Are there more differences between the fixed-output and adjustable-output LM2651-s than the voltage divider at the FB input in the fixed-output versions? How high will the FB input current to a LM2651-2.5 be? Could I put a resistor in series with the FB input, of a LM2651-2.5, shorting the resistor when I want 2.5V of output, leaving it un-shorted when I want 3.3V? The FB input current will define the value of this resistor.
/Staffan Cronstrom