3999 - <p>ispMACH4000 : For ispMACH4000 devices, is the bus-keeper option a global constraint for all the I/Os? When configuring I/O as bus-keeper, what is the signal status on power up?</p>
For the ispMACH 4000V/B/C/Z devices, the bus-keeper option is a global constraint for all I/Os. For ispMACH4000 ZE devices, it is available on per-pin basis.
During power up, the I/Os are at default state. After the device enters user mode, the I/Os are pulled as Hold. If the signal is set to PULL HOLD, the pin is held to the previous state after the source has been removed. The bus-keeper option latches the signal in the last driven state, holding it at a valid level with minimal power dissipation.
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