Do I need to look at RFI shielding for a Mega 2560-controlled SMPS

Hi all,
This may need to be in the power forum, but it's my first time yada-yada, please don't flame me too badly.

I'm needing some guidance on the feasibility of running two low-current SMPS on a chip-programming shield for the Mega (e.g. whether they would cause RFI issues with either the Arduino itself, or the shield).

My design goal is a MEGA version of the Meeprommer shield that handles both 27Cxxx and 28Cxxx (E)EPROMs. Mario, the original designer, has made a few comments on the 6502 forum that he may eventually do one, but since it's open source hardware, I figured why not...

Basically, my board needs to generate +6.5VDC and +13VDC from either the VIN or 5V rails without interfering with the Arduino or the chip being programmed. I also want to use two of the PWM channels to adjust these rails independently using software since every vendor of these old-school (E)EPROMs introduced a slight variant on the programming voltages to sell their particular programmers. Most of the tolerances overlap, but still...

Finally, any suggestions on which SMPS design to use would be appreciated. I've done both IC based and traditional MOSFET designs on paper and don't have a preference either way.

I think when you talk of getting 13V from a 5V supply it's called a "DC to DC Converter" or "Boost Converter" rather than a Switch-Mode Power Supply. (if the voltage is lowered it's called a "Buck Converter".)

Look at the High Voltage Rescue Shield which has a 12V DC-to-DC boost converter. I have one and the boost converter doesn't bother the Arduino at all.

SMPS uses a transformer (or coupled inductors), as I understand it...

Buck and boost converters are probably what you want, as they're simpler and use fewer components than an SMPS... I've put a buck converter on the same board as an AVR chip, with a sub-optimal layout (it was done on an attiny85 prototyping board, like the ones I sell on tindie rather than a purpose-made chip) an inch and a quarter from the chip, handling a 500mA load, and everything was fine - so I'd say you're probably good to go. Do pay attention to layout guidelines though - buck/boost converter circuits can be picky about layout.