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_USB supply rail.
- ROC, slew rate and voltage
sequence requirements for processor core and peripheral core supply
rails.
- Connection of VDD_CORE and
VDDR_CORE when VDD_CORE supply is 0.75V or 0.85V.
- Peripheral core supply
filters.
- Connection of core supply
when specific peripherals are not used.
- Connection of SERDES0 core supply (VDDA_0P85_SERDES0, VDDA_0P85_SERDES0_C)
when peripheral is not used but the boundary scan function is required
- Connection of VDD_MMC0,
VDD_DLL_MMC0 when eMMC is used or when eMMC is not used
Schematics 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 or SK schematic implementation or refer PDN
application note.
- The supply rail operating
voltage connected to processor core supplies follows the ROC.
- Recommended supply voltage
0.75V or 0.85V is applied to the processor core VDD_CORE and peripheral core
VDDA_CORE_USB supply rail operating voltage.
- Processor core and peripheral
core supply rails connected to the relevant supply pins follow the
recommended voltage sequence. 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.
- Slew rate of the supply rail
follows the data sheet requirements.
- The potential applied to
VDDR_CORE never exceeds 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.
- The recommendation is to
power VDD_CORE and VDDR_CORE from the same source when the VDD_CORE is
operating at 0.85V.
- Ferrite filters are provided
for peripheral core supplies (SERDES0, USB) as per the EVM or SK schematic
implementation.
- Connection of core supply
when specific peripherals are not used as per pin connectivity
requirements.
- Connection of core supply
(VDDA_0P85_SERDES0, VDDA_0P85_SERDES0_C for SERDES0), when peripheral is not
used but the boundary scan function is required, follow data sheet pin
connectivity requirements. Ferrites and bulk capacitors are optional for
peripheral core supplies.
- Peripheral core supplies
VDD_MMC0 and VDD_DLL_MMC0 are specified to operate at 0.85V when MMC0
interface (eMMC) is used. The recommendation is to connect VDD_MMC0 and
VDD_DLL_MMC0 to the same power source as VDD_CORE when MMC0 interface is not
used.
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 is not
allowed after the device is released from reset. If the core supply is turned
off, the recommendation is to ramp down all the power 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 is acceptable. Grounding the
USB supplies as per pin connectivity requirements when both USB interfaces are
not used reduces power when low power is a critical requirement.