SNLA423A March   2023  – June 2025 DP83826E , DP83826I

 

  1.   1
  2.   Trademarks
  3. 1DP83826 Application Overview
  4. 2Troubleshooting the Application
    1. 2.1 Schematic and Layout Checklist
    2. 2.2 Device Health Checks
      1. 2.2.1 Voltage Checks
      2. 2.2.2 Probe the RESET_N Signal
      3. 2.2.3 Probe RBIAS and CEXT
      4. 2.2.4 Probe the XI Clock
      5. 2.2.5 Probe the Strap Pins During Initialization
      6. 2.2.6 Probe the Serial Management Interface Signals (MDC, MDIO)
        1. 2.2.6.1 Read and Check Register Values
          1. 2.2.6.1.1 Extended Register Access
    3. 2.3 MDI Health Checks
      1. 2.3.1 Magnetics
      2. 2.3.2 Probe the MDI Signals
      3. 2.3.3 Link Quality Check
      4. 2.3.4 Compliance
    4. 2.4 MII Health Checks
      1. 2.4.1 MII Check
      2. 2.4.2 RMII Check
    5. 2.5 Loopback and PRBS
      1. 2.5.1 Loopback Modes
      2. 2.5.2 Transmitting and Receiving Packets With the MAC
      3. 2.5.3 Transmitting and Receiving Packets With BIST
  5. 3Summary
  6. 4References
  7. 5Revision History

2.3.1 Magnetics

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

Table 2-5 Magnetic Isolation Requirements
ParameterTest ConditionsTYPUNIT
Turns Ratio±2% Tolerance1:1-
Insertion Loss1-100MHz-1dB
Return Loss1-30MHz-16dB
30-60MHz-12dB
60-80MHz-10dB
Differential to Common Mode Rejection Ratio1-50MHz-30dB
50-150MHz-20dB
Crosstalk30MHz-35dB
60MHz-30dB
IsolationHPOT1500Vrms

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

  • Turns ratio
    • Ideally 2%, 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 -1 dB 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.