Thank you all so much! @asmi I cannot believe I missed that 1.8v supply issue, that is absolutely horrible . I was worried about using a switching supply for the FPGA because I didn't want to introduce any high-frequency noise. I could add some sort of filter, but I didn't know how to quantify the noise and I don't know how much is acceptable.
Thank you very much, that is incredibly helpful and very kind! Because of time and budget constraints, I'm probably not going to incorporate the switching supply because I don't want to reorder a solder stencil, and I don't have a ton of time to put into layout. I realize that it won't be a great design, but at this point in the semester I just have to get it to work. I'll fix those issues with the FPGA supply voltage and the FTDI chip though. Also yeah I'm aware of the situation with the mounting holes and the screws scraping the solder mask. I will probably put some sort of spacer in the final solution to prevent shorting. And yes, I will certainly keep you updated!
There is no reason to use a switching power supply for every little voltage rail. How much current do you expect to draw from the 1.2V rail? Maybe a few 10's of mA? Times 2V that is still very small losses and simply not worth the bother. Linear regulators are simple and effective. No reason to not use them for the low power drain devices.
Thank you very much, that is incredibly helpful and very kind! Because of time and budget constraints, I'm probably not going to incorporate the switching supply because I don't want to reorder a solder stencil, and I don't have a ton of time to put into layout. I realize that it won't be a great design, but at this point in the semester I just have to get it to work.
There is no reason to use a switching power supply for every little voltage rail. How much current do you expect to draw from the 1.2V rail? Maybe a few 10's of mA? Times 2V that is still very small losses and simply not worth the bother. Linear regulators are simple and effective. No reason to not use them for the low power drain devices.Any loss is unacceptable for battery-powered designs. I wouldn't ever called LDOs "effective". Switchers, on the other hand, ARE simple and effective. Nowadays you can get even switchers with integrated inductors, so you barely need any external parts. Nowadays the only reason to use LDO is when you need extra-quiet power rails - and even that is combined with switcher pre-regulator to limit losses and increase efficiency. Remember that poor efficiency results not only in waste of power, but also increase heating, possibly requiring implementing some additional measures to deal with that.
In this design on the other side of PCB it says max current for 3.3 V rail is 2.1 Amps, and up to 10 V of Vin is acceptable, this leads to LDO dissipating (10 - 3.3) * 2.1 = 14.07 W of power!!! There is NO way this little LDO can handle that kind of heat load.
In my particular use case for this board, I'm using a 6V switching regulator to step down my battery voltage to supply the development board, and I estimate the current draw on the 3.3V rail to be around 600mA in the worst case, so using your calculation I get (6-3.3)*0.6 = 1.62 watts. My labeling of the maximum input voltage being 10V had to do with the capacitor voltage ratings on the input of the supply, and the 2.1 A output current came from the data sheet of the 3.3V regulator. I suppose that wasn't the best way to label things.
In my particular use case for this board, I'm using a 6V switching regulator to step down my battery voltage to supply the development board, and I estimate the current draw on the 3.3V rail to be around 600mA in the worst case, so using your calculation I get (6-3.3)*0.6 = 1.62 watts. My labeling of the maximum input voltage being 10V had to do with the capacitor voltage ratings on the input of the supply, and the 2.1 A output current came from the data sheet of the 3.3V regulator. I suppose that wasn't the best way to label things.
That absolute preference for switchers is not an engineering decision, it is a personal preference not supported by facts. An engineering decision would be supported by facts, not statements like, "Any loss is unacceptable for battery-powered designs". Power consumption is a requirement to be met like any other. Meet the requirement and the design is a success. Absolute minimum is not a requirement and not considering the downside of switchers is not appropriate in a design process either.
That is right up there with a comment I once heard that resistors were to be avoided because they use power.
That absolute preference for switchers is not an engineering decision, it is a personal preference not supported by facts. An engineering decision would be supported by facts, not statements like, "Any loss is unacceptable for battery-powered designs". Power consumption is a requirement to be met like any other. Meet the requirement and the design is a success. Absolute minimum is not a requirement and not considering the downside of switchers is not appropriate in a design process either.The only use case I can justify using LDO for is when I need it's high PSRR. For everything else, switchers are superior.
That is right up there with a comment I once heard that resistors were to be avoided because they use power.Don't be ridiculous.