TIDUEB8C July 2018 – March 2021 TPS274160
The turn on of the L+ line is tested by applying a capacitor of 1000 µF, shorted by 150-Ω resistive load. The IO-Link master has to deliver at least 400 mA for 50 ms to pass this test. This load simulates a IO-Link device with a large input capacitor and a static load.
Figure 3-6 shows the test results. Channel 2 shows the voltage on the L+ line, channel 4 shows the current on L+. As the load is capacitive and resistive, at the beginning the current is limited to 600 mA by the high-side switch, for about 70 ms. After this time, the resistive load remains and draws a current of 200 mA. Since this energy is more than the necessary 400 mA × 50 ms = 20 mA, this test is passed.
However, different IO-Link master implementations behave very different in this test.