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I am attempting to create a 0-5V analog output signal. No need to drive a load. I desire to control this via a 3.3 digital MCU.

I have attempted to translate the 3.3v PWM to 5v via a n channel mosfet and then through a single or double RC low pass filter.

This there a more accurate or better way to do this besides using a separate IC to do so?

schematic

simulate this circuit – Schematic created using CircuitLab

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2 Answers 2

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You could replace the MOSFET with a single CMOS logic converter - this will drive the filtering circuit and be somewhat more accurate because it has a push pull output and can work up to much higher frequencies than an open-drain MOSFET and 1 kohm resistor. Use a single-element logic device to keep board usage small. I'm sure TI have a device that fits the bill - look for TTL to CMOS inverter or buffer.

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  • \$\begingroup\$ Thank you for the answer! I am thinking of using the SN74LVC1T. \$\endgroup\$ Commented Jan 22, 2019 at 23:16
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  • R3 participates in charging the capacitors but it doesn't participate in its discharge. To obtain the average value accurately, the rations R1/R3 and R2/R3 should be as high as possible. Try 100k and 10n.

  • Depending on what you connect at the output, some kind of buffer could be necessary (load stage may charge or discharge the capacitors and affect the average value you detect).

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