors L1.

[0072] Embodiment two

[0073] Based on the embodiment one, the structure is optimized and specified, such as Figure 7 and Figure 8As shown, taking the boost circuit as an example, optionally, the impedance compensation unit 30 comprises a potentiometer U1, the potentiometer U1 is connected in series between the control end of the DC conversion circuit 110 and the gate of the power switch tube Q1, the control end of the potentiometer U1 is connected with the signal end of the ring detection feedback unit 20.

[0074] In this embodiment, the ring detection feedback unit 20 acquires the ring amplitude voltage, and outputs the impedance compensation signal CS, INC, U / D according to the size of the ring amplitude voltage, wherein, as shown in Table 1, when the high and low levels and the rising and falling edges of the output impedance compensation signal CS, INC, U / D are different, the potentiometer U1 changes correspondingly, thereby outputting resistors with different resistance values to the gate of the power switch tube Q1, so as to increase, decrease or maintain the gate resistance of the power switch tube Q1, wherein, the corresponding mapping relationship between CS, INC, U / D and the ring amplitude voltage can be set according to requirements and the connection relationship of the potentiometer U1. Figure 8 As shown in Table 1, when the high and low levels and the rising and falling edges of the output impedance compensation signal CS, INC, U / D are different, the potentiometer U1 changes correspondingly, thereby outputting resistors with different resistance values to the gate of the power switch tube Q1, so as to increase, decrease or maintain the gate resistance of the power switch tube Q1, wherein, the corresponding mapping relationship between CS, INC, U / D and the ring amplitude voltage can be set according to requirements and the connection relationship of the potentiometer U1.

[0075]

[0076] Table 1

[0077] Embodiment three

[0078] Based on the optimization and concretization of embodiment one, as shown in Table 1, in another optional embodiment, taking the boost circuit as an example, the impedance compensation unit 30 comprises a switching switch K1 and a plurality of first resistors R1, the switching switch K1 comprises a first end and a plurality of second ends; Figure 9 As shown in Table 1, in another optional embodiment, taking the boost circuit as an example, the impedance compensation unit 30 comprises a switching switch K1 and a plurality of first resistors R1, the switching switch K1 comprises a first end and a plurality of second ends;

[0079] The plurality of second ends of the switching switch K1 are connected in series with the first ends of the plurality of first resistors R1 one by one, the first end of the switching switch K1 is connected with the control end of the DC conversion circuit 110, the second ends of the plurality of first resistors R1 are connected in parallel and connected with the gate of the power switch tube Q1, and the control end of the switching switch K1 is connected with the signal end of the ring detection feedback unit 20.

[0080] In this embodiment, the resistance values of the first resistors R1 are different, which can change in equal difference or equal proportion, the ring detection feedback unit 20 acquires the ring amplitude voltage, and outputs the switching switching signal Ctr, i.e. the impedance compensation signal, according to the size of the ring amplitude voltage, when the switching switching signal Ctr is different, the switching position of the switching switch K1 changes correspondingly, thereby outputting the first resistors R1 with different resistance values to the gate of the power switch tube Q1, so as to increase, decrease or maintain the gate resistance of the power switch tube Q1, wherein, the corresponding mapping relationship between the switching switching signal Ctr and the ring amplitude voltage can be set according to requirements and the resistance value change relationship of the first resistors R1.

[0081] Or, as shown in Table 1, in another optional embodiment, taking the boost circuit as an example, the impedance compensation unit 30 comprises a switching switch K1 and a plurality of first resistors R1, the switching switch K1 comprises a first end and a plurality of second ends; Figure 10As shown, in another optional embodiment, the impedance compensation unit 30 includes a plurality of parallel resistance units connected in series between the control end of the DC conversion circuit 110 and the gate of the power switch tube Q1, and each resistance unit includes a switching switch K1 and a first resistor R1 connected in series, and the control end of each switching switch K1 is connected with the signal end of the ring detection feedback unit 20 respectively.

[0082] In this embodiment, the resistance values of the first resistors R1 can be the same or different, the ring detection feedback unit 20 obtains the ring amplitude voltage, and outputs the switching switch signal Ctr, i.e. the impedance compensation signal, according to the size of the ring amplitude voltage. When the switching switch signals Ctr are different, the combination modes of the on and off of the plurality of switching switches K1 are different, so that the first resistors R1 with different resistance values are output to the gate of the power switch tube Q1, so as to increase, decrease or maintain the gate resistance of the power switch tube Q1. The corresponding mapping relationship between the switching switch signal Ctr and the ring amplitude voltage can be set according to the requirements and the resistance value change relationship of the first resistor R1.

[0083] Embodiment four

[0084] Based on the embodiment one, the optimization and concretization are carried out, such as Figure 11 As shown, taking the boost circuit as an example, in order to further solve the ring problem, the DC conversion circuit 110 further includes:

[0085] The buffer circuit 40 is connected with the common node, and the buffer circuit 40 is used for absorbing and inhibiting the ring.

[0086] The buffer circuit 40 is arranged at the common node position, and the buffer circuit 40 further absorbs and inhibits the ring in cooperation with the impedance compensation unit 30.

[0087] The buffer circuit 40 can adopt a corresponding resonance circuit, and optionally, as shown, Figure 4 The buffer circuit 40 includes a second resistor R2 and a capacitor C1.

[0088] The first end of the second resistor R2 is connected with the common node, the second end of the second resistor R2 is connected with the first end of the capacitor C1, and the second end of the capacitor C1 is grounded.

[0089] In this embodiment, the second resistor R2 and the capacitor C1 constitute a resonance circuit, which further absorbs and inhibits the ring, and the ring inhibition and absorption effect of the buffer circuit 40 can be changed by adjusting the resistance value of the second resistor R2.

[0090] Embodiment five

[0091] Based on the embodiment one, the optimization and concretization are carried out, such as Figure 12As shown, in order to improve the output effect of the load end and reduce the interference of spurious, optionally, the direct current conversion circuit 110 further comprises a filter capacitor C2 and a load resistor R3;

[0092] The first end of the filter capacitor C2, the first end of the load resistor R3 and the output end of the direct current conversion unit 10 are connected, and the second end of the filter capacitor C2 and the second end of the load resistor R3 are grounded.

[0093] The filter capacitor C2 performs filtering work on the one hand, and cooperates with the inductor L1 and the freewheeling diode D1 to perform energy storage and discharge work on the other hand, and the load obtains the output voltage through the two ends of the load resistor R3.

[0094] Compared with the prior art, the embodiment of the present application has the beneficial effects that: the above-mentioned direct current conversion circuit 110 is composed of the direct current conversion unit 10, the ring detection feedback unit 20 and the impedance compensation unit 30, the ring detection feedback unit 20 detects the ring amplitude voltage of the direct current conversion unit 10, and outputs the impedance compensation signal when the ring amplitude voltage is greater than the preset amplitude voltage, so as to control the impedance compensation unit 30 to output the impedance with the corresponding resistance value to the gate of the power switch tube Q1, so as to increase the gate resistance of the power switch tube Q1, reduce the ring amplitude voltage, make the direct current conversion unit 10 normally perform the direct current conversion work, realize the boost, buck or boost-buck work, and improve the working reliability of the direct current conversion circuit 110.

[0095] Embodiment six

[0096] The present application also proposes a display driving circuit, such as Figure 13 As shown, the display driving circuit can be a backlight driving circuit 1, the backlight driving circuit 1 comprises an LED driving chip 120 and a direct current conversion circuit 110, and the specific structure of the direct current conversion circuit 110 is referred to the above-mentioned embodiments. Since the display driving circuit adopts all the technical solutions of the above-mentioned embodiments, it at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be repeated here. The direct current conversion circuit 110 is connected with the LED driving chip 120 and the LED backlight 200 respectively.

[0097] And / or, the display driving circuit is a display panel driving circuit 2, the display panel driving circuit 2 includes a power management integrated circuit 210, a timing controller 220, a gate driving circuit 240 and a source driving circuit 230, the power management integrated circuit 210 includes at least one DC conversion circuit 110, the specific structure of the DC conversion circuit 110 is referred to the above embodiment, since the display driving circuit adopts all the technical solutions of the above all embodiments, at least has all the beneficial effects brought by the technical solutions of the above embodiments, here will not be repeated. Among them, the power management integrated circuit 210 is connected with the timing controller 220, the gate driving circuit 240 and the source driving circuit 230 respectively, the timing controller 220 is also connected with the gate driving circuit 240 and the source driving circuit 230 respectively, the gate driving circuit 240 and the source driving circuit 230 are connected with the display panel 300 respectively.

[0098] In the embodiment, as shown in Figure 13 And Figure 14 As shown, when the display panel is an LCD (Liquid Crystal Display) panel, the display driving circuit can include a backlight driving circuit 1 and a display panel driving circuit 2, the backlight driving circuit 1 includes an LED driving chip and a DC conversion circuit 110, the LED driving chip 120 outputs a PWM signal with a corresponding duty cycle size to the DC conversion circuit 110 according to the received backlight enable signal and brightness modulation signal, the DC conversion circuit 110 outputs a driving signal with a corresponding size to the LED backlight 200 according to the PWM signal, so as to drive the LED backlight 200 to emit corresponding light to the display panel 300 to provide backlight.

[0099] The display panel driving circuit 2 includes a power management integrated circuit 210, a timing controller 220, a gate driving circuit 240 and a source driving circuit 230, the power management integrated circuit 210 is used for providing working power supply for the timing controller 220, the gate driving circuit 240, the source driving circuit 230 and the like, the timing controller 220 outputs a driving control signal to the gate driving circuit 240 and the source driving circuit 230, the gate driving circuit 240 and the source driving circuit 230 correspondingly output a row scanning signal and a data driving signal to the display panel 300, so as to drive the display panel 300 to display corresponding image information.

[0100] When the display panel is an OLED (Organic Light Emitting Diode) panel, there is no need for a backlight driving circuit 1. The display driving circuit is a display panel driving circuit 2, which includes a power management integrated circuit 210, a timing controller 220, a gate driving circuit 240, and a source driving circuit 230. The power management integrated circuit 210 provides operating power to the timing controller 220, the gate driving circuit 240, and the source driving circuit 230. The timing controller 220 outputs driving control signals to the gate driving circuit 240 and the source driving circuit 230. The gate driving circuit 240 and the source driving circuit 230 output line scanning signals and data driving signals to the display panel 300, thereby driving the display panel 300 to display the corresponding image information.

[0101] When the display driving circuit is a backlight driving circuit 1, since there is only one load, the backlight driving circuit 1 can be equipped with a DC-DC conversion circuit 110. When the display driving circuit is a display panel driving circuit 2, since there are multiple loads, the power management integrated circuit 210 is equipped with multiple DC-DC conversion circuits 110. The DC-DC conversion units 10 in each DC-DC conversion circuit 110 can be the same or different. The ringing detection feedback unit 20 can share one or be set separately. The specific structure is not limited.

[0102] Example 7

[0103] This application also proposes a display device, which includes a display panel 300 and at least one display driving circuit. The specific structure of the display driving circuit is as described in the above embodiments. Since this display device adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, and will not be described in detail here. The display panel 300 and the display driving circuit are disposed opposite to each other, and / or the display panel 300 and the display driving circuit are connected.

[0104] Corresponding to the display panel 300 and the display driving circuit structure, in this embodiment, the display device may be a backlight module and / or a display module, such as... Figure 13 As shown, the backlight module includes a backlight driving circuit 1 and an LED backlight 200. The backlight driving circuit 1 is electrically connected to the backlight 200. The backlight 200 is positioned opposite to the display panel 300 and provides backlight to the display panel. The display module includes a display panel 300 and a display panel driving circuit 2. The display panel driving circuit 2 includes at least a power management integrated circuit 210, a timing controller 220, a gate driving circuit 240, and a source driving circuit 230. The display panel 300 can be an OLED panel or an LCD panel, and the specific structure is not limited.

[0105] The above-described embodiments are only used to illustrate the technical solutions of the present application, but not limit them; although the present application is described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. A DC-DC converter circuit, characterized in that, include: A DC-DC conversion unit, wherein the DC-DC conversion unit is an inductive DC / DC topology circuit composed of a power switch, an inductor and a freewheeling diode, wherein the first or second terminal of the power switch, the first or second terminal of the inductor and the first or second terminal of the freewheeling diode are connected together; The ringing detection feedback unit is connected to the common node of the power switch, the inductor and the freewheeling diode, and detects the ringing amplitude voltage of the common node. When the ringing amplitude voltage is greater than the preset amplitude voltage, it outputs an impedance compensation signal. An impedance compensation unit is connected to the ringing detection feedback unit and the gate of the power switch. The impedance compensation unit is triggered by the impedance compensation signal to output an impedance of a preset value to the gate of the power switch. The value of the impedance changes in a positive correlation with the ringing amplitude voltage.

2. The DC-DC converter circuit as described in claim 1, characterized in that, The first terminal of the power switch forms the input terminal of the DC-DC converter unit. The second terminal of the power switch, the first terminal of the inductor, and the second terminal of the freewheeling diode are connected together. The second terminal of the inductor forms the output terminal of the DC-DC converter unit. The first terminal of the freewheeling diode is grounded. Alternatively, the first end of the inductor forms the input terminal of the DC-DC converter, the second end of the inductor, the first end of the power switch and the first end of the freewheeling diode are connected together, the second end of the freewheeling diode forms the output terminal of the DC-DC converter, and the second end of the power switch is grounded; Alternatively, the first terminal of the power switch forms the input terminal of the DC-DC converter, the second terminal of the power switch, the first terminal of the inductor and the second terminal of the freewheeling diode are connected together, the second terminal of the inductor is grounded, and the first terminal of the freewheeling diode forms the output terminal of the DC-DC converter.

3. The DC-DC conversion circuit as described in claim 1, characterized in that, The ring detection feedback unit includes: The comparison unit is connected to the common node of the power switch, the inductor and the freewheeling diode, and compares the ringing amplitude voltage of the common node with the preset amplitude voltage, and outputs a level signal; The signal output unit, connected to the comparison unit and the impedance compensation unit, is used to receive a level signal characterizing the ringing amplitude voltage of the common node, and output an impedance compensation signal when the ringing amplitude voltage is greater than a preset amplitude voltage.

4. The DC-DC conversion circuit as described in claim 1, characterized in that, The impedance compensation unit includes a potentiometer, which is connected in series between the control terminal of the DC-DC conversion circuit and the gate of the power switch. The control terminal of the potentiometer is connected to the signal terminal of the ringing detection feedback unit.

5. The DC-DC converter circuit as described in claim 1, characterized in that, The impedance compensation unit includes a switching switch and multiple first resistors, and the switching switch includes a first terminal and multiple second terminals; The multiple second terminals of the switching switch are connected in series with the first terminals of the multiple first resistors, the first terminal of the switching switch is connected to the control terminal of the DC-DC conversion circuit, the second terminals of the multiple first resistors are connected in parallel and connected to the gate of the power switch, and the control terminal of the switching switch is connected to the signal terminal of the ringing detection feedback unit. Alternatively, the impedance compensation unit may include multiple parallel resistor units connected in series between the control terminal of the DC-DC conversion circuit and the gate of the power switch. Each resistor unit may include a switching switch and a first resistor connected in series. The control terminal of each switching switch may be connected to the signal terminal of the ringing detection feedback unit.

6. The DC-DC converter circuit as described in claim 1, characterized in that, The DC-DC conversion circuit also includes: A buffer circuit, connected to the common node, is used to absorb and suppress ringing.

7. The DC-DC conversion circuit as described in claim 6, characterized in that, The buffer circuit includes a second resistor and a capacitor; The first end of the second resistor is connected to the common node, the second end of the second resistor is connected to the first end of the capacitor, and the second end of the capacitor is grounded.

8. The DC-DC converter circuit as described in claim 1, characterized in that, The DC-DC conversion circuit also includes a filter capacitor and a load resistor; The first terminal of the filter capacitor, the first terminal of the load resistor, and the output terminal of the DC-DC converter are connected, and the second terminal of the filter capacitor and the second terminal of the load resistor are grounded.

9. A display driving circuit, characterized in that, The display driving circuit includes an LED driver chip and a DC-DC conversion circuit as described in any one of claims 1 to 8, wherein the DC-DC conversion circuit is connected to the LED driver chip and the LED backlight respectively. And / or, the display driving circuit includes a power management integrated circuit, a timing controller, a gate driving circuit, and a source driving circuit. The power management integrated circuit includes at least one DC-DC conversion circuit as described in any one of claims 1 to 8. The power management integrated circuit is connected to the timing controller, the gate driving circuit, and the source driving circuit, respectively. The timing controller is also connected to the gate driving circuit and the source driving circuit, respectively. The gate driving circuit and the source driving circuit are respectively connected to the display panel.

10. A display device, characterized in that, It includes a display panel and at least one display driving circuit as described in claim 9, wherein the display panel is disposed opposite to the display driving circuit, and / or the display panel is connected to the display driving circuit.

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