SPRS993E March   2017  – December 2018 DRA76P , DRA77P

PRODUCTION DATA.  

  1. 1Device Overview
    1. 1.1 Features
    2. 1.2 Applications
    3. 1.3 Description
    4. 1.4 Functional Block Diagram
  2. 2Revision History
  3. 3Device Comparison
    1. 3.1 Device Comparison Table
    2. 3.2 Related Products
  4. 4Terminal Configuration and Functions
    1. 4.1 Pin Diagram
    2. 4.2 Pin Attributes
    3. 4.3 Signal Descriptions
      1. 4.3.1  VIP
      2. 4.3.2  DSS
      3. 4.3.3  HDMI
      4. 4.3.4  Camera Serial Interface 2 CAL bridge (CSI2)
      5. 4.3.5  EMIF
      6. 4.3.6  GPMC
      7. 4.3.7  Timers
      8. 4.3.8  I2C
      9. 4.3.9  HDQ1W
      10. 4.3.10 UART
      11. 4.3.11 McSPI
      12. 4.3.12 QSPI
      13. 4.3.13 McASP
      14. 4.3.14 USB
      15. 4.3.15 SATA
      16. 4.3.16 PCIe
      17. 4.3.17 DCAN and MCAN
      18. 4.3.18 GMAC_SW
      19. 4.3.19 MLB
      20. 4.3.20 eMMC/SD/SDIO
      21. 4.3.21 GPIO
      22. 4.3.22 KBD
      23. 4.3.23 PWM
      24. 4.3.24 ATL
      25. 4.3.25 Test Interfaces
      26. 4.3.26 System and Miscellaneous
        1. 4.3.26.1 Sysboot
        2. 4.3.26.2 PRCM
        3. 4.3.26.3 SDMA
        4. 4.3.26.4 INTC
        5. 4.3.26.5 Observability
        6. 4.3.26.6 Power Supplies
    4. 4.4 Pin Multiplexing
    5. 4.5 Connections for Unused Pins
  5. 5Specifications
    1. 5.1  Absolute Maximum Ratings
    2. 5.2  ESD Ratings
    3. 5.3  Power-On Hours (POH)
    4. 5.4  Recommended Operating Conditions
    5. 5.5  Operating Performance Points
      1. 5.5.1 AVS and ABB Requirements
      2. 5.5.2 Voltage And Core Clock Specifications
      3. 5.5.3 Maximum Supported Frequency
    6. 5.6  Power Consumption Summary
    7. 5.7  Electrical Characteristics
      1. Table 5-6  LVCMOS DDR DC Electrical Characteristics
      2. Table 5-7  Dual Voltage LVCMOS I2C DC Electrical Characteristics
      3. Table 5-8  IQ1833 Buffers DC Electrical Characteristics
      4. Table 5-9  LVCMOS CSI2 DC Electrical Characteristics
      5. Table 5-10 IHHV1833 Buffers DC Electrical Characteristics
      6. Table 5-11 BMLB18 Buffers DC Electrical Characteristics
      7. Table 5-12 Dual Voltage SDIO1833 DC Electrical Characteristics
      8. Table 5-13 Dual Voltage LVCMOS DC Electrical Characteristics
      9. 5.7.1      HDMIPHY DC Electrical Characteristics
      10. 5.7.2      USBPHY DC Electrical Characteristics
      11. 5.7.3      SATAPHY DC Electrical Characteristics
      12. 5.7.4      PCIEPHY DC Electrical Characteristics
    8. 5.8  VPP Specifications for One-Time Programmable (OTP) eFuses
      1. Table 5-14 Recommended Operating Conditions for OTP eFuse Programming
      2. 5.8.1      Hardware Requirements
      3. 5.8.2      Programming Sequence
      4. 5.8.3      Impact to Your Hardware Warranty
    9. 5.9  Thermal Resistance Characteristics
      1. 5.9.1 Package Thermal Characteristics
    10. 5.10 Timing Requirements and Switching Characteristics
      1. 5.10.1 Timing Parameters and Information
        1. 5.10.1.1 Parameter Information
          1. 5.10.1.1.1 1.8V and 3.3V Signal Transition Levels
          2. 5.10.1.1.2 1.8V and 3.3V Signal Transition Rates
          3. 5.10.1.1.3 Timing Parameters and Board Routing Analysis
      2. 5.10.2 Interface Clock Specifications
        1. 5.10.2.1 Interface Clock Terminology
        2. 5.10.2.2 Interface Clock Frequency
      3. 5.10.3 Power Supply Sequences
      4. 5.10.4 Clock Specifications
        1. 5.10.4.1 Input Clocks / Oscillators
          1. 5.10.4.1.1 OSC0 External Crystal
          2. 5.10.4.1.2 OSC0 Input Clock
          3. 5.10.4.1.3 Auxiliary Oscillator OSC1 Input Clock
            1. 5.10.4.1.3.1 OSC1 External Crystal
            2. 5.10.4.1.3.2 OSC1 Input Clock
        2. 5.10.4.2 RC On-die Oscillator Clock
        3. 5.10.4.3 Output Clocks
        4. 5.10.4.4 DPLLs, DLLs
          1. 5.10.4.4.1 DPLL Characteristics
          2. 5.10.4.4.2 DLL Characteristics
          3. 5.10.4.4.3 DPLL and DLL Noise Isolation
      5. 5.10.5 Recommended Clock and Control Signal Transition Behavior
      6. 5.10.6 Peripherals
        1. 5.10.6.1  Timing Test Conditions
        2. 5.10.6.2  Virtual and Manual I/O Timing Modes
        3. 5.10.6.3  VIP
        4. 5.10.6.4  DSS
        5. 5.10.6.5  HDMI
        6. 5.10.6.6  EMIF
        7. 5.10.6.7  GPMC
          1. 5.10.6.7.1 GPMC/NOR Flash Interface Synchronous Timing
          2. 5.10.6.7.2 GPMC/NOR Flash Interface Asynchronous Timing
          3. 5.10.6.7.3 GPMC/NAND Flash Interface Asynchronous Timing
        8. 5.10.6.8  Timers
        9. 5.10.6.9  I2C
          1. Table 5-60 Timing Requirements for I2C Input Timings
          2. Table 5-61 Timing Requirements for I2C HS-Mode (I2C3/4/5 Only)
          3. Table 5-62 Switching Characteristics Over Recommended Operating Conditions for I2C Output Timings
        10. 5.10.6.10 HDQ1W
          1. 5.10.6.10.1 HDQ / 1-Wire — HDQ Mode
          2. 5.10.6.10.2 HDQ/1-Wire—1-Wire Mode
        11. 5.10.6.11 UART
          1. Table 5-67 Timing Requirements for UART
          2. Table 5-68 Switching Characteristics Over Recommended Operating Conditions for UART
        12. 5.10.6.12 McSPI
        13. 5.10.6.13 QSPI
        14. 5.10.6.14 McASP
          1. Table 5-75 Timing Requirements for McASP1
          2. Table 5-76 Timing Requirements for McASP2
          3. Table 5-77 Timing Requirements for McASP3/4/5/6/7/8
          4. Table 5-78 Switching Characteristics Over Recommended Operating Conditions for McASP1
          5. Table 5-79 Switching Characteristics Over Recommended Operating Conditions for McASP2
          6. Table 5-80 Switching Characteristics Over Recommended Operating Conditions for McASP3/4/5/6/7/8
        15. 5.10.6.15 USB
          1. 5.10.6.15.1 USB1 DRD PHY
          2. 5.10.6.15.2 USB2 PHY
          3. 5.10.6.15.3 USB3 and USB4 DRD ULPI—SDR—Slave Mode—12-pin Mode
        16. 5.10.6.16 SATA
        17. 5.10.6.17 PCIe
        18. 5.10.6.18 CAN
          1. 5.10.6.18.1 DCAN
          2. 5.10.6.18.2 MCAN-FD
          3. Table 5-95  Timing Requirements for CANx Receive
          4. Table 5-96  Switching Characteristics Over Recommended Operating Conditions for CANx Transmit
        19. 5.10.6.19 GMAC_SW
          1. 5.10.6.19.1 GMAC MII Timings
            1. Table 5-97  Timing Requirements for miin_rxclk - MII Operation
            2. Table 5-98  Timing Requirements for miin_txclk - MII Operation
            3. Table 5-99  Timing Requirements for GMAC MIIn Receive 10/100 Mbit/s
            4. Table 5-100 Switching Characteristics Over Recommended Operating Conditions for GMAC MIIn Transmit 10/100 Mbits/s
          2. 5.10.6.19.2 GMAC MDIO Interface Timings
          3. 5.10.6.19.3 GMAC RMII Timings
            1. Table 5-105 Timing Requirements for GMAC REF_CLK - RMII Operation
            2. Table 5-106 Timing Requirements for GMAC RMIIn Receive
            3. Table 5-107 Switching Characteristics Over Recommended Operating Conditions for GMAC REF_CLK - RMII Operation
            4. Table 5-108 Switching Characteristics Over Recommended Operating Conditions for GMAC RMIIn Transmit 10/100 Mbits/s
          4. 5.10.6.19.4 GMAC RGMII Timings
            1. Table 5-112 Timing Requirements for rgmiin_rxc - RGMIIn Operation
            2. Table 5-113 Timing Requirements for GMAC RGMIIn Input Receive for 10/100/1000 Mbps
            3. Table 5-114 Switching Characteristics Over Recommended Operating Conditions for rgmiin_txctl - RGMIIn Operation for 10/100/1000 Mbit/s
            4. Table 5-115 Switching Characteristics for GMAC RGMIIn Output Transmit for 10/100/1000 Mbps
        20. 5.10.6.20 MLB
        21. 5.10.6.21 eMMC/SD/SDIO
          1. 5.10.6.21.1 MMC1—SD Card Interface
            1. 5.10.6.21.1.1 Default speed, 4-bit Data, SDR, Half-Cycle
            2. 5.10.6.21.1.2 High-Speed, 4-bit Data, SDR, Half-Cycle
            3. 5.10.6.21.1.3 SDR12, 4-bit Data, Half-Cycle
            4. 5.10.6.21.1.4 SDR25, 4-bit Data, Half-Cycle
            5. 5.10.6.21.1.5 UHS-I SDR50, 4-bit Data, Half-Cycle
            6. 5.10.6.21.1.6 UHS-I SDR104, 4-bit Data, Half-Cycle
            7. 5.10.6.21.1.7 UHS-I DDR50, 4-bit Data
          2. 5.10.6.21.2 MMC2 — eMMC
            1. 5.10.6.21.2.1 Standard JC64 SDR, 8-bit Data, Half Cycle
            2. 5.10.6.21.2.2 High-Speed JC64 SDR, 8-bit Data, Half Cycle
            3. 5.10.6.21.2.3 High-Speed HS200 JC64 SDR, 8-bit Data, Half Cycle
            4. 5.10.6.21.2.4 High-Speed JC64 DDR, 8-bit Data
          3. 5.10.6.21.3 MMC3 and MMC4—SDIO/SD
            1. 5.10.6.21.3.1 MMC3 and MMC4, SD Default Speed
            2. 5.10.6.21.3.2 MMC3 and MMC4, SD High-Speed
            3. 5.10.6.21.3.3 MMC3 and MMC4, SD and SDIO SDR12 Mode
            4. 5.10.6.21.3.4 MMC3 and MMC4, SD SDR25 Mode
            5. 5.10.6.21.3.5 MMC3 SDIO High-Speed UHS-I SDR50 Mode, Half Cycle
        22. 5.10.6.22 GPIO
        23. 5.10.6.23 ATL
          1. 5.10.6.23.1 ATL Electrical Data/Timing
            1. Table 5-171 Switching Characteristics Over Recommended Operating Conditions for ATL_CLKOUTx
        24. 5.10.6.24 System and Miscellaneous Interfaces
      7. 5.10.7 Emulation and Debug Subsystem
        1. 5.10.7.1 JTAG
          1. 5.10.7.1.1 JTAG Electrical Data/Timing
            1. Table 5-172 Timing Requirements for IEEE 1149.1 JTAG
            2. Table 5-173 Switching Characteristics Over Recommended Operating Conditions for IEEE 1149.1 JTAG
            3. Table 5-174 Timing Requirements for IEEE 1149.1 JTAG With RTCK
            4. Table 5-175 Switching Characteristics Over Recommended Operating Conditions for IEEE 1149.1 JTAG With RTCK
        2. 5.10.7.2 TPIU
          1. 5.10.7.2.1 TPIU PLL DDR Mode
  6. 6Detailed Description
    1. 6.1  Description
    2. 6.2  Functional Block Diagram
    3. 6.3  MPU
    4. 6.4  DSP Subsystem
    5. 6.5  ISS
    6. 6.6  IVA
    7. 6.7  EVE
    8. 6.8  IPU
    9. 6.9  VPE
    10. 6.10 GPU
    11. 6.11 ATL Overview
    12. 6.12 Memory Subsystem
      1. 6.12.1 EMIF
      2. 6.12.2 GPMC
      3. 6.12.3 ELM
      4. 6.12.4 OCMC
    13. 6.13 Interprocessor Communication
      1. 6.13.1 Mailbox
      2. 6.13.2 Spinlock
    14. 6.14 Interrupt Controller
    15. 6.15 EDMA
    16. 6.16 Peripherals
      1. 6.16.1  VIP
      2. 6.16.2  DSS
      3. 6.16.3  Timers
      4. 6.16.4  I2C
      5. 6.16.5  HDQ1W
      6. 6.16.6  UART
        1. 6.16.6.1 UART Features
        2. 6.16.6.2 IrDA Features
        3. 6.16.6.3 CIR Features
      7. 6.16.7  McSPI
      8. 6.16.8  QSPI
      9. 6.16.9  McASP
      10. 6.16.10 USB
      11. 6.16.11 SATA
      12. 6.16.12 PCIe
      13. 6.16.13 CAN
      14. 6.16.14 GMAC_SW
      15. 6.16.15 MLB
      16. 6.16.16 CSI2
        1. 6.16.16.1 CSI-2 MIPI D-PHY
      17. 6.16.17 eMMC/SD/SDIO
      18. 6.16.18 GPIO
      19. 6.16.19 ePWM
      20. 6.16.20 eCAP
      21. 6.16.21 eQEP
    17. 6.17 On-Chip Debug
  7. 7Applications, Implementation, and Layout
    1. 7.1 Introduction
      1. 7.1.1 Initial Requirements and Guidelines
    2. 7.2 Power Optimizations
      1. 7.2.1 Step 1: PCB Stack-up
      2. 7.2.2 Step 2: Physical Placement
      3. 7.2.3 Step 3: Static Analysis
        1. 7.2.3.1 PDN Resistance and IR Drop
      4. 7.2.4 Step 4: Frequency Analysis
      5. 7.2.5 System ESD Generic Guidelines
        1. 7.2.5.1 System ESD Generic PCB Guideline
        2. 7.2.5.2 Miscellaneous EMC Guidelines to Mitigate ESD Immunity
      6. 7.2.6 EMI / EMC Issues Prevention
        1. 7.2.6.1 Signal Bandwidth
        2. 7.2.6.2 Signal Routing
          1. 7.2.6.2.1 Signal Routing—Sensitive Signals and Shielding
          2. 7.2.6.2.2 Signal Routing—Outer Layer Routing
        3. 7.2.6.3 Ground Guidelines
          1. 7.2.6.3.1 PCB Outer Layers
          2. 7.2.6.3.2 Metallic Frames
          3. 7.2.6.3.3 Connectors
          4. 7.2.6.3.4 Guard Ring on PCB Edges
          5. 7.2.6.3.5 Analog and Digital Ground
    3. 7.3 Core Power Domains
      1. 7.3.1 General Constraints and Theory
      2. 7.3.2 Voltage Decoupling
      3. 7.3.3 Static PDN Analysis
      4. 7.3.4 Dynamic PDN Analysis
      5. 7.3.5 Power Supply Mapping
      6. 7.3.6 DPLL Voltage Requirement
      7. 7.3.7 Loss of Input Power Event
      8. 7.3.8 Example PCB Design
        1. 7.3.8.1 Example Stack-up
        2. 7.3.8.2 vdd_mpu Example Analysis
    4. 7.4 Single-Ended Interfaces
      1. 7.4.1 General Routing Guidelines
      2. 7.4.2 QSPI Board Design and Layout Guidelines
    5. 7.5 Differential Interfaces
      1. 7.5.1 General Routing Guidelines
      2. 7.5.2 USB 2.0 Board Design and Layout Guidelines
        1. 7.5.2.1 Background
        2. 7.5.2.2 USB PHY Layout Guide
          1. 7.5.2.2.1 General Routing and Placement
          2. 7.5.2.2.2 Specific Guidelines for USB PHY Layout
            1. 7.5.2.2.2.1  Analog, PLL, and Digital Power Supply Filtering
            2. 7.5.2.2.2.2  Analog, Digital, and PLL Partitioning
            3. 7.5.2.2.2.3  Board Stackup
            4. 7.5.2.2.2.4  Cable Connector Socket
            5. 7.5.2.2.2.5  Clock Routings
            6. 7.5.2.2.2.6  Crystals/Oscillator
            7. 7.5.2.2.2.7  DP/DM Trace
            8. 7.5.2.2.2.8  DP/DM Vias
            9. 7.5.2.2.2.9  Image Planes
            10. 7.5.2.2.2.10 JTAG Interface
            11. 7.5.2.2.2.11 Power Regulators
        3. 7.5.2.3 Electrostatic Discharge (ESD)
          1. 7.5.2.3.1 IEC ESD Stressing Test
            1. 7.5.2.3.1.1 Test Mode
            2. 7.5.2.3.1.2 Air Discharge Mode
            3. 7.5.2.3.1.3 Test Type
          2. 7.5.2.3.2 TI Component Level IEC ESD Test
          3. 7.5.2.3.3 Construction of a Custom USB Connector
          4. 7.5.2.3.4 ESD Protection System Design Consideration
        4. 7.5.2.4 References
      3. 7.5.3 USB 3.0 Board Design and Layout Guidelines
        1. 7.5.3.1 USB 3.0 interface introduction
        2. 7.5.3.2 USB 3.0 General routing rules
      4. 7.5.4 HDMI Board Design and Layout Guidelines
        1. 7.5.4.1 HDMI Interface Schematic
        2. 7.5.4.2 TMDS General Routing Guidelines
        3. 7.5.4.3 TPD5S115
        4. 7.5.4.4 HDMI ESD Protection Device (Required)
        5. 7.5.4.5 PCB Stackup Specifications
        6. 7.5.4.6 Grounding
      5. 7.5.5 SATA Board Design and Layout Guidelines
        1. 7.5.5.1 SATA Interface Schematic
        2. 7.5.5.2 Compatible SATA Components and Modes
        3. 7.5.5.3 PCB Stackup Specifications
        4. 7.5.5.4 Routing Specifications
      6. 7.5.6 PCIe Board Design and Layout Guidelines
        1. 7.5.6.1 PCIe Connections and Interface Compliance
          1. 7.5.6.1.1 Coupling Capacitors
          2. 7.5.6.1.2 Polarity Inversion
        2. 7.5.6.2 Non-standard PCIe connections
          1. 7.5.6.2.1 PCB Stackup Specifications
          2. 7.5.6.2.2 Routing Specifications
            1. 7.5.6.2.2.1 Impedance
            2. 7.5.6.2.2.2 Differential Coupling
            3. 7.5.6.2.2.3 Pair Length Matching
        3. 7.5.6.3 LJCB_REFN/P Connections
      7. 7.5.7 CSI2 Board Design and Routing Guidelines
        1. 7.5.7.1 CSI2_0 and CSI2_1 MIPI CSI-2 (1.5 Gbps)
          1. 7.5.7.1.1 General Guidelines
          2. 7.5.7.1.2 Length Mismatch Guidelines
            1. 7.5.7.1.2.1 CSI2_0 and CSI2_1 MIPI CSI-2 (1.5 Gbps)
          3. 7.5.7.1.3 Frequency-domain Specification Guidelines
    6. 7.6 DDR2/DDR3 Board Design and Layout Guidelines
      1. 7.6.1 DDR2/DDR3 General Board Layout Guidelines
      2. 7.6.2 DDR2 Board Design and Layout Guidelines
        1. 7.6.2.1 Board Designs
        2. 7.6.2.2 DDR2 Interface
          1. 7.6.2.2.1  DDR2 Interface Schematic
          2. 7.6.2.2.2  Compatible JEDEC DDR2 Devices
          3. 7.6.2.2.3  PCB Stackup
          4. 7.6.2.2.4  Placement
          5. 7.6.2.2.5  DDR2 Keepout Region
          6. 7.6.2.2.6  Bulk Bypass Capacitors
          7. 7.6.2.2.7  High-Speed Bypass Capacitors
          8. 7.6.2.2.8  Net Classes
          9. 7.6.2.2.9  DDR2 Signal Termination
          10. 7.6.2.2.10 VREF Routing
        3. 7.6.2.3 DDR2 CK and ADDR_CTRL Routing
      3. 7.6.3 DDR3 Board Design and Layout Guidelines
        1. 7.6.3.1  Board Designs
        2. 7.6.3.2  DDR3 EMIF
        3. 7.6.3.3  DDR3 Device Combinations
        4. 7.6.3.4  DDR3 Interface Schematic
          1. 7.6.3.4.1 32-Bit DDR3 Interface
          2. 7.6.3.4.2 16-Bit DDR3 Interface
        5. 7.6.3.5  Compatible JEDEC DDR3 Devices
        6. 7.6.3.6  PCB Stackup
        7. 7.6.3.7  Placement
        8. 7.6.3.8  DDR3 Keepout Region
        9. 7.6.3.9  Bulk Bypass Capacitors
        10. 7.6.3.10 High-Speed Bypass Capacitors
          1. 7.6.3.10.1 Return Current Bypass Capacitors
        11. 7.6.3.11 Net Classes
        12. 7.6.3.12 DDR3 Signal Termination
        13. 7.6.3.13 VREF_DDR Routing
        14. 7.6.3.14 VTT
        15. 7.6.3.15 CK and ADDR_CTRL Topologies and Routing Definition
          1. 7.6.3.15.1 Four DDR3 Devices
            1. 7.6.3.15.1.1 CK and ADDR_CTRL Topologies, Four DDR3 Devices
            2. 7.6.3.15.1.2 CK and ADDR_CTRL Routing, Four DDR3 Devices
          2. 7.6.3.15.2 Two DDR3 Devices
            1. 7.6.3.15.2.1 CK and ADDR_CTRL Topologies, Two DDR3 Devices
            2. 7.6.3.15.2.2 CK and ADDR_CTRL Routing, Two DDR3 Devices
          3. 7.6.3.15.3 One DDR3 Device
            1. 7.6.3.15.3.1 CK and ADDR_CTRL Topologies, One DDR3 Device
            2. 7.6.3.15.3.2 CK and ADDR/CTRL Routing, One DDR3 Device
        16. 7.6.3.16 Data Topologies and Routing Definition
          1. 7.6.3.16.1 DQS and DQ/DM Topologies, Any Number of Allowed DDR3 Devices
          2. 7.6.3.16.2 DQS and DQ/DM Routing, Any Number of Allowed DDR3 Devices
        17. 7.6.3.17 Routing Specification
          1. 7.6.3.17.1 CK and ADDR_CTRL Routing Specification
          2. 7.6.3.17.2 DQS and DQ Routing Specification
  8. 8Device and Documentation Support
    1. 8.1  Device Nomenclature
      1. 8.1.1 Standard Package Symbolization
      2. 8.1.2 Device Naming Convention
    2. 8.2  Tools and Software
    3. 8.3  Documentation Support
      1. 8.3.1 FCC Warning
      2. 8.3.2 Information About Cautions and Warnings
    4. 8.4  Receiving Notification of Documentation Updates
    5. 8.5  Related Links
    6. 8.6  Community Resources
    7. 8.7  Trademarks
    8. 8.8  Electrostatic Discharge Caution
    9. 8.9  Export Control Notice
    10. 8.10 Glossary
  9. 9Mechanical Packaging and Orderable Information
    1. 9.1 Mechanical Data

Package Options

Refer to the PDF data sheet for device specific package drawings

Mechanical Data (Package|Pins)
  • ACD|784
Thermal pad, mechanical data (Package|Pins)
Orderable Information

7.2.4 Step 4: Frequency Analysis

Delivering low noise voltage sources are very important to allowing a system to operate at the lowest possible Operational Performance Point (OPP) for any one Use Case. An OPP is a combination of the supply voltage level and clocking rate for key internal processor domains. A SCH and PCB designed to provide low noise voltage supplies will then enable the processor to enter optimal OPPs for each Use Case that in turn will minimize power dissipation and junction temperatures on-die. Therefore, it is a good engineering practice to perform a Frequency Analysis over the key power domains.

Frequency analysis and design methodology results in a PDN design that minimizes transient noise voltages at the processor’s input power balls. This allows the processor’s internal transistors to operate near the minimum specified operating supply voltage levels. To accomplish this one must evaluate how a voltage supply will change due to impedance variations over frequency. This analysis will focus on the decoupling capacitor network (VDD_xxx and VSS/Gnd rails) at the load. Sufficient capacitance with a distribution of self-resonant points will provide for an overall lower impedance vs frequency response for each power domain.

Decoupling components that are distant from their load’s input power are susceptible to encountering spreading loop inductance from the PCB design. Early analysis of each key power domain’s frequency response helps to determine basic decoupling capacitor placement, optimal footprint, layer assignment, and types needed for minimizing supply voltage noise/fluctuations due to switching and load current transients.

NOTE

Evaluation of loop inductance values for decoupling capacitors placed ~300mils closer to the load’s input power balls has shown an 18% reduction in loop inductance due to reduced distance.
  • Decoupling capacitors must be carefully placed in order to minimize loop inductance impact on supply voltage transients. A real capacitor has characteristics not only of capacitance but also inductance and resistance.

    • Figure 7-12 shows the parasitic model of a real capacitor. A real capacitor must be treated as an RLC circuit with effective series resistance (ESR) and effective series inductance (ESL).

    DRA77P DRA76P SWPS040-175.gifFigure 7-12 Characteristics of a Real Capacitor With ESL and ESR

    The magnitude of the impedance of this series model is given as:

    DRA77P DRA76P SWPS040-e002.gifFigure 7-13 Series Model Impedance Equation

Figure 7-14 shows the resonant frequency response of a typical capacitor with a self-resonant frequency of 55 MHz. The impedance of the capacitor is a combination of its series resistance and reactive capacitance and inductance as shown in the equation above.

DRA77P DRA76P SWPS040-176.gifFigure 7-14 Typical Impedance Profile of a Capacitor

Because a capacitor has series inductance and resistance that impacts its effectiveness, it is important that the following recommendations are adopted in placing capacitors on the PDN.

Wherever possible, mount the capacitor with the geometry that minimizes the mounting inductance and resistance. This was shown earlier in Figure 7-1. The capacitor mounting inductance and resistance values include the inductance and resistance of the pads, trace, and vias. Whenever possible, use footprints that have the lowest inductance configuration as shown in Figure 7-15

The length of a trace used to connect a capacitor has a big impact on parasitic inductance and resistance of the mounting. This trace must be as short and as wide as possible. wherever possible, minimize distance to supply and Gnd vias by locating vias nearby or within the capacitor’s solder pad landing. Further improvements can be made to the mounting by placing vias to the side of capacitor lands or doubling the number of vias as shown in Figure 7-15. If the PCB manufacturing processes allow it and if cost-effective, via-in-pad (VIP) geometries are strongly recommended.

In addition to mounting inductance and resistance associated with placing a capacitor on the PCB, the effectiveness of a decoupling capacitor also depends on the spreading inductance and resistance that the capacitor sees with respect to the load. The spreading inductance and resistance is strongly dependent on the layer assignment in the PCB stack-up. Therefore, try to minimize X, Y and Z dimensions where the Z is due to PCB thickness (as shown in Figure 7-2).

From left (highest inductance) to right (lowest inductance) the capacitor footprint types shown in Figure 7-15 are known as:

  • 2-via, Skinny End Exit (2vSEE)
  • 2-via, Wide End Exit (2vWEE)
  • 2-via, Wide Side Exit (2vWSE)
  • 4-via, Wide Side Exit (4vWSE)
  • 2-via, In-Pad (2vIP)
DRA77P DRA76P SWPS040-177.gifFigure 7-15 Capacitor Placement Geometry for Improved Mounting Inductance

NOTE

Evaluation of loop inductance values for decoupling capacitor footprints 2vSEE (worst case) vs 4vWSE (2nd best) has shown a 30% reduction in inductance when 4vWSE footprint was used in place of 2vSEE.

Decoupling Capacitor (Dcap) Strategy:

  1. Use lowest inductance footprint and trace connection scheme possible for given PCB technology and layout area in order to minimize Dcap loop inductance to power pin as much as possible (see Figure 7-15).
  2. Place Dcaps on “same-side” as component within their power plane outline to minimize “decoupling loop inductance”. Target distance to power pin should be less than ~500mils depending upon PCB layout characteristics (plane's layer assignment and solid nature). Use PI modeling CAD tool to verify minimum inductance for top vs bottom-side placement.
  3. Place Dcaps on “opposite-side” as component within their power plane outline if “same-side” is not feasible or if distance to power pin is greater than ~500mils for top-side location. Use PI modeling CAD tool to verify minimum inductance for top vs bottom-side placement.
  4. Use minimum 10mil trace width for all voltage and gnd planes connections (i.e. Dcap pads, component power pins, etc.).
  5. Place all voltage and gnd plane vias “as close as possible” to point of use (i.e. Dcap pads, component power pins, etc.).
  6. Use a “Power/Gnd pad/pin to via” ratio of 1:1 whenever possible. Do not exceed 2:1 ratio for small number of vias within restricted PCB areas (i.e. underneath BGA components).

Frequency analysis for the MPU power domain has yielded the vdd_mpu Impedance vs Frequency response shown in Section 7.3.8.2, vdd_mpu Example Analysis. As the example shows the overall MPU PDN Reff meets the maximum recommended PDN resistance of 10 mΩ.