The FSQ321 from Fairchild/ON Semiconductor is a current-mode PWM controller IC designed for valley switching flyback converters. It is a low-cost, high-performance solution for a wide range of applications, including power adapters, battery chargers, and industrial supplies.

The FSQ321 features a number of key benefits, including:

• Complete solution: The FSQ321 integrates all of the necessary components for a flyback converter, including a power switch, PWM controller, and protection circuitry. This simplifies circuit design and reduces component count.
• Valley switching: Valley switching allows the converter to operate at higher switching frequencies while maintaining high efficiency. This results in smaller and lighter transformers and output capacitors.
• Green mode: Green mode operation reduces power consumption at light loads, improving overall efficiency.
• Protection circuitry: The FSQ321 includes a variety of protection features, such as overvoltage protection, overcurrent protection, and overtemperature protection. This helps to ensure the safety and reliability of the converter.

The FSQ321 is available in an 8-pin DIP package and can operate over a wide input voltage range of 8V to 20V. It has a maximum output power of 12W and a switching frequency of 55kHz to 67kHz.

The FSQ321 is a versatile and easy-to-use solution for a wide range of flyback converter applications. It is ideal for cost-sensitive designs where high performance and reliability are required.

Here are some specific examples of applications where the FSQ321 can be used:

• Power adapters: The FSQ321 is ideal for designing power adapters for a variety of electronic devices, such as laptops, smartphones, and tablets.
• Battery chargers: The FSQ321 can be used to design battery chargers for a variety of battery types, such as lithium-ion, lithium-polymer, and lead-acid.
• Industrial supplies: The FSQ321 can be used to design industrial supplies for a variety of applications, such as motor control, automation, and instrumentation.

Additional features and benefits of the FSQ321:

• High efficiency: The FSQ321 can achieve efficiency levels of up to 90%, depending on the load and input voltage.
• Low standby power: The FSQ321 consumes very little power in standby mode, making it ideal for energy-efficient applications.
• Easy to use: The FSQ321 is very easy to use, with a simple and straightforward design.
• Wide operating temperature range: The FSQ321 can operate over a wide temperature range of -40°C to 85°C, making it suitable for a variety of environments.

Conclusion:

The FSQ321 from Fairchild/ON Semiconductor is a versatile, high-performance, and cost-effective solution for a wide range of flyback converter applications. It is ideal for use in power adapters, battery chargers, and industrial supplies.