TEA1771

TEA1771 GreenChip PC primary control IC Rev. 01 — 6 February 2009 www.datasheet4u.com Product data sheet 1. General description The TEA1771 is a primary control IC for an active clamp forward converter. This converter enables higher duty cycles of up to 70 %. A higher maximum duty cycle lowers the required breakdown voltage of both the primary and secondary switches, reducing the total cost of the system. The IC is optimized for (ATX) PC power supplies. Together with the TEA1781 and TEA1782 a unique system can be made that reduces costs by integrating the standby supply. It assures high output voltage accuracy and avoids cross regulation as the output voltages are regulated separately. This system exceeds the current and proposed efficiency standards such as 80 plus-gold, energy star and blue angel. The TEA1771 is implemented in the high voltage EZ-HV SOI process. It enables direct start-up from the rectified mains voltage, excluding the need for a start-up resistor. The high voltage reset switch, required for the active clamp, is integrated in the IC. The IC has a feed-forward control regulation, avoiding high resonant voltage peaks as a result of output load or input voltage transients. This also assures proper regulation of the output voltages at input voltage variations. 2. Features I I I I I I I I I I I I Designed for ATX PC power supplies Universal mains operation, 90 V (AC) to 265 V (AC) Integrated start-up current source Integrated high-voltage, high-side active clam...