L6585DE PFC and Ballast Control Integrated Circuit 3

Choke saturation protection

The saturation of the ballast choke means that a very high current flows into the resonant network and the almost instantaneous modification of the resonant curve occurs immediately at the operating point in capacitive mode. The stable operation in capacitive mode severely damages the ballast.

Therefore, in ignition and operation modes, the activation threshold of the comparator connected to the HBCS pin is equal to 2.75 V and 1.6 V, respectively. It senses the sensing resistance in the ballast and immediately locks the IC in low consumption mode. The width trigger peak is above 200 ns. This ensures that switching events (with a typical duration between 40 ns and 100 ns) in operating mode cannot trigger the comparator. However, hard switch protection and anti saturation protection are not yet fully independent. We can point out four different regions regarding pulse width: diode

(a) Peaks with a duration of less than 40ns: (noise zone) unprotected triggering.

(b) Peaks with a duration between 40 nanoseconds and 100 nanoseconds: (HSw region) Only hard switch protection will be activated after approximately 420 events.

(c) Peaks with a duration between 100ns and 200ns: (uncertain area) hard switch protection action, which can also activate anti saturation protection, which may result in early activation of hard switch protection or delayed activation of anti saturation protection (in which case the blocking will not be too deep).

(d) Peaks with a duration exceeding 200ns: (ASP area) Anti saturation protection will definitely be activated during the first activity. diode