Swiss Pi Extensions – PWM to Voltage Converter
The PWM to 0–10 V converter board is intended to drive light dimmers (including LED dimmers), most of which use 0–10 V control signals. The PWM signal from the Swiss Pi is converted to a DC voltage by a RC filter, and this voltage is then buffered and doubled by the opamps (see Figure 5).
The current consumption of the opamps is low and the load on the 0–10 V signals is usually low, so a simple DC/DC converter is used to provide the higher supply voltage for the opamps. It converts the 5 V supply voltage from the Swiss Pi to 15 V, which is then reduced to a regulated 12 V by a 78L12. That eliminates the need for an external power source.
You should bear in mind that the output voltage range may not be exactly 0 to10 V — in practice it extends from 0 V to twice the supply voltage of the PWM IC on the Swiss Pi board.