Electronics > FPGA

5V on 3V3 Altera CPLD I/O

(1/3) > >>

pyroesp:
So I have this idea where I have to use a CPLD to do some logic on a 5V board, but the CPLD (EPM240T100) is 3V3 only.
I can't just change the 5V board into 3V3.

So my question is: Can I connect 5V on a 3V3 I/O, without a level shifter ?
My thought on this is you can, but I'll have to limit the current and power dissipated on those pins, right ?

RoadRunner:
i guess this may be helpful

http://ww1.microchip.com/downloads/en/DeviceDoc/chapter%208.pdf

mikeselectricstuff:
Series resistor and clamp diode. According to the datasheet, some MAX II devices have internal clamp diodes

pyroesp:
Oups, EPM240 is altera... not Lattice :palm:. Changed the title.
Thanks for the pdf Gaurav and thanks for the help Mike.
I have to find out if the EPM240 has clamping diodes.

Cheers,
pyroesp

EDIT:
Doesn't seem like it has clamp diodes.

--- Quote from: MAX II Device Handbook ---The I/O clamp diode is only supported in the EPM1270 and EPM2210 devices’ I/O
Bank 3. An external protection diode is needed for other I/O banks in EPM1270 and
EPM2210 devices and all I/O pins in EPM240 and EPM570 devices.
--- End quote ---

Which is strange because if you look at the image below, I can't see any clamp diodes, just a couple of 100 ohm resistors to limit the current.

marshallh:
He's cheating on that pcb... not surprising.

Buy a few proper octal level converters, problem solved.

Navigation

[0] Message Index

[#] Next page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod