The outputs of the ISO121x devices can be used to drive status LEDs on the controller side as shown in Figure 26. The output buffers of the ISO121x can provide 4-mA, 3-mA, and 2-mA currents while working at VCC1 values of 5 V, 3.3 V, and 2.5 V respectively.
In some cases, placing the LED on the field side is desirable although it is powered from VCC1. In such cases, the signal carrying current to the LED can be routed in an inner layer without compromising the isolation of the digital-input module. For more information, see the Layout Guidelines section.