
Altera Corporation
25
Configuration Devices for SRAM-Based LUT Devices Data Sheet
For EPC1 and EPC1441 configuration devices, 3.3-V or 5.0-V operation is
controlled by a programming bit in the POF. The programming bit value
is determined by the core supply voltage of the targeted device during
design compilation with the MAX+PLUS II software. For example, EPC1
devices are programmed automatically to operate in 3.3-V mode when
configuring FLEX 10KA devices, which have a V
CC
voltage of 3.3 V. In this
example, the EPC1 device’s
VCC
pin is connected to a 3.3-V power supply.
Designers may choose to set the configuration device for low voltage
when using the MultiVolt
TM
feature, which allows an ACEX, APEX,
APEX II, FLEX, or Mercury device to bridge between systems operating
with different voltages. When compiling for 3.3-V FLEX 6000 devices, set
the configuration device for low-voltage operation. To set the EPC1 and
EPC1441 configuration devices for low-voltage operation, turn on the
Low-Voltage I/O
option in the
Global Project Device Options
dialog box
(Assign menu) in the MAX+PLUS II software.
Configuration Chain with Multiple Voltage Levels
An EPC2 or EPC1 device can configure a device chain with multiple
voltage levels. All 3.3-V and 2.5-V ACEX, APEX, APEX II, FLEX, and
Mercury devices can be driven by higher-voltage signals.
When configuring a mixed-voltage device chain, the APEX II, APEX 20K,
Mercury, ACEX 1K, or FLEX devices’
VCCINT
and
VCCIO
pins may be
connected to 2.5 V, 3.3 V, or 5.0 V, depending upon the device. The
configuration device may be powered at 3.3 V or 5.0 V. If an EPC1,
EPC1441, EPC1213, EPC1064, or EPC1064V configuration device is
powered at 3.3 V, the
nSTATUS
and
CONF_DONE
pull-up resistors must be
connected to 3.3 V. If these configuration devices are powered at 5.0 V, the
nSTATUS
and
CONF_DONE
pull-up resistors must be connected to 3.3 V or
5.0 V.