Answers Database

9500: Usage of internal pullup in IOB


Record #3026

Product Family:  Hardware

Product Line:  9500

Problem Title:
9500:  Usage of internal pullup in IOB


Problem Description:
Keywords:  9500, pullup, IOB

Urgency:  Standard

and when can the user program them?


Solution 1:

The IOB of every 9500 device has a control pull-up resistor
(typically 10K ohms) attached to each IO pin to prevent them
from floating when the device is not in normal operation.

The resistor becomes active during device programming and
system power-up.  The resistor is also activated for an erased
device.  This includes a new device and a device that has been
programmed then erased.

At all other times the resistor is de-activated.  The resistor
is not available to the developer during normal operation.  If
a pullup is required in the design, one will have to be added
externally.



End of Record #3026