There are some lighting applications which uses stepdown transformers to bring the mains voltage down to 12V AC. Power supply IC company Dialog Semiconductor has designed LED driver iW3662,which can make the SSL bulbs compatible with virtually any transformer (electronic or magnetic), even in lighting applications with output power as low as 4W.
These LED drivers are good fit for MR16 LED retrofit bulbs, where MR16 halogen lamps require transformers to convert the standard electric line voltage down to 12VAC.
Dialog explains "Most low-voltage halogen lighting systems use small, inexpensive electronic transformers to perform this conversion. These transformers are designed to power resistive loads and can typically require a minimum load of 20W. While this load is easily provided by 50W halogen lamps, an equivalent LED MR16 lamp drawing 8W struggles to latch the transformer, with lower wattage bulb replacements often completely failing."
The iW3662 LED driver uses digital analytics to detect installed electronic transformers and dynamically increases the peak loading to latch the transformer, even during low dimming ranges, while maintaining the high efficiency expected from SSL LED bulbs. The iW3662 includes detection for magnetic step-down transformers as well to automatically switch in a compatible loading mechanism for these older models.
The iW3662 dimmable MR16 SSL LED driver also uses digital technology to provide dimmer compatibility (both TRIAC and digital dimmers) and dimmer performance, with either electronic or magnetic transformers. It delivers dimming down to 5% of measured light.
iW3662 Key features as Provided by Dialog:
Flexible single-stage or two-stage design
4W to 8W output power
Optimised for compatibility with all transformers
− Electronic and magnetic
Exceptional dimmer compatibility
− TRIAC (leading and trailing-edge) and digital
− Wide dimming range: 5% to 100%
Low total BOM size/cost
− Uses low-cost, off-the-shelf inductor
− High frequency operation for smaller external components
LED over-temperature protection derating
MR16 bulbs, AR111 fixtures, bulbs