SNLS647I December   2019  – August 2025 DP83826E , DP83826I

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Mode Comparison Tables
  6. 5 Pin Configuration and Functions (ENHANCED Mode)
  7. 6 Pin Configuration and Functions (BASIC Mode)
  8. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Timing Requirements
    7. 7.7 Timing Diagrams
    8. 7.8 Typical Characteristics
  9. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1  Auto-Negotiation (Speed/Duplex Selection)
      2. 8.3.2  Auto-MDIX Resolution
      3. 8.3.3  Energy Efficient Ethernet
        1. 8.3.3.1 EEE Overview
        2. 8.3.3.2 EEE Negotiation
      4. 8.3.4  EEE for Legacy MACs Not Supporting 802.3az
      5. 8.3.5  Wake-on-LAN Packet Detection
        1. 8.3.5.1 Magic Packet Structure
        2. 8.3.5.2 Magic Packet Example
        3. 8.3.5.3 Wake-on-LAN Configuration and Status
      6. 8.3.6  Low Power Modes
        1. 8.3.6.1 Active Sleep
        2. 8.3.6.2 IEEE Power-Down
        3. 8.3.6.3 Deep Power Down State
      7. 8.3.7  RMII Repeater Mode
      8. 8.3.8  Clock Output
      9. 8.3.9  Media Independent Interface (MII)
      10. 8.3.10 Reduced Media Independent Interface (RMII)
      11. 8.3.11 Serial Management Interface
        1. 8.3.11.1 Extended Register Space Access
        2. 8.3.11.2 Write Address Operation
        3. 8.3.11.3 Read Address Operation
        4. 8.3.11.4 Write (No Post Increment) Operation
        5. 8.3.11.5 Read (No Post Increment) Operation
        6. 8.3.11.6 Example Write Operation (No Post Increment)
      12. 8.3.12 100BASE-TX
        1. 8.3.12.1 100BASE-TX Transmitter
          1. 8.3.12.1.1 Code-Group Encoding and Injection
          2. 8.3.12.1.2 Scrambler
          3. 8.3.12.1.3 NRZ to NRZI Encoder
          4. 8.3.12.1.4 Binary to MLT-3 Converter
        2. 8.3.12.2 100BASE-TX Receiver
      13. 8.3.13 10BASE-Te
        1. 8.3.13.1 Squelch
        2. 8.3.13.2 Normal Link Pulse Detection and Generation
        3. 8.3.13.3 Jabber
        4. 8.3.13.4 Active Link Polarity Detection and Correction
      14. 8.3.14 Loopback Modes
        1. 8.3.14.1 Near-end Loopback
        2. 8.3.14.2 MII Loopback
        3. 8.3.14.3 PCS Loopback
        4. 8.3.14.4 Digital Loopback
        5. 8.3.14.5 Analog Loopback
        6. 8.3.14.6 Far-End (Reverse) Loopback
      15. 8.3.15 BIST Configurations
      16. 8.3.16 Cable Diagnostics
        1. 8.3.16.1 Time Domain Reflectometry (TDR)
      17. 8.3.17 Fast Link-Drop Functionality
      18. 8.3.18 LED and GPIO Configuration
    4. 8.4 Programming
      1. 8.4.1 Hardware Bootstraps Configuration
        1. 8.4.1.1 Bootstrap Configurations (ENHANCED Mode)
        2. 8.4.1.2 Strap Configuration (BASIC Mode)
    5. 8.5 Register Maps
      1. 8.5.1 DP83826 Registers
  10. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      1. 9.2.1 Twisted-Pair Interface (TPI) Network Circuit
      2. 9.2.2 Transformer Recommendations
      3. 9.2.3 Capacitive DC Blocking
      4. 9.2.4 Design Requirements
        1. 9.2.4.1 Clock Requirements
          1. 9.2.4.1.1 Oscillator
          2. 9.2.4.1.2 Crystal
      5. 9.2.5 Detailed Design Procedure
        1. 9.2.5.1 MII Layout Guidelines
        2. 9.2.5.2 RMII Layout Guidelines
        3. 9.2.5.3 MDI Layout Guidelines
      6. 9.2.6 Application Curves
    3. 9.3 Power Supply Recommendations
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
        1. 9.4.1.1 Signal Traces
        2. 9.4.1.2 Return Path
        3. 9.4.1.3 Transformer Layout
        4. 9.4.1.4 Metal Pour
        5. 9.4.1.5 PCB Layer Stacking
          1. 9.4.1.5.1 Layout Example
  11. 10Device and Documentation Support
    1. 10.1 Related Documentation
    2. 10.2 Receiving Notification of Documentation Updates
    3. 10.3 Support Resources
    4. 10.4 Trademarks
    5. 10.5 Electrostatic Discharge Caution
    6. 10.6 Glossary
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information

Package Options

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

8.3.10 Reduced Media Independent Interface (RMII)

The DP83826 incorporates the reduced media-independent interface (RMII) as specified in the RMII specification v1.2. The purpose of this interface is to provide a reduced pin count alternative to the IEEE 802.3 MII as specified in Clause 22. Architecturally, the RMII specification provides an additional reconciliation layer on either side of the MII, but can be implemented in the absence of an MII. The DP83826 offers two types of RMII operations: RMII Follower and RMII Leader. In RMII Leader operation, the DP83826 operates from either a 25MHz CMOS-level oscillator connected to XI pin, a 25MHz crystal connected across XI and XO pins. A 50MHz output clock referenced from DP83826 can be connected to the MAC. In RMII Follower operation, the DP83826 operates from a 50MHz CMOS-level oscillator connected to the XI pin and shares the same clock as the MAC. Alternatively, in RMII follower mode, the PHY can operate from a 50MHz clock provided by the Host MAC

The RMII specification has the following characteristics:

  • Supports 100BASE-TX and 10BASE-Te
  • Single clock reference sourced from the MAC to PHY (or from an external source)
  • Provides independent 2-bit wide transmit and receive data paths
  • Uses CMOS signal levels, the same levels as the MII interface

In this mode, data transfers are 2 bits for every clock cycle using the internal 50MHz reference clock for both transmit and receive paths.

The RMII signals are summarized below:

Table 8-2 RMII Signals
FUNCTION PINS
Receive data lines TX_D[1:0]
Transmit data lines RX_D[1:0]
Receive control signal TX_EN
Transmit control signal CRS_DV
DP83826E DP83826I RMII Follower Signaling with an External 50MHz CMOS-level Oscillator Figure 8-5 RMII Follower Signaling with an External 50MHz CMOS-level Oscillator
DP83826E DP83826I RMII Follower Signaling with 50MHz Clocking from MAC Figure 8-6 RMII Follower Signaling with 50MHz Clocking from MAC
DP83826E DP83826I RMII Leader Signaling Figure 8-7 RMII Leader Signaling

Data on TX_D[1:0] are latched at the PHY with reference to the 50MHz clock in RMII leader mode and follower mode. Data on RX_D[1:0] is provided in reference to 50MHz clock.

In addition, CRX_DV can be configured as RX_DV signal. This allows a simpler method of recovering receive data without the need to separate RX_DV from the CRS_DV indication.