| Electronics > FPGA |
| 5V on 3V3 Altera CPLD I/O |
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| 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. |
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