General
Review and verify the following for
the custom schematic design:
- Reviewed above "Common
checklist for all sections" section of the user's guide.
- Connection of processor core
VDD_CORE and peripheral core VDDA_CORE_DSI, VDDA_CORE_DSI_CLK,
VDDA_CORE_USB, and VDDA_DDR_PLL0 supply (fixed, 0.75V only)
- ROC, slew rate as per
processor-specific data sheet and voltage sequence requirements for
processor core and peripheral core supply rails.
- Addition of the required bulk
and decoupling capacitors, and peripheral core supply filters.
- Connection of peripheral core
supply pins when specific peripherals are not used.
- Connection of peripherals
core supplies VDDA_CORE_DSI, VDDA_CORE_DSI_CLK (DSITX0) when peripheral is
not used but boundary scan function is required.
Schematic Review
Follow the below list for the custom
schematic design:
- The recommendation is to compare the implementation of the bulk and decoupling
capacitors for the supply rails with EVM schematic implementation or refer PDN
application note
- A fixed and recommended supply
voltage of 0.75V is applied to the processor core VDD_CORE and peripheral core
VDDA_CORE_DSI, VDDA_CORE_DSI_CLK, VDDA_CORE_USB, and VDDA_DDR_PLL0 supply
rails
- The supply rail operating voltage connected to processor core and peripheral
core supplies follows the ROC
- The recommendation is to connect
supply rail VDDA_3P3_USB to a 3.3V supply for supporting USB 2.0 interface. The
recommendation is to connect 3.3V supply voltage to VDDA_3P3_SDIO (same as
output of SD card power control power switch that can be reset) integrated LDO
input.
- Ferrite filters are provided for peripheral core supplies (DSI, USB)
- Connection of core supply when specific peripherals are not used as per pin
connectivity requirements
- Connection of core supply (VDDA_CORE_DSI, VDDA_CORE_DSI_CLK for DSITX0), when
peripheral is not used but the boundary scan function is required, follow data
sheet pin connectivity requirements
Additional
- The recommendation is to add a 0Ω
resistor or jumper for isolation or current measurement at the PMIC DC/DC or LDO
output for the core supply. The recommendation is to add TPs for measurement.
The recommendation is to follow kelvin current sense connection to connect the
TPs. Choose the resistor package based on the supply rail current and the
resistor current carrying capacity.
- Dynamic voltage scaling (DVS) of
core supplies is not supported (not recommended or allowed).
- Changing the core voltage after
the device is released from reset is not allowed. When the core supply is turned
off, the recommendation is to ramp down all the power supply rails as per the
power-down sequence and wait until all supply rails decay below 300mV before
turning on power.
- When 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 not used reduces power when low power is a critical requirement.