ON Semiconductor SG3525ADW Pulse Width Modulator Control Circuit

The SG3525ADW from ON Semiconductor is a versatile pulse width modulator (PWM) control circuit designed to offer improved performance and lower external parts count when implemented in switching power supplies, converters, and other power control applications. This integrated circuit (IC) is engineered to provide all the necessary features to implement off-line or DC-to-DC fixed-frequency current-mode control schemes with minimal external components.

The SG3525ADW incorporates a precision voltage reference of 5.1V and an on-chip oscillator that is highly adjustable and can range from 100 Hz to 500 kHz. This feature allows designers to set the operating frequency of their power supply to their specific requirements. The oscillator can also be synced to an external clock to maintain frequency coherence in multiple power supply systems.

One of the key features of the SG3525ADW is its dual alternating outputs, which are designed to drive power MOSFETs or IGBTs in a push-pull configuration. These outputs are capable of delivering 400 mA of peak current with minimal cross-conduction, ensuring high-efficiency operation of the power stage. Additionally, the outputs are protected by an under-voltage lockout, which ensures that the outputs remain in the off state whenever the supply voltage is below a certain threshold.

The device also includes a shutdown pin that allows all outputs to be disabled with a low-level input signal. This feature is particularly useful for implementing various protection mechanisms, such as over-current shutdown or thermal shutdown, to enhance the safety and reliability of the power supply system.

Other features of the SG3525ADW include a soft-start capability that gradually increases the duty cycle from zero to the maximum value to prevent large inrush currents at startup, an error amplifier for closed-loop control, and a dead-time control comparator that allows the user to set the dead time to the desired value to prevent transformer saturation and optimize efficiency.

Housed in a 16-pin wide-body SOIC package, the SG3525ADW is designed for easy implementation and is suitable for a wide range of applications including switch-mode power supplies, DC/DC converters, battery chargers, and motor control systems. Its robust design and comprehensive feature set make it a go-to solution for designers looking to create stable and efficient power control systems.