Infineon BCR185S Low-Drop Linear Regulator: Features and Application Circuits
The Infineon BCR185S is a robust, low-dropout (LDO) linear regulator designed for a wide range of applications, particularly where stable voltage regulation and low noise are critical. As a PNP transistor-based regulator, it offers a low dropout voltage and is capable of delivering output currents up to 350 mA. Its primary use includes powering microcontrollers, sensors, and other low-power digital or analog circuits in automotive, industrial, and consumer electronics.
Key Features of the BCR185S
One of the standout characteristics of the BCR185S is its low dropout voltage, typically around 0.35 V at 300 mA, which enhances efficiency, especially when the input voltage is only marginally higher than the output. The device operates with an input voltage range from 2.5 V to 42 V, making it highly versatile for both low-voltage and automotive environments (e.g., 12 V or 24 V systems). It provides a fixed output voltage of 5 V with a tolerance of ±2%, ensuring reliable performance for sensitive loads.
The regulator integrates overcurrent protection and thermal shutdown, safeguarding both the IC and the application circuit under fault conditions. Additionally, it features very low quiescent current, typically 0.5 mA, which is beneficial for battery-operated devices. Its high power supply rejection ratio (PSRR) helps in attenuating input voltage ripple, resulting in a clean, stable output.
Application Circuits
A typical application circuit for the BCR185S is straightforward, requiring only a few external components. The basic configuration includes input and output capacitors for stability and noise reduction.
1. Standard Regulator Circuit:
The input pin (VIN) is connected to the power supply, decoupled with a ceramic capacitor (e.g., 100 nF) placed close to the pin. The output pin (VOUT) requires a larger capacitor (e.g., 10 µF to 47 µF) to ensure stability and improve transient response. The ground pin (GND) is connected to the system ground.
2. Adjustable Output Voltage (with external resistors):
Although the BCR185S is a fixed 5 V regulator, an adjustable output can be achieved using a resistor divider network between VOUT, the ADJ pin (if available in similar variants), and GND. However, the standard BCR185S is fixed-output; for adjustable voltage, Infineon offers other variants in the series.
3. Reverse Voltage Protection:
In automotive applications, reverse voltage protection can be implemented by adding a series diode between the battery and the VIN pin. This diode prevents damage if the input polarity is accidentally reversed.
4. Enhancing Load Transient Response:
For applications with dynamic load changes, increasing the output capacitor value or using a capacitor with low equivalent series resistance (ESR) can improve the regulator’s transient response.
Design Considerations
When designing with the BCR185S, thermal management is crucial due to the linear regulator’s inherent power dissipation. The power dissipated is calculated as (VIN – VOUT) × IOUT. For high current or high differential voltage, a heatsink may be necessary to prevent thermal shutdown.
Moreover, the input voltage should always remain above the output voltage plus the dropout voltage to maintain regulation. Attention should also be paid to the maximum junction temperature (150°C) to ensure long-term reliability.
The Infineon BCR185S is an excellent choice for designers seeking a reliable, low-dropout linear regulator for medium-current applications. Its wide input voltage range, integrated protections, and minimal external component count make it particularly suitable for automotive and industrial systems where robustness and stability are paramount.
Keywords:
Low-Dropout Regulator, Voltage Regulation, Infineon BCR185S, Thermal Shutdown, Application Circuits
