Intel® MAX® 10 FPGA Design Guidelines

ID 683196
Date 10/19/2020
Public
Document Table of Contents

1.6.2.13. Review available device I/O features that can help I/O interfaces

Check the available I/O features and consider the following guidelines:
  • Programmable current strength—ensure that the output buffer current strength is sufficiently high, but does not cause excessive overshoot or undershoot that violates voltage threshold parameters for the I/O standard. Intel recommends performing an IBIS or SPICE simulations to determine the right current strength setting for your specific application.
  • Programmable slew rate—confirm that your interface meets its performance requirements if you use slower slew rates. Intel recommends performing IBIS or SPICE simulations to determine the right slew rate setting for your specific application.
  • Programmable input/output element (IOE) delays—helps read and time margins by minimizing the uncertainties between signals in the bus. For delay specifications, refer to the relevant device datasheet.
  • Open-drain output—if configured as an open-drain, the logic value of the output is either high-Z or 0. This feature is used in system-level control signals that can be asserted by multiple devices in the system. Typically, an external pull-up resistor is required to provide logic high.
  • Bus hold—If the bus-hold feature is enabled, you cannot use the programmable pull-up option. Disable the bus-hold feature if the I/O pin is configured for differential signals. For the specific sustaining current driven through this resistor and the overdrive current used to identify the next driven input and level for each VCCIO voltage, refer to the relevant device datasheet.
  • Programmable pull-up resistors—weakly holds the I/O to the VCCIO level when in user mode. This feature can be used with the open-drain output to eliminate the need for an external pull-up resistor. If the programmable pull-up option is enabled, you cannot use the bus-hold feature.
  • Programmable pre-emphasis—increases the amplitude of the high frequency component of the output signal, and thus helps to compensate for the frequency-dependent attenuation along the transmission line.