Boundary conduction mdoe LED drivers

[Flyback]

Hi,
Why do virtually all offline LED driver IC’s involve the Boundary Conduction Mode (BCM) principle? (AKA critical conduction mode) It certainly has advantages, but the one huge disadvantage is that you can’t dim them down to low light levels without the switching frequency getting ridiculously high. It’s possible to avoid this by making them with a minimum off time, but virtually none of these BCM led dirver chips have this facility.

So why is this?

LED driver datasheet (NCL30002)
https://www.onsemi.com/pub/Collateral/NCL30002-D.PDF

 

[tomizett]

Off the top of my head, possibly because the average current is always proportional to the peak current, so you can just program the peak (trip) current and there is no need for an average-current feedback loop? Other then that, no idea!