I found this part using the parts.io search. Since I have filed so many bugs, I figured it was time for a success story!
I am helping a friend design a circuit for a really big LED-blinky project.
I need an oscillator to drive the clock of a switched-capacitor filter that I am using as an anti-aliasing filter. I have used the LTC switched-capacitor filters before, and they have always worked great. But it needs a clock, and in the past I have always used a crystal and a divider. This circuit has two filters, and needs two clocks. It would be really nice to be able to adjust the frequency. I could use a 555 timer, but I would like a little more stability and digital control via I2C. (The guy who is doing the software likes I2C. I am more of an SPI person).
I didn't know what I was really looking for. (My last clock chip design used an 8253.)
I looked around with keyword search for a while but didn't find anything interesting. I tried the part hierarchy, and first drilled down to the clocks at http://parts.io/category/Oscillators. I didn't really want the various fixed oscillators, so I tried http://parts.io/search/Class-Oscillators/Category-Voltage%20Controlled%20Oscillators . After scrolling halfway down the page, I saw that LTC had a part, and their stuff is always interesting. The part was an LTC6990, and is in a part family called TimerBlox. Never heard of it, but soon I saw that it was just the thing. It is in a family of digitally controlled oscillators with about 1% frequency accuracy. Plus it has an analog input that can be used for adjustment or modulation. After looking them over, I settled on the LTC6904, which should "work perfectly the first time" for setting the clock to the switched capacitor filter. The convenience of only needing to wire up an eight pin SOIC to an I2C port more than makes up for the $4.22 single-piece price tag. Now it's the software guy's problem! I think he will like it because LTC provides some tools including some sort of design spreadsheet.