STMicroelectronics unveils 'revolutionary' power supply controller

The L6699D is, says ST, the first of its type to combine anti capacitive protection, auto adaptive dead time and enhanced safe start operation. The features are implemented using patented techniques and are designed to effectively reduce stress on associated power semiconductors, while enabling optimised zero switching for greater efficiency across the power supply's full load range. By reducing stress on the power mosfets of the converter half bridge, ST says the L6699D's anti capacitive protection and safe start up allow designers to specify smaller, lower cost mosfets. There is also a patented method for improving burst mode operation, which is designed to reduce audible noise from the converter without requiring a large or expensive filter. The company's patented auto adaptive dead time adjusts the duration when both power switches in the half bridge are turned off. This enables optimised zero voltage switching over the complete load range from light load to full load using a smaller transformer and resonant components. According to ST, this minimises both solution size and energy losses in the resonant components. By increasing efficiency at light loads, the L6699D can also save the need for a separate standby power supply in equipment such as televisions or all in one pcs. The device is used with two companion chips, the L6563H Power Factor Correction (PFC) controller and SRK2000 synchronous rectifier driver. ST claims that the discrete devices enhance functionality and flexibility for designers, describing the L6699D as 'the most feature rich LLC resonant controller on the market'. The company adds that the three packages enable small form factors and high power density that cannot be achieved using a bulky, integrated device. The L6699D is sampling now in the SO16N package with mass production due to begin within Q1 2012.