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Lucent Technologies Inc.
Preliminary Data Sheet, Rev. 1
ORCA Series 3 FPGAs
September 1998
Programmable Input/Output Cells
(continued)
5 V Tolerant I/O
The I/O on the OR3Txxx Series devices allow intercon-
nection to both 3.3 V and 5 V device (selectable on a
per-pin basis).
The OR3Txxx devices will drive the pin to the 3.3 V lev-
els when the output buffer is enabled. If the other
device being driven by the OR3Txxx device has TTL-
compatible inputs, then the device will not dissipate
much input buffer power. This is because the OR3Txxx
output is being driven to a higher level than the TTL
level required. If the other device has a CMOS-compat-
ible input, the amount of input buffer power will also be
small. Both of these power values are dependent upon
the input buffer characteristics of the other device when
driven at the OR3Txxx output buffer voltage levels.
The OR3Txxx device has internal programmable pull-
ups on the I/O buffers. These pull-up voltages are
always referenced to VDD and are always sufficient to
pull the input buffer of the OR3Txxx device to a high
state. The pin on the OR3Txxx device will be at a level
1.0 V below VDD (minimum of 2.0 V with a minimum
VDD of 3.0 V). This voltage is sufficient to pull the exter-
nal pin up to a 3.3 V CMOS high input level (1.8 V, min)
or a TTL high input level (2.0 V, min) in a 5 V tolerant
system. Therefore, in a 5 V tolerant system using 5 V
CMOS parts, care must be taken to evaluate the use of
these pull-ups to pull the pin of the OR3Txxx device to
a typical 5 V CMOS high input level (2.2 V, min).
PCI Compliant I/O
The I/O on the OR3Txxx Series devices allows compli-
ance with PCI Local Bus (Rev. 2.1) 5 V and 3.3 V sig-
naling environments. The signaling environment used
for each input buffer can be selected on a per-pin
basis. The selection provides the appropriate I/O
clamping diodes for PCI compliance. OR3Cxx devices
have PCI Local Bus compliant I/Os for 5 V signaling.
Table 9. PIO Options
Input
Option
Input Level
TTL (OR3Cxx only), CMOS,
3.3 V PCI Signaling
(OR3Txxx only)
Input Speed
Fast, Delayed
Float Value
Pull-up, Pull-down, None
Register Mode
Latch, FF, Fast Zero Hold FF,
None (direct input)
Clock Sense
Inverted, Noninverted
Input Selection
Input 1, Input 2, Clock Input
Output
Option
Output Drive
Current
12 mA/6 mA or 6 mA/3 mA
Output Function
Normal, Fast Open Drain
Output Speed
Fast, Slewlim, Sinklim
Output Source
FF Direct-out, General Routing
Output Sense
Active-high, Active-low
3-State Sense
Active-high, Active-low (3-state)
FF Clocking
ExpressCLK
, System Clock
Clock Sense
Inverted, Noninverted
Logic Options
I/O Controls
Option
Clock Enable
Active-high, Active-low,
Always Enabled
Set/Reset Level
Active-high, Active-low,
No Local Reset
Set/Reset Type
Synchronous, Asynchronous
Set/Reset Priority
CE over LSR, LSR over CE
GSR Control
Enable GSR, Disable GSR