I am trying to drive a 3 pin fan using my MCU.
The 3 pins of the fan are 1- Gnd, 2- Vdd, 3- Open drain RPM output
The fan can draw up to 0.5 Amp.
My initial idea was to use a Darlington transistor, something like the circuit below.
The problem was however that this would mess up the RPM output.
Net idea was to use a RC low pass filter and a Power Op Amp, but I think an Op Amp rated 0.5+A would be too expensive.
Any better ideas/suggestions?