Using Webench, for the design and subsequently building, I get very low O/P voltage.
I have +10.8V to +13.2V input and attempting to obtain -12V O/P upto 200mA. Webench recommended the LM25574 part and this is the circuit I have built-up. With a light load (<< 10mA) I have an O/P at approx -1.4V. If I increase the load value to obtain ~100mA, the O/P drops to approx -1V. Within normal prefered values I have followed the webench design. I have 3 Prototype PCB's all exhibiting the same problem. Not even sure where to start looking. I have already downloaded several TI docs. on these modes of operation, but cannot see any particular errors.
This is the complete schematic where the LM3478 Buck / Boost works just fine but the following Invertor does not.
4606.3731.WebenchReportsServlet.pdf
Any help would be greatly appreciated !!!
Graham