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First off - i'm an EE noob, but i've muddled my way through a number of arduino projects, so have some experience there.

I'm building a breakout board for a CMOS camera sensor for use with an arduino mega (ATmega2560 mcu). The mega has a +3.3v and a +5v rail. The camera has two different VINs, one for the analog circuitry one for the digital. both are listed for a max of +3v, and one is recommended at 1.8, the other at 2.8.

My question is how do i get those voltages from the 3.3 rail - just make a voltage divider? Also, won't this also affect the logic levels dealing with the circuit? if i build a divider, do all lines have to run through one? do i need a level shifter?

a little lost here..

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  • \$\begingroup\$ doing some more digging, i think i need something like this: sparkfun.com/products/10403 ... but do i need one per line (that's like 20), or is there a way to run multiples through one of these? \$\endgroup\$
    – kolosy
    May 26, 2012 at 21:13
  • \$\begingroup\$ Couple of thoughts so far. (1) Level translator (aka level shifter), which you found on SparkFun is specialized for I2C bus. I wouldn't use it for anything other than I2C. More level translators can be found here (among other places). (2) Your original post is missing a link to the datasheet of the CMOS sensor, which you're working with. We don't know what types of signals you have to deal with (speed, uni- or bi-directions, open collector or not, etc). \$\endgroup\$ May 26, 2012 at 22:56
  • \$\begingroup\$ unfortunately the datasheet is under NDA, so i can't post it up here. \$\endgroup\$
    – kolosy
    Jun 4, 2012 at 6:21

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A voltage divider is not a good idea because the output voltage will depend too much on current draw, or it will always draw lots of current from the supply. A better idea is to linearly regulate the 3.3 V supply down to the other voltages you need. That will be somewhat wasteful of power, but if the arduino supply can handle it, it will be the easiest solution.

Whenever you say you need to power something at a particular voltage, you should also mention the current requirement. Since you didn't, there is little more specific advice to give. If it's only a few 10s of mA, then linear regulators are a no brainer. If it's 1 A then it gets more complicated, and quite possibly the existing power supply doesn't have enough extra to provide that power.

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  • \$\begingroup\$ it's 10s of mA. \$\endgroup\$
    – kolosy
    Jun 4, 2012 at 6:22
  • \$\begingroup\$ @Kolosy: Then linear regulators should be good enough. However, add up the total current and make sure the arduino power supply is capable of delivering the extra current. With linear regulators, the total current your device draws will be the extra load current the arduino power supply will see. \$\endgroup\$ Jun 4, 2012 at 11:47

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