atf280e ATMEL Corporation, atf280e Datasheet - Page 30

• Manufacturer Part Number: atf280e
• Description: Rad Hard Reprogrammable Fpga
• Manufacturer: ATMEL Corporation

8.1.7
8.1.8
30
ATF280E
Tri-State
Dual-use I/O
Drive capability is dependent upon setting FAST, MEDIUM and SLOW performance and sup-
plies voltage.
Table 8-1.
Table 8-2.
When no modification is performed by the user on the IDS software, the default configuration of
the drive for the I/Os is SLOW.
The output of each I/O can be made tri-state (0, 1 or Z), open source (1 or Z) or open drain (0 or
Z) by programming an I/O’s Source Selection mux. Of course, the output can be normal (0 or 1),
as well.
Any pin which functions as user I/O and configuration I/O is a dual-use I/O pin. INIT, HDC, LDC,
D
It must be noted that while the configuration logic controls dual-use I/O pins during a particular
mode of operation, the configuration logic does not control the pull-up, pull-down, CMOS/TTL
threshold select, or Schmitt trigger selects.
The user must be cautioned to avoid possible system problems with the use of dual-use I/O
pins. For example, turning off the internal pull-up resistor for the open drain INIT pin would not
apply the weak High required of an open drain driver. Conversely, disabling the pull-up and
enabling the pull-down of the HDC pin might be a good idea, since the user may then actually
see the pin go Low at the end of configuration.
Dual-use pins share input buffers. It should be noted that even when the configuration has
claimed a pin for its own purposes, the user input buffer is still fully functional. This implies that
any user logic tied to the input buffers of the pins in question will remain operational.
0
:D
15
, A
0
:A
19
, CS
VCC = 3.3V
Drive Capability for VCC = 3.3V
Drive Capability for VCC = 1.8V
VCC =1.8V
Medium
Medium
config.
config.
Slow
Slow
Fast
Fast
0
, CS
1
, CSOUT, CHECK, and OTS are all dual-use I/O pins.
Worst case
Worst case
18.5
13
5
6
2
8
IOh(mA)
IOh(mA)
typical
typical
20
29
10
15
8
4
Worst case
Worst case
17
23
10
5
7
2
IOl(mA)
IOl(mA)
7750A–AERO–07/07
typical
typical
30
10
40
15
21
5