General
Review and verify the following for
the custom schematic design:
- Above sections, including
relevant application notes and FAQ links
- Pin attributes, signal
description, and electrical specifications
- Electrical characteristics
and additional available information
- A valid fixed supply source is connected to
(VDDSHV_CANUART, VDDSHV_MCU, VDDSHV0, VDDSHV1,
VDDSHV2, VDDSHV3) all the IO supply for IO groups as
per the ROC
- A valid supply (that can be dynamically changed)
source is connected to VDDSHV5, VDDSHV6 as per the
ROC of the processor-specific data sheet
- Slew rate requirements for IO supply rails for IO
groups are followed
- Internal LDO output pins have
the recommended capacitors connected (across CAP_VDDSn pin and VSS)
- Power sequence recommendations as per the
processor-specific data sheet are followed
Schematic Review
Follow the below list for the custom
schematic design:
- Connection of the recommended
capacitor to CAP_VDDSn pins and VSS
- CAP_VDDSn capacitor package
(use the smallest possible (0201 or greater package possible which is
closest to 0201) package to minimize loop inductance)
- Voltage rating of the capacitor selected for the
capacitance value to be in the range 0.8 to 1.5μF
including aging, temperature and effect of DC
bias
- All IO supply rails for IO groups have a valid
supply irrespective of the use of the IOs
- Supply rails connected follow
the ROC
- Each CAP_VDDSn pin requires a
separate 1μF capacitor connected with respect to VSS (ground)
- Select CAP_VDDSn capacitor with < 1Ω ESR, keep
the trace loop inductance < 2.5nH
Additional
- For all supply
rails, use a 0Ω resistor or jumper for isolation or current
measurement at the output of the supply rails. Choose the
package of the resistor based on the supply rail current and
the resistor current carrying capacitor.
- When any of the VDDSHVx power rails are sourced
from the 3.3V supply, all IOs referenced to the VDDSHVx must
operate at 3.3V IO level. If a VDDSHVx power rail is sourced
from a 1.8V supply, all IOs referenced to the VDDSHVx must
operate at 1.8V IO level.
- Some interfaces span multiple VDDSHVx, for
example MMC2 and GPMC. When using one of the interfaces, all
VDDSHVx domains supporting a specific interface need to
share the same voltage source.
- Most processor IOs are not fail-safe. Applying
input voltage to the IOs while the corresponding VDDSHVx
supply is off is not recommended or allowed.
- Verify all IO pins on each VDDSHVx (or
VDDSHV_MCU) only connects to a single voltage level.
- Follow the processor-specific SK
for implementation of ferrites and capacitors.
- Leaving VDDSHV5
rail unconnected is not recommended. Connect the power pins
to either 1.8V or 3.3V, depending on the use case.