Electronics > FPGA

5V on 3V3 Altera CPLD I/O

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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 ?

i guess this may be helpful


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

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.


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.

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

Buy a few proper octal level converters, problem solved.


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