Infineon BCR133W Low-Dropout Linear Regulator: Features and Application Circuits
The Infineon BCR133W is a robust, low-dropout (LDO) linear regulator designed for a broad range of applications requiring stable and clean voltage regulation. As a PNP-based transistor in a compact SOT-223 package, it is engineered to deliver a fixed output voltage with high accuracy and excellent load regulation. Its primary use cases include powering microcontrollers, sensors, and other low-voltage integrated circuits in automotive, industrial, and consumer electronics.
Key Features of the BCR133W
The BCR133W stands out due to several critical characteristics. It offers a very low dropout voltage, typically around 300 mV at a 300 mA load, which is essential for battery-powered applications where every millivolt of available supply voltage must be utilized efficiently. The device provides a fixed 3.3 V output with a tight tolerance of ±2%, ensuring a reliable reference for sensitive components.
Furthermore, it boasts a very low quiescent current of only 70 µA (typical), significantly enhancing energy efficiency in always-on systems. The regulator incorporates vital protection mechanisms, including internal current limiting and thermal shutdown, which safeguard both the IC and the application circuit from damage under fault conditions. Its wide operating input voltage range of up to 42 V adds to its versatility, allowing it to handle significant voltage transients commonly found in automotive environments.
Application Circuits
The basic application circuit for the BCR133W is refreshingly simple, requiring only two external capacitors for stability, which underscores its ease of use.
1. Standard Regulation Circuit:
The most straightforward configuration involves connecting an input capacitor (C_IN, typically 100 nF) between the input voltage (V_IN) and ground to suppress high-frequency noise. The output capacitor (C_OUT, typically 1–10 µF) is connected between the output pin (V_OUT) and ground to ensure stability and improve transient response. The adjustable version of this family (BCR135W) would require an external resistor divider network to set the output voltage, but the fixed BCR133W requires no such components.
2. Circuit with Enhanced Transient Suppression:
In applications with noisy input supplies, such as automotive systems, a larger electrolytic or ceramic capacitor (e.g., 10–47 µF) can be added at the input in parallel with the smaller ceramic capacitor. This combination effectively filters out low-frequency voltage ripples and transients.
3. Reverse Voltage Protection:
While the BCR133W itself is not inherently reverse-voltage protected, a series diode can be added at the input terminal to protect the regulator from accidental reverse polarity connection, a crucial addition for automotive and battery-backed systems.
In summary, the Infineon BCR133W is an exceptionally reliable and efficient low-dropout linear regulator. Its combination of low dropout voltage, low quiescent current, high accuracy, and built-in protection makes it an ideal, robust choice for designers seeking a simple and effective power management solution for demanding environments.
Keywords: Low-Dropout Regulator, Thermal Shutdown, Quiescent Current, Voltage Regulation, Application Circuit
