Matrix Keypad routine

[mister_e]

I tend to not use any resistor. If i need to drive high current, i sure use something else in between...

[passion1]

Thank you Steve & Ioannis.

Steve, what do you mean with:
"If i need to drive high current, i sure use something else in between..."

[Ioannis]

Another transistor or other driver I suppose.

Microchip has such Mosfet drivers (either for high or los side)

Ioannis

[passion1]

Ioannis / Steve

I would like to drive a 220V circuit with a power mosfet.
Do you think an optocoupler is a MUST or will I be able to get away with a diode to protect my pic?
If so, what diode or alternative protection would you recommend?

[mister_e]

it's up to you. Everything will depend of what the whole beast will do, and how the enclosure design is done. But to me, as long as there's room to fit a transformer and optocoupler and keep away the AC line away of the user... i feel better and sleep all night without any problem.

What do you need to drive?

[Ioannis]

...

But to me, as long as there's room to fit a transformer and optocoupler and keep away the AC line away of the user... i feel better and sleep all night without any problem.

I double that. Even if the end user is well isolated from the circuit, YOU are not trying to make it work. You will have to debug the circuit while alive and sure put your life in danger.

How many pcs are you going to sell? If it is say low quantity, for sure you will be paid by your time to develop the system. That money should be more than enough to let you put that transformer without second thought.

In my country people say that coward's mother will never cry over the grave! Of course it sounds more elegant in greek than the awkard translation!!!

Ioannis

[passion1]

Ioannis / Steve

Thank you for the wise advice!! I agree 100%.