SLLA634 March   2024 ISOM8610

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
    1. 1.1 OptoMOS Usage and Considerations
  5. 2Application Use Cases
    1. 2.1 Software Controllable Termination on CAN Nodes
    2. 2.2 Analog Current/Voltage Drivers to Load Isolation in a Programmable Logic Controller
    3. 2.3 Channel to Channel Isolated Universal Analog Input Module
    4. 2.4 Switching Precision Burden Resistor in Universal Analog Input Modules
    5. 2.5 Switch Outputs for Intrusion Detection Systems
  6. 3Summary
  7. 4References

Software Controllable Termination on CAN Nodes

ISOMOS enables a software configurable termination on the CAN bus, needed in networks where new nodes can be continually added. This design can enable or disable termination across CANH-CANL by driving TERM high or low with appropriate current limiting series resistor on LED emulator pins via MCU GPIO, as illustrated in Figure 2-1. Farthest terminals on the CAN Bus must be driving TERM = High to enable 120Ω resistor across the bus, while all other nodes drive TERM = Low.

ISOM8610 easily supports ±70V common mode with no distortion of CAN signals on the bus, with minimal loading on the bus with <1uA off-state leakage across temperature at blocking voltage of 70V. With a possibility of multiple nodes being added on the CAN bus, low off-state leakage and capacitance becomes more important for proper system functionality.

Additionally, ISOM8610 also does not require a bulky secondary side isolated power supply, to perform the switching operation. The TERM control is also galvanically isolated from the exposed CAN lines, enabling system protection. With this architecture, 60Ω effective termination across the CAN bus can be achieved with flexibility on enabling or disabling a node, with no hardware change.


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Figure 2-1 ISOM8610 for Software Controllable Switchable Termination on CAN Bus