step down switching frequency
In addition to the other answer:

I would not use a module where Vin(max) is the same as the voltage it is being fed. I would want at least a few volts of margin (in case the primary power supply goes a little high). 

Even if the absolute maximum rating is not necessarily reached (the statement above does not state if this is the recommended maximum or absolute maximum), the device will be under more stress and will not necessarily last as long than one rated for a higher voltage.

In addition, when doing LED drivers, make sure that LED OPEN sensing is incorporated.

HTH