I want to use the TPSM5601R5H to convert from 28VDC to -8VDC. This means using the part in IBB configuration as described in SNVA962. I require a custom UVLO at Vin = 5VDC. In a standard buck configuration this is achieved via a resistive divider between Vin, enable and GND. But in IBB configuration the enable reference is Vout and not GND, as described in the application note. The app note describes a NMOS/PMOS circuit for level shifting. But I fail to see how this circuit can be used to implement a specific input UVLO value. Is a dedicated comparator IC (with a resistive divider between Vin and GND) required to implement this? The output of the comparator would then be the input to the SYS Enable as specified in the app note.
I do not plan any other negative voltages in the system, so I guess I need some sort of level translation for the EN pin.
Regards
Lars
