R1243S001C050-EV Evaluation Board Nisshinbo R1243S001C050-EV Evaluation Board is designed to evaluate the R1243S converter. The R1243S is a CMOS-based step-down DC-DC converter that provides a maximum 2A output current and operates at a 4.5V to 30V voltage range. The R1243S001C050-EV evaluation board features 300kHz fixed frequency and offers latch protection with a 2ms delay time.