Analog Devices LT3825 Product Info

• Senses Output Voltage Directly from Primary Side Winding—No Opto-Isolator Required
• Synchronous Driver for High Efficiency
• Input Voltage Limited Only by External Power Components
• Accurate Output Regulation without User Trims
• Switching Frequency from 50kHz to 250kHz
• Synchronizable
• Load Compensation
• Programmable Undervoltage Lockout
• Available in a Thermally Enhanced 16-Lead TSSOP Package

The LT3825 is an isolated switching regulator controller designed for medium power flyback topologies. A typical application is 10W to 60W with input voltage limited only by external power path components. A third transformer winding provides output voltage feedback.

The LT3825 is a current mode controller that regulates output voltage based on sensing secondary voltage via a transformer winding during flyback. This allows for tight output regulation without the use of an opto-isolator, improving dynamic response and reliability. Synchronous rectification increases converter efficiency and improves output cross regulation in multiple output converters.

The LT3825 operates in forced continuous conduction mode which improves cross regulation in multiple winding applications. Switching frequency is user programmable and can be externally synchronized. The part also has load compensation, undervoltage lockout and soft-start circuity.

Applications

• Isolated Medium Power (10W to 60W) Supplies
• Isolated Telecom, Medical Converters
• Instrumentation Power Supplies
• Isolated Power over Ethernet Supplies