Serial Port Complete - Latest Microcontroller projects

Chapter 7

If the line has a termination but the value is greater than the characteristic

impedance, the effect is similar but less extreme. Some of the initial current

flows in the termination and the rest reflects.

The reflected current eventually returns to the driver. The driver absorbs part of

the reflection and bounces the rest back, resulting in a reduced voltage at the

receiver. The reflections may continue to bounce back and forth for a few

Figure 7-5: The initial voltages across a parallel termination vary depending on the

difference between the termination and the line’s characteristic impedance.