SNLA246C October   2015  – April 2024 DP83867CR , DP83867CS , DP83867E , DP83867IR , DP83867IS

 

  1.   1
  2.   Trademarks
  3. 1Introduction
  4. 2Troubleshooting the Application
    1. 2.1 Read and Check Register Values for Basic Health Check
    2. 2.2 Schematic and Layout Checklist
    3. 2.3 Component Checklist
      1. 2.3.1 Magnetics
      2. 2.3.2 Crystal / Oscillator
    4. 2.4 Peripheral Pin Checks
      1. 2.4.1 Power Supplies
      2. 2.4.2 RBIAS Voltage and Resistance
      3. 2.4.3 Probe the XI Clock
      4. 2.4.4 Probe the RESET_N Signal
      5. 2.4.5 Probe the Strap Pins During Initialization
      6. 2.4.6 Probe the Serial Management Interface Signals (MDC, MDIO)
      7. 2.4.7 Probe the MDI Signals
    5. 2.5 Link Quality Check
    6. 2.6 Built-in Self Test With Various Loopback Modes
    7. 2.7 Debugging MAC Interface
      1. 2.7.1 RGMII Debug
      2. 2.7.2 SGMII Debug
  5. 3Application Specific Debugs
    1. 3.1 Improving Link-up Margins for Short Cables
    2. 3.2 Improving Link Margins across Different Channels
    3. 3.3 Link up in 100Mbps Full Duplex Force Mode
    4. 3.4 Unstable Link Up Debug in 1Gbps communication
    5. 3.5 DP83867PHY and DP83867PHY Cannot Link Up in 1Gbps
    6. 3.6 Compliance Debug
    7. 3.7 EMC Debug
    8. 3.8 Tools and References
      1. 3.8.1 DP83867 Register Access
      2. 3.8.2 Extended Register Access
  6. 4Conclusion
  7. 5References
  8. 6Revision History

2.3.1 Magnetics

The following guidelines are the main specifications to reference for compatible magnetics:

Table 2-2 Magnetic Isolation Requirements
PARAMETER TEST CONDITIONS TYP UNIT
Turns Ratio ±2% Tolerance 1:1 -
Open Circuit Inductance - 320 to 350 µH
Insertion Loss 1-100MHz -1 dB
Return Loss 1-30MHz -16 dB
30-60MHz -12 dB
60-100MHz -10 dB
Differential to Common Mode Rejection Ratio 1-50MHz -30 dB
50-150MHz -20 dB
Crosstalk 30MHz -35 dB
60MHz -30 dB
Isolation HPOT 1500 Vrms

If these exact requirements cannot be met, the following allowances can be made:

  • Turns ratio
    • 2% preferred, but 3% is tolerable.
  • Inductance
    • High inductance is preferred. Usual numbers seen are around 350μH.
  • Insertion loss
    • As close to 0dB as possible compared to specified value for each range stated in data sheet. If specification gives -1dB as typical. finding a component with -1dB, -0.9dB, … is recommended.
  • Return loss
    • At or lower than the magnitude specified in data sheet. If specification gives -16dB as typical, finding a component with -16dB, -17dB, … is recommended.