The REF_ICL8800_LED_43W is a 43W reference design featuring Infineon’s high power factor flyback controllerICL8800. The board is a constant voltage (CV) secondary-side regulated (SSR) system and is intended to be used with a constant current (CC) converter for LED lighting applications. Two-stage topologies are growing because of the convenient scalability of power on the primary side and the features on the secondary side. REF_ICL8800_LED_43W is designed as plug-and-play solution and can be combined withsecondary-side DC/DC boards. As a default setup, the reference design board is assembled with a start-up circuit based on a depletion-mode MOSFETBSS126Ion a very small adapter board. This setup offers the lowest standby losses. If low standby consumption is not necessary, the start-up circuit can be changed to a resistive start-up. This reference design is provided with two regulation circuits. Both circuits are designed as plug-and-play solutions, but at least one has to be connected to the main board. The two boards shall show the trade-off between cost; here the TL431 board offers a low-cost solution, and standby performance, while the op-amp board shows an overall 30mW better performance.