is the row drive tube, the power tube, and each display rowThe required current is relatively large, to use the row drive tube, each 4953 can drive 2 display rows 5024 is a 16-bit constant current led driver, can achieve serial input, parallel output, and maintain the output current of 3-45ma per output pin. The output can withstand 17v, and multiple leds can be connected in series at each output end.
LED driver chips can be divided into general purpose chips and special chips. General purpose chips are generally used for low-end LED display products, such as indoor single and two-color LED display screens. The most commonly used general-purpose chip is 74HC595, with 8-bit latches and stringsTogether with shift register and tri-state output function. The maximum output current of each channel is 35 mA (not constant current). General IC manufacturers can produce such chips.
ED displays four large parts of the array and the power supply. Among them, there are many problems: interface problems. Symptom: The computer information cannot be displayed. Check the cable power supply. The LED display uses a low-voltage high-current power supply, which is not much different from the ordinary DC power supply. Each row or column is not displayed, that is, the corresponding driver circuit (chip) problem, and the replacement can display the problem.
Chip includedShift register, data latch, three-channel constant current driver current value can be controlled by corresponding three external resistors, and built-in shaker for PWM function. DM412 and MOJAY, M8914, M8910 are LED driver chips with pulse width modulation PWM output and enable control, designed for LED lighting, LED display, decoration and other applications.
The main circuit of ee-sx671 adopts imported SOP-5 isolated driver chip. At present, Omron sensor main circuit chip. LED driver chip can be divided into universal cored=' What are the LED driver power chips '> What are the LED driver power chips
1, MOJAY (MOjie) M8900 is a original side reverse strip single-stage active PFC high-precision LED constant current control chip, M8900 integrated single-stage active PFC line, can achieve higher power factors and very low total harmonic distortion, the chip can enter the quasi-resonant mode, so as to achieve higher efficiency and reduce switching loss. < / p > < p > 2, there are national semiconductor production LM351LM270LM2795LM2795LM2796 All the same, depending on your own to give people like.
3, DOB is to put the LED constant current Driver source driver on the aluminum substrate, this technology has been available as early as 5 years ago, of course, at that time not called DOB and called light engine. The two names are very different, DOB said is a method or practice, is to put the drive power on the aluminum substrate, and the light engine is a new product name, all LED aluminum substrate with constant current drive source is called the light engine.
Constant voltage drive. That is to say, the luminous chip common led driver chip constant 5V voltage drive. Constant current drive. At present, the LED display is basically driven by constant current. Constant current driver is a constant current source added to the ground pin of the light-emitting chip, which makes the current through the chip unchanged in the case of changes in the external power supply, so as to avoid damage to the chip. Constant current drive can be divided into static constant current drive.
HengStream driven! - is characterized by a constant circuit output current, even in the face of load short circuit, can protect the LED from damage. The constant current drive also helps to keep the current stable, which significantly improves the service life and stability of the LED display. However, this type of drive is relatively expensive because it requires more electrical components. Therefore, in practical applications, there is a trade-off between cost and performance.
Generally, the maximum constant current output current is less than the maximum allowed output current. Constant current output channel Constant current source output channels are 8-bit (8-way constant source) and 16-bit (16-way constant source)Two specifications, now 16-bit source is dominant, its main advantage is to reduce the chip size, easy to LED driver board (PCB) wiring, especially for the small point spacing LED driver board is more favorable.
In the working world of LED display, the two protagonists of the drive mode - constant current and constant voltage, each in a unique way to guard the brightness and stability of the screen. / First, let's unravel the mystery of constant current drive. LED, this electronic pearl, its brightness is like the dancer of the current, and the strength of the current is closely related. Constant current drive is like a master of dimming, by accurately controlling the stability of the currentKeep the brightness of the LED silky smooth and consistent.
In the selection and design of LED driver power to take into account: 1. High Reliability 2. High efficiency 3. High power factor 4. There are two kinds of driving methods: one is a constant voltage source for multiple constant current sources, each constant current source separately to each LED power supply. The other is direct constant current power supply, LED series or parallel operation.
LED display commonled driver chip IC introduction Common led driver chip : 74HC245 function is to amplify the signal, all the input signal must pass through this IC. Sometimes the whole board has problems or does not transmit there may be damage to this IC or solder. 2, 4953 function is the control line, if the horizontal direction of the board is faulty and the whole line is generally the fault of this IC. 1 piece 4953 controls 8 rows.
The customer's original display unit board interface is not exactly the same as described above, in this case, the cost of transformation is larger. In addition to the LED module and part of the IC retention, other such as PCB board, system, etc., all have to be replaced, the cost is higher. Maintenance display unit board Maintenance display unit board is not bright reasons Common led driver chip : there may be no power supply, input interface 74HC245 bad, E signal short circuit to high level.
Therefore, the advantages and disadvantages of the driver chip play an important role in the display quality of the LED display. LED driver chips can be divided into general purpose chips and special chips. General purpose chips are generally used in low-end LED display products, such as householdsInside the single, two-color LED display screen. The most commonly used general-purpose chip is the 74HC595, which has an 8-bit latch, serial-and-shift register, and three-state output. The maximum output current of each channel is 35 mA (not constant current).
The difference between dob and linear scheme is mainly about DoB, Driver on Board or Driverless, that is, what we usually call depower, in fact, it is not no power, but a new driving method different from traditional switching power supply. It is a new driving method derived from LED characteristics.
Each output channel can output adjustable linear current up to 16 bit gray scale. The chip includes a shift register, a data latch, a three-channel constant current driver whose current value can be controlled by three corresponding external resistors, and a built-in shaker for PWM function.