The STSW-LLL009FW firmware runs on the STEVAL-LLL009V1 evaluation kit control board.
The firmware is based on libraries generated from STM32CubeMX on the STM32F334R8T6 high performance 32-bit ARM®
-M4 microcontroller and controls the DC-DC half bridge LCC resonant converter and the output synchronous rectification.
The power supply can be either configured in constant voltage (CV) or constant current (CC) mode.
In CV mode, the PI control loop executed at 50 kHz provides the PWM switching period of primary side MOSFETs, changing the gain of the resonant tank and regulating the output voltage at the desired value. The primary devices are driven by 50% duty cycle PWM signals, with a proper dead time for each leg to ensure ZVS operation and avoid input voltage shot-through.
In CC mode, the firmware detects 0-10 V input signals and manages the dimming (with a resolution of 1%) by changing the current through the LED lighting application.