I made some tests using the final component values for our FAB1248 DC/DC converter.
Using a 12Volts DC input, phantom power voltage output remained constant at 47.90Volts, up to 47.84Volts at various loads and current draw.
For example, at 57mA current load, voltage output measured is 47.87Volts, with 152mV ripple according to our oscilloscope. This translates to about 0.31% ripple! Ripple frequency has a period of 6.07us, or 164.7khz.
Using a load of 500-ohms, measured output voltage still remained at 47.84Volts, while drawing 89mA current load. I wouldn’t suggest loading the converter this much (almost 5Watts), as the chip would need some form of heatsinking. But it’s nice to know, that our converter could perform at that load and still deliver a good “48Volt” output.
With typical condenser mics drawing 5mA, and at most 10mA, this FAB1248 DC/DC converter for phantom power will serve your phantom power needs very well.