The BCR420U and BCR421U Constant Current Regulators (CCR) provide a simple means of driving low power LED strings. Target applications are those that benefit from the improved efficiency, flexibility and longer life offered by LEDs as an emerging lighting source. These include LED strips for:
- Architectural and mood lighting • Emergency lighting • Advertising signage • Retail refrigeration and vending machines
These CCRs support adjustable currents from 10mA to 350mA allowing for platform designs based on a single device to be used across multiple LED strip applications, considerably easing a manufacturer’s overall qualification process. These LED drivers also enhance system reliability as the monolithic integration of a transistor, diodes and resistors both simplifies system design and reduces component count.
With a minimum 1.4V supply voltage the BCR420/1 maintain regulation under low voltage operation, whilst the 40V maximum input rating ensures sufficient headroom for transient supply voltages and allows for LED short failures on long strings. Along with a negative temperature coefficient, which reduces the output current as the temperature increases, allowing current sharing between two or more BCR420/1 devices. This enables them to be connected in parallel to create a higher current output without risk of thermal runaway. With its low-side driver configuration, the BCR421U has the added feature of an enable function that can adjust the light output level using a PWM input signal. Both devices are supplied in SOT26 (SC-74) packages, providing pin-compatibility with other sources.