[FAQ] DDR part selection guidance for Sitara Processors

Other Parts Discussed in Thread: AM62P, AUDIO-AM62D-EVM, AM62L, AM67, AM67A

Introduction

This FAQ serves to offer guidance and supplementary details for choosing appropriate LPDDR4 and DDR4 memory components that are compatible with TI's Sitara processors. The information provided is intended to assist customers in evaluating project viability when considering these system-on-chip solutions for integration into their product designs.  Successful designs not only require compatible memory devices, but also require a proper high speed board layout which must follow the DDR Board Design and Layout Guidelines application note for your particular device (see the TI product page for your specific device).  In addition, all new designs must use the DDR Register Configuration Tool (see dev.ti.com/sysconfig) to configure the DDR controller/PHY registers in software for proper operation.    

Customers must evaluate memory devices for features that are needed in their design.  The table below lists devices that have undergone certain levels of validation using one of TI's EVMs.  See below the table for Tier description. This table does not represent the only devices compatible with Sitara processors.      

Tier 1 Full Characterization Performed on TI development boards.  The devices are typically the ones you will find on the TI EVMs

Tier 2 Functional Validation across operating temperature performed.  Compliance tests passed.  Functional validation include running linux memtester.  No other features (eg, low power, FSP) is validated.

Tier 3 Memory device used in customer designs.  Memory compatible based on device datasheet.

Several other manufacturers devices are also compatible with Sitara devices, based on datasheets timing and descriptions.  Specific part numbers are not listed, but guidance is given below to help choose a compatible device.  Tier 3 devices from the following manufacturers have been used across many customer designs successfully: Micron, Nanya, Samsung, ISSI, Kingston, Winbond, SK Hynix, Gigadevice, Alliance Memory, Changxin Memory Technology (CXMT).   The DDR interface on Sitara devices is compatible with DDR4 devices that are JESD79-4B standard-compliant for those devices that support DDR4, and LPDDR4 devices that are JESD209-4B standard-compliant for those devices that support LPDDR4.  While TI has not independently validated Tier 3 vendor parts, JEDEC-compliant devices that meet the
requirements in this FAQ have proven compatible across many production designs.

Validation with Nanya memories

Nanya has performed functional validation on the device above, and has provided the reports below:

AM62Ax with Nanya LPDDR4 validation report: /cfs-file/__key/communityserver-discussions-components-files/791/Nanya-DRAM-Validation-AM62A-20241009-_2800_Copyright_2900_.pdf

AM62x with Nanya LPDDR4/DDR4 validation report: /cfs-file/__key/communityserver-discussions-components-files/791/Nanya-DRAM-Validation-AM62x-20241009-_2800_Copyright_2900_.pdf

AM64x with Nanya LPDDR4 validation report: /cfs-file/__key/communityserver-discussions-components-files/791/Nanya-DRAM-Validation-AM64x-20241009-_2800_Copyright_2900_.pdf

AM62P with Nanya LPDDR4 validation report:  /cfs-file/__key/communityserver-discussions-components-files/791/Nanya-DRAM-Validation-AM62P-20251114-_2800_Copyright_2900_.pdf

How to Select a Compatible DDR Device

General requirements

• only power-of-2 memories should be used (ie, 1GB, 2GB, 4GB, 8GB, etc).  Non power-of-2 memories may be compatible, but full address range may not be accessible and have not been tested

Processor DDR compatibility

• AM243x, AM64x, AM62x, AM62L: LPDDR4/DDR4
• AM62Ax, AM62Px, AM62Dx, AM67, AM67A: LPDDR4 only
• AM335x: DDR2, DDR3L
• AM437x: DDR3L, LPDDR2

Maximum Compatible Densities

(1) Most LPDDR4 x16 devices on the market are single rank.  Dual rank is only supported with single package LPDDR4.   Designing with two single channel memory packages is not supported due to board routing limitations (routing data bus (DQ) as T-branch not supported). 

(2) Although AM62x is capable of addressing 4GByte LPDDR4, this capacity is only achievable with the following topologies:

• 4GB in single-channel /single-rank memory package: not currently available in the market

• 4GB in single-channel/dual-rank memory package: not currently available in the market

• 8GB in dual-channel/dual-rank memory package, and only connect one channel:  functionally can work, but half the available memory is not accessible.

  Due to the limited availability of these options, the practical maximum capacity for AM62x with LPDDR4 is 2GBytes.  If more is needed, consider moving to DDR4. 

DDR4 specific requirements

• choose memory devices that are JEDEC standard compliant (JESD79-4B).    Memories that support the latest standard (ie, JESD79-4D) can be used, but some of the newer features not mentioned in 4B version of the spec are not supported.
• choose memory devices that support Read DBI.  Some devices do not support this.    

LPDDR4 specific requirements

• choose memory devices that are JEDEC standard compliant (JESD209-4B).    Memories that support the latest standard (ie, JESD209-4E) can be used, but some of the newer features not mentioned in 4B version of the specs are not supported.
• only LPDDR4 devices with IO voltage VDDQ = 1.1V are supported.  LPDDR4x (with IO voltage VDDQ = 0.6V) is not supported.  Some memory datasheets and device will combine LPDDR4/LPDDR4x functionality.  Ensure the device supports LPDDR4 IO voltages: VDD1=1.8V, VDD2=VDDQ=1.1V
• LPDDR4 byte mode memories are not supported
• Connecting multiple LPDDR4 devices is not supported.  This would require a T-branched split of the DQ/DM/DQS on the board (to route a byte to each channel), but data bus is required to be routed point to point.
  • Single channel, dual-rank LPDDR4 choices are limited in the market.
• Byte-wide LPDDR4 devices are not supported.  Choose only devices with x16 channels (single or dual channel, depending on the processor you are using)

AM64x/AM243x specific information

• Refer to Maximum Compatibility Table for information.  Note AM64x only supports single channel interface and single rank 

AM62x specific information

• Refer to Maximum Compatibility Table for information. 
• AM62x can support single or dual rank devices for DDR4. 
• Maximum density of 8GByte can be achieved with two x8 DDR4 devices such as Micron MT40A4G8.  Each x8 device has two ranks.  Consult the DDR Layout Guidelines for connection example.

AM62L specific information

• Refer to Maximum Compatibility Table for information
• only single rank is supported
• can support both LPDDR4 and DDR4

AM62A/AM62P/AM62D/AM67/AM67A specific information

• Refer to Maximum Compatibility Table for information
• only LPDDR4 is supported

Step-by-Step Design Guide

1. Board designers should consult the following application notes during DDR portion of their board design

AM64x/AM243x DDR Board Design and Layout Guidelines: https://www.ti.com/lit/pdf/spracu1

AM62x, AM62Lx DDR Board Design and Layout Guidelines: https://www.ti.com/lit/pdf/sprad06

AM62Ax, AM62Px, AM62Dx LPDDR4 Board Design and Layout Guidelines: https://www.ti.com/lit/pdf/sprad66

High-Speed Interface Layout Guidelines: https://www.ti.com/lit/pdf/spraar7

2. Power aware board simulation are highly recommended to ensure proper board design.  Application note above have guidance on running simulations

3. Software engineers: Using DDR Register Configuration Tool to generate DDR software configuration header file is mandatory.  Do not rely on configurations provided in SDKs, those are optimized for the EVMs.  Guidance on setting parameters in the tool can be found in the README link in the tool.  Here are direct links to each tool per device:

• AM243x: dev.ti.com/.../
• AM64x:  https://dev.ti.com/sysconfig/?product=Processor_DDR_Config&device=AM64x
• AM62x:  https://dev.ti.com/sysconfig/?product=Processor_DDR_Config&device=AM62x
• AM62Ax: https://dev.ti.com/sysconfig/?product=Processor_DDR_Config&device=AM62Ax
• AM62Px: https://dev.ti.com/sysconfig/?product=Processor_DDR_Config&device=AM62Px
• AM62Lx: https://dev.ti.com/sysconfig/?product=Processor_DDR_Config&device=AM62L
• AM62Dx: https://dev.ti.com/sysconfig/?product=Processor_DDR_Config&device=AM62Dx
• AM67x: https://dev.ti.com/sysconfig/?product=TDA4x_DRA8x_AM67x-AM69x_DDR_Config&device=AM67
• AM67A: https://dev.ti.com/sysconfig/?product=TDA4x_DRA8x_AM67x-AM69x_DDR_Config&device=AM67A

Validation Guidance

Knobs to turn:

Temperature

• run memtester across your operating temperature, especially at both extremes
• boot at one extreme temp, run memtester and ramp to other extreme temp(do this both cold to hot, hot to cold)
• ensure your DDR configuration is set for the high temp operation

Voltage

• if possible, change core or DDR IO voltage (up to -5% of nominal) and run memtester.  Probably -1 to -3% is practical enough, you don’t want to get too close to Vmin or you may experience fails because voltage is out of spec.  But this type of test will help determine the stability of your power network.

Frequency

• run memtester with DDR configuration at +5% frequency (ie, 840MHz).  You have to create a new DDR configuration using the DDR Register Configuration tool to do this.  Technically this is above the spec’ed limit, but practically this should be able to run without fail.

For further stress, you can combine any or all three of the above.

DDR Margin Tool

The DDR margin firmware and supporting scripts allow visualization and measurement of system margin to LPDDR4 memories in the DDR interface on board. These tools enable probe-less measurement of critical data signals to understand the integrity and robustness of the interface.  Find the latest tool here: https://www.ti.com/tool/download/DDR-MARGIN-FW

Frequently Asked Questions

Do I need a new DDR configuration file for each vendor's device i have on my board?

It's very likely that you can generate a common DDR configuration file that will work with multiple vendor's devices.  Most timing parameters in the DDR Register Configuration Tool will be equivalent for memories of the same density and topology since they will conform to the JEDEC specification.  You may have to find common IO parameters (termination and drive strength) for proper signal integrity.

How do I know if a device not in the table is compatible?

When choosing a device, first ensure you follow the guidelines for your device type and the processor you are interfacing with as outlined in this FAQ.  Start with the vendors listed above, but you may also consider vendors not in the list that have JEDEC compliant memory devices.  Sitara processors are compatible with any JEDEC compliant memory device.