Electronic – Microcontroller PWM output

Here is some references of MCUs with high PWM outputs (> 12)

• Freescale Kinetis K10 @ 120 MHz series (ARM-Based) : 2x8ch + 2x2ch = 20 PWM channels
• A small number of dsPIC33 have a high number of PWM output:
  • dsPIC33EP256MU814 : up to 30 PWM outputs
  • dsPIC33FJ64GS610 : up to 22 PWM outputs
• Atmel 32-bit AVR MCU have some references with high PWM outputs:
  • ATUC256L3U : up to 36 PWM channels

But as Wouter van Ooijen said in a comment, maybe you should review your architecture and instead of using one big MCU with many PWM outputs, you should use one small MCU for each "component" (SMPS, motor, etc.), and use one big MCU for the general control of all other MCUs. This will lead to a more flexible design: you can add a motor simply by adding a small controlling MCU and linked to the big one in SPI or I2C.

For the CPLD/FPGA approach, you can take a look at Lattice ice40 CPLD and to this reference design : MxN Channel PWM Do some searchs about PWM on Altera and Xilinx website to have other CPLD references.

It depends on what you mean by "control". Are you confining yourself to simple combinatorial logic, or are serial protocols allowed?

In theory, you could control an arbitrary number of outputs from a single pin by using something like the Dallas/Maxim 1-wire (serial) protocol to drive a set of I/O expander chips. Similar approaches can be used with I²C, SPI, or simple shift registers, each of which would require a minimum of 2 pins.