Design of High Brightness LED Linear Driver Chip and Analysis of Typical Application Schemes

High-brightness LEDs are widely used in automotive lighting, displays, camera flashes, panel backlights, bokeh lighting, and interior decoration, because of their high luminous intensity, high luminous efficiency, energy saving and long life. Since the luminance of the LED is related to the magnitude of its current, and the small changes in the on-voltage, the operating voltage, and the ambient temperature have a large influence on the LED current, it is necessary to design a special driver chip to maintain the brightness of the LED array. The linear constant current type LED driving circuit has the advantages of simple structure, low electromagnetic interference, rapid response, small size and low cost, and is therefore often used in a battery electronic system using a battery.

Block diagram and technical features of AT8803/AT8800

This paper introduces the high-voltage, high-current LED linear drive chips AT8803 and AT8800 developed by Wuhan Xinjing Technology Co., Ltd., which are mainly used in automotive taillights, central high-position brake lights (CHMSL), map lights and door-controlled interior lighting. Wait. Provides a total current of up to 350mA to drive one or more columns of high-brightness LEDs over a 6.5V to 40V input voltage range. Compared to the AT8800, the AT8803 adds DIM dimming control pins.

AT8803/AT8800 structure schematic

Figure 1: Schematic diagram of AT8803/AT8800 structure

The output current is adjusted by an external current-sense resistor RSENSE in series with the LED. The enable input EN enables a wide range of "pulse" brightness control. The waveform shaping circuit reduces EMI. Differential current sense input improves noise rejection. The AT8803 and AT8800 are ideal for applications requiring high voltage inputs and can withstand automotive load dumps up to 40V. Integrated on-chip power devices reduce the number of external components and provide ±3.5% output current accuracy. The chip also provides 5V regulated output as well as short-circuit protection and thermal protection.

Dimming application of AT8803

The AT8803 provides two dimming modes as shown in Figures 2 and 3, respectively. The DIM pin is resistant to 40V high voltage and offers a wide range of PWM dimming functions. Connecting EN to the VIN pin and inputting the PWM signal to the DIM or connecting the DIM to the V5 pin to the EN input PWM signal produces an adjustable duty cycle LED current that controls the brightness of the LED.

Figure 2: AT of the AT8803 is connected to VIN, dimming with DIM pin

Wire Feeding Roller is part of the spraying system.

Wire Feeding Roller

Wire Feeding Roller,Welding Wire Feed Roller,Wire Feeder Roller,Wire Feed Drive Roller

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