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

2.1 Strap Resistor Value

The DP83826A supports either basic Mode or enhanced mode. Basic mode supports the same bootstrap options as the KSZ8081. To set the DP83826A for basic mode, pin 1 (ModeSelect) must be tied to ground. In a KSZ8081 design, pin 1 is already tied to GND, so there is no change required to select the correct mode. To understand the difference between DP83826A basic Mode and enhanced mode, see the DP83826A data sheet.

Both devices use a 2-level strap that require a pull-up or pull-down resistor. The table below shows the difference in pull-up and pull-down resistor values between the DP83826A and the KSZ8081. See the TI Precision Labs Video 'How Do Ethernet bootstraps work?' to properly calculate the correct strap resistors.

Table 2-1 Strap Resistor Values
KSZ8081MNX/RNBDP83826A
Pull-Up Resistor Value4.7kΩ2.49kΩ
Pull-Down Resistor Value1kΩ1.5kΩ