However, the DPM is not just for power applications. Displayed here is a four gas sensing circuit using the ISL28023, several precision amplifiers, and four electrochemical sensors. These sensors are used in mining, household carbon monoxide detectors, in the food industry, and in manufacturing to monitor the concentration of gas elements. Most electrochemical sensors do not require an activation voltage. For those that do, such as sensor one in the circuit, the 8-bit digital to analog converter (DAC) is used to set the activation voltage of the sensor. When the selected gas is detected, the sensor reacts and creates a current that is proportional to the concentration of gas. The current flows through the shunt resistor RSH1 and is measured by the DPM. The SMBAlert2 line drives a depletion PFET to activate the sensor when needed or deactivate it to maintain a safe potential when not in use. Sensor two also has current flow proportional to the concentration of a selected gas, but it requires a trans-impedance amp to convert the current into an amplified voltage. The voltage is then measured by the auxiliary port of the ISL28023. In both of the cases, a formula is applied to the voltage measurements in software to determine the gas levels. Sensors three and four can be used in a similar manner as the first two sensors, with the output of the DAC being shared if using another biased sensor.