Well, I was calculating absolute maximums, not necessarily the average current the regs would be putting out. In my particular setup for example, I would like to power a 3v vibration motor or a few lasers. A massive 10G vibration motor or a green laser might need 200mA. A smaller vibration motor or three red lasers might need 150mA. And a small vibration motor or a single laser might need onl 60mA. But in any case, they would only be on for brief periods of time. A few seconds at most, usually.
Well, my plan as of this moment is to forget trying to run the 3.3v off the battery because even a NiMh doesn't leave me with much amperage to work with before the 3.3v reg would overheat. So the plan now is to run both 3.3v regs on my board off the 5v regulator. That will allow them to put put almost 350mA, which is 150mA more than what I ever expect the reg will need to put out, and even if does get to 200mA, it will only be for brief periods as I mentioned earlier.
... but I don't really have the space for it, and it would make the way everything connects to the main board a lot more complicated for people. Trying to keep things simple. The board is already studded with pinouts:http://shawnswift.com/arduino/layout2.png
Fourthly, I don't even like the SOT223 parts [160degC/W], let alone the tiny ones you're using. Igo for the NCP1117 DPAKs [67 degC/W].That looks like a nice part, but the problem is, that regulator doesn't have an enable pin, and the plan is to switch the motor and laser using the enable pin on the regulator.
I saw the photo from the board layout, having so many row headers is a lot of effort to solder, why don't you just only install a few row headers, and use flat cable connectors for the rest of the pins?
It's also more difficult to separate and strip ribbon cable.
I think you're still being a little optimistic in choosing the 70 value versus the 125 degree value, since 1" square of copper means just that
I assume, when I talk about flat cable, you think of these used for ATA hard drives, and legacy floppy drives?I mean the type used for modern LC displays, and generally more and more found inside consumer electronics gadgets.
The idea is to save time (the connectors can be soldered at once), space (they are much smaller than row headers), and in some cases, it's also cheaper to use a ready-made flat cable.My idea was to have a number of conventional row headers, and if these run out, flat cables are used.
Well, it's true that the expansion board this will be placed on is a bit less than a full square inch, but I'll have thermal vias going to the ground plane like on my 5v regulator, so it should function as a reasonable heatsink.
Full square inch of copper isn't the same as saying 1" square pcb. That's what the other number means:"approximately 125°C/W when soldered down to a minimum sized pattern (less than 0.1 square inch)".
However I do not know the depth of the design or the considerations for instance using it inside guns.
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