UC3825BDWTR

The UC3825BDWTR is a high performance current mode Pulse-Width Modulation (PWM) controller designed specifically for switching mode power supplies (SMPS) applications where line and load regulation is required. It has improved energy saving features, such as advanced current peak protection, dynamic current limitation and soft-start feature which make the chip ideal for offline dimmer enabled LED driver applications.The UC3825BDWTR is a high performance BiCMOS device with an advanced current mode control loop architecture. It features an operating frequency range up to 500 kHz, precision 0.5% typical over-temperature current sense, one-cycle current mode control, improved peak current limit for two-level dimming LED lighting applications, automatic restart timer and soft-start feature.The UC3825BDWTR, classified under PMIC – AC-DC Converters and Offline Switchers, operates with a wide operating frequency range and offers a high operating temperature range (-45°C to +85°C). The chip can accurately regulate output voltages with a variety of switching topologies making it suitable for lighting applications, such as Compact Fluorescent lamp (CFL), AC/DC adapters, DC/DC converters and switch power supplies among others.The chip operates by providing a control signal to the power switching device, including on/off switch, gate driver, and rectifier. The gate driver drives the gate of power switching device and the rectifier rectifies the AC input and regulates it to the output voltage of the degree. The oscillator of the chip and the feedback loop ensures that the output voltage of the system is regulated at the desired set point.The integrated maximum peak current limit circuit of the UC3825BDWTR, together with the current sensing resistor, control and limit the maximum peak current during the switching phase of the power switch device. The peak current level can be adjusted using the external resistor connected to the Ipeak pin. The device can be programmed in two or four levels dimming applications depending on the behavior of the power switch device.The UC3825BDWTR also has an adjustable soft-start circuit which can be used to reduce the inrush current during system power up and reduce the outputs stress applied to the filter capacitors. The Soft-start period is adjustable via the programming of an external resistor connected between the SS and GND pins.The UC3825BDWTR also provides an automatic restart circuit that helps the system to repeatedly attempt to restart. The main advantage of this is that it eliminates the need for an external timer to restart the system when the output voltage is low.Overall UC3825BDWTR is an efficient current mode PWM controller and gate driver IC that has been optimized for SMPS applications, and is suitable for a wide range of applications from power converters to LED driver circuits.