PWM Generator IC Selection

[scootermcgoober]

So I've been using the PCA9685 for PWM generation for a while now (for driving LED strips); but I would like to add a circuit which can control triacs for dimming incandescent fixtures.  Its my understanding that in order to dim the triac must be switched in sync with the zero-cross time of the AC.  So I guess what I'm looking for is a multi channel PWM generator IC (which can be controlled over SPI or I2C) which supports synchronization via an input.  The input would be a zero-cross detector off a low voltage transformer.  This could easily be done with a microcontroller but I would prefer an off-the-shelf solution.  Any thoughts?  Currently I'm running this on a raspberryPi; I like the PCA9685 because its a set and forget operation; just set the duty cycle of the outputs and let it run. 

[penfold]

I have not personally come across any ICs that meet your needs, the latest phase angle controller I've come across used an 8-pin microcontroller.

If you're not too afraid of analogue circuits (the most set and forget of them all) you could use an I2C/SPI DAC to control a 'voltage controlled dimmer' (<- a search term that should produce some of them)