The VLED1 signal is typically connected to an LED indicator to show the status of system initialization and the status of the clock circuits. The VLED1 signal is asserted only when system initialization is complete and clock circuits are initialized. Logically, these signals are ANDed together to show an indication of the health of the system. If the Phase Locked Loop (PLL) connected to the data clock and the DMD clock are functioning correctly after system initialization, the LED will be illuminated.