Diodes Adjustable current regulator simplifies LED string drive process

     Diodes Incorporated introduces the BCR420U and BCR421U constant current regulators that simplify the drive process for low power linear LED strings. The new products target the use of leds as emerging lighting sources for greater efficiency, flexibility and longer life, including mood lighting systems, LED strings for emergency notices and advertising signs, and decorative lighting for commercial refrigeration equipment and vending machines.

     The BCR420U and BCR421U enable optimized LED currents to be set based on consistent brightness and extend LED life. Both devices offer adjustable current ranges from 10mA to 350mA, enabling platform designs to be based on a single device that can be used in multiple LED string applications, effectively simplifying the overall certification process for manufacturers. These LED drivers integrate transistors, diodes, and resistors on a single chip to simplify system design and reduce the number of components, while also improving system reliability.

     The negative temperature coefficient reduces the output current when the temperature rises, while distributing the current between two or more constant current regulators. This ensures that these constant current regulators can be connected in parallel, resulting in a higher current output without causing thermal runaway. With an input rating of up to 40V, the new product provides sufficient headroom for transient power supply voltages and also allows short circuits in long LED strings. The low side drive configuration of the BCR421U provides additional enabling capabilities to adjust the optical output using pulse width modulation (PWM) input signals. Both devices are packaged in a SOT26 package with pins that are compatible with other light sources.