Programming interface schematics for Icom:
Programming software for Icom IC-E90 (IC E90 ICE90) :
PDF User Manual for Icom IC-E90 (IC E90 ICE90) :
PDF Service Manual with schematics for Icom IC-E90 (IC E90 ICE90) :
As you see, this scheme permits to use IC-E90 with normal power supply (3A, 13.8V). IC-E90, for the right use, needs about 2A with 5 watt RF output and 8 Volt. I use this circuit about 8 months with great satisfaction.