The FAN7543 is a Quasi-Resonant Current Mode PWM Controller from Fairchild Semiconductor (now ON Semiconductor). It is designed for off-line power supplies where high efficiency and low EMI (Electromagnetic Interference) are crucial. It employs quasi-resonant operation to minimize switching losses.

Applications

• AC-DC Adapters
• Open Frame Power Supplies
• Battery Chargers
• Set-Top Boxes

Features

• Quasi-Resonant Operation
• Low Startup Current
• Built-in Soft-Start
• Over-Voltage Protection (OVP)
• Over-Current Protection (OCP)

Benefits

• Improves efficiency by reducing switching losses
• Minimizes electromagnetic interference
• Reduces stress on switching components
• Protects the power supply from damage

Specifications

The FAN7543 operates in quasi-resonant mode, switching at the valley of the resonant waveform. It features a low startup current to minimize power consumption during standby. Built-in soft-start limits inrush current during startup. The device also incorporates OVP and OCP for protection. The controller is typically packaged in a DIP or SOIC package.