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I need a +12V reference voltage for an op amp circuit, so it doesn't need much current. I just want a simple surface mount device that takes up little room, and doesn't need a ton of passives or large capacitors to work.

I am currently using this device.

I no longer need the -12V rail, and this one takes up a lot of room. Anyone have any ideas?

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Look into charge pump voltage doublers (or tripler). Few components, low cost. – Nick Alexeev Mar 3 '12 at 4:41

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It depends what you want to do in the general case (and the op-amp...) but:

http://www.micrel.com/_PDF/mic2141.pdf

http://www.ti.com/lit/ds/symlink/tps61170.pdf

Generally-speaking, for what I believe you're looking for the parts rarely integrate the inductor, but it's only 2x2 mm and a SMT inductor plus 2 caps in many cases, so still a smaller footprint than what you're currently using. With more searching you may find a lower-current part.

I would imagine you also have noise requirements? Is this a reference or a supply?

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This is a reference voltage, the opamp is supplied with 48v. I would assume the current draw is very low on the 12v line, but I don't have any way to measure it. I would also assume that lower noise is better for a reference voltage. – John Vickers Mar 3 '12 at 13:48
The amounts of noise is all relative to whatever it is that you are doing. If you can get by with more noise you can probably save some cost and space. – Kellenjb Mar 3 '12 at 14:32
cost isn't that much of an issue, the board this is going on is over $300 in other components. I would rather spend $10 to get a good converter with low noise than $2 on a noisy one. – John Vickers Mar 3 '12 at 14:35
At lot of these modern switchers are relatively low-noise, at least compared to the part you are currently using (they are designed for ULV cell phone electronics where the noise sensitivity is very important). You can calculate the output ripple approximately based on the switching frequency of the regulator and the LC circuit on the output. If you are really concerned you can add an additional stage of filtering afterwards. – Jxj Mar 8 '12 at 0:38
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In a comment to the other answer you say the opamp has a +48V supply. Then why don't you use that instead of the more complicated step-up from +5V?

A low-current zener like the MMSZ4699T1G will give you 12V nominal at only 50\$\mu\$A. If the zener isn't precise enough you should be more specific.

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