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This is the final iteration. Some minor changes from the previous. Mainly, the 100pf cap on the gate side is not required - the resistor value is also reduced as per Garbz IRF2804 circuit. The cap on the Drain side is increased to 3N3 to further restrict current reversal in the TEC.
The prototype helped me sort out the errors in previous versions as well as fine tuning. I've used a lot of resistors in parallel to provide a bit more safety given the current requirements of the TEC.
This circuit achieves a full 3C advantage over the hard switched version with no gate switching interference. Coupled with careful choice of active heatsink my DSLR cooling system achieves an additional 7C differential. 12V 6A TEC 27C differential, which means imaging at 0 on a warm night.
However, there is technically no low PWM state and the PWM Pin must be hard set LOW to prevent cooling during setpoint temperature and target PWM calculations - small change in the Arduino code.
Very happy with this.
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