Answers Database
XPLA1: Internal pull ups or pull downs.
Record #7641
Product Family: Hardware
Product Line: R3000
Product Part: R3128
Problem Title:
XPLA1: Internal pull ups or pull downs.
Problem Description:
Urgency: Standard
General Description: Do the XPLA1 devices have internal pull ups or
pull downs?
Solution 1:
The XPLA1 family in the 32A, 64 and 128 devices have internal pull
down resistors that are automatically activated by the fitter for outputs
that are 'no connects'. These pull downs can not be implemented
on active or 'used' I/O. The value of the pull downs are not guaranteed,
but by characterization they range from approximately 50k to 200k Ohms.
The 32 and 32C macrocell parts do not have internal pull down resistors.
It is important for end users to properly terminate all unused inputs in order
that the CMOS inputs do not float into the linear region.
It is recommended that all unused inputs be terminated with a 10k pull
up resistor on the 32 macrocell devices. Unused I/O can be forced low or
high (as an output) or have external pull up/down resistors to ensure that
pin drift does not occur.
End of Record #7641 - Last Modified: 10/11/99 16:11 |
