Solution : https://service.sap.com/sap/support/notes/923012 (SAP Service marketplace login required)
Key words : 
terms ipc dataloader unicode reason, download unicode data, ipc dataloader, download data, ipc datloader 3, /3 unicode system, unicode system, 0 dataloader, prerequisites
Related Notes : 
       
| 1319517 | Unicode Collection Note | 
| 919835 | Collation of local IPC database in unicode. | 
| 916166 | error in the log during the download on a unicode database | 
| 903893 | Shortdump MESSAGE_TYPE_X during download | 
| 852059 | |
| 687389 | incorrect Varkeys/Vardat for condition from unicode system |