SPRAD21F May   2022  – November 2024 AM620-Q1 , AM623 , AM625 , AM625-Q1 , AM625SIP , AM62A3 , AM62A3-Q1 , AM62A7 , AM62A7-Q1 , AM62P , AM62P-Q1

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1 Introduction
    1. 1.1 Application Note Usage Guidelines
      1. 1.1.1 Schematics Design Guidelines
      2. 1.1.2 Schematic Review Checklist
      3. 1.1.3 FAQ Reference for Application Note Usage Guidelines
    2. 1.2 AM62x Processor Family
      1. 1.2.1 AM625
      2. 1.2.2 AM623
      3. 1.2.3 AM625SIP
      4. 1.2.4 AM625-Q1
      5. 1.2.5 AM620-Q1
    3. 1.3 AM62Ax Processor Family
      1. 1.3.1 AM62A7
      2. 1.3.2 AM62A7-Q1
      3. 1.3.3 AM62A3
      4. 1.3.4 AM62A3-Q1
    4. 1.4 AM62Px Processor Family
      1. 1.4.1 AM62P
      2. 1.4.2 AM62P-Q1
  5. 2 Related Collaterals
    1. 2.1 Links to Commonly Available and Applicable Collaterals
      1. 2.1.1 AM625 / AM623 / AM625SIP / AM625-Q1 / AM620-Q1
      2. 2.1.2 AM62A7 / AM62A3 / AM62A7-Q1 / AM62A3-Q1
      3. 2.1.3 AM62P / AM62P-Q1
    2. 2.2 Hardware Design Considerations for Custom Board
      1. 2.2.1 AM625 / AM623 / AM625SIP / AM625-Q1 / AM620-Q1
      2. 2.2.2 AM62A7 / AM62A3 / AM62A7-Q1 / AM62A3-Q1
      3. 2.2.3 AM62P / AM62P-Q1
  6. 3 Processor Selection
    1. 3.1 Data Sheet Use Case and Version References in the Application Note
    2. 3.2 Device Selection and OPN
    3. 3.3 Peripheral Instance Naming Convention
    4. 3.4 Unused Peripherals
    5. 3.5 Device Ordering and Quality
    6. 3.6 Processor Selection Checklist
  7. 4 Power Architecture
    1. 4.1 Generating Supply Rails
      1. 4.1.1 AM625 / AM623 / AM625SIP / AM625-Q1 / AM620-Q1
        1. 4.1.1.1 Power Management IC (PMIC)
          1. 4.1.1.1.1 PMIC Checklist
          2. 4.1.1.1.2 Additional References
        2. 4.1.1.2 Discrete Power
          1. 4.1.1.2.1 DC/DC Converter
          2. 4.1.1.2.2 LDO
          3. 4.1.1.2.3 Discrete Power Checklist
      2. 4.1.2 AM62A7 / AM62A3 / AM62A7-Q1 / AM62A3-Q1
        1. 4.1.2.1 PMIC
          1. 4.1.2.1.1 PMIC Checklist
        2. 4.1.2.2 Discrete Power
          1. 4.1.2.2.1 Discrete Power Checklist
      3. 4.1.3 AM62P / AM62P-Q1
        1. 4.1.3.1 PMIC
          1. 4.1.3.1.1 PMIC Checklist
        2. 4.1.3.2 Discrete Power
          1. 4.1.3.2.1 Discrete Power Checklist
    2. 4.2 Power Control and Circuit Protection
      1. 4.2.1 Load Switch (Power Switching)
        1. 4.2.1.1 Load Switch Checklist
      2. 4.2.2 eFuse IC (Power Switching and Protection)
  8. 5 General Recommendations
    1. 5.1 Processor Performance Evaluation Module (SK - Starter Kit)
      1. 5.1.1 Evaluation Module Checklist
    2. 5.2 Device-Specific (Processor-Specific, Processor-Family Specific) SK Versus Data Sheet
      1. 5.2.1 Notes About Component Selection
        1. 5.2.1.1 Series Resistor
        2. 5.2.1.2 Parallel Pull Resistor
        3. 5.2.1.3 Drive Strength Configuration
        4. 5.2.1.4 Data Sheet Recommendations
        5. 5.2.1.5 Processor IOs - External ESD Protection
        6. 5.2.1.6 Peripheral Clock Output Series Resistors
        7. 5.2.1.7 Component Selection Checklist
      2. 5.2.2 Additional Information Regarding Reuse of SK Design
        1. 5.2.2.1 Updated SK Schematic With Design, Review and CAD Notes Added
          1. 5.2.2.1.1 AM625 / AM623
          2. 5.2.2.1.2 AM625-Q1 / AM620-Q1
          3. 5.2.2.1.3 AM625SIP
          4. 5.2.2.1.4 AM62A7 / AM62A3 / AM62A7-Q1 / AM62A3-Q1
          5. 5.2.2.1.5 AM62P / AM62P-Q1
        2. 5.2.2.2 SK Design Files Reuse
          1. 5.2.2.2.1 Reuse of SK Design Checklist
    3. 5.3 Before Beginning the Design
      1. 5.3.1  Documentation
      2. 5.3.2  Processor Pin Attributes (Pinout) Verification
      3. 5.3.3  Device Comparison and IOSET
      4. 5.3.4  RSVD Reserved Pins (Signals)
      5. 5.3.5  Note on PADCONFIG Registers
      6. 5.3.6  Processor IO (Signal) Isolation for Fail-Safe Operation
      7. 5.3.7  Reference to Device-Specific SK
      8. 5.3.8  High-Speed Interface Design Guidelines
      9. 5.3.9  Recommended Current Source or Sink for LVCMOS (GPIO) Outputs
      10. 5.3.10 Connection of Slow Ramp Inputs or Capacitors to LVCMOS IOs (Inputs or Outputs)
      11. 5.3.11 Queries and Clarifications Related to Processor During Custom Board Design
      12. 5.3.12 Before Beginning the Design
      13. 5.3.13 Device Recommendations
  9. 6 Processor-Specific Recommendations
    1. 6.1 Common (Processor Start-Up) Connection
      1. 6.1.1 Power Supply
        1. 6.1.1.1 Supply for Core and Peripherals
          1. 6.1.1.1.1 AM625 / AM623 / AM625SIP / AM625-Q1 / AM620-Q1 and AM62A7 / AM62A3 / AM62A7-Q1 / AM62A3-Q1
          2. 6.1.1.1.2 AM62P / AM62P-Q1
          3. 6.1.1.1.3 Additional Information
          4. 6.1.1.1.4 Processor Core and Peripheral Core Power Supply Checklist
          5. 6.1.1.1.5 Peripheral Analog Power Supply Checklist
        2. 6.1.1.2 Supply for IO Groups
          1. 6.1.1.2.1 AM625 / AM623 / AM625SIP / AM625-Q1 / AM620-Q1 and AM62A7 / AM62A3 / AM62A7-Q1 / AM62A3-Q1
          2. 6.1.1.2.2 AM62P / AM62P-Q1
          3. 6.1.1.2.3 Additional Information
          4. 6.1.1.2.4 Supply for IO Groups Checklist
        3. 6.1.1.3 Supply for VPP (eFuse ROM Programming)
          1. 6.1.1.3.1 VPP Checklist
        4. 6.1.1.4 Supply Connection for Partial IO Mode (Low-Power) Configuration
          1. 6.1.1.4.1 Partial IO Used
          2. 6.1.1.4.2 Partial IO Unused
          3. 6.1.1.4.3 Data Sheet Reference for Power Sequence
          4. 6.1.1.4.4 Partial IO Low Mode Checklist
        5. 6.1.1.5 Additional Information
      2. 6.1.2 Capacitors for Supply Rails
        1. 6.1.2.1 AM625 / AM623 / AM625SIP / AM625-Q1 / AM620-Q1
        2. 6.1.2.2 AM62A7 / AM62A3 / AM62A7-Q1 / AM62A3-Q1 and AM62P / AM62P-Q1
        3. 6.1.2.3 Additional Information
          1. 6.1.2.3.1 AM625 / AM623 / AM625SIP / AM625-Q1 / AM620-Q1 and AM62A7 / AM62A3 / AM62A7-Q1 / AM62A3-Q1
          2. 6.1.2.3.2 AM62P / AM62P-Q1
        4. 6.1.2.4 Capacitors for Supply Rails Checklist
      3. 6.1.3 Processor Clock
        1. 6.1.3.1 Clock Inputs
          1. 6.1.3.1.1 High Frequency Oscillator (MCU_OSC0_XI / MCU_OSC0_XO)
          2. 6.1.3.1.2 Low Frequency Oscillator (WKUP_LFOSC0_XI / WKUP_LFOSC0_XO)
          3. 6.1.3.1.3 EXT_REFCLK1 (External Clock Input to Main Domain)
          4. 6.1.3.1.4 Additional Information
          5. 6.1.3.1.5 Clock Input Checklist - MCU_OSC0
          6. 6.1.3.1.6 Clock Input Checklist - WKUP_LFOSC0
        2. 6.1.3.2 Clock Outputs
          1. 6.1.3.2.1 Clock Output Checklist
      4. 6.1.4 Processor Reset
        1. 6.1.4.1 External Reset Inputs
        2. 6.1.4.2 Reset Status Outputs
        3. 6.1.4.3 Additional Information
        4. 6.1.4.4 Processor Reset Input Checklist
        5. 6.1.4.5 Processor Reset Status Output Checklist
      5. 6.1.5 Configuration of Boot Modes (for Processor)
        1. 6.1.5.1 Processor Boot Mode Inputs Isolation Buffers Use Case and Optimization
        2. 6.1.5.2 Boot Mode Selection
          1. 6.1.5.2.1 Notes for USB Boot Mode
        3. 6.1.5.3 Boot Mode Implementation Approaches
        4. 6.1.5.4 Additional Information
        5. 6.1.5.5 Configuration of Boot Modes (for Processor) Checklist
    2. 6.2 Board Debug Using JTAG and EMU
      1. 6.2.1 JTAG and EMU Used
      2. 6.2.2 JTAG and EMU Not Used
      3. 6.2.3 Additional Information
      4. 6.2.4 Board Debug Using JTAG and EMU Checklist
  10. 7 Processor Peripherals
    1. 7.1 Supply Connections for IO Groups
      1. 7.1.1 AM625 / AM623 / AM625SIP / AM625-Q1 / AM620-Q1 and AM62A7 / AM62A3 / AM62A7-Q1 / AM62A3-Q1
      2. 7.1.2 AM62P / AM62P-Q1
      3. 7.1.3 Supply Connections for IO Groups Checklist
    2. 7.2 Memory Interface (DDRSS (DDR4 / LPDDR4), MMCSD (eMMC / SD / SDIO), OSPI / QSPI and GPMC)
      1. 7.2.1 DDR Subsystem (DDRSS)
        1. 7.2.1.1 DDR4 SDRAM (Double Data Rate 4 Synchronous Dynamic Random-Access Memory)
          1. 7.2.1.1.1 AM625 / AM623 / AM625-Q1 / AM620-Q1
            1. 7.2.1.1.1.1 Memory Interface Configuration
            2. 7.2.1.1.1.2 Routing Topology and Terminations
            3. 7.2.1.1.1.3 Resistors for Control and Calibration
            4. 7.2.1.1.1.4 Capacitors for the Power Supply Rails
            5. 7.2.1.1.1.5 Data Bit or Byte Swapping
            6. 7.2.1.1.1.6 VTT Termination Schematics Reference
            7. 7.2.1.1.1.7 DDR4 Implementation Checklist
          2. 7.2.1.1.2 AM625SIP
          3. 7.2.1.1.3 AM62A7 / AM62A3 / AM62A7-Q1 / AM62A3-Q1
          4. 7.2.1.1.4 AM62P / AM62P-Q1
        2. 7.2.1.2 LPDDR4 SDRAM (Low-Power Double Data Rate 4 Synchronous Dynamic Random-Access Memory)
          1. 7.2.1.2.1 AM625 / AM623 / AM625-Q1 / AM620-Q1
            1. 7.2.1.2.1.1 Memory Interface Configuration
            2. 7.2.1.2.1.2 Routing Topology and Terminations
            3. 7.2.1.2.1.3 Resistors for Control and Calibration
            4. 7.2.1.2.1.4 Capacitors for the Power Supply Rails
            5. 7.2.1.2.1.5 Data Bit or Byte Swapping
            6. 7.2.1.2.1.6 LPDDR4 Implementation Checklist
          2. 7.2.1.2.2 AM625SIP
          3. 7.2.1.2.3 AM62A7 / AM62A3 / AM62A7-Q1 / AM62A3-Q1 and AM62P / AM62P-Q1
            1. 7.2.1.2.3.1 Memory Interface Configuration
            2. 7.2.1.2.3.2 Routing Topology and Terminations
            3. 7.2.1.2.3.3 Resistors for Control and Calibration
            4. 7.2.1.2.3.4 Capacitors for the Power Supply Rails
            5. 7.2.1.2.3.5 Data Bit or Byte Swapping
            6. 7.2.1.2.3.6 LPDDR4 Implementation Checklist
      2. 7.2.2 Multi-Media Card/Secure Digital (MMCSD)
        1. 7.2.2.1 MMC0 - eMMC (Embedded Multi-Media Card) Interface
          1. 7.2.2.1.1 AM625 / AM623 / AM625SIP / AM625-Q1 / AM620-Q1 and AM62A7 / AM62A3 / AM62A7-Q1 / AM62A3-Q1
            1. 7.2.2.1.1.1 IO Power Supply
            2. 7.2.2.1.1.2 eMMC (Attached Device) Reset
            3. 7.2.2.1.1.3 Signals Connection
            4. 7.2.2.1.1.4 Capacitors for the Power Supply Rails
            5. 7.2.2.1.1.5 MMC0 (eMMC) Checklist for AM62x and AM62Ax
          2. 7.2.2.1.2 AM62P / AM62P-Q1
            1. 7.2.2.1.2.1 MMC0 Used
              1. 7.2.2.1.2.1.1 IO Power Supply
              2. 7.2.2.1.2.1.2 eMMC (Attached Device) Reset
              3. 7.2.2.1.2.1.3 Signals Connection
              4. 7.2.2.1.2.1.4 Capacitors for the Power Supply Rails
            2. 7.2.2.1.2.2 MMC0 Not Used
            3. 7.2.2.1.2.3 MMC0 (eMMC) Checklist for AM62P
          3. 7.2.2.1.3 Additional Information on eMMC PHY
          4. 7.2.2.1.4 MMC0 – SD (Secure Digital) Card Interface
        2. 7.2.2.2 MMC1/MMC2 – SD (Secure Digital) Card Interface
          1. 7.2.2.2.1 IO Power Supply
          2. 7.2.2.2.2 SD Card Supply Reset and Boot Configuration
          3. 7.2.2.2.3 Signals Connection
          4. 7.2.2.2.4 ESD Protection
          5. 7.2.2.2.5 Capacitors for the Power Supply Rails
          6. 7.2.2.2.6 MMC1 SD Card Interface Checklist
        3. 7.2.2.3 MMC1 / MMC2 SDIO (Embedded) Interface
          1. 7.2.2.3.1 IO Power Supply
          2. 7.2.2.3.2 Signals Connection
          3. 7.2.2.3.3 MMC2 SDIO (Embedded) Interface Checklist
        4. 7.2.2.4 Additional Information
      3. 7.2.3 Octal Serial Peripheral Interface (OSPI) and Quad Serial Peripheral Interface (QSPI)
        1. 7.2.3.1 IO Power Supply
        2. 7.2.3.2 OSPI / QSPI Reset
        3. 7.2.3.3 Signals Connection
        4. 7.2.3.4 Loopback Clock
        5. 7.2.3.5 Interface to Multiple Devices
        6. 7.2.3.6 Capacitors for the Power Supply Rails
        7. 7.2.3.7 OSPI / QSPI Implementation Checklist
      4. 7.2.4 General-Purpose Memory Controller (GPMC)
        1. 7.2.4.1 IO Power Supply
        2. 7.2.4.2 GPMC Interface
        3. 7.2.4.3 Memory (Attached Device) Reset
        4. 7.2.4.4 Signals Connection
          1. 7.2.4.4.1 GPMC NAND
        5. 7.2.4.5 Capacitors for the Power Supply Rails
        6. 7.2.4.6 GPMC Interface Checklist
    3. 7.3 External Communication Interface (Ethernet (CPSW3G), USB2.0, PRUSS, UART and Controller Area Network (CAN))
      1. 7.3.1 Ethernet Interface Using CPSW3G (Common Platform Ethernet Switch 3-Port Gigabit)
        1. 7.3.1.1  IO Power Supply
        2. 7.3.1.2  Ethernet PHY Reset
        3. 7.3.1.3  Ethernet PHY Pin Strapping
        4. 7.3.1.4  Ethernet PHY (and MAC) Operation and Media Independent Interface (MII) Clock
          1. 7.3.1.4.1 Crystal
          2. 7.3.1.4.2 Oscillator
          3. 7.3.1.4.3 Processor Clock Output (CLKOUT0)
        5. 7.3.1.5  MAC (Data, Control and Clock) Interface Signals Connection
        6. 7.3.1.6  External Interrupt (EXTINTn)
          1. 7.3.1.6.1 External Interrupt (EXTINTn) Checklist
        7. 7.3.1.7  MAC (Media Access Controller) to MAC Interface
        8. 7.3.1.8  MDIO (Management Data Input/Output) Interface
        9. 7.3.1.9  Ethernet MDI (Medium Dependent Interface) Including Magnetics
        10. 7.3.1.10 Capacitors for the Power Supply Rails
        11. 7.3.1.11 Ethernet Interface Checklist
      2. 7.3.2 Universal Serial Bus (USB2.0)
        1. 7.3.2.1 USBn (n = 0-1) Used
          1. 7.3.2.1.1 USB Host Interface
          2. 7.3.2.1.2 USB Device Interface
          3. 7.3.2.1.3 USB Dual-Role-Device Interface
          4. 7.3.2.1.4 USB Type-C®
        2. 7.3.2.2 USBn (n = 0-1) Not Used
        3. 7.3.2.3 Additional Information
        4. 7.3.2.4 USB Interface Checklist
      3. 7.3.3 Programmable Real-Time Unit Subsystem (PRUSS)
        1. 7.3.3.1 AM625 / AM623 / AM625SIP / AM625-Q1 / AM620-Q1
          1. 7.3.3.1.1 PRU Subsystem
          2. 7.3.3.1.2 PRUSS Checklist
        2. 7.3.3.2 AM62A7 / AM62A3 / AM62A7-Q1 / AM62A3-Q1 and AM62P / AM62P-Q1
      4. 7.3.4 Universal Asynchronous Receiver/Transmitter (UART)
        1. 7.3.4.1 Universal Asynchronous Receiver/Transmitter (UART) Checklist
      5. 7.3.5 Controller Area Network (CAN)
        1. 7.3.5.1 Controller Area Network Checklist
    4. 7.4 On-board Synchronous Communication Interface (MCSPI, MCASP and I2C)
      1. 7.4.1 Multichannel Serial Peripheral Interface (MCSPI) and Multichannel Audio Serial Ports (MCASP)
        1. 7.4.1.1 MCSPI Checklist
        2. 7.4.1.2 MCASP Checklist
      2. 7.4.2 Inter-Integrated Circuit (I2C)
        1. 7.4.2.1 I2C Open-drain Output Type Buffer Checklist
        2. 7.4.2.2 I2C Emulated Open-drain Output Type Buffer Checklist
    5. 7.5 User Interface (CSIRX0, DPI, OLDI, DSI), GPIO and Hardware Diagnostics
      1. 7.5.1 Camera Serial Interface (CSI-Rx (CSI-2 port, CSIRX0 Instance))
        1. 7.5.1.1 CSIRX0 Used
        2. 7.5.1.2 CSIRX0 Not Used
        3. 7.5.1.3 CSI Checklist
      2. 7.5.2 Display Subsystem
        1. 7.5.2.1 Display Parallel Interface (DPI)
          1. 7.5.2.1.1 AM625 / AM623 / AM625SIP / AM625-Q1 and AM62A7 / AM62A3 / AM62A7-Q1 / AM62A3-Q1 and AM62P / AM62P-Q1
            1. 7.5.2.1.1.1 IO Power Supply
            2. 7.5.2.1.1.2 DPI (Attached Device) Reset
            3. 7.5.2.1.1.3 Connection
            4. 7.5.2.1.1.4 Signals Connection
            5. 7.5.2.1.1.5 Capacitors for the Power Supply Rails
            6. 7.5.2.1.1.6 DPI Checklist
          2. 7.5.2.1.2 AM620-Q1
        2. 7.5.2.2 Open LVDS Display Interface (OLDI)
          1. 7.5.2.2.1 AM625 / AM623 / AM625SIP / AM625-Q1 and AM62P / AM62P-Q1
            1. 7.5.2.2.1.1 OLDI0 Used
              1. 7.5.2.2.1.1.1 IO Power Supply
              2. 7.5.2.2.1.1.2 OLDI (Attached Device) Reset
              3. 7.5.2.2.1.1.3 OLDI Interface Compatibility
              4. 7.5.2.2.1.1.4 Capacitors for the Power Supply Rails
              5. 7.5.2.2.1.1.5 OLDI Checklist
            2. 7.5.2.2.1.2 OLDI0 Not Used
            3. 7.5.2.2.1.3 Additional Information
          2. 7.5.2.2.2 AM620-Q1 and AM62A7 / AM62A3 / AM62A7-Q1 / AM62A3-Q1
        3. 7.5.2.3 Display Serial Interface (DSI)
          1. 7.5.2.3.1 AM625 / AM623 / AM625SIP / AM625-Q1 / AM620-Q1 and AM62A7 / AM62A3 / AM62A7-Q1 / AM62A3-Q1
          2. 7.5.2.3.2 AM62P / AM62P-Q1
            1. 7.5.2.3.2.1 DSITX0 Used
              1. 7.5.2.3.2.1.1 DSITX0 Checklist
            2. 7.5.2.3.2.2 DSITX0 Not Used
      3. 7.5.3 General Purpose Input/Output (GPIO)
        1. 7.5.3.1 Availability of CLKOUT on Processor GPIO
        2. 7.5.3.2 Connection and External Buffering
        3. 7.5.3.3 Additional Information
        4. 7.5.3.4 GPIO Checklist
      4. 7.5.4 On-board Hardware Diagnostics
        1. 7.5.4.1 Monitoring of On-board Supply Voltages Using Processor Voltage Monitors
          1. 7.5.4.1.1 Voltage Monitor Pins Used
            1. 7.5.4.1.1.1 Voltage Monitor Checklist
          2. 7.5.4.1.2 Voltage Monitor Pins Not Used
        2. 7.5.4.2 Internal Temperature Monitoring
          1. 7.5.4.2.1 Internal Temperature Monitoring Checklist
        3. 7.5.4.3 Connection of Error Signal Output (MCU_ERRORn)
        4. 7.5.4.4 High Frequency Oscillator (MCU_OSC0) Clock Loss Detection
    6. 7.6 Verifying Board Level Design Issues
      1. 7.6.1 Processor Pin Configuration Using PinMux Tool
      2. 7.6.2 Schematics Configurations
      3. 7.6.3 Connecting Supply Rails to Pullups
      4. 7.6.4 Peripheral (Subsystem) Clock Outputs
      5. 7.6.5 General Board Bring-up and Debug
        1. 7.6.5.1 Clock Output for Board Bring-Up, Test, or Debug
        2. 7.6.5.2 Additional Information
        3. 7.6.5.3 General Board Bring-up and Debug Checklist
  11. 8 Layout Notes (Added on the Schematic)
    1. 8.1 Layout Checklist
  12. 9 Custom Board Design Simulation
  13. 10Additional References
    1. 10.1 FAQ Covering AM6xx Processor Family
    2. 10.2 FAQs - Processor Product Family Wise and Sitara Processor Families
    3. 10.3 Processor Attached Devices
  14. 11Summary
  15. 12References
    1. 12.1 AM625 / AM623 / AM625SIP / AM625-Q1 / AM620-Q1
    2. 12.2 AM62A7 / AM62A3 / AM62A7-Q1 / AM62A3-Q1
    3. 12.3 AM62P / AM62P-Q1
    4. 12.4 Common for all Processor Families
    5. 12.5 Master List of Available FAQs - Processor Family Wise
    6. 12.6 Master List of Available FAQs - Sitara Processor Families
    7. 12.7 FAQs Including Software Related
    8. 12.8 FAQs for Attached Devices
  16. 13Terminology
  17. 14Revision History

6.1.5.5 Configuration of Boot Modes (for Processor) Checklist

General

Review and verify the following for the custom schematic design:

  1. Above sections, including relevant application notes and FAQ links
  2. Pin attributes, signal description, and electrical specifications
  3. Electrical characteristics and any additional available information
  4. All BOOTMODE pins have external pulls or a circuit to drive the desired boot mode. Leaving any of the boot mode inputs unconnected is not allowed or recommended
  5. Connecting the boot mode inputs directly to supply or VSS is not recommended. Shorting of multiple boot mode inputs together and connecting a common resistor is not recommended. (Users can have problems with the firmware configuration, where the LVCMOS GPIOs that are intended as inputs are mistakenly configured as outputs, driving a logic high signal instead of remaining in a high-impedance state.) Boot mode outputs are connected to the processor using resistor divider or through buffers as per the SK implementation
  6. Boot mode configuration using dip switches or resistors. When only resistors are used, a resistor divider is optional. A pullup or pulldown can be used
  7. IO compatibility (1.8V or 3.3V referenced to VDDSHV3, boot mode inputs are not fail-safe)
  8. The boot mode inputs are stable before cold reset status output is pulled high
  9. Boot mode pins connected to alternate functions through 0Ω for isolation or testing

Schematic Review

Follow the below list for the custom schematic design:

  1. Use a common resistor value (10kΩ or similar) when dip switch is not used for boot mode configuration
  2. Use 470Ω and 47kΩ resistors when dip switches are used to configure the boot
  3. Series resistor 1kΩ is used at the output of the buffer when boot mode is implemented with buffers or driven by external control signals
  4. Boot mode configuration for PLL clock, primary and secondary boot

Additional

  1. BOOTMODE pins do not have internal pullup or pulldown resistors that are active during power reset.
  2. For early designs, recommend that all boot mode pins are brought out to an optional PU/PD pair with pop and no-pop options, depending on the required boot mode. See processor-specific TRM for complete boot mode definitions.
  3. Boot values are latched at the release of power-on reset. If the boot mode pins are redefined for another purpose during operation, boot mode pins must be released/set back to the proper levels to select the boot mode whenever the device enters the power-on reset state. Boot mode pin configuration specifically is a concern if signal is driven from external peripheral.
  4. Add external ESD protection in case the boot mode switches are set in an uncontrolled environment.
  5. Boot mode inputs are not fail-safe. No input can be applied before the processor IO supplies ramp. Applying an external input before supply ramps can cause voltage feed and affect the processor performance.
  6. Boot mode buffers are optional.
  7. When using buffers or logic gates to configure the boot mode, verify the device used has OE (output enable feature).