Camera FPGA PSRAM interface check

[freeskier89]

Yep, that and the camera.

 

[hjames]

Ah, I was going to try out some layouts to see if things would fit - and promptly forgot about it.

Take a look at the new post over at SparkFun. Lots of "what not to do" when laying out boards.

https://www.sparkfun.com/commerce/present.php?p=Prototyping-1

 

[freeskier89]

This thread never seems to die lol. I got the boards back a month or two ago, and amazingly, as far as I can tell, nothing is too drastically wrong. The LTC3441 buck/boost 3.3V regulator is giving me the most trouble. I hooked it up exactly like the "Typical Application Circuit" in the datasheet (**broken link removed**, but its still not working right. I made sure to follow the recommended pcb layout in the datasheet too.

It is outputting 4.8V instead of 3.3V. When I put the circuit up to my ear, I can hear the inductor making we weird sounds (it periodically 'clicks'). I would expect it to make a constant high frequency squeal if anything. When I press my finger against any one of the resistors on the output end (340k, 200k, 15k, 1.5nF), the output voltage will drop close to 3.3V. It does cause the chip to heat up more though, and that worries me. If it didn't heat up, I wouldn't worry about sticking a rheostat in place of the resistors to try to fix the problem. Besides, shouldn't it work as is? I am quite sure that everything is soldered correctly in place. Oh, btw, if it helps, under normal conditions, the buck-boost converter causes the battery voltage to drop .02V, and when I touch the resistors, it drops up to .06V.

I am kind of at a spot, where I am reluctant to do a lot of tweaking, for a few reasons. My analog knowledge is poor, and I really do not want to burn out the chip, because replacing it would put me back a week

Do you have any advice about how I should proceed? It seems to be a problem with the feedback section, but I am not sure how to go about fixing it.

Thanks!