基于LYT2002的LED照明应用中精确的一次侧调节开关

　　The LYTSwitch™-2 family of ICs dramatically simplifies low power CC LED drivers by eliminating the optocoupler and secondary control circuitry. The family introduces a revolutionary control technique which provides accurate output current regulation， compensating for transformer and external component variations， and device parameter tolerances as well as input voltage variations. The device incorporates a high-voltage switching MOSFET， an ON/OFF control state-machine， a high-voltage switched current source for self-biasing， frequency jitter to reduce EMI， cycle-by-cycle current limit and hysteretic thermal shutdown circuitry into a monolithic IC. This high level of integration enables cost-effective designs with very few external components， reducing solution cost and driver size. LYTSwitch-2 parts minimize energy consumption when the output is unloaded. Practical designs can easily achieve less than 30 mW no-load consumption. The 725 V power MOSFET used in LYTSwitch-2 devices increases the circuits’ ability to withstand input surge. In addition， each package is designed to maximize the creepage distance between high-voltage pins and logic level inputs. This increased pin spacing increases driver lifetime and reliability in polluted environments. These in-built protection features also protect the entire circuit from excess temperature operation， increasing lifetime in thermally challenging environments.