General
Review and verify the following for
the custom schematic design:
- Reviewed above "Common
checklist for all sections" section of the user's guide.
- Standards referenced in the
electrical characteristics including recommended operating conditions and
any additional information available.
- IO buffer type and the allowed supply configuration.
- Connection of supply to all the IO supply for IO groups (VDDSHVx [x = 0-3,
5-6], VDDSHV_MCU, and VDDSHV_CANUART).
- Sequencing of the processor
IO supply.
- Connection of processor DDRSS IO supply.
- IOs pullup supply voltage reference.
Schematic Review
Follow the list below for the custom schematic
design:
- IO groups supported included LVCMOS, SDIO and I2C OD type IO buffers.
- IO buffer type LVCMOS
supports fixed (1.8V or 3.3V) or SDIO type dynamic voltage switching (1.8V
or 3.3V).
- Connection of valid supply
(fixed, 1.8V or 3.3V) to IO supply for IO groups (VDDSHVx [x = 0-3],
VDDSHV_MCU, VDDSHV_CANUART) and dynamically switched (1.8V or 3.3V) supply
to IO supply for IO groups (VDDSHVx [x = 5-6]).
- IO supply for IO groups referenced by the signals interfaced to the
attached device and the attached device IO supply are connected to the same
supply source.
- Pullups are connected to the same supply rail or voltage level that is
connected to the processor VDDSHVx and the attached device.
- IO supply source used follows the ROC as per processor-specific data
sheet.
- Connection of the IO supply and supply sequencing follows the
processor-specific data sheet.
- Connection of processor DDRSS IO supply (PHY IO and Clock IO, VDDS_DDR and
VDDS_DDR_C shall be sourced from the same power source) based on the
selected memory type (LPDDR4).
Additional
- The recommendation is to follow
the power sequencing requirements as per the processor-specific data sheet based
on the IO supply for IO groups voltage level (3.3V or 1.8V) used.
- Dynamic voltage switching is supported by
specific IO supply for IO groups (VDDSHV5 and VDDSHV6).
- Dynamic voltage switching for the IO supply for IO group referenced by (connected to) LVCMOS IO buffers is not recommended or allowed (VDDSHV0-3, VDDSHV_MCU, VDDSHV_CANUART).
- Connecting 3.3V input supply (non sequenced, permanently ON, 3.3V supply
connected to the PMIC input) directly to the IO supply for IO groups VDDSHVx is
not recommended, since the IO supply is available for an undefined time in case
the PMIC does not start-up and generate the other processor supply rails. The
recommendation is to refer the updated power sequence diagrams in the
processor-specific data sheet.