I didn’t mention that the uC will get supplied by a battery because I didn’t think it would be relevant.
Then I would change that 10k resister, that goes from the Gate [of the Logic Level MOSFET] to GND, to a 1Meg resistor [to reduce the power demand on the battery]. All this resistor does is discharge the gate capacitance, which is quite small.
According to your schematic, a digitalHigh is required at the uC pin to pull the gates of the power mosfets from 12V to ground and a current of 60V/10kOhm will flow. So the uC has to be powered and the 6mA will flow in order to switch the load off and keep it off right?
Not quite sure what your question is, so I’ll take a shot in the dark: When the PWM1 pin is set to HIGH, the [Logic Level] MOSFET will “switch ON” [i.e. the Drain to Source channel resistance will drop to a low value, allowing considerably more current to flow]. This will pull “Out” as low as it can go. This will, also, allow a current equivalent to [essentially, 'cuz we’re going to ignore the MOSFETs channel resistance, since it’s so low in relation to the 10k resistor in the Drain Circuit] 60V/10k = 6ma. When the PWM1 pin goes LOW, the MOSFET will turn off, and restrict current flow. But, current will still flow through the Zener, causing Out to rise to approximately 12V.
So, when PWM1 is HIGH, your mystery MOSFETs will be turned off, because the voltage at their gates will be nearly zero. When the PWM1 pin goes LOW, around 12V will be applied to the mystery gates, thus turning those MOSFETs on. What we have here, folks, is an inverter!
Also, when PWM1 is HIGH, 6ma will be drawn from the 60V source, and when PWM1 goes LOW, more like 4.8ma will be involved. Now, if that’s too much current, then the Drain resistor can, probably be changed to a higher value. The intention was to drive that Zener to near the “Nominal Point” – i.e. where the Zener will produce a solid voltage and be closest to the specified voltage, i.e. “12 volts”, and not waver for nothin’. But, like I said before, the goal here isn’t necessarily to regulate voltage, but to protect the gates on your mystery MOSFETs. So, the Drain resistor can be adjusted to a higher value until the Zener is just producing enough voltage to get those MOSFETs turned on as much as desired – BUT, to really engineer the s**t out of this, you will need to consider environmental conditions, and tolerances and such.
And, like I also said, there are zeners that can do the job at much lower current, but the only ones I could find are hard to work with ['cuz they’re SMD and all – in fact, one of the ones I use, is around the size of a flea!!]