EPF10K30AQC240-2 Datasheet, PDF (39/128 Pages) Altera Corporation – Embedded Programmable Logic Device Family

FLEX 10K Embedded Programmable Logic Device Family Data Sheet
Slew-Rate Control
The output buffer in each IOE has an adjustable output slew rate that can
be configured for low-noise or high-speed performance. A slower slew
rate reduces system noise and adds a maximum delay of approximately
2.9 ns. The fast slew rate should be used for speed-critical outputs in
systems that are adequately protected against noise. Designers can specify
the slew rate on a pin-by-pin basis during design entry or assign a default
slew rate to all pins on a device-wide basis. The slow slew rate setting
affects only the falling edge of the output.
Open-Drain Output Option
FLEX 10K devices provide an optional open-drain (electrically equivalent
to an open-collector) output for each I/O pin. This open-drain output
enables the device to provide system-level control signals (e.g., interrupt
and write enable signals) that can be asserted by any of several devices. It
can also provide an additional wired-OR plane. Additionally, the Altera
software can convert tri-state buffers with grounded data inputs to open-
drain pins automatically.
Open-drain output pins on FLEX 10K 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 open-drain pin is active, it will drive low. 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.
Output pins on 5.0-V FLEX 10K devices with V_CCIO = 3.3 V or 5.0 V (with
a pull-up resistor to the 5.0-V supply) can also drive 5.0-V CMOS input
pins. In this case, the pull-up transistor will turn off when the pin voltage
exceeds 3.3 V. Therefore, the pin does not have to be open-drain.
MultiVolt I/O Interface
The FLEX 10K device architecture supports the MultiVolt I/O interface
feature, which allows FLEX 10K devices to interface with systems of
differing supply voltages. These devices have one set of V_CC pins for
internal operation and input buffers (VCCINT) and another set for I/O
output drivers (VCCIO).
Altera Corporation
39