CN117037729B - Self-adaptive adjustment mini LED backlight driving method and driving chip thereof - Google Patents
Self-adaptive adjustment mini LED backlight driving method and driving chip thereof Download PDFInfo
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- G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
- G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
- G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
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Abstract
The invention discloses a mini LED backlight driving method and a driving chip thereof capable of self-adaptively adjusting, and mainly solves the problems that the existing driving mode affects the display effect and the adjustment speed is low and the duty ratio is not utilized enough. The method enables the LED driving chip to automatically detect and automatically adjust the duty ratio and the current amplitude of the LED driving pulse, and finally enables all the voltages of the LED driving ports to be near the set reference voltage, thereby achieving the purpose of reducing the power consumption of the LED driving chip. The self-adaptive LED backlight driving method can realize accurate LED constant current driving, and can reduce the power consumption of the driving chip, so that the LED display is more accurate and stable, and the driving chip generates lower heat.
Description
Technical Field
The invention relates to the technical field of integrated circuits, in particular to a self-adaptive adjustment mini LED backlight driving method.
Background
The matrix type backlight source made of mini LEDs (sub-millimeter light emitting diodes) is combined with liquid crystal display, so that the liquid crystal display screen has the advantages of high contrast ratio and wide color gamut, the display effect close to OLED is achieved, and the cost is greatly reduced compared with that of OLED. Therefore, the matrix mini LED backlight liquid crystal television has very rapid development.
In the current mini LED backlight driving technology, for simplifying driving and reducing cost, a common driving chip integrates multiple current output ends, and the multiple current output ends are respectively connected to the cathodes of multiple LED strings, as shown in fig. 1. The LED is of a constant current drive type, and the voltage difference of the LED is exponentially related to the current. Also, for manufacturing reasons, the same current, the differential voltage VF of the LEDs will vary, and the differential voltage nVF of the string will amplify this difference. The existing LED driving technology adopts a Pulse Width Modulation (PWM) technology with a constant current amplitude, and when each LED string works, the current flowing through each LED string is the same, and because of the difference in voltage drop nVF of the strings, and the impedance difference in wiring, the difference in total voltage drop of each string can be caused. The voltage drop nVF of the LED string is subtracted from the LED power supply voltage, and the remaining voltage falls on the driver chip port, which can cause greater losses in the LED driver chip if the remaining voltage is greater. The LED driving system needs to ensure that the lamp string with the lowest voltage can normally work, namely, the lamp string with the largest voltage drop can normally and constantly drive, so that the lamp string with the small voltage drop has large voltage drop of the driving port, more power consumption is generated, and the driving chip is caused to generate larger heat. The patent of application No. 202210367425.0 proposes a method of obtaining an optimized channel current on each LED sub-string branch other than the maximum conduction branch, then adjusting each LED sub-string channel current to the optimized channel current, and then generating a corresponding number of PWM cycles according to the optimized current. Adjusting the number of periods of the PWM can cause the average current of the LEDs to fluctuate, and the LED off time is long, so that the display effect can be affected. Patent US11432386B2 proposes a driving method of gradually decreasing the driving current with low driving port voltage while increasing the duty ratio, and finally making all driving port voltages the same. According to the unidirectional adjustment method, the driving current is required to be continuously reduced, the duty ratio is increased, so that a larger duty ratio is required to be reserved for adjustment, and the duty ratio utilization rate is low. And the device needs to be adjusted successively by successive detection, and has low adjustment speed.
Disclosure of Invention
The invention aims to provide a self-adaptive adjustment mini LED backlight driving method and a driving chip thereof, which mainly solve the problems that the existing driving mode affects the display effect and the adjustment speed is slow and the duty ratio is not utilized enough.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
a self-adaptive adjustment mini LED backlight driving method comprises the following steps:
s1, when power is on, initializing the LED driving chip through the controller, and setting the LED power supply voltage V LED ；
S2, the LED driving chip opens the driving ports to light the LED lamp string, and the LED driving chip detects the OUT voltages of all the driving ports and compares the OUT voltages with Vi+dv and Vi-dv respectively to output Vo1 and Vo2; wherein Vi is a reference voltage set by a register value and adjusted by a reference voltage set value, dv is a voltage value set by the LED driving chip;
s3, if the outputs Vo1 and Vo2 have high levels, the driving port OUT voltage is higher or lower, and the step S4 is performed after the OUT voltage is regulated to the reference voltage Vi; otherwise, directly entering step S4;
s4, the LED driving chip detects the grid electrode Gc voltage VGc of all the driving switching tubes, compares the grid electrode Gc voltage VGc with a reference voltage VGH or Vgl and outputs Vo3;
s5, if VGc > VgH and Vo3 is high level, the LED power supply voltage V is increased LED The method comprises the steps of carrying out a first treatment on the surface of the If VGc < Vgl and Vo3 is low, the LED power supply voltage V is reduced LED The method comprises the steps of carrying out a first treatment on the surface of the Otherwise, the LED is normally driven without adjustment.
Further, in the step S1, the initialization process of the LED driving chip includes the controller inputting the reference voltage register value, the default duty ratio data d0, and the gray data a to the LED driving chip through the SDI and DCLK data lines.
Further, in the step S3, if the output Vo1 is at a high level, it indicates that the voltage of the driving port OUT is higher, the new gray data obtained by the LED driving chip processing will be improved, so that the pulse current amplitude is increased, the current flowing through the LED string is increased, and the string voltage difference nVF is increased, so as to reduce the voltage of the driving port OUT;
if the output Vo2 is at a high level, it indicates that the voltage of the driving port OUT is low, the new gray data obtained by processing the LED driving chip will decrease, so that the pulse current amplitude decreases, and the current flowing through the LED string becomes smaller, so that the string voltage difference nVF decreases, and the voltage of the driving port OUT is increased.
Based on the method, the invention also provides a mini LED backlight driving chip with self-adaptive adjustment, which comprises an LED driving control unit and a detection operation adjustment output unit; the LED drive control unit comprises a gray control unit, an operation unit, a pulse output unit, a clock unit, an operational amplifier U1, a switch tube N1, m+1 switches s0-sm and m+1 constant current sources I-2 m I, a step of I; the Pulse output unit outputs PWM Pulse signal Pulse to control the on and off of the operational amplifier U1, and the operational amplifierWhen the U1 is closed, the output Gc of the U-shaped switching tube is pulled to the ground, the switching tube N1 is closed, the driving port OUT does not output current, and the LED is not lighted; when the operational amplifier U1 is opened, the output Gc of the operational amplifier U1 is pulled to a proper voltage so that the voltage of the node A1 is equal to the reference voltage Vr, the gray control unit outputs m+1 bits of gray data to control the corresponding m+1 switches s0-sm to be closed, the corresponding constant current source is connected, the switching tube N1 is opened, the driving port OUT outputs the set constant current source, and the LED is on;
the operation unit is used for receiving the duty ratio d0, m+1 bit gray data a and detecting the duty ratio adjusting signal output by the operation adjusting output unit, and outputting the adjusted duty ratio d1 to the Pulse output unit to generate a Pulse control signal; the operation unit outputs the gray data a1 and the remainder b subjected to a x d0/d1 operation to the gray control unit at the same time;
the gray control unit outputs gray data a1, controls s0-sm switches to be connected with corresponding constant current sources, simultaneously opens a 1-reduction counter for d1, outputs gray data a1+1 when the result is equal to remainder b, and adds 1 to the constant current sources until PWM is finished.
Further, in the invention, the detection operation regulation output unit comprises a processing unit, a comparator U2, a comparator U3, a comparator U4, a reference voltage generating circuit, a subtracter, a current counter, a reference current selecting circuit, a switching tube N2, a switch sg1 and a switch sg2;
in the opening process of the switching tube N1, the control signal vt controls the switching tube N2 to be opened, and the driving output OUT voltage is connected to the comparator U2 and the comparator U3 to be compared with Vi+dv and Vi-dv respectively; when the OUT voltage is lower than the Vi+dv voltage, the output Vo1 of the comparator U2 is high level, otherwise, the output Vo1 is low level; when the OUT voltage is lower than the Vi-dv voltage, the output Vo2 of the comparator U3 is high level, otherwise, the output Vo2 is low level;
the processing unit controls the switch sg1 to be closed and the switch sg2 to be opened, and the reference voltage VgH is connected to the comparator U4; when the switching tube N1 is opened, the gate voltage VGc is connected to the input of the comparator U4 and is compared with the reference voltage VGH or the reference voltage VGL, when the gate voltage VGc is higher than the reference voltage VGH, the output Vo3 becomes high level, the processing unit outputs a signal to the subtracter, and the current counter is used for processingProcessing reference current control information, storing a reference current value and performing a counting function of adding 1 or subtracting 1; the reference current selection circuit outputs a control signal to the configured reference current selection circuit according to the current value of the current counter, so that the reference current selection circuit generates a reference current with the size and direction corresponding to the current value of the current counter, and the IFB current is adjusted to enable V LED The voltage is increased;
when Vo3 of all driving ports is low level, the processing unit controls the switch sg1 to be opened and the switch sg2 to be closed, the reference voltage Vgl is connected to the comparator U4, and if Vo3 of all driving ports is low level, the processing unit outputs signals to the subtracter to adjust IFB current to enable V LED The voltage is reduced, so that the LED driving chip connects the output signals of Vo1, vo2 and Vo3 of the driving port to the processing unit; when Vo1 of the driving port is at a high level, indicating that the voltage of the current driving port is higher, the processing unit outputs an adjusting signal with reduced duty ratio to the operation unit; the operation unit outputs a duty ratio d1 signal to the pulse output unit after the duty ratio is reduced from d0 to d1, and simultaneously obtains new gray data a1 and remainder through operation according to a formula a1=a×d0/d1 and outputs the new gray data a1 and remainder to the gray control unit.
Compared with the prior art, the invention has the following beneficial effects:
according to the self-adaptive adjustment mini LED backlight driving method, the LED driving chip can automatically detect and automatically adjust the duty ratio and the current amplitude of the LED driving pulse, and finally, the voltages of all the LED driving ports are near the set reference voltage, so that the purpose of reducing the power consumption of the LED driving chip is achieved. The self-adaptive LED backlight driving method can realize accurate LED constant current driving, and can reduce the power consumption of the driving chip, so that the LED display is more accurate and stable, and the driving chip generates lower heat.
Drawings
Fig. 1 is a circuit diagram of a prior art LED display system.
FIG. 2 is a flow chart of a method for driving a mini LED backlight in an adaptive adjustment manner
Fig. 3 is a circuit diagram of an LED driver chip of the present invention.
Fig. 4 is an enlarged view of the LED driving control unit of fig. 3.
Fig. 5 is an enlarged view of the detection operation adjustment output unit in fig. 3.
FIG. 6 is a graph of regulated front drive port output voltage and current in an embodiment of the invention.
Fig. 7 is a graph of the output voltage and current obtained using the driving method of the present invention.
Detailed Description
The invention will be further illustrated by the following description and examples, which include but are not limited to the following examples.
As shown in fig. 2, in the self-adaptive adjustment mini LED backlight driving method disclosed in the present invention, when the driving chip is powered on, initialization is performed, and the controller inputs the reference voltage register value, the default duty cycle data d0 and the gray data a to the LED driving chip through the SDI and DCLK data lines. Meanwhile, the LED power supply voltage V is preliminarily set by setting the resistance values of the resistors R1 and R2 according to theoretical calculation LED 。
And after the initialization is finished, the LED driving chip opens the driving port to light the LED lamp string. The LED driving chip detects the OUT voltages of all the driving ports, compares the OUT voltages with Vi+dv and Vi-dv respectively, and if the outputs Vo1 and Vo2 have high levels, the OUT voltages of the driving ports are higher or lower, and the OUT voltages need to be regulated to be close to the reference voltage Vi.
If Vo1 is at high level, it indicates that the voltage of the driving port OUT is higher, the processing unit outputs a signal to the operation unit to lower the duty ratio data d0, and the operation unit obtains new gray data through the processing of the formula a1=a×d0/d1, so that the pulse current amplitude is increased. When the current flowing through the LED string becomes large, the string voltage difference nVF increases, thereby decreasing the driving port OUT voltage.
If Vo2 is at high level, it indicates that the voltage of the driving port OUT is low, the processing unit outputs a signal to the operation unit to increase the duty ratio data d0, and the operation unit obtains new gray data through the operation process of the formula a1=a×d0/d1, so that the pulse current amplitude is reduced. When the current flowing through the LED string becomes smaller, the string voltage difference nVF decreases, thereby increasing the driving port OUT voltage. Continuing the detection and adjustment after the next LED turn on, finally Vo1 and Vo2 are both low, and all the driving port OUT voltages are in the range of Vi-dv to Vi+dv. The LED supply voltage then needs to be fine-tuned and dynamically adjusted. Under the default condition that the sg1 switch is closed and the sg2 switch is opened, the grid voltage VGc of the switch tube is compared with the VGH reference voltage to output Vo3, when Vo3 has high level, the driving port OUT voltage is low, the LED power voltage needs to be raised, and the processing unit adjusts the subtracter, so that IFB reference current output is adjusted, and the LED power voltage is improved. The reference voltage VgL input is switched when all Vo3 are low, the sg1 switch is open and the sg2 switch is closed. And judging whether all Vo3 outputs low level or not, if so, indicating that the LED power supply voltage is too high, and reducing the LED power supply voltage is needed, and if not, indicating that the LED power supply voltage is in a proper range. When all Vo3 outputs high level, the processing unit switches on the sg1 switch and switches off the sg2 switch, and the reference voltage VgH is input to the comparator for comparison with the voltage VGc.
Based on the method, the invention also provides a mini LED backlight driving chip with self-adaptive adjustment, which comprises an LED driving control unit and a detection operation adjustment output unit, as shown in fig. 3-5; the LED drive control unit comprises a gray control unit, an operation unit, a pulse output unit, a clock unit, an operational amplifier U1, a switch tube N1, m+1 switches s0-sm and m+1 constant current sources I-2 m I, a step of I; the Pulse output unit outputs a PWM Pulse signal Pulse to control the on and off of the operational amplifier U1, when the operational amplifier U1 is turned off, the output Gc of the operational amplifier U1 is pulled to the ground, the switching tube N1 is turned off, the driving port OUT does not output current, and the LED is not lighted; when the operational amplifier U1 is opened, the output Gc of the operational amplifier is pulled to a proper voltage so that the voltage of the node A1 is equal to the reference voltage Vr, the gray control unit outputs m+1 bits of gray data to control the corresponding m+1 switches s0-sm to be closed, the corresponding constant current source is connected, the switching tube N1 is opened, the set constant current source is output by the driving port OUT, and the LED is on.
The operation unit is used for receiving the duty ratio d0, m+1 bit gray data a and detecting the duty ratio adjusting signal output by the operation adjusting output unit, and outputting the adjusted duty ratio d1 to the Pulse output unit to generate a Pulse control signal; the operation unit outputs the gray data a1 and the remainder b after the operation of a x d0/d1 to the gray control unit at the same time.
The gray control unit outputs gray data a1, controls s0-sm switches to be connected with corresponding constant current sources, simultaneously opens a 1-reduction counter for d1, outputs gray data a1+1 when the result is equal to remainder b, and adds 1 to the constant current sources until PWM is finished.
The detection operation regulation output unit comprises a processing unit, a comparator U2, a comparator U3, a comparator U4, a reference voltage generating circuit, a subtracter, a current counter, a reference current selecting circuit, a switching tube N2, a switch sg1 and a switch sg2. In the opening process of the switching tube N1, the control signal vt controls the switching tube N2 to be opened, and the driving output OUT voltage is connected to the comparator U2 and the comparator U3 to be compared with Vi+dv and Vi-dv respectively; when the OUT voltage is lower than the Vi+dv voltage, the output Vo1 of the comparator U2 is high level, otherwise, the output Vo1 is low level; when the OUT voltage is lower than the Vi-dv voltage, the output Vo2 of the comparator U3 is high, and conversely, a low is output.
The processing unit controls the switch sg1 to be closed and the switch sg2 to be opened, and the reference voltage VgH is connected to the comparator U4; when the switching tube N1 is opened, the grid voltage VGc of the switching tube N1 is connected to the input of the comparator U4 and is compared with the reference voltage VGH or the reference voltage VGL, when the grid voltage VGc is higher than the reference voltage VGH, the output Vo3 becomes high level, the processing unit outputs a signal to the subtracter, and the current counter is used for processing reference current control information, storing a reference current value and can perform a counting function of adding 1 or subtracting 1; the reference current selection circuit outputs a control signal to the configured reference current selection circuit according to the current value of the current counter, so that the reference current selection circuit generates a reference current with the magnitude and the direction corresponding to the current value of the current counter, wherein when the current value of the current counter is positive, the direction of the reference current flows in from the current regulation terminal IFB, and when the current value of the current counter is negative, the direction of the reference current flows out from the current regulation terminal IFB. Thereby adjusting IFB current to V LED The voltage is increased;
when Vo3 of all the driving ports is at low level, the processing unit controls the switch sg1 to be opened and the switch sg2 to be closed,the reference voltage VgL is connected to the comparator U4, and if Vo3 of all driving ports is low, the processing unit outputs a signal to the subtractor to adjust IFB current to V LED The voltage is reduced, so that the LED driving chip connects the output signals of Vo1, vo2 and Vo3 of the driving port to the processing unit; when Vo1 of the driving port is at a high level, indicating that the voltage of the current driving port is higher, the processing unit outputs an adjusting signal with reduced duty ratio to the operation unit; the operation unit outputs a duty ratio d1 signal to the pulse output unit after the duty ratio is reduced from d0 to d1, and simultaneously obtains new gray data a1 and remainder through operation according to a formula a1=a×d0/d1 and outputs the new gray data a1 and remainder to the gray control unit.
As known from the formula a1=ad0/d 1, when d1 becomes smaller, new gray data a1 increases, the output of the corresponding constant current source driving the LED increases, and the voltage difference nVF increases after the LED string current increases, so that the OUT voltage decreases. When Vo2 of the driving port is at a high level, which indicates that the current driving port voltage is low, the processing unit outputs an adjusting signal with increased duty ratio to the operation unit. The operation unit outputs the duty ratio which is increased from d0 to d1 to the pulse output unit, and simultaneously obtains new gray data a1 and remainder by operation according to a formula a1=a×d0/d1 and outputs the new gray data a1 and remainder to the gray control unit.
As known from the formula a1=ad0/d 1, when d1 becomes larger, the new gray data a1 will decrease, the output of the corresponding constant current source driving the LED decreases, and the voltage difference nVF will decrease after the LED string current decreases, so that the OUT voltage increases. The detection of the OUT voltage is continued after the next LED turn-on after such adjustment, and the above operation is repeated until all the driving port OUT voltages are in the range of Vi-dv and Vi+dv. The simultaneous processing unit receives Vo3 signals from all the drive ports, switch sg1 being closed and switch sg2 being open. When Vo3 output high level exists, the processing unit outputs a signal to adjust the subtracter, and then adjusts IFB reference current to increase the LED power supply voltage. After the LED power supply voltage increases, the driving port voltage increases, and the Gc voltage decreases, so that Vo3 outputs a low level. When all Vo3 output low level, switch sg1 is opened and switch sg2 is closed, and when all Vo3 output low level, the processing unit outputs a signal to adjust the subtracter, and then adjusts the IFB reference current to reduce the power supply voltage of the LED. Then the drive port voltage will follow down and the voltage VGc will rise. When not all Vo3 outputs low, switch sg1 is closed and switch sg2 is open. Finally, the signals Vo1, vo2 and Vo3 are all low level, and the LED driving self-adaptive adjustment is finished.
Fig. 6 is a diagram showing the output voltage and current of the driving port before adjustment, wherein the amplitudes of the output current IOUT pulses of all driving ports before adjustment are the same, but the driving port voltages are different due to different lamp string voltage differences nVF. After the LED driving system is regulated by the LED power supply, the intermediate value of all the driving port voltages is close to the reference voltage Vi. The drive port voltage is now embodied partly higher than the reference voltage Vi and partly lower than the reference voltage Vi.
Fig. 7 is a diagram of output voltage and current obtained by the driving method of the present invention, and referring to fig. 6, it is known that the voltages of the driving ports O1 and On-1 are lower than the reference voltage, which affects the constant current output of the driving port, and the driving port current needs to be reduced to reduce the lamp string voltage difference nVF, thereby increasing the driving port voltage. Therefore, the driving chip increases the pulse duty ratio of the driving ports O1 and On-1 step by step, and obtains new gray data a1 to be smaller through the formula a1=ad0/d 1, so that the currents of the driving ports O1 and On-1 become smaller, the differential pressure nVF of the LED lamp string is reduced, the voltage of the driving port is increased, and the target value shown in fig. 7 is reached after detection and adjustment for a plurality of times. The voltages of the driving ports O2 and On are higher than the reference voltage, which causes the driving chip to generate larger power consumption, and the LED current needs to be increased to reduce the driving port voltage, so that the driving chip gradually decreases the pulse duty ratio of the driving ports O2 and On, and new gray data a1 is obtained through the formula a1=a×d0/d1, so that the currents of the driving ports O2 and On are increased, the LED string voltage difference nVF is increased, and the driving port voltage is reduced. Because the small change of the current of the LED light string can cause the pressure difference nVF of the light string to generate larger change, the power consumption of the adjusted driving port is reduced, and the target value shown in fig. 7 is reached after detection and adjustment for multiple times. The regulated drive port voltages are ultimately within the range of reference voltages Vi-dv to Vi + dv. The driving adjustment method can be known to adjust the reference voltage from the high direction and the low direction respectively, and the voltages of all the driving ports are close to the middle reference voltage, so that the driving adjustment method has the advantage of high adjustment speed.
The above embodiment is only one of the preferred embodiments of the present invention, and should not be used to limit the scope of the present invention, but all the insubstantial modifications or color changes made in the main design concept and spirit of the present invention are still consistent with the present invention, and all the technical problems to be solved are included in the scope of the present invention.
Claims (5)
1. The self-adaptive adjustment mini LED backlight driving method is characterized by comprising the following steps of:
s1, when power is on, initializing the LED driving chip through the controller, and setting the LED power supply voltage V LED ；
S2, the LED driving chip opens the driving ports to light the LED lamp string, and the LED driving chip detects the OUT voltages of all the driving ports and compares the OUT voltages with Vi+dv and Vi-dv respectively to output Vo1 and Vo2; wherein Vi is a reference voltage set by a register value and adjusted by a reference voltage set value, dv is a voltage value set by the LED driving chip;
s3, if the outputs Vo1 and Vo2 have high levels, the driving port OUT voltage is higher or lower, and the step S4 is performed after the OUT voltage is regulated to the reference voltage Vi; otherwise, directly entering step S4;
s4, the LED driving chip detects the grid electrode Gc voltage VGc of all the driving switching tubes, compares the grid electrode Gc voltage VGc with a reference voltage VGH or Vgl and outputs Vo3;
s5, if VGc > VgH and Vo3 is high level, the LED power supply voltage V is increased LED The method comprises the steps of carrying out a first treatment on the surface of the If VGc < Vgl and Vo3 is low, the LED power supply voltage V is reduced LED The method comprises the steps of carrying out a first treatment on the surface of the Otherwise, the LED is normally driven without adjustment.
2. The method according to claim 1, wherein in the step S1, the initialization process of the LED driving chip includes the controller inputting the reference voltage register value, the default duty cycle data d0 and the gray data a to the LED driving chip through the SDI and DCLK data lines.
3. The method according to claim 2, wherein in the step S3, if the output Vo1 is at a high level, it indicates that the voltage of the driving port OUT is higher, the new gray data obtained by the LED driving chip processing will be improved, so that the pulse current amplitude is increased, the current flowing through the LED string is increased, and the string voltage difference nVF is increased, so as to reduce the voltage of the driving port OUT;
if the output Vo2 is at a high level, it indicates that the voltage of the driving port OUT is low, the new gray data obtained by processing the LED driving chip will decrease, so that the pulse current amplitude decreases, and the current flowing through the LED string becomes smaller, so that the string voltage difference nVF decreases, and the voltage of the driving port OUT is increased.
4. The self-adaptive adjustment mini LED backlight driving chip is characterized by comprising an LED driving control unit and a detection operation adjustment output unit, wherein the mini LED backlight driving chip is used for realizing the self-adaptive adjustment according to the claim 3; the LED drive control unit comprises a gray control unit, an operation unit, a pulse output unit, a clock unit, an operational amplifier U1, a switch tube N1, m+1 switches s0-sm and m+1 constant current sources I-2 m I；
The input end of the gray control unit and one input end of the pulse output unit are connected with the operation unit, and the clock unit is connected with the other input end of the pulse output unit; the output end of the pulse output unit is connected with the control end of the operational amplifier U1, the output end of the operational amplifier U1 is connected with the grid electrode of the switching tube N1, one input end of the operational amplifier U1 is connected with the reference voltage Vr, the other input end of the operational amplifier U1 is connected with the drain electrode of the switching tube N1, each switch is connected with a current source in series and then connected in parallel to form an m+1 group gray scale control string, the drain electrode of the switching tube N1 is connected to a switch connection node A1 in the gray scale control string, and the gray scale control unit is correspondingly connected to the control end of each switch; the source electrode of the switching tube N1 is connected to the LED lamp string, and the output end of the operational amplifier U1 outputs the OUT voltage to the detection operation regulation output unit; the operation unit is also connected with the detection operation adjustment output unit;
the Pulse output unit outputs a PWM Pulse signal Pulse to control the on and off of the operational amplifier U1, when the operational amplifier U1 is turned off, the output Gc of the operational amplifier U1 is pulled to the ground, the switching tube N1 is turned off, the driving port OUT does not output current, and the LED is not lighted; when the operational amplifier U1 is opened, the output Gc of the operational amplifier U1 is pulled to a proper voltage so that the voltage of the node A1 is equal to the reference voltage Vr, the gray control unit outputs m+1 bits of gray data to control the corresponding m+1 switches s0-sm to be closed, the corresponding constant current source is connected, the switching tube N1 is opened, the driving port OUT outputs the set constant current source, and the LED is on;
the operation unit is used for receiving the duty ratio d0, m+1 bit gray data a and detecting the duty ratio adjusting signal output by the operation adjusting output unit, and outputting the adjusted duty ratio d1 to the Pulse output unit to generate a Pulse control signal; the operation unit outputs the gray data a1 and the remainder b subjected to a x d0/d1 operation to the gray control unit at the same time;
the gray control unit outputs gray data a1, controls s0-sm switches to be connected with corresponding constant current sources, simultaneously opens a 1-reduction counter for d1, outputs gray data a1+1 when the result is equal to remainder b, and adds 1 to the constant current sources until PWM is finished.
5. The adaptively adjusted mini LED backlight driving chip according to claim 4, wherein said detection operation adjustment output unit comprises a processing unit, a comparator U2, a comparator U3, a comparator U4, a reference voltage generating circuit, a subtractor, a current counter, a reference current selecting circuit, a switching tube N2, a switch sg1, and a switch sg2;
the output end of the comparator U2, the output end of the comparator U3 and the output end of the comparator U4 are connected to the processing unit, the source electrode of the switch tube N2 is respectively connected to one input end of the comparator U2 and one input end of the comparator U3, the drain electrode of the switch tube N2 is connected to the LED lamp string, the grid electrode of the switch tube N2 is connected to an external control signal vt, the other input end of the comparator U2 is connected to Vi+dv voltage, the other input end of the comparator U3 is connected to Vi-dv voltage, one end of the switch sg1 and one end of the switch sg2 are connected to one input end of the comparator U4, the other end of the switch sg1 and the other end of the switch sg2 are respectively connected to the reference voltage Vgl, the other input end of the switch sg1 and the control end of the switch sg2 are connected to the processing unit, the other input end of the comparator U4 is connected to the output end of the operational amplifier U1, one input end of the subtracter and one input end of the reference voltage generating circuit are also connected to the processing unit, the other input end of the subtracter is connected to the current counter, and the current of the subtracter is connected to the counter; the reference current selection circuit outputs IFB current; the processing unit is also connected with the operation unit;
in the opening process of the switching tube N1, an external control signal vt controls the switching tube N2 to be opened, the voltage of the driving port OUT is driven to be output to the comparator U2 and the comparator U3, and the voltage of the driving port OUT is compared with Vi+dv and Vi-dv respectively; when the voltage of the driving port OUT is lower than the voltage Vi+dv, the output Vo1 of the comparator U2 is high level, otherwise, the output Vo1 is low level; when the voltage of the driving port OUT is lower than the voltage Vi-dv, the output Vo2 of the comparator U3 is high level, otherwise, the output Vo2 is low level;
the processing unit controls the switch sg1 to be closed and the switch sg2 to be opened, and the reference voltage VgH is connected to the comparator U4; when the switching tube N1 is opened, the grid voltage VGc of the switching tube N1 is connected to the input of the comparator U4 and is compared with the reference voltage VGH or the reference voltage VGL, when the grid voltage VGc is higher than the reference voltage VGH, the output Vo3 becomes high level, the processing unit outputs a signal to the subtracter, and the current counter is used for processing reference current control information, storing a reference current value and can perform a counting function of adding 1 or subtracting 1; the reference current selection circuit outputs a control signal to the configured reference current selection circuit according to the current value of the current counter, so that the reference current selection circuit generates a reference current with the size and direction corresponding to the current value of the current counter, and the IFB current is adjusted to enable V LED The voltage is increased;
when Vo3 of all driving ports is low level, the processing unit controls the switch sg1 to be opened and the switch sg2 to be closed, and the reference voltage Vgl is connected to the comparator U4, if allVo3 of the drive port is low level, the processing unit outputs a signal to the subtracter, and IFB current is adjusted to enable V LED The voltage is reduced, so that the LED driving chip connects the output signals of Vo1, vo2 and Vo3 of the driving port to the processing unit; when Vo1 of the driving port is at a high level, indicating that the voltage of the current driving port is higher, the processing unit outputs an adjusting signal with reduced duty ratio to the operation unit; the operation unit outputs a duty ratio d1 signal to the pulse output unit after the duty ratio is reduced from d0 to d1, and simultaneously obtains new gray data a1 and remainder through operation according to a formula a1=a×d0/d1 and outputs the new gray data a1 and remainder to the gray control unit.
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