ON Semiconductor UC2843B High-Performance Current Mode PWM Controller

The UC2843B from ON Semiconductor is a versatile and robust current mode pulse width modulation (PWM) controller designed for high-performance power supply applications. This integrated circuit (IC) is specifically engineered to provide cost-effective solutions for offline and DC-to-DC converter applications, offering a range of features that enhance system reliability and efficiency.

At the heart of the UC2843B is its ability to operate at a fixed frequency, which can be programmed by the user through external resistors and a capacitor. The device's current mode operation ensures improved response to load transients and provides inherent overcurrent protection. With a wide operating range, the UC2843B can handle input voltages from 12V to 30V, making it suitable for a variety of power supply designs.

The UC2843B boasts an impressive array of features, including an oscillator with a precision-trimmed discharge current, which ensures consistent and accurate duty cycle control across the entire range of input voltages and output loads. The IC also includes an under-voltage lockout (UVLO) with hysteresis, ensuring that the power supply operates only when the input voltage is within an acceptable range, thus protecting the system from low voltage conditions.

Another key feature of the UC2843B is its optimized gate driver designed to drive a power MOSFET or IGBT directly. This gate driver is capable of delivering high peak currents, ensuring fast and efficient switching. The device also includes a high-current totem pole output, which is capable of sourcing or sinking up to 1A, providing robust drive capability for the power stage.

With its built-in error amplifier, the UC2843B provides excellent loop stability and fast transient response. The error amplifier also allows for easy implementation of various feedback topologies to regulate output voltage or current. Furthermore, the UC2843B offers features such as soft-start, which limits the inrush current during start-up, and a shutdown function that can be activated by pulling the COMP/SD pin low.

In summary, the UC2843B from ON Semiconductor is a highly reliable and efficient solution for designers looking to develop power supplies that require tight regulation, fast response times, and robust protection features. Its flexibility and comprehensive feature set make it an ideal choice for a wide range of applications, including switch-mode power supplies, DC-DC converters, and battery chargers.