ST HVLED805离线反激LED驱动解决方案

ST公司的HVLED805是具有初级检测的离线LED驱动器,包括了高性能低压PWM控制器和800V耐雪崩击穿的功率MOSFET,可直接连接到火线整流电压,恒流LED输出电流精度5%,不需要光耦器件,准谐振(QR)零电压开关(ZVS)工作,内部HV起动电路,能对LED串的开路或短路进行管理,主要用在AC/DC LED驱动器,LED替代灯(如E27, GU10)等.本文介绍了HVLED80主要特性, 应用框图以及多种性能测试电路.
HVLED805: Off-line LED driver with primary-sensing
The HVLED805 is a high-voltage primary switcher intended for operating directly from the rectified mains with minimum external parts to provide an efficient, compact and cost effective solution for LED driving. It combines a high-performance low-voltage PWM controller chip and an 800V, avalanche-rugged power MOSFET, in the same package.
The PWM is a current-mode controller IC specifically designed for ZVS (zero voltage switching) fly-back LED drivers, with constant output current (CC) regulation using primarysensing feedback. This eliminates the need for the opto-coupler, the secondary voltage reference, as well as the current sense on the secondary side, still maintaining a good LED current accuracy. Moreover it guarantees a safe operation when short circuit of one or more LEDs occurs.
In addition, the device can also provide a constant output voltage regulation (CV): it makes the application able to work safely when the LED string opens due to a failure.Quasi-resonant operation is achieved by means of a transformer demagnetization sensing input that triggers MOSFET’s turn-on. This input serves also as both output voltage monitor, to perform CV regulation, and input voltage monitor, to achieve mains-independent CC regulation (line voltage feed forward).
The maximum switching frequency is top-limited below 166 kHz, so that at medium-light load a special function automatically lowers the operating frequency still maintaining the operation as close to ZVS as possible. At very light load, the device enters a controlled burst-mode operation that, along with the bui...