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

12 Layer Stackup

The AM263x, AM263Px, and one of the four packages of the AM261x MCUs are packaged in a ZCZ0324A 324 ball, 0.8mm pitch, 18 x 18 full NFBGA array 15mm x 15mm package (referred to as 'ZCZ package' in this document). The larger pitch on this package allows for a low layer count for power and full signal fan-out. In the case of the LP-AM263 EVM, a 6-layer stackup design was able to fully route all power and signal pins across the device for the LaunchPad form-factor of boards. The LP-AM263 LaunchPad stackup below represents the most optimized stackup example for the ZCZ package devices at this time.

Lower layer count stackups for the ZCZ package are likely possible, especially when considering partial signal fan-out designs. However, these have not yet been explored by TI.

LP-AM263 Stackup Figure 12-1 LP-AM263 Stackup

The other three packages of the AM261x MCU are described in the table below:

Table 12-1 AM261x Package Sizes
Package Name (Type, Ball Count) Package Dimensions BGA Pitch BGA Array
ZNC
(NFBGA, 293)		 10mm x 10mm 0.5mm 19 x 19
ZEJ
(NFBGA, 256)		 13mm x 13mm 0.8mm 16 x 16
ZFG
(NFBGA, 304)		 13.25mm x 13.25mm 0.65mm 20 x 20

In the case of the LP-AM261 EVM, a 6-layer stackup design was able to fully route all power and signal pins across the ZFG package device for the LaunchPad form-factor of boards. The LP-AM261 LaunchPad stackup below represents an optimized, full-system stackup example for the ZFG package at this time:

LP-AM261 Stackup Figure 12-2 LP-AM261 Stackup

Lower layer count stackups for the AM261x ZFG and ZNC packages have been explored by TI. Pictured below is an example of a 4-layer stackup for PCB systems utilizing the AM261x ZFG or ZNC package sizes:

AM261x ZFG/ZNC PCB System Stackup Figure 12-3 AM261x ZFG/ZNC PCB System Stackup