The UBA2211 and UBA2213 have three protections inside the control logic.  The most important protection is against coil saturation. A lamp which has been switched on within seconds of being switched off will have an inductor with a temperature of up to 115°C. At this temperature the inductor is likely to saturate at ignition. Coil saturation will result in currents exceeding the internal MOSFET saturation current level (1.65 A for the UBA2211C). Without protection this high current will destroy the device. The UBA2211 and UBA2213 will abort the half bridge cycle if the current in the FETs exceeds the limit the IC can handle. If there is coil saturation, then a very high voltage is put over the tube for about 300 ms. This should be enough to ignite the lamp if it is not broken. After this 300 ms the over temperature protection will switch the IC off as these high currents heat the IC rapidly.