I have this very simple circuit - actually there are 6 of them on a board.
The MCU is connected to an MCU, and it is used to drive RGB led strips with PWM singals. My problem is that the MOSFET is not fully turned off. Or so it seems. When the MCU line is high and the Q1 transistor is fully turned on, then the gate of the M1 MOSFET is at 0.6V (one junction). Even though the threshold voltage of M1 should be about 2V, it is not 100% turned off at 0.6V. The result is that the LED strip glimmers a bit. It is almost nothing, but the LED strip is 20 meters long, and all of that small glimmering adds up. Basically, I cannot use this circuit as it is, because of that small glimmering. It becomes very distrubing in room that is used to watch movies in the dark.
Would it be possible to turn the FET fully off? My only idea is to use a dual power supply, and put the emitter of the Q1 transistor at -0.7V instead of 0V. However, creating a -0.7V supply just for this seems to be an overkill.