Concerning the LED multiple strings management, are available the high power-density DC-DC LED driver buck converters LED5000 and LED6000 (fig.4) or the new HVLED002 current mode LED controller based on fixed off-time (FOT) algorithm for reverse Buck topology (fig.5) can be used.
- Digital approach
In this case two digital ICs need to be used: one for all primary side (PFC and HB-LLC stages) and another one for the secondary side (all Reverse Buck circuits for LED strings control) (fig.10).
ST’s offer for these two digital ICs is the one reported in the single string case, but relating the Reverse Buck of secondary side, the STM8 family microcontroller can be used also.
The suggested low side gate drivers for PFC and Reverse Buck are PM88 or TD35; the high side ones L638, L639 and L649 can be adopted for HB-LLC.
A wide offer of system evaluation boards for Street lighting single a multiple strings are available and some of these are showed in fig.11. Also, the STEVAL-ILL074V1/V2 (60W analog power supply for LED driving) and STEVAL-ILL077V1 (60W digital multiple-string LED driver) showed in fig.11 fit with street lighting applications.
eDesignSuite software tool
eDesignSuite is an easy-to-use, comprehensive software suite ready to help customers define their needs by transforming their application requirements into satisfactory solutions based on the wide range of ST products. The suite includes:
- a smart simulator and system design engine (fig.12) able to suggest products and topologies for various types of applications (power supply, photovoltaic, battery charger, LED lighting, signal conditioning and RF design);
- smart selectors to help select the types of products (e.g. diodes) best suited to your application;
- configurators to reduce implementation time and efforts for setting product parameters for the specific application (e.g. STLUX SMEDs for lighting)Among the applications mentioned, the tool supports LED Lighting with a wide offer of products and topologies. To discover and test all the features of eDesignSuite, you can visit (after the online registration) https://my.st.com/analogsimulator/