"ADP3050 Buck Regulator Design Tool" can not design the ADP3050 in a buck-boost configuration that produces a negative output voltage from a positive input voltage.
In the datasheet 18 page, "INVERTING (BUCK BOOST) REGULATOR"The circuit in Figure 29 shows the ADP3050 in a buck-boost configuration.
For example, following output setting is available for ADP3050?VIN:+5.0VVOUT:-12.0VIOUT:0.5~1A ;need to set less current ?
You may also want to check LT3863 and LT3579. These products also fit your given specifications.