Max outpt per pin Aurduino mega

I am using axuillary relays to supply voltage to my 12Vdc power relays. The spec for the auxillary relay is 5Vdc, 170mW 130ohm. If I am not mistaken, this means the relay current is just under 40mA. As the relays are non-latching they will be on for long periods of time. I am thinlking of using 2 output pins to share the "continuous load". The current required to operate the auxillary relay relays is just below the 40mA absolute maximum (excluding in-rush peaks). As the outputs will switch on with a small delay, the first output will have to supply the full current before the second pin is switch on. Once both pins are on, I assume they will share the load roughtly 50/50.
I am not sure of the duration/magnitude of the in-rush current - will this also be shared by both output pins? Also what if there is a reduction of the 5V voltage?
I am using a 12vDC 4500mA power supply connected to Vin. and will be using 3 auxillary relays plus a couple if LEDs
Hope someone can advise me. Thanks

Not a good idea. Use direct port writes to set the pin states at the same time.

It would be much safer to use a transistor to switch the relay coils, and to use a separate power supply for them. Or, just buy a relay board designed for Arduino.

The Arduino on board voltage regulator is NOT designed to handle significant loads and may overheat in your scheme. Avoid using a 12V supply on Vin, as that makes the problem worse. 7V is much better.

That is unlikely to be a valid assumption.

Thanks for your swift reply. I did originally think of using an Arduino relay shield, but as I´m using a screw shield plus a Wifi shield, the addition relay sield seemed a bit too much.
I´m using din rail relay sockets for the auxillary relays. I think I have ust found a suitable solid state relay that might solve all my "problems". The SSL pulls only 10mA so maybe the problems solved (just need to make certain).

the addition relay sield seemed a bit too much

You don't need to use shields.

The SSR is a much better choice than attempting to use pins to drive relay coils. Keep in mind that relay coils require diodes to suppress inductive voltage spikes.

I think I am going to use SSR´s. Thamnks for your input.

…or logic level MOSFETs.

Would be a good idea to actually cite the datasheet itself.

Relays are inductors. There is no such thing as an "in-rush current". You need to study up on inductors. :grin:

Very bad idea!

Sounds perfectly reasonable to me! The effective internal resistance of about 30 Ohms is likely to be very similar per pin as they should have identical geometry.