EP20K300EQC240-1 Datasheet, PDF (46/117 Pages) Altera Corporation – Programmable Logic Device Family

APEX 20K Programmable Logic Device Family Data Sheet
MultiVolt I/O
Interface
Under hot socketing conditions, APEX 20KE devices will not sustain any
damage, but the I/O pins will drive out.
The APEX device architecture supports the MultiVolt I/O interface
feature, which allows APEX devices in all packages to interface with
systems of different supply voltages. The devices have one set of VCC pins
for internal operation and input buffers (VCCINT), and another set for I/O
output drivers (VCCIO).
The APEX 20K VCCINT pins must always be connected to a 2.5 V power
supply. With a 2.5-V V_CCINT level, input pins are 2.5-V, 3.3-V, and 5.0-V
tolerant. The VCCIO pins can be connected to either a 2.5-V or 3.3-V power
supply, depending on the output requirements. When VCCIO pins are
connected to a 2.5-V power supply, the output levels are compatible with
2.5-V systems. When the VCCIO pins are connected to a 3.3-V power
supply, the output high is 3.3 V and is compatible with 3.3-V or 5.0-V
systems.
Table 12 summarizes 5.0-V tolerant APEX 20K MultiVolt I/O support.
Table 12. 5.0-V Tolerant APEX 20K MultiVolt I/O Support
V_CCIO (V)
2.5
3.3
Input Signals (V)
2.5
3.3
5.0
v
v(1)
v(1)
v
v
v(1)
Output Signals (V)
2.5
3.3
5.0
v
v(2)
v
v
Notes to Table 12:
(1) The PCI clamping diode must be disabled to drive an input with voltages higher
than V_CCIO.
(2) When V_CCIO = 3.3 V, an APEX 20K device can drive a 2.5-V device with 3.3-V
tolerant inputs.
Open-drain output pins on 5.0-V tolerant APEX 20K devices (with a pull-
up resistor to the 5.0-V supply) can drive 5.0-V CMOS input pins that
require a V_IH of 3.5 V. When the pin is inactive, the trace will be pulled up
to 5.0 V by the resistor. The open-drain pin will only drive low or tri-state;
it will never drive high. The rise time is dependent on the value of the pull-
up resistor and load impedance. The I_OL current specification should be
considered when selecting a pull-up resistor.
46
Altera Corporation