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
- Recommended voltages are
applied to the core VDD power supply rails 0.75V or 0.85V
- Refer Power-Up Sequencing
– Supply / Signal Assignments section of the processor-specific data
sheet for sequencing the core supplies when partial IO low power mode is
used and when partial IO low power mode is not used.
- The potential applied to
VDDR_CORE must never exceed the potential applied to VDD_CORE +0.18V during
power-up or power-down. The sequencing requires VDD_CORE to ramp up before
VDDR_CORE and ramp down after VDDR_CORE when VDD_CORE is operating at
0.75V
- Power VDD_CORE and VDDR_CORE
from the same source to ramp together when the VDD_CORE is operating at
0.85V
- Connection of core supply
when specific peripheral is not used as per pin connectivity
requirements
- Connection of core supply
(CSIRX0, DSITX0), when a specific peripheral is unused but the boundary scan
function is required, as per pin connectivity requirements
Schematics Review
Have you followed the below for the
custom schematic design:
- Compare the implementation of
the bulk and decoupling capacitors for all the supplies rails with SK
schematics
- Ferrite filters are provided
for peripheral core supplies (CSI0, USB0-1, CANUART) as per the SK
schematics
- When peripherals are unused
but the boundary scan function is required, ferrites and bulk capacitors are
optional for peripheral core supplies
- Supply rails connected follow
the ROC
Additional
- For all supply rails, place a 0Ω resistor or jumper for isolation or current
measurement at the output of the supply rails
- Changing the core voltage is not allowed after the device is released from
reset. If the core supply is turned off, turn off and ramp down all power rails
per the power-down sequence and wait until all supply rails decay below 300mV
before turning on power again
- When the USB driver is not initialized and the USB calibration procedure does
not happen, connecting the supplies and leaving all of the USB pins for USB0,
USB1, or both is acceptable. Grounding the USB supplies per pin connectivity
requirements when both USB interfaces are unused saves power when low power is a
critical requirement
- Follow the processor-specific SK for implementation of ferrites and
capacitors
- Dynamic scaling of the core supplies is not allowed or recommended