Infineon BCR523 Low-Dropout Linear LED Driver: Features and Application Circuits
The Infineon BCR523 is a low-dropout linear constant current LED driver designed for low-power, space-constrained lighting applications. As a highly integrated and cost-effective solution, it simplifies driving single or multiple LEDs by eliminating the need for an external series resistor, enhancing efficiency and design reliability.
A standout feature of the BCR523 is its extremely low dropout voltage, enabling stable operation even when the supply voltage is only marginally higher than the forward voltage of the LED string. This makes it exceptionally suitable for automotive interior lighting, consumer electronics indicator lights, and battery-powered devices, where maintaining brightness across a varying supply voltage is critical.
The device offers a wide operating voltage range from 3 V to 42 V, providing flexibility for both 12 V and 24 V systems. Its adjustable output current, set using a single external resistor, allows designers to tailor the drive current from a few milliamps up to 100 mA to meet specific luminance requirements. Furthermore, the BCR523 incorporates built-in protection features, including thermal shutdown and over-current protection, safeguarding the IC and LEDs under fault conditions.
Application Circuits
The BCR523’s simplicity is demonstrated in its typical application circuits. The basic setup requires only the IC and one external resistor (R_ext) to set the current.
1. Basic Constant Current Circuit: The anode of the LED(s) is connected to the supply voltage (V_supply). The cathode is connected to the OUT pin of the BCR523. The SET pin is connected to ground via the external resistor (R_ext). The value of R_ext is calculated using the formula: I_out ≈ 200 mV / R_ext. A capacitor at the IN pin is recommended for filtering and stability.
2. Multi-LED String Configuration: Multiple BCR523 units can be used in parallel to independently drive several strings of LEDs from a common supply rail. This architecture ensures uniform brightness across all strings, as each driver regulates its own current, compensating for variances in LED forward voltage.
3. PWM Dimming Interface: For brightness control, a PWM signal can be applied directly to the SET pin. By pulsing the SET pin with a variable duty cycle signal, the average output current—and thus the LED intensity—can be efficiently dimmed over a wide range without a noticeable shift in color.
ICGOODFIND Summary
The Infineon BCR523 stands out as a robust, simple, and highly efficient linear LED driver. Its integration of critical functions into a compact SOT-23-6 package reduces component count and PCB area. The combination of a wide input voltage range, low dropout operation, and flexible dimming capability makes it an ideal choice for designers seeking a reliable solution for low-to-medium power LED driving applications across various industries.
Keywords: Low-Dropout Voltage, Constant Current Driver, PWM Dimming, Automotive Lighting, Thermal Shutdown.
