I converted the LM5007 into an inverting buck-boost to get a negative output voltage of -5V from a +24V input supply voltage.
Following TI's application report about how to work with IBBs, I created this circuit to obtain the +24V to -5V - conversion:
The problem is, that at the output there aren't the desired -5V, it only reaches about -4V.
In operation with a load I got these signals as a result:
Vout (output voltage) SW (switching node) BST (bootstrap)
Well, I don't understand why the On- and Off-Time is not going to be adjusted correctly, so that the IBB regulates a -5V output. (attached also an on-time measurement)
Maybe someone has an advice to solve this problem or an idea where there might be an error.
