SNLA437A December   2023  – October 2025 DP83822H , DP83822HF , DP83822I , DP83822IF , DP83826I

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1DP83822 Application Overview
  5. 2Troubleshooting the PHY Application
    1. 2.1 Schematic and Layout Checklist
    2. 2.2 Device Health Checks
      1. 2.2.1 Power Supply Ramp Sequence Check
        1. 2.2.1.1 Power Supply Ramp with Unstable XI Clock
      2. 2.2.2 Voltage Checks
      3. 2.2.3 Probe the RESET_N Signal
      4. 2.2.4 Probe the RBIAS pin
      5. 2.2.5 Probe the XI Clock
      6. 2.2.6 Probe the Strap Pins During Initialization
      7. 2.2.7 Probe the Serial Management Interface (MDC, MDIO) Signals
        1. 2.2.7.1 Read and Check Register Values
          1. 2.2.7.1.1 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 Debug the Fiber Connection
      5. 2.3.5 Debug the Start of Frame Detect
      6. 2.3.6 Compliance
    4. 2.4 MII Health Checks
      1. 2.4.1 MII Check
      2. 2.4.2 RMII Check
      3. 2.4.3 RGMII 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
  6. 3Tools and References
    1. 3.1 DP83822 Register Access
    2. 3.2 Software and Driver Debug on Linux
      1. 3.2.1 Common Terminal Outputs and Solutions
  7. 4Summary
  8. 5References
  9. 6Revision History

2.3.1 Magnetics

Because DP83822 is current mode driver, ensure that the MDI lines are pulled to AVD with 49.9Ω resistors. See Figure 2-8

DP83822 TPI Network Circuit Figure 2-8 DP83822 TPI Network Circuit

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

Table 2-9 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.