Answers Database
CPLD: Can the 9500 output buffer drive the load of several 9500s?
Record #3322
Problem Title:
CPLD: Can the 9500 output buffer drive the load of several 9500s?
Problem Description:
URGENCY: Standard
General Description: Can the 9500 output buffer drive the load presented w/3-5 other 9500 outputs (t
ri-stated) and have an input w/a resistance between 100-200 ohm w/o damaging itself and w/acceptable
noise margins?
Solution 1:
The datasheets specify that the output buffers can source 4 mA at Voh = 4.2V and can sink 24 mA at V
ol = 0.5V.
When the other outputs are tri-stated, you have a
situation of an attached pullup (assume worst case 100 ohms).
When Vol occurs, the pullup will supply (5V-0.5V)/100. This
comes out to roughly 45 mA. It will probably pull up the Voh a
little, but not much.
End of Record #3322 - Last Modified: 03/05/98 10:06 |
