SPRADO8 March 2025 AM62L
Provide provisions for adding parallel pulls to the processor IOs. Parallel pull polarity and the values depend on the specific peripheral connectivity recommendations, recommendations for improved processor performance, and relevant interface or standards requirements.
Processor-specific EVM pull values can be used as a starting point and board designer can select the appropriate pull values based on the recommendations for the processor and attached device, or specific board design implementation.
When traces are connected to the processor IO pads and is not being actively driven, a parallel pull is recommended. Pull polarity is design use case dependent. During reset, processor IO buffers are off and the IOs are in a high impedance state, effectively serving as an antenna that picks up noise. Without any termination, the IOs are in high impedance state. High impedance makes noise easily couple energy on the floating signal trace and develop a potential that can exceed the recommended operating conditions, which creates an electrical over-stress (EOS) on the IOs. Electrostatic discharge (ESD) protection circuits inside the processor are designed to protect the device from handling before being installed on a PCB assembly.