Texas Instruments

UCC3805N

UCC3805N Description

The UCC3805N from Texas Instruments is an obsolete but historically significant PWM controller IC designed for DC-DC switching converters. It operates within a 3.6V to 12V supply range, making it suitable for low-to-moderate voltage applications. This 8-pin DIP device supports multiple topologies, including Buck, Boost, Flyback, and Forward Converters, with a fixed 31kHz switching frequency. Its single-output, positive-configuration transistor driver ensures efficient power delivery, while its 49% maximum duty cycle provides stable performance in voltage regulation tasks.

UCC3805N Features

• Wide Input Range: Operates from 3.6V to 12V, accommodating diverse power sources.
• Multi-Topology Support: Compatible with Buck, Boost, Flyback, and Forward Converters for design flexibility.
• Fixed Frequency (31kHz): Ensures predictable noise characteristics and simplifies filtering.
• Frequency Control: Enables precise regulation without external synchronization.
• ROHS3 Compliant & REACH Unaffected: Meets environmental standards despite its obsolete status.
• Through-Hole Packaging (8-DIP): Facilitates prototyping and legacy system repairs.

UCC3805N Applications

The UCC3805N excels in low-power, isolated, and non-isolated DC-DC converters, including:

• AC/DC Adapters: For consumer electronics requiring stable low-voltage outputs.
• Auxiliary Power Supplies: In industrial systems where reliability is critical.
• LED Drivers: Due to its ability to handle Boost and Flyback topologies.
• Battery-Powered Systems: Where moderate efficiency and compact design are prioritized.

Conclusion of UCC3805N

Though obsolete, the UCC3805N remains a robust choice for legacy designs and repairs, offering simplicity, multi-topology support, and reliable performance. Its fixed-frequency operation and wide input range make it ideal for cost-sensitive, low-complexity power solutions. Engineers seeking modern alternatives should consider TI's newer PWM controllers, but the UCC3805N's legacy applications underscore its enduring utility in low-to-moderate power conversion.