General
Review and verify the following for the custom
schematic design:
- Reviewed above "Common
checklist for all sections" section of the user's guide.
- Memory selected confirms to the relevant JEDEC (JESD209-4B) standard.
- Memory configuration used.
- The recommendation is to add layout notes on the schematic (the
recommendation is to follow the AM62Ax, AM62Px, AM62Dx LPDDR4 Board
Design and Layout Guidelines).
- Supply rails connected to the processor DDRSS peripheral supply rail and
the attached memory device IO.
- Connection of address, clock, control and data signals.
- Connection of DDRSS RESETn signal to LPDDR4_RESET_N memory reset input.
- Connection of chip select CSn0, CSn1 to the attached memory device.
- ODT pullup connection, DDR CAL0 and Memory ZQn resistor connections.
- Swapping of Data Bits or Data Bytes.
Schematic Review
Follow the below list for the custom schematic
design:
- For LPDDR4 memory interface,
x16 and x32 are the supported memory configurations. For connecting the
DDRSS to 16-bit or 32-bit memory devices - refer AM62Ax, AM62Px, AM62Dx
LPDDR4 Board Design and Layout Guidelines.
- The recommendation is to
compare the bulk and decoupling capacitors used and values with SK or EVM
schematic implementation.
- Supply rails connected to
the processor DDRSS peripheral supply and the attached memory device IO
follow the processor and attached memory device ROC.
- Connection of address, clock,
control and data signals. For LPDDR4 memory interface, x16 and x32 are the
supported data bus width. For connecting the DDRSS to 16-bit or 32-bit
memory devices - refer AM62Ax, AM62Px, AM62Dx LPDDR4 Board Design and
Layout Guidelines.
- Connection of DDRSS RESETn
signal directly to LPDDR4_RESET_N memory reset input (to hold the signal low
during power-on initialization). The recommendation is to add a pulldown
(10kΩ) for DDRSS RESETn signal and place close to the memory device reset
input pin.
- Connection of chip select
CSn0, CSn1 to the attached memory device. Follow AM62Ax, AM62Px, AM62Dx
LPDDR4 Board Design and Layout Guidelines based on selected
memory.
- Memory device ODT pulled up
through a resistor (2.2kΩ or similar, the recommendation is to not connect
DDRSS signals and follow the SK or EVM schematics).
- DDR0_CAL0, DDRSS IO pad
calibration resistor (240Ω, ±1%) connected across DDR0_CAL0 and VSS.
- ZQ0, ZQ1, Memory device IO
calibration resistor (240Ω, ±1%) connected across ZQ and VDD_LPDDR4.
- Data Bit or Byte Swapping.
Follow AM62Ax, AM62Px, AM62Dx LPDDR4 Board Design and Layout
Guidelines.