OA1NP Datasheet, PDF (22/31 Pages) STMicroelectronics – Rail-to-rail input and output

Application information
OA1NP, OA2NP, OA4NP
Figure 40. Potentiostat schematic using the OA1NP (or OA2NP)

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4.8
Fast desaturation
When the OA1NP, OA2NP, and OA4NP, operational amplifiers go into saturation mode, they
take a short period of time to recover, typically thirty microseconds. When recovering after
saturation, the OA1NP, OA2NP, and OA4NP series does not exhibit any voltage peaks that
could generate issues (such as false alarms) in the application (see Figure 17). This is
because the internal gain of the amplifier decreases smoothly when the output signal gets
close to the V_CC+ or V_CC- supply rails (see Figure 15 and Figure 16).
Thus, to maintain signal integrity, the user should take care that the output signal stays at
100 mV from the supply rails.
With a trans-impedance schematic, a voltage reference can be used to keep the signal
away from the supply rails.
4.9
Using the OA1NP, OA2NP, OA4NP series in comparator mode
The OA1NP, OA2NP, and OA4NP series can be used as a comparator. In this case, the
output stage of the device always operates in saturation mode. In addition, Figure 4 shows
the current consumption is not bigger and even decreases smoothly close to the rails. The
OA1NP, OA2NP, and OA4NP are obviously operational amplifiers and are therefore
optimized to be used in linear mode. We recommend to use the TS88 series of nanopower
comparators if the primary function is to perform a signal comparison only.
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