Supertex Inc. introduces HV9805 LED DRIVER
An LED Driver IC where the LED light source us arranged as a high voltage LED string in order to accommodate certain lamp form factors, while allowing for cost savings through less complicated cooling and optical arrangements. The driver includes a linear post regulator to provide a pure DC current drive, for flicker free light output. The linear post regulator also provides protection from line voltage transients.
HV9805 supports a simple and low cost driver circuit, which combines a PFC boost stage and a linear post regulator for regulating the LED current to a DC value. The boost stage employs the boundary conduction mode, with the output regulated for the lowest overhead voltage at the linear regulator. The headroom voltage can be freely selected to optimize the efficiency of the post regulator or to minimize the cost or size of the bus capacitor.
The boost converter employs a cascade switch for high speed switching and convenient generation of the housekeeping (Vdd) supply. The low voltage device of the cascade switch is integral to the HV9805 and us rated at a current of 1A. Vdd power is derived with high efficiency and without the need for extra components or magnetic windings.