I am working on below circuit in my organization.
TPS5430(U14) is used to get 7.5V and negative voltage (-5V) is generated using LM7905 and negative Clamper circuit as shown. We have also connected dummy load of 560Ohm at o/p of U14 to ensure regulation of -5V and avoid U14 from entering into discontinuous mode of operation.
But when we tested above schematic, we observed that 7.5V (o/p of U14) is getting dropped to ~0V and also output of 7905 IC and 7805 Ic is dropping to 0. If we remove C33 then Output of U14 is 7.5V, which is correct.
Is it mostly because TPS5430 is going to discontinuous mode of operation. If we change C33 (say, 0.1 uF,1uF, 4.4nf), surprisingly sometimes it works, sometimes doesn't.
How to ensure proper regulation 7.5V,5V and -5V? Please advise us. Thanks.
