EPM570 Altera, EPM570 Datasheet - Page 42

• Manufacturer Part Number: EPM570
• Description: MAX II Device Family
• Manufacturer: Altera

I/O Structure
2–36
MAX II Device Handbook, Volume 1
MAX II devices also provide a chip-wide output enable pin (DEV_OE) to
control the output enable for every output pin in the design. An option
set before compilation in the Quartus II software controls this pin. This
chip-wide output enable uses its own routing resources and does not use
any of the four global resources. If this option is turned on, all outputs on
the chip operate normally when DEV_OE is asserted. When the pin is de-
asserted, all outputs are tri-stated. If this option is turned off, the DEV_OE
pin is disabled when the device operates in user mode and is available as
a user I/O pin.
Programmable Drive Strength
The output buffer for each MAX II device I/O pin has two levels of
programmable drive strength control for each of the LVTTL and
LVCMOS I/O standards. Programmable drive strength provides system
noise reduction control for high performance I/O designs. Although a
separate slew-rate control feature exists, using the lower drive strength
setting provides signal slew rate control to reduce system noise and signal
overshoot without the large delay adder associated with the slew-rate
control feature.
standards with drive strength control. The PCI I/O standard is always set
at 20 mA with no alternate setting.
Note to
(1)
3.3-V LVTTL
3.3-V LVCMOS
2.5-V LVTTL/LVCMOS
1.8-V LVTTL/LVCMOS
1.5-V LVCMOS
Table 2–6. Programmable Drive Strength
The I
minimum, where the V
current strength numbers shown are for a condition of a V
where the V
LVTTL/LVCMOS, the I
V
I/O Standard
OUT
Table
OH
= 0.7 V.
Core Version a.b.c variable
current strength numbers shown are for a condition of a V
2–6:
OL
Table 2–6
maximum is specified by the I/O standard. For 2.5-V
OH
OH
shows the possible settings for the I/O
minimum is specified by the I/O standard. The I
condition is V
I
OH
/I
OL
Current Strength Setting (mA)
OUT
= 1.7 V and the I
Note (1)
16
14
8
8
4
7
6
3
4
2
OUT
Altera Corporation
OL
= V
December 2004
condition is
OL
OUT
maximum,
= V
OH
OL