Slew Rate Control

GPIO supports slew rate control in non-differential output mode. Turning the slew rate on results to faster slew rate improves the available timing margin. See respective PolarFire FPGA Datasheet or PolarFire SoC Advance Datasheet for the timing data. When slew rate is turned OFF, the device uses the default slew rate to reduce the impact of simultaneous switching noise (SSN).

The following table lists the I/O standards that support slew rate control.

Table 1. Slew Rate Control
I/O Standards Supported I/O Type Options
PCI GPIO (output only) ON (default),


LVTTL GPIO (output only) ON (default),


LVCMOS25 and LVCMOS33 GPIO (output only) ON (default),


Slew rate settings are controlled using the I/O attribute editor in Libero SoC or by using the following PDC command:

set_io –slew <value>

The value can be set as ON or OFF.

Slew rate control is not available in HSIO buffers. However, these buffers have built-in PVT-compensated slew rate controllers for optimized signal integrity.