The UCC3809 family is an economy low power integrated circuit designed for off-line and isolated DC-to-DC fixed frequency current mode switching power supplies. It features user programmable soft start, maximum duty cycle, accessible 5V reference, undervoltage lockout, and more.
The UCC1809‑1/-2, UCC2809‑1/-2 and UCC3809‑1/-2 are BCDMOS economy low‑power primary‑side controllers for off‑line and isolated flyback converters. The document describes their integrated functions, such as programmable soft‑start, UV‑lockout, 5 V reference, and a 0.4 A source/0.8 A sink FET driver.
Key sections include electrical characteristics tables, pin descriptions, typical application diagrams, oscillator design, synchronization options, mechanical package data, and revision history. The handbook provides design guidance for setting oscillator frequency, duty‑cycle limits, and component selection.
| Startup current | < 100 µA |
|---|---|
| Maximum duty cycle | 70 % |
| FET driver capability | 0.4 A source / 0.8 A sink |
| Oscillator frequency range | up to 1 MHz |
| Operating temperature (UCC1809) | -55 °C to +125 °C |
| Operating temperature (UCC2809) | -40 °C to +85 °C |
| Operating temperature (UCC3809) | 0 °C to +70 °C |
The startup current is less than 100 µA.
The controller can be programmed for a maximum duty cycle of 70 %.
It can source 0.4 A and sink 0.8 A.
The oscillator can operate up to 1 MHz.