Proposal/Question regarding charge-pump input #41
Description
a. Thank you for the very nice design. Very simple hardware and well written software. I'm aware that a while has passes since you created this project.
b. I was trying to get my head around the charge pump voltage limit. This is obviously to not kill the gate as most MOSFETS have a Vgs<20V. but the 18V Zener is a pain - it dissipates power and so on. However, since many easy to find MOSFETS (including yours) are logic-level, they are easily driven with 5V. Since 5V exists on the circuit, why not drive the charge pump with 5V? i.e.:
Then the Zener is not required, and charge current is significantly lower (4.3mA vs ~20), enabling to easily use 1N1418 without it heating up. Am I missing something? This seems safer than just using a larger diode able to dump larger current and a beefier transistor.