SBAA783 January   2026 ISOM8600 , ISOM8610

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Digital Output in PLC/DCS, Motor Drives and Robotics
    1. 1.1 Sink and Source Outputs: Supports Bidirectional Operation
    2. 1.2 PLC/DCS
    3. 1.3 Motor Drives
    4. 1.4 Robotics
  5. 2Design Procedures for Driving a Relay (Inductive Load)
    1. 2.1 Introduction to a Mechanical Relay
    2. 2.2 ISOM8600 Design Example
    3. 2.3 Test Results based on ISOM8600 and relay
      1. 2.3.1 Test 1: No Protection
      2. 2.3.2 Test 2: Capacitive Filter
      3. 2.3.3 Test 3: Zener Active Clamping Diode
  6. 3ISOM86x0 Advantages
    1. 3.1 Isolation Technology
    2. 3.2 Opto-Emulator Signal Chain
  7. 4Summary
  8. 5References

2.2 ISOM8600 Design Example

The input side of the ISOM86x0 is current-driven. As shown in Figure 1-2, a user can place RLIM in series with the input to limit the current flowing into AN pin. RLIM is selected to set the input current ON threshold according to the Recommended Operating Conditions (0.8mA to 20mA) for the ISOM8600.

The equation to calculate RIN for a given input voltage (VIN) and desired input forward current (IF) is shown in Equation 1 where VF is the maximum specification for the ISOM8610 input forward voltage:

Equation 1. RLIM = VIN − VF / IF_MAX
For example, with a 24V input and 2mA desired IF, RLIM can be calculated as:
Equation 2. RLIM = 24V − 1.5V / 2mA = 11.25kΩ