All of Analog Devices digital input devices have a programmable on-chip current limit for each of the inputs. For traditional discrete designs with a resistor divider, the current increases linearly as the input voltage reaches a value that is determined to be a logic “1” as shown here in the diagram on the right. With Analog Devices' current limiting feature, it clamps the current down at a programmable level, even as the input voltage reaches its maximum value. While obviously reducing current draw from the field voltage, more importantly, it dramatically reduces heat build-up in the module. Compared to the discrete solution, it reduces “hot spots” in the module, which enables a high channel count compared to the traditional approach. In addition to allowing increased channel density, it can result in an overall system cost reduction with a smaller field voltage power supply and reduced system cooling electronics. For the ultra low power mode, there is even further reduction in power consumption by using the internal clock to switch the current limit from 100% down to 20% for half of the duty cycle. For example, if the current limit is set to 2.4 mA, then the current limit will switch between 2.4 mA and 0.48 mA. This is a proprietary design and is patent pending.