The configuration of LEDs in an application depends on many factors, including application requirements, LED parameters and quantities, input voltage, efficiency, thermal management, size and layout constraints, and optics. The simplest form of configuration is a single LE. There are many examples of applications that use this design, such as interior ceiling lights (map lights, reading lights).
Since the power and brightness of LEDs are not very high at present, and the actual use occasions usually require planar light emission, it is necessary to arrange and arrange a plurality of LEDs in accordance with needs to meet applications such as larger range, higher brightness, dynamic display, and color conversion. Requirements and matching requirements between LED and supporting driver.
First, the common connection form
1, the overall series form (1) simple series form Generally simple series connection form LED1 ~ LEDn connected end to end, LED current flow when the work is equal. For the same specification and batch of LEDs, although the voltage on a single LED may have slight differences, but because the LED is a current-type device, it can ensure that the respective luminous intensity is consistent, this trapped, simple tandem form LED has the characteristics of simple circuit and convenient connection. However, due to the series connection, when one of the LEDs fails, the entire LED string will be extinguished, which affects the reliability of use.
(2) Series connection with parallel Zener diodes Each LED is connected in parallel with an improved series connection of Zener diodes. In this connection, the breakdown voltage of each Zener diode is higher than the operating voltage of the LED. In normal operation of the LED, since the Zener diodes VD1 to VDn are not conductive, the current mainly flows through the LED1 to LEDn. When the LED string caused by the damaged LED in the LED string is opened, VD1 to VDn are turned on, except for Outside the faulty LED, other LEDs still emit light when they pass through. This type of connection is greatly improved in terms of reliability compared with the simple serial form.
2. Integral parallel connection (1) Simple parallel connection The LED1~LEDn of the simple parallel connection is connected in parallel at the end and end. Each working LED has the same voltage. It can be seen from the characteristics of the LED that it is a current-type device, and small changes in the voltage applied to the LED will cause large changes in the current. In addition, due to LED manufacturing technology limitations, even the same batch of LED, the performance difference is also inherent, so LED1 ~ LEDn work, who passed each LED current is not equal. It can be seen that the uneven distribution of the current of each LED may lead to a sharp drop in the life of an LED with excessive current, or even burn out. Although this connection is relatively simple. However, the reliability is not high, especially for applications where the number of LEDs is large.
(2) Parallel connection of independent matching For the reliability problem existing in simple parallel connection, the parallel connection of independent matching is a good way. Each LED in this way has its own adjustable current (driver V+ output terminals L1~Ln, respectively) to ensure that the current flowing through each LED is within its required range, with good driving effect and a single LED. Protection integrity, failure does not affect the other LED work, can match the characteristics of the LED with a large difference. The main problems that exist are: the composition of the entire drive circuit is relatively complex, the cost of the device is high, and the occupied volume is too large to be applied to a large number of LED circuits.
3. Mixed-joint form The form of joint-joint is proposed by combining the respective advantages of the serial form and the parallel form. The main forms are the following two types.
(1) First-in-a-series and rear-type hybrids When a large number of LEDs are used, simple series or parallel connections are not realistic. The former requires that the driver output a very high voltage (n times the single LED voltage VF). To drop the driver output a large current (n times the single LED current IF). This brings difficulties to the design and manufacture of the driver, and also involves the structural problems of the drive circuit and the overall efficiency problems. The product nVE of the number of LEDs in series and the operating voltage VF of a single LED determines the output voltage of the driver; the product mIF of the number m of parallel connected LED strings and the operating current IF of a single LED determines the driver output current, and mIF* The nVF value determines the output power of the driver.
Therefore, the use of a mixed-parallel hybrid method is mainly to ensure that there is a certain degree of reliability (the LED failure in each string affects only the normal light emission of the string at most), and the matching with the drive circuit is ensured (the driver outputs an appropriate voltage ), improved reliability over pure tandem form. The entire circuit has the characteristics of simpler structure, convenient connection, and high efficiency, and is applicable to a large number of LED applications.
(2) First and second clusters are the first and second series of hybrids. Since LED1-n~LEDm-n are first connected in parallel, the reliability of each group of LED failures is improved, but the problem of sharing the current of each group of parallel LEDs is crucial.
For this reason, pairing and selection can be used to make the LED whose working voltage and current are as same as possible parallel as one group, or to connect each LED in series with a small current sharing resistor. The other characteristics and existing problems of this hybrid form are similar to those of the first string and the first.
(3) Cross-array form Cross-array form is mainly to improve the reliability of LED work and reduce the failure rate. The main form is: Each string is composed of 3 LEDs and is respectively connected to the output terminals of the driver Va, Vb and Vc. When three LEDs in a string are all normal, three LEDs emit light at the same time; once one or both LEDs fail open, at least one LED is guaranteed to work. In this way, the reliability of light emission of each group of LEDs can be greatly improved, and the overall reliability of the entire LED light can be improved.
Reliability two different forms of connection <br> <br> compare different connection forms having different characteristics and requirements of the driver is not the same, the circuit in particular when operating single LED fails, the entire light emission It is particularly important to ensure the overall LED's ability to continue working as much as possible and reduce the overall LED failure rate.
All in all, the LED population application is an important way for LED applications. Different types of LED connections are critical for the convenience of large-area LED lighting and the design requirements of the driver circuit. Therefore, in the actual circuit combination, the correct choice of the appropriate LED connection method has a positive significance for improving the luminous effect, the reliability of the work, the ease of driver design and manufacturing, and the efficiency of the entire circuit.
Three, LED light module <br> <br> phenomenon faults and solutions: All LED flashes;
Problem: poor contact;
Solution: re-fix or insert loose;
Phenomenon: LED dim;
Problem: 1, LED polarity reversed; 2, LED is too long; 3, switching power supply and LED voltage labels are inconsistent;
Solution: 1, to ensure that the positive and negative wiring is correct; 2, reduce the LED connection; 3, to ensure that the switching power supply and LED voltage label consistency;
Phenomenon: LED lights on some lines are off;
Question: 1. Is the insertion direction correct? 2. Is the power output wiring correct? 3. The power cable is plugged in and reversed.
Solution: 1, remove the correct direction of the plug; 2, to ensure that the red wire to connect the positive, black wire to the negative; 3, find the part of the anti-reverse line; reconnect;
Phenomenon: All LEDs are off
Problems: 1. No switching power supply voltage output; 2. Switching power supply output wiring is correct;
Solution: 1. Test power access to the input end of the switching power supply; 2. Whether the positive and negative terminals of the power supply connection are correct;
Text / Shenzhen LED base
Since the power and brightness of LEDs are not very high at present, and the actual use occasions usually require planar light emission, it is necessary to arrange and arrange a plurality of LEDs in accordance with needs to meet applications such as larger range, higher brightness, dynamic display, and color conversion. Requirements and matching requirements between LED and supporting driver.
First, the common connection form
1, the overall series form (1) simple series form Generally simple series connection form LED1 ~ LEDn connected end to end, LED current flow when the work is equal. For the same specification and batch of LEDs, although the voltage on a single LED may have slight differences, but because the LED is a current-type device, it can ensure that the respective luminous intensity is consistent, this trapped, simple tandem form LED has the characteristics of simple circuit and convenient connection. However, due to the series connection, when one of the LEDs fails, the entire LED string will be extinguished, which affects the reliability of use.
(2) Series connection with parallel Zener diodes Each LED is connected in parallel with an improved series connection of Zener diodes. In this connection, the breakdown voltage of each Zener diode is higher than the operating voltage of the LED. In normal operation of the LED, since the Zener diodes VD1 to VDn are not conductive, the current mainly flows through the LED1 to LEDn. When the LED string caused by the damaged LED in the LED string is opened, VD1 to VDn are turned on, except for Outside the faulty LED, other LEDs still emit light when they pass through. This type of connection is greatly improved in terms of reliability compared with the simple serial form.
2. Integral parallel connection (1) Simple parallel connection The LED1~LEDn of the simple parallel connection is connected in parallel at the end and end. Each working LED has the same voltage. It can be seen from the characteristics of the LED that it is a current-type device, and small changes in the voltage applied to the LED will cause large changes in the current. In addition, due to LED manufacturing technology limitations, even the same batch of LED, the performance difference is also inherent, so LED1 ~ LEDn work, who passed each LED current is not equal. It can be seen that the uneven distribution of the current of each LED may lead to a sharp drop in the life of an LED with excessive current, or even burn out. Although this connection is relatively simple. However, the reliability is not high, especially for applications where the number of LEDs is large.
(2) Parallel connection of independent matching For the reliability problem existing in simple parallel connection, the parallel connection of independent matching is a good way. Each LED in this way has its own adjustable current (driver V+ output terminals L1~Ln, respectively) to ensure that the current flowing through each LED is within its required range, with good driving effect and a single LED. Protection integrity, failure does not affect the other LED work, can match the characteristics of the LED with a large difference. The main problems that exist are: the composition of the entire drive circuit is relatively complex, the cost of the device is high, and the occupied volume is too large to be applied to a large number of LED circuits.
3. Mixed-joint form The form of joint-joint is proposed by combining the respective advantages of the serial form and the parallel form. The main forms are the following two types.
(1) First-in-a-series and rear-type hybrids When a large number of LEDs are used, simple series or parallel connections are not realistic. The former requires that the driver output a very high voltage (n times the single LED voltage VF). To drop the driver output a large current (n times the single LED current IF). This brings difficulties to the design and manufacture of the driver, and also involves the structural problems of the drive circuit and the overall efficiency problems. The product nVE of the number of LEDs in series and the operating voltage VF of a single LED determines the output voltage of the driver; the product mIF of the number m of parallel connected LED strings and the operating current IF of a single LED determines the driver output current, and mIF* The nVF value determines the output power of the driver.
Therefore, the use of a mixed-parallel hybrid method is mainly to ensure that there is a certain degree of reliability (the LED failure in each string affects only the normal light emission of the string at most), and the matching with the drive circuit is ensured (the driver outputs an appropriate voltage ), improved reliability over pure tandem form. The entire circuit has the characteristics of simpler structure, convenient connection, and high efficiency, and is applicable to a large number of LED applications.
(2) First and second clusters are the first and second series of hybrids. Since LED1-n~LEDm-n are first connected in parallel, the reliability of each group of LED failures is improved, but the problem of sharing the current of each group of parallel LEDs is crucial.
For this reason, pairing and selection can be used to make the LED whose working voltage and current are as same as possible parallel as one group, or to connect each LED in series with a small current sharing resistor. The other characteristics and existing problems of this hybrid form are similar to those of the first string and the first.
(3) Cross-array form Cross-array form is mainly to improve the reliability of LED work and reduce the failure rate. The main form is: Each string is composed of 3 LEDs and is respectively connected to the output terminals of the driver Va, Vb and Vc. When three LEDs in a string are all normal, three LEDs emit light at the same time; once one or both LEDs fail open, at least one LED is guaranteed to work. In this way, the reliability of light emission of each group of LEDs can be greatly improved, and the overall reliability of the entire LED light can be improved.
Reliability two different forms of connection <br> <br> compare different connection forms having different characteristics and requirements of the driver is not the same, the circuit in particular when operating single LED fails, the entire light emission It is particularly important to ensure the overall LED's ability to continue working as much as possible and reduce the overall LED failure rate.
All in all, the LED population application is an important way for LED applications. Different types of LED connections are critical for the convenience of large-area LED lighting and the design requirements of the driver circuit. Therefore, in the actual circuit combination, the correct choice of the appropriate LED connection method has a positive significance for improving the luminous effect, the reliability of the work, the ease of driver design and manufacturing, and the efficiency of the entire circuit.
Three, LED light module <br> <br> phenomenon faults and solutions: All LED flashes;
Problem: poor contact;
Solution: re-fix or insert loose;
Phenomenon: LED dim;
Problem: 1, LED polarity reversed; 2, LED is too long; 3, switching power supply and LED voltage labels are inconsistent;
Solution: 1, to ensure that the positive and negative wiring is correct; 2, reduce the LED connection; 3, to ensure that the switching power supply and LED voltage label consistency;
Phenomenon: LED lights on some lines are off;
Question: 1. Is the insertion direction correct? 2. Is the power output wiring correct? 3. The power cable is plugged in and reversed.
Solution: 1, remove the correct direction of the plug; 2, to ensure that the red wire to connect the positive, black wire to the negative; 3, find the part of the anti-reverse line; reconnect;
Phenomenon: All LEDs are off
Problems: 1. No switching power supply voltage output; 2. Switching power supply output wiring is correct;
Solution: 1. Test power access to the input end of the switching power supply; 2. Whether the positive and negative terminals of the power supply connection are correct;
Text / Shenzhen LED base
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