FT839NB1-RT

Overview

The FT839NB1-RT is an integrated offline switch designed for flyback topology applications. It operates with a supply voltage range of 6V to 30V and features a breakdown voltage of 650V. The device utilizes pulse frequency modulation (PFM) control and includes primary-side feedback capabilities, eliminating the need for optocouplers. It offers comprehensive protection mechanisms including cycle-by-cycle current limiting, overvoltage protection, overtemperature protection, and open-loop detection. The component is housed in an 8-SOP package with a maximum duty cycle of 47% and supports surface-mount installation.

Feature Summary

• Integrates primary-side feedback control to eliminate external optocouplers and TL431 components
• Employs pulse frequency modulation (PFM) for improved EMI performance and low standby power consumption
• Includes built-in cable compensation and line voltage compensation for enhanced output accuracy
• Features comprehensive protection against overcurrent, overvoltage, overtemperature, and output short circuits

Applications

• Adapters and chargers for mobile phones, PDAs, and digital cameras
• ADSL modems, wireless routers, and cordless phone power supplies
• RGB infrared or RF remote-controlled LED lighting systems
• Standby power supplies requiring strict low-power consumption standards

Procurement Notes

Verify the specific suffix RB or RT indicates the correct packaging format required for your assembly process. Confirm that the 650V breakdown rating aligns with your transformer design requirements. Ensure the 8-SOP footprint matches your PCB layout constraints. Cross-reference the datasheet for thermal derating curves relevant to your operating environment.

Selection Notes

Select this component for designs prioritizing cost reduction through the removal of secondary-side feedback circuitry. It is suitable for low-to-medium power isolated converters where high efficiency at light loads is critical. Consider the internal switching characteristics and thermal performance when designing the heat dissipation strategy for the SOP package.

Part Context

This part belongs to the FT839 series of primary-side controlled offline switches manufactured by Fremont Micro Devices Ltd. It shares functional similarities with other models in the family but differs in packaging and specific electrical parameters. The series is optimized for high-performance constant-current and constant-voltage applications without auxiliary windings.

Replacement Considerations

FT838NB1-RT is a related model within the same manufacturer's portfolio offering similar functionality with different voltage ratings.