What is meant by filtered PWM outputs on the PMAC2-PC/104?
The filtered PWM technique is different from a low-resolution DAC IC. The filtered PWM uses the square-wave PWM outputs from our ASIC and runs them through a low-pass filter to turn the output into a gentle sawtooth wave. We recommend setting up the PWM for 30 kHz output; the low-pass filter has a 10 kHz breakpoint. The idea is that the output can still respond quickly to new servo commands at 1-5kHz, but have little ripple at the 30 kHz frequency. This technique will work in many applications, but it will probably not be good for very high-bandwidth applications or very high-precision applications. It depends on the physical system not being fast enough to react to the 30 kHz ripple, and the resolution is not as good as our 16-bit and 18-bit DACs, and it is a technique our competitors have used for many years. Real DACs are essentially programmable voltage dividers, where the number sent to the DAC quickly selects which resistors above and below the output are to be used to control th
