I out together the LM3445 circuit as outlined in the "Triac Dimmable Offline LED Driver" data sheet for the LM3445
http://www.ti.com/lit/ds/symlink/lm3445.pdf
I constructed my own PCB.
I customized it as follows using a single LED with a forward voltage of 35V at 1.5 Amps current.
Instead of using the pnp transistor constant current source I placed an RC timer on the Coff pin with 244K and 120pF for approximately 3uS off time.
Current sense resistor is 0.5 Ohm. Valley fill caps at 150uF each.
The dimming of the LED is good but there is ringing/ spikes on the switching FET.
The scope trace illustrates this ringing. 
I tried RC snubbers from the drain to ground but that interfered with the switching.
Is this to be expected and what level of ringing is acceptable? In this case the peaks reach about 1.5 volts on the sense resistors.