LED full color display performance parameters driver chip classification.

Led full-color display driver chip is an important part of the display screen. Different driving methods of LED chip can obtain different display effect of video screen image. Стога, the advantages and disadvantages of driver chip play an important role in the display effect of full-color LED display screen.

&1. LED driver chips are classified into the following two types: they are more commonly used in low-end LED panel production, and the commonly used general-purpose chip is 74HC595, which has the functions of 8-bit latch, serial parallel shift memory and tri state output.

Each channel can output 35 ma current (not constant current).

Special chip: a feature of special chip is to supply constant current source. As LED is a current characteristic device, its brightness changes with the change of current size, not with the change of voltage at its two ends. The constant current source can ensure the stable driving of LED and eliminate the flashing phenomenon of LED.

The maximum output current of the mainstream constant current source chip is about 90 ma. Constant current is the basic characteristic of special chip, and it is also the basis to get high image quality. The maximum constant current output of each channel at the same time (i.e. the maximum constant output current) is more meaningful for the display screen, because under white balance condition, each channel is requested to output constant current at the same time.

Current output error: there are two kinds of current output error: one is the inter bit current error, то је, the error between the outputs of the same chip; the other is the inter chip current error, то је, the output current error between different chips. Current output error is a key parameter, which has great influence on the uniformity of full-color display screen. The larger the error is, the worse the uniformity of the display screen is, and it is difficult to make the screen reach white balance. Сада, the bit to bit error of mainstream constant current source chip is generally within + 60%, and the chip to chip current error is within ± 15%. &There are two specifications of constant current source: 8-channel constant source and 16 channel constant source. Now 16 bit source is the mainstream. The advantage is that the size of LED driver chip is small, which is convenient for LED driver board (PCB) wiring, and it is more favorable for LED driver board with small point spacing.

Data shift clock: the data shift clock determines the transmission speed of display data, and is the key index affecting the update rate of display screen. As a large-scale display device, the display refresh rate should be above 85 Hz to ensure a stable picture (no scanning flicker). High data shift clock is the basis of high refresh rate screen. Сада, the shift clock frequency of mainstream constant current driver chips is generally above 15 MHz.