OA1ZHA datasheet(23/35 Pages) STMICROELECTRONICS

tên linh kiện	OA1ZHA

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23 / 35 page

OA1ZHA, OA2ZHA, OA4ZHA

Application information

DocID025994 Rev 2

23/35

5.11

Application examples

5.11.1

Oxygen sensor

The electrochemical sensor creates a current proportional to the concentration of the gas

being measured. This current is converted into voltage thanks to R resistance. This voltage

is then amplified by OA1ZHA, OA2ZHA and OA4ZHA CMOS op amp (see Figure 47:

"Oxygen sensor principle schematic").

Figure 47: Oxygen sensor principle schematic

The output voltage is calculated using Equation 2:

Equation 2

As the current delivered by the O2 sensor is extremely low, the impact of the Vio can

become significant with a traditional operational amplifier. The use of the chopper amplifier

of the OA1ZHA, OA2ZHA and OA4ZHA is perfect for this application.

In addition, using OA1ZHA, OA2ZHA and OA4ZHA op amp for the O2 sensor application

ensures that the measurement of O2 concentration is stable even at different temperature

thanks to a very good ∆Vio/∆T.

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