Application of linear constant current LED driver circuit

Linear constant current LED drive circuit has the advantages of simple structure, low electromagnetic interference, fast response, small size and low cost, structure and technical features of.AT8803/AT8800 automotive electronic systems which are often used in the battery in the car for the electronic high voltage, high current linear LED driver chip AT8803 and AT8800.

LED has the advantages of high brightness light intensity, high luminous efficiency, energy saving and environmental protection, long service life and is widely used in automotive lighting, display, camera flash, backlight, landscape lighting and interior decoration etc.. Due to the size of LED brightness and current, small changes and turn-on voltage, working voltage and temperature has great effect on the current LED, so we need to maintain consistency of LED array driver chip designed by brightness. The linear constant current LED drive circuit has the advantages of simple structure, low electromagnetic interference, rapid response, small size and low cost, and is often used in the automotive electronic system with battery powered.

The structure and technical characteristics of AT8803/AT8800

High voltage, high current LED linear drive chip AT8803 and AT8800 for automotive electronics, mainly used in automotive taillights, central high brake lights (CHMSL), map lights and gated car lighting, etc.. In the 6.5V to 40V input voltage range, up to 350mA of the total current can be provided to drive one or more columns of high brightness LED. Compared to AT8800, the AT8803 increases the DIM dimming control pin.

Figure 1:AT8803/AT8800 schematic structure

The output current is regulated by an external RSENSE resistor in series with the LED. Enable input EN to achieve a wide range of "pulse" brightness control. Waveform shaping circuit reduces EMI. The differential current detection input improves the noise rejection capability. AT8803, AT8800 is very suitable for applications requiring high voltage input, and can withstand up to 40V of the vehicle load rejection. The on-chip integrated power device reduces the number of external components and provides an output current accuracy of + 3.5%. The chip also provides 5V regulator output as well as short circuit protection and thermal protection functions.