Arasan I3C PHY - Ternary vs. Non-Ternary

By _Arasan Blog

September 20, 2024

I3C (Improved Inter-Integrated Circuit) is a communication protocol that builds on the I2C standard, offering improved performance, power efficiency, and data rates. In the I3C PHY layer, ternary and non-ternary modes refer to the encoding methods used for signaling.

Ternary Mode

• Definition: In ternary mode, three signal states are used for communication. This allows more information to be encoded in fewer transitions. HDR-TSP and HDR-TSL use Ternary signaling on the two wires.
• Advantages:
  • Higher Data Rates: By encoding more data per signal transition, ternary mode can achieve faster data transfer rates.
  • Power Efficiency: It can be more power-efficient as fewer transitions are required to send the same amount of data.
  • Noise Immunity: The intermediate state provides better noise tolerance, as small fluctuations in voltage may not result in misinterpreted signals.
• Applications: Ternary signaling is typically used in high-speed I3C communication where maximizing data throughput is important.

Non-Ternary Mode

• Definition: Non-ternary mode refers to traditional binary signaling with two states. But no HDR-TSL/TSP support.
• Advantages:
  • Simplicity: Easier to implement in hardware since it uses only two states (high and low).
  • Compatibility: Works well with legacy I2C devices that only support binary signaling.
  • Lower Complexity: Non-ternary mode may be easier to design and debug due to simpler signaling.
• Applications: Non-ternary mode is commonly used in lower-speed, lower-power applications where the simplicity of binary signaling is sufficient.

Key Differences

1. Data Encoding:
   • Ternary mode uses three states, allowing more data per transition.
   • Non-ternary mode uses two states (binary signaling).
2. Speed:
   • Ternary mode offers higher data rates.
   • Non-ternary mode operates at lower speeds.
3. Complexity:
   • Ternary mode is more complex to implement but more efficient.
   • Non-ternary mode is simpler but less efficient in terms of data rate.
4. Use Case:
   • Ternary mode is typically used for high-performance devices requiring fast communication.
   • Non-ternary mode is used in simpler, cost-sensitive, or legacy systems.

If you're designing or selecting an I3C PHY, the choice between ternary and non-ternary mode will depend on your application's speed, power efficiency, and hardware complexity requirements.