Other Parts Discussed in Thread: LMR10510, LM43602, UNIFLASH, LM2830
I have a PCB with a TMS320F28375S. The situation is, that code execution in the controller stucks (controller hangs up?), when the different controller components are activated. I think the cause of the problem is the 1.2V-rail.
The PCB uses a switcher LM43602 to generate the 3.3V (Input 24V). The 1.2V are generate out of the 3.3V with a switcher LMR10510. I have no ferrites in series between the two rails. At each VDD pin I placed closely a 3.3uF capacitor. At each VDDIO pin I placed closely a 0.1uF capacitor. For VDDA, VDDOSC and VDD3VFL I did the same.
Notice to "placed closely": all decoupling capacitors are placed on the opposite board side to the controller. But I guaranteed the current flow through the capacitor from the power supply rail. That means: rail -> capacitor -> via (to controller board side) -> pin (of controller).
Observation: After adding a large 22uF capacitor "in front of the controller" to the 1.2V rail, the controller runs in particular. That means when stepping through the code with a debugger and activating the different controller components one by one with some delay, the controller finally runs and I can communicate via RS232. Nevertheless flashing of the device is still not possible.
I used a scope to find spikes on the 1.2V rail. I found nothing so far.
1. Is the LMR10510 not suited for this controller?
2. Would it help to add some more capacitance to the 1.2V rail?
3. Would it help to add some ferrites between the 3.3V and 1.2V rail?
Thank you for your support.
Beste wishes, Marcus