SPRABJ8D September   2022  – May 2025 AM2612 , AM2631 , AM2631-Q1 , AM2632 , AM2632-Q1 , AM2634 , AM2634-Q1 , AM263P2 , AM263P2-Q1 , AM263P4 , AM263P4-Q1

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1 Introduction
  5. 2 Power
    1. 2.1 Discrete DC-DC Power Solution
    2. 2.2 Integrated PMIC Power Solution
    3. 2.3 Power Decoupling and Filtering
      1. 2.3.1 ADC/DAC Voltage Reference Decoupling
    4. 2.4 Estimated Power Consumption
    5. 2.5 Power Distribution Network
      1. 2.5.1 Simulations
        1. 2.5.1.1 Core Digital Power 1.2V
        2. 2.5.1.2 Digital and Analog I/O Power 3.3V
    6. 2.6 eFuse Power
  6. 3 Clocking
    1. 3.1 Crystal and Oscillator Input Options
    2. 3.2 Output Clock Generation
    3. 3.3 Crystal Selection and Shunt Capacitance
    4. 3.4 Crystal Placement and Routing
  7. 4 Resets
  8. 5 Bootstrapping
    1. 5.1 SOP Signal Implementation
  9. 6 OSPI and QSPI Memory Implementation
    1. 6.1 ROM OSPI and QSPI Boot Requirements
      1. 6.1.1 AM263x QSPI Boot Pin Requirements
      2. 6.1.2 AM263Px OSPI and QSPI Boot Pin Requirements
      3. 6.1.3 AM261x OSPI and QSPI Boot Pin Requirements
    2. 6.2 Additional OSPI and QSPI References
  10. 7 Debug Interfaces
    1. 7.1 JTAG Emulators and Trace
    2. 7.2 UART
  11. 8 USB
    1. 8.1 USB Device Mode
    2. 8.2 USB Host Mode
  12. 9 Multiplexed Peripherals
  13. 10Digital Peripherals
    1. 10.1 General Digital Peripheral Routing Guidelines
    2. 10.2 Trace Length Matching
  14. 11Analog Peripherals
    1. 11.1 General Analog Peripheral Routing Guidelines
      1. 11.1.1 Resolver ADC Routing Guidelines
  15. 12Layer Stackup
    1. 12.1 Key Stackup Features
  16. 13Vias
  17. 14BGA Power Fan-Out and Decoupling Placement
    1. 14.1 Ground Return
      1. 14.1.1 Ground Return - ZCZ Package AM26x Devices
      2. 14.1.2 Ground Return - ZNC and ZFG Package AM261x Devices
    2. 14.2 1.2V Core Digital Power
      1. 14.2.1 1.2V Core Digital Power Key Layout Considerations - ZCZ
      2. 14.2.2 1.2V Core Digital Power Key Layout Considerations - ZFG
    3. 14.3 3.3V Digital and Analog Power
      1. 14.3.1 3.3V I/O Power Key Layout Considerations - ZCZ
      2. 14.3.2 3.3V I/O Power Key Layout Considerations - ZFG
    4. 14.4 1.8V Digital and Analog Power
      1. 14.4.1 1.8V Key Layout Considerations - ZCZ
      2. 14.4.2 1.8V Key Layout Considerations - ZFG
  18. 15Summary
  19. 16References
  20. 17Revision History

14.2.2 1.2V Core Digital Power Key Layout Considerations - ZFG

For AM261x ZFG package devices, the 1.2V core digital power routing of the AM261x LaunchPad EVM (LP-AM261) is explored - from the 1.2V buck output of the PMIC (TPS650366), through the board power planes and ending at the BGA bulk and per pin decoupling capacitor array. A 4-layer PCB layout is also explored at the end of this section.
  • AM261x (ZFG) must be co-located with the 1.2V core digital regulator to allow for minimal IR drop from the regulator/PMIC to the BGA power pins.
  • Wide 10 mil traces must be used for all power and ground return via fan-out.
  • A dedicated power layer, with tightly coupled ground return reference plane must be used for best transient performance and EMI coupling
  • A wide power plane entry into the center of the BGA 1.2V power pin areas must be used for minimal IR drop and best transient performance
  • Larger packaged, lower-frequency, bulk capacitance must be placed adjacent to the BGA with vias directly to power plane paths
  • Smaller packaged, higher-frequency decoupling capacitance must be placed directly on BGA fan-out vias with as small of a dog-bone to power and ground return vias as possible

The below figures detail the 1.2V core digital power flow from the source to AM261x device on the AM261x LaunchPad EVM (LP-AM261).

AM261x LaunchPad Excerpt – 1.2V Core Power Output, Power Plane Vias and BGA Vias Figure 14-9 AM261x LaunchPad Excerpt – 1.2V Core Power Output, Power Plane Vias and BGA Vias
AM261x LaunchPad Excerpt – 1.2V Core Power Plane, Layer 4 Figure 14-10 AM261x LaunchPad Excerpt – 1.2V Core Power Plane, Layer 4
AM261x LaunchPad Excerpt – 1.2V Core Power Decoupling Mounting, Layer 6 Figure 14-11 AM261x LaunchPad Excerpt – 1.2V Core Power Decoupling Mounting, Layer 6

A 1.2V core digital power flow for a 4-layer PCB is under study for a future revision of this document.