5V input COMPATIBLE ALTERA FPGA FAMILY

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Some of the X products had built-in clamping diodes which could sink 12mA or so from 5V down to 3.3V. This let you read 5V safely as long as you had a series resistor from your peripheral ic. You would still need a shifter to drive, if VOH's voltage was not high enough for the peripheral's VIH.

I'm curious if any of Altera's products have this feature.

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Some devices have a PCI clamping diode. However, if you're going to create a PCI board, and you implement hot-swap, you end up needing to use BusSwitch buffers with a 1V precharge, so you get 3.3V clamping for "free" by powering the BusSwitches appropriately.

All the handbooks for the latest generation devices indicate a 100% duty over-shoot of around 4.1V maximum. So none of the devices are 5V tolerant.

Cheers,

Dave