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

7.2.3 Step 3: Static Analysis

Delivering reliable power to circuits is always of critical importance because voltage drops (also known as IR drops) can happen at every level within an electronic system, on-chip, within a package, and across the board. Robust system performance can only be ensured by understanding how the system elements will perform under typical stressful Use Cases. Therefore, it is a good practice to perform a Static or DC Analysis.

Static or DC analysis and design methodology results in a PDN design that minimizes voltage or IR drops across power and ground planes, traces and vias. This ensures the application processor’s internal transistors will be operating within their specified voltage ranges for proper functionality. The amount of IR drop that will be encounter is based upon amount power drawn for a desired Use Case and PCB trace (widths, geometry and number of parallel traces) and via (size, type and number) characteristics.

Components that are distant from their power source are particularly susceptible to IR drop. Designs that rely on battery power must minimize voltage drops to avoid unacceptable power loss that can negatively impact system performance. Early assessments a PDN’s static (DC) performance helps to determine basic power distribution parameters such as best system input power point, optimal PCB layer stackup, and copper area needed for load currents.

DRA77P DRA76P SWPS040-178.gifFigure 7-9 Depiction of Sheet Resistivity and Resistance

Ohm’s Law (V = I × R) relates conduction current to voltage drop. At DC, the relation coefficient is a constant and represents the resistance of the conductor. Even current carrying conductors will dissipate power at high currents even though their resistance may be very small. Both voltage drop and power dissipation are proportional to the resistance of the conductor.

Figure 7-10 shows a PCB-level static IR drop budget defined between the power management device (PMIC) pins and the application processor’s balls when the PMIC is supplying power.

  • It is highly recommended to physically place the PMIC as close as possible to the processor and on the same side. The orientation of the PMIC vs. processor should be aligned to minimize distance for the highest current rail.
DRA77P DRA76P VAYU_PCB_PO_10.gifFigure 7-10 Static IR Drop Budget for PCB Only

The system-level IR drop budget is made up of three portions: on-chip, package, and PCB board. Static IR or DC analysis/design methodology consists of designing the PDN such that the voltage drop (under DC operating conditions) across power and ground pads of the transistors of the application processor device is within a specified value of the nominal voltage for proper functionality of the device.

A PCB system-level voltage drop budget for proper device functionality is typically 1.5% of nominal voltage. For a 1.35-V supply, this would be ≤20 mV.

To accurately analyze PCB static IR drop, the actual geometry of the PDN must be modeled properly and simulated to accurately characterize long distribution paths, copper weight impacts, electro-migration violations of current-carrying vias, and “Swiss-cheese” effects via placement has on power rails. It is recommended to perform the following analyses:

  • Lumped resistance/IR drop analysis
  • Distributed resistance/IR drop analysis

NOTE

The PMIC companion device supporting Processor has been designed with voltage sensing feedback loop capabilities that enable a remote sense of the SMPS output voltage at the point of use.

The NOTE above means the SMPS feedback signals and returns must be routed across PCB and connected to the Device input power ball for which a particular SMPS is supplying power. This feedback loop provides compensation for some of the voltage drop encountered across the PDN within limits. As such, the effective resistance of the PDN within this loop should be determined in order to optimize voltage compensation loop performance. The resistance of two PDN segments are of interest: one from the power inductor/bulk power filtering capacitor node to the Processor’s input power and second is the entire PDN route from SMPS output pin/ball to the Processor input power.

In the following sections each methodology is described in detail and an example has been provided of analysis flow that can be used by the PCB designer to validate compliance to the requirements on their PCB PDN design.