Control amplifier
The control amplifier (A1 op amp in Figure 2) has two tasks:
a) providing initial charge to the sensor, b) providing a bias
voltage to the sensor. A1 has the capability to drive up to 10-
mA into the sensor in order to to provide a fast initial conditioning.
A1 is able to sink and source current according to the
connected gas sensor (reducing or oxidizing gas sensor). It
can be powered down to reduce system power consumption.
However powering down A1 is not recommended, as it may
take a long time for the sensor to recover from this situation.