Half way there
Thanks guys, I was also doing some side research, and determined I needed a transistor and was just about to add that, when I saw your replies. So you confirmed that for me!
Now I am just stuck with specifics.
The output of the Dynon is a PWM at about 120hz (Dynon also says they might raise this to 3khz in the future), and varies it's duty cycle between 100% and 0.02%. As mentioned above, it is an open collector to ground. It can sink a maximum current of 120mA, and a maximum voltage of 40v.
I am driving about 36 LED's and 2 LED backlight panels.
The gounds of these LED's are already cross connected with other circuits, hence why I need a PWM + voltage. They consume about 500ma in total. The "rail" voltage (aircraft voltage) will be in the range of 12v to 14.6v. While my over voltage protection comes on at 14.6v, it would probably be best to withstand up to 20v.
So am I understanding the correctly, that I would connect
- Gate to Pin 26 on the Dynon
- Drain to the + terminals of the LEDs
- Source to the + Aircraft +12 power.
Is that correct?
I found the data sheet here:
http://www.redrok.com/MOSFET_IRF4905_-55V_-74A_20mO_Vth-4.0_TO-220.pdf
Now here is where my electronics fails me.
If I use a IRF4905 MOSFET, is the 10k resistor in Mich48041's diagram the correct value? Is the P-channel 18v diode required, and if so, what values for that would I need? Given the numbers above, which I think are very low compared to what the MOSFET can handle, will this need to be bonded to a heat sink?