I have a customer with a card that needs to be hot pluggable. They use an SN74ALVTH162244G buffer on the plug-in card to interface to all of the signals going to the motherboard. There is a problem in that they seem to be getting current backflow through the buffer when it is powered down. The current backflow is causing other parts on the board to be partially powered-up. The result is that these parts latch-up when power is applied to the board.
They are considering changing to an SN74LVTH162244G buffer to solve this problem. Both of these buffers are listed as ABT, but the SN74LVTH162244G has a special mention of an Ioff mode that is targeted at this issue. Are these parts truly different in this respect, or is this difference simply a spec sheet oversight? Do you think that the SN74LVTH162244G will solve this problem?
Both parts have Ioff. They also both have powerup 3state and High Latchup immunity.
Both parts should be hard to latchup
The device datasheet recommends to put a pullup from OE to VCC to ensure 3-state during power cycling. Did they put a pullup? BTW, this pullup is recommended both for the ALVT and the LVT parts.