Many low cost LED fixtures have a 2X line frequency flicker. Since flicker free switching LED power supplies are not difficult to design, I assume that flickering drivers are cheaper than flicker free drivers.
Some pictures of the driver from a low cost 120 Hz flickering LED strip fixture are shown below, followed by the typical application circuit for the on board BP2326A chip from this data sheet.
What is it about flickering driver circuits that makes them presumably lower cost and thus so ubiquitous?
Best Answer
Basically the input cap across the HV DC bus is hopelessly tiny so the bus voltage pretty much tracks the envelope of the mains.
This means that there is no need for an expensive HV electrolyic and that the power factor is actually quite good even with a simple minded converter like that.
If you want flicker free, you need to hold the bus voltage up sufficiently to avoid the thing dropping out or regulation, and that means a rather large electrolytic. If you also want good power factor, that means an additional PFC stage (at least for simple designs).