The DP83TD510 has external termination on the MDI pins suitable for intrinsic safety applications. A key advantage of this design allows the DP83TD510 to be used with cables with varying characteristic impedances. The 10Base-T1L standard uses 100 ohm reference impedance in its link segment characteristics specifications. However, if a customer wants to introduce the DP83TD510 into an existing application with different characteristic impedance, the external termination of the DP83TD510 can be adjusted to accommodate the application.

The schematic shown in Figure 4-1 highlights the external MDI termination resistor in the DP83TD510 design that can be tuned for cable impedance. Figure 4-1 shows a design for 100 ohm characteristic impedance with R1 and R2 values of 49.9 ohms on TD_P and TD_N pins.

Figure 4-2 shows a design for 125 ohm characteristic impedance cable with R3 and R4 values of 62.5 ohms on TD_P and TD_N pins.