This paper addresses efficient DC-DC converters for neural recording and processing implants in 22 nm FDSOI from a 3.7 V battery supply. Default solution with several supplies is impracticable w.r.t. complex cabling, PCB design and larger form factor. Thus we present a DC-DC which is robust regarding input voltage range and flexible regarding output voltage range. A bandgap-derived output voltage from 0.5 V to 0.8 V is selectable. The battery supply voltage is monitored as an additional safety feature for bio-medical applications. In combination with a neural recording system in 22 nm FDSOI, feasibility of scaling up to 1024 channels with an efficiency of up to 78.4 % is shown.