General
Review and verify the following for
the custom schematic design:
- Reviewed above "Common
checklist for all sections" section of the user's guide.
- Supported interface are PCIe 1x Single Lane Gen 2 or 1x USB 3.1 DRD
- HCSL clocking is required when SERDES0 clock is operating in clock-input
mode
- Processor can source the 100MHz PCIe bus clock. The note applies to processor
silicon PG2.0. Refer to the silicon errata for more details
- Supported Interfaces: USB SuperSpeed and PCIe share a common SerDes PHY.
Therefore, USB is limited to non-SuperSpeed modes when using the SerDes PHY for
PCIe
- When PCIe or USB3.0 interface is
used, the recommendation is to connect the analog and IO supplies
VDDA_0P85_SERDES0, VDDA_0P85_SERDES0_C and VDDA_1P8_SERDES0 to the recommended
power supply rails as per the processor-specific data sheet.
- The recommendation is to use the
same analog filters used in latest EVM design, as these have been validated
- When SERDES0 is used, the
recommendation is to connect a resistor (pulldown) for SERDES0_REXT (close to
processor pin). Refer processor-specific data sheet for resistor value and
tolerance. When SERDES0 is not used and boundary scan is required (SERDES0
supplies connected as per processor ROC) connecting SERDES0_REXT is recommended,
Ferrites and bulk capacitors are optional for the supplies. When SERDES0 is not
used and boundary scan is not required (SERDES0 supplies connected as per pin
connectivity requirements (connected to VSS)) SERDES0_REXT pin can be left
unconnected.
- AC-coupling capacitors are recommended for SERDES0 transmit and receive
pairs
Schematic Review
Follow the below list for the custom
schematic design:
- The recommendation is to refer
below:
Additional
- The use of USB3.0 and PCIe interface are mutually exclusive (USB3.0 or PCIe).
USB3.0 and PCIe cannot be used at the same time
- SERDES0 inputs are not fail-safe
- If clock or data inputs are available before the processor supply ramps,
VDDR_CORE rail can be affected causing booting issues based on the power
architecture implementation
- The recommendation is to
implement the SERDES0 interface as-intended and as-tested. Example, PCIe or
SuperSpeed USB. Anything other custom interface use case or configuration is not
supported
- SERDES0 when not used has
specific connection requirements for interface signals and power supplies. For
connecting the interface signals, analog and IO supplies, see the Pin
Connectivity Requirements section of the processor-specific data
sheet
- When the boundary scan function is used, decoupling capacitors are recommended
for the analog and IO supply pins. Bulk capacitors and ferrites are
optional
- When the pin connectivity
requirement includes connecting processor analog and IO supply pins (boundary
scan not used) to VSS. The recommendation is to connect to VSS through separate
0Ω resistors
- When boundary scan function is not used and SERDES0 supplies are connected to
VSS, decoupling capacitors, bulk capacitors and ferrites can be deleted.
SERDES0_REXT provision can also be deleted