SNLA487 May   2025 DP83826AE , DP83826AI

 

  1.   1
  2.   KSZ8081MNX/RNB to DP83826A System Rollover
  3.   Trademarks
  4. 1Purpose
  5. 2Required Changes
    1. 2.1 Strap Resistor Value
    2. 2.2 External Capacitor on Pin 2
    3. 2.3 Duplex Strap on Pin 16 (DP83826A Basic Mode)
    4. 2.4 Selecting 10M with Auto-Negotiation Enabled (DP83826A Basic Mode)
    5. 2.5 Configuring LED_1 for Tx and Rx Activity for EtherCAT Slave (DP83826A Basic Mode)
    6. 2.6 Thermal Pad Adjustments in Layout
    7. 2.7 Physical Layer ID Register
  6. 3Potential Changes
    1. 3.1 MDIO Pull-Up Resistor on Pin 11
    2. 3.2 MDIO Register Writes
    3. 3.3 Capacitors on Center Tap of Magnetics
  7. 4Informational Changes
  8. 5Pinout Mapping
    1. 5.1 Pin Mapping
  9. 6DP83826A Strap Configurations
    1. 6.1 Bootstrap Configurations

2.4 Selecting 10M with Auto-Negotiation Enabled (DP83826A Basic Mode)

KSZ8081MNX and DP83826A default to 100M speed. To select 10M speed, KSZ8081 recommends a pull-down on the strap along with a series resistor on the LED. For DP83826A Basic Mode, 10M speed selection is done through register configuration and the strap resistor on Pin 31 is removed.

  • Remove the strap resistor on Pin 31 for 10M selection.
  • Program register 0x0004 with 0x0061 to select 10M speed when auto-negotiation is enabled.
  • Program register 0x0000 with 0x3300 to restart auto-negotiation.