IC Electric Druid TAPLFO 3C
The chip generates a number of PWM LFO waveforms that can be used in stompboxes and synth applications. Here is a link to the datasheet.
The datasheet includes example circuit diagrams, example waveforms, and the chip pinout diagram.
Notes from The Electric Druid on the newest version of the TAPLFO:
Updating the V2, the V3C processor allows the increase of the output sample rate and removes the need for an external crystal, which frees up a couple of pins on the chip for extra features. Also added: a waveform smoothing filter (so your tremolo never clicks!) and a second set of eight waveforms, plus the option of a unipolar output instead of the standard bipolar. The intention has been to keep the chip compatible with existing TAPLFO2D circuits and PCBs as far as possible, and for the most part, it looks like that will be achieved - you just leave off the few parts that are now no longer required and it works the same as the old one. Should be easier to use and more flexible too.
Here is a link to the build information for Taylor Livingston's popular Tap Tempo Tremolo: http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=43017