Simultaneous Switching Noise

When multiple output drivers switch simultaneously, they induce a voltage drop in the chip or package power distribution. The simultaneous switching momentarily raises the ground voltage within the device relative to the system ground. This apparent shift in the ground potential to a non-zero value is known as simultaneous switching noise (SSN) or ground bounce.

For SSO guidelines for SmartFusion2 and IGLOO2 I/Os, see UG0445: SmartFusion2 SoC FPGA and IGLOO2 FPGA Fabric User Guide.