SPRADO8A March 2025 – May 2026 AM62L
The recommendation is to implement the attached device (EPHY) reset using a 2-input ANDing logic since the ANDing logic provides the flexibility to be able to reset the attached device (EPHY) in all processor reset condition including local reset (in use cases where the attached device becomes non-responsive and needs to be reset without a power cycle). Processor GPIO (used to locally reset the EPHY) is connected as one of the input to the AND gate with provision for pullup (10kΩ or 47kΩ) (to support boot) near to the ANDing logic AND gate input and provision for 0Ω to isolate the GPIO output for testing or debug. The other input to the AND gate is the MAIN domain warm reset status output (RESETSTATz).
When more than one (x2) EPHYs are used, the recommendation is to provide provision to reset the EPHYs individually.
A pullup or pulldown (10kΩ) at the output of the ANDing logic can be used based on the EPHY reset input polarity. The EPHY is required to be held in reset for a specified minimum time after the clock is valid.
In case the processor MAIN domain warm reset status output (RESETSTATz) is directly used (connected) to reset the EPHY (attached device), the recommendation is to match the IO voltage level of RESETSTATz with the attached device. A level translator is recommended to match the IO level. A resistor divider can be used alternatively for level shifting, provided optimum value of the resistor divider is selected. In case the resistor divider value is too high the rise/fall time of the processor IO connected to EPHY reset input can be slow and introduce delay. Use of too low value resistors as divider causes the processor to source too much steady-state current during normal operation.