I'm trying to minimize part count and cost of my project. It needs to have a 6V power rail with about 1.5A peak current from a 12V input. I'm shying away from a linear regulator because of the power dissipation but I would like to keep cost and part count down.
Do switching regulators exist with internal diode and inductor to match these parameters or would it be less expensive to have a linear regulator with a big heatsink?
lowest cost, lowest part count. Pick one. There are many ready-made SMPS modules - some even have the same footprint as 78xx regulators. A seach for Integrated switching regulators will find some of them.
You won't find an integrated inductor for these specs and I doubt they exist for smaller currents. You'll need something in the order of 33-100uH and at >1A this is huge from an integration point of view.
Synchronous switchers use a MOSFET instead of the Schottky diode, and that's often integrated. They also have higher efficiencies.
Have a look at National's Simple Switcher series, which includes parts like LM22676 which require minimal external components and provide high efficiency (for the LM22676 >90%). National has an online Webench design tool to help you select the right components.
Most switching regulators have got an internal switch. There are also plenty switching controllers which would need an external FET.
There are some regulaturs with an internal diode, but not plenty. I haven't seen internal inductor. Typical required inductors are well pretty large. I don't think they will be able to fit on the die of a chip.
If you're seeking for a way to decrease the size of the power supply, try using a more faster switching regulator. They are a bit harder to work with (in terms of PCB design and such), but require smaller inductance values and thus smaller inductors (in a smaller package).
