Small size, 12V/500mA, synchronous, optocouplerless, flyback DC-DC converter with 91.9% efficiency.

Due to their simplicity and low cost, flyback converters are the preferred choice for low-to-medium isolation DC-DC power conversion applications. However, using optocouplers or auxiliary windings on the flyback transformer to isolate voltage feedback on the barrier increases component count and design complexity. The MAX17690 eliminates the need for optocouplers or auxiliary transformer windings, achieving ±5% output voltage regulation across line, load, and temperature variations. The MAX17690 employs an innovative algorithm to precisely determine the output voltage by detecting the reflected voltage on the primary winding during the flyback interval. By sampling and regulating this reflected voltage when the secondary current is near zero, the impact of secondary-side DC losses in the transformer windings, PCB rails, and rectifier diodes on output voltage regulation is minimized. The MAX17690 also compensates for the negative temperature coefficient of the rectifier diodes. Key Features: 4.5V to 60V input voltage range; Programmable switching frequency from 50kHz to 250kHz; Programmable input enable/UVLO function; Programmable input overvoltage protection; Adjustable soft start; 2A/4A peak source/sink gate drive capability; Hiccup mode short-circuit protection; Fast cycle-by-cycle peak current limiting; Thermal shutdown protection; Space-saving 16-pin, 3mm x 3mm TQFN package; -40°C to +125°C operating temperature range. Isolated, non-optical flyback DC-DC converters using the MAX17690 and MAX17606 are suitable for 12V DC output applications. Up to 500mA of current can be delivered from a 12V supply.