SNLA443 December   2023 DP83869HM

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1DP83869 Application Overview
  5. 2Troubleshooting the Application
    1. 2.1 Configuring Correct Operational Mode
    2. 2.2 Schematic and Layout Checklist
    3. 2.3 Component Checklist
    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 Built-In Self Test with Various Loopback Modes
    6. 2.6 Debugging MAC Interface
      1. 2.6.1 RGMII
      2. 2.6.2 SGMII
  6. 3Operational Mode Clarification
    1. 3.1 Bridge Modes
    2. 3.2 Fiber Configuration
      1. 3.2.1 Fiber Registers
  7. 4Tools and References
    1. 4.1 DP83869HM Register Access
    2. 4.2 Extended Register Access
      1. 4.2.1 Read (No Post Increment) Operation
      2. 4.2.2 Write (No Post Increment) Operation
    3. 4.3 Software and Driver Debug on Linux
      1. 4.3.1 Common Terminal Outputs
  8. 5Summary
  9. 6References

2.3 Component Checklist

Magnetics:

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

Table 2-2 Magnetic Electrical Specification
PARAMETER TEST CONDITIONS TYP UNIT
Turns Ratio ±2% Tolerance 1:1 -
Insertion Loss 1-100 MHz -1 dB
Return Loss 1-30 MHz -16 dB
30-60 MHz -12 dB
60-80 MHz -10 dB
Differential to Common Mode Rejection 1-50 MHz -30 dB
60-150 MHz -20 dB
Crosstalk 30 MHz -35 dB
60 MHz -30 dB
Open Circuit Inductance 8-mA DC Bias 350 μH
Isolation HPOT 1500 Vrms
  • Turns Ratio
    • Ideally 2% but 3% is tolerable
  • Insertion Loss
    • As close to 0 dB as possible
  • Return Loss
    • At or smaller magnitude than specified in Table 2-2
      • If specification gives -16 dB typical, finding a component with -16 dB, -17 dB is recommended.
GUID-8BE95117-CEC7-49E6-A274-43094DE2C93A-low.gif Figure 2-1 PHY to RJ45 and Magnetics
  • Each center tap on the side connected to the PHY must be isolated from one another and connected to ground by a decoupling capacitor (0.1 µF recommended).
  • Pulse Electronics part, HX5008FNL is recommended for a discrete magnetics solution.

Crystal or Oscillator

The following guidelines are the main specifications to reference for compatible crystals and oscillators:

Table 2-3 25-MHz Crystal Specifications
PARAMETER TEST CONDITION MIN TYP MAX UNIT
Frequency 25 MHz
Frequency Tolerance Including operational temperature, aging, and other factors ±100 ppm
Load Capacitance 15 40 pF
ESR 50 ohm
Table 2-4 25-MHz Oscillator Specifications
PARAMETER TEST CONDITION MIN TYP MAX UNIT
Frequency 25 MHz
Frequency Tolerance Operational temperature, 1 year aging ±100 ppm
Rise and Fall Time 20% - 80% 5 ns
Symmetry Duty cycle 40% 60%