RL78 F12 (R5F109AAJ1745EM405) Debugging Voltage 2.1V VDD?

I have to debug the RL78 F12 with an Voltage of 2.1V VDD. I couldn't find anything about it in the documentation. Is it like the G10 that it needs over 4V to debug or an low voltage OCD Board? I tried to debug and couldn't get a connection to the E1 with less than 3.8V.