digital ballasts
 

Magnetic coil type ballasts are also known to cause the bulb to
flicker or strobe. This takes place so quickly that the neither human
eye nor light meter can pick it up. Eclipse LED digital ballasts
provide a uniform power supply to the bulb, thus eliminating the
flickering from the bulb and saving you money with fewer bulb
replacements.

http://www.eclipseledcompany.com/Digital_Ballasts.html