Why split termination in a CAN bus than standard termination?

 

Split termination in a CAN bus offers advantages over standard 120-ohm termination, especially in electrically noisy environments. Here’s why it’s preferred in certain applications:

1. Enhanced Electromagnetic Interference (EMI) Suppression

• Split termination uses two 60-ohm resistors with a capacitor (typically 10nF) in between.
• The capacitor acts as a low-pass filter, reducing high-frequency noise and improving signal stability.
• Helps prevent unwanted voltage fluctuations caused by external interference.

2. Better Common-Mode Noise Reduction

• CAN bus systems are susceptible to common-mode noise, which can cause transmission errors.
• The capacitor in split termination helps stabilize the common-mode voltage, reducing noise pickup.
• Improves performance in automotive, industrial, and long-distance CAN networks.

3. Improved Differential Signal Integrity

• Unlike a single 120Ω resistor, split termination evenly distributes resistance across the network.
• This minimizes signal distortion, resulting in a cleaner and more reliable differential signal.

4. Increased Stability in High-Speed Applications

• At higher CAN speeds (e.g., 500 kbps or 1 Mbps), reflections and noise can become problematic.
• Split termination improves signal integrity, reducing the risk of bit errors.

When to Use Split Termination?

• If your system is in a harsh electrical environment, like near motors or RF sources.
• If your CAN network operates at higher speeds.
• If noise immunity is a major concern, especially in automotive and industrial applications.