No HO pulse on IR2184 in half h-bridge
The type of MOSFETs typically used with a 600V driver chip like that require 10V to be turned on fully, so there is a undervoltage lockout feature provided to disable MOSFET drive when the supply voltage is too low: 



You should be able to get just enough voltage with a 12-15V supply, but remember you cannot have 100% drive high- it needs both MOSFETs to be present and to drive the lower MOSFET on regularly to refresh the bootstrap supply (so duty cycle must be less than 100%). If the lower MOSFET 'on' voltage is too high you may not get there, but normally you'd choose a MOSFET with &lt; 1V Vds(on) at the kind of very low supply voltages you are using.