AN838 Datasheet, PDF (1/4 Pages) Silicon Laboratories – NANOPOWER CIRCUIT DESIGN IN LOW-FREQUENCY SENSOR APPLICATIONS

AN838
NANOPOWER CIRCUIT DESIGN IN LOW-FREQUENCY
SENSOR APPLICATIONS
1. Introduction
Oxygen sensors (O2 sensors) are used in life safety and industrial applications and can be found inside a low
power portable, handheld device or integrated into a larger system. Life safety applications use these sensors to
monitor adequate oxygen levels in a confined space such as inside an aircraft or in a lab. Industrial applications
use these sensors to measure the absence of atmospheric oxygen to make sure bacterial growth is inhibited in the
vacuum packaging of food products. Although this design is specific to an O2 sensor, the application circuit
development here applies equally to other types of dc or low-frequency sensors.
2. Overview
The right combination of dc specifications and low power operation is essential in selecting the right operational
amplifier for low-voltage, low-current sensor signal conditioning applications where signal frequencies are often
below 100 Hz.
A 1.5 V-powered O2 sensor signal conditioning circuit that can detect and amplify an O2 sensor’s signal voltage is
shown in Figure 1.
Figure 1. Op Amp O2 Sensor Circuit
Rev. 1.0 1/15
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AN838