At present, the maximum output current of the mainstream constant current source chip is mostly defined as the single maximum output current, generally about 90 mA. Constant current is the basic characteristic of special purpose chip, and also the basis of obtaining high image quality. And each channel simultaneously output the maximum constant current (that is, the maximum constant output current) is more meaningful for the display screen, because in the white balance state, each way is required to output constant current at the same time. Generally, the maximum constant current output current is less than the maximum allowable output current.
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2) Constant current output channel
Constant current source output path has 8 bit (8-way constant source) and 16 bit (16-way constant source) two specifications, now the 16-bit source is the mainstream, 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.
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3) Current output error
The current output error is divided into two kinds, one is the inter-bit current error, that is, the error between each output of the same chip; The other is the inter-chip current error, that is, the error of the output current between different chips. Current output error is a very critical parameter, which has a great impact on the uniformity of the display screen. The greater the error, the worse the uniformity of the display, and it is difficult to achieve white balance of the screen body. Led display manufacturers introduce the current mainstream constant current source chip inter-bit current error (bit to bit) is generally within 60%, (chip to chip) inter-chip current error is within ± 15%.
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4) Data shift clock
The data shift clock determines the transmission speed of the display data and is a key indicator affecting the update rate of the display screen. As a large-size display device, the display refresh rate should be above 85 Hz to ensure a stable picture (no scanning flicker). The high data shift clock is the basis for the display to obtain a high refresh rate picture. At present, the mainstream constant current source driver chip shift clock frequency is generally more than 15 MHz.