LMP2012QML

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SNOSAU5H – MARCH 2007 – REVISED APRIL 2013

LMP2012 AS ADC INPUT AMPLIFIER

The LMP2012 is a great choice for an amplifier stage immediately before the input of an ADC (Analog-to-Digital

Converter), whether AC or DC coupled. See Figure 8 and Figure 9. This is because of the following important

characteristics:

A)

Very low offset voltage and offset voltage drift over time and temperature allow a high closed-loop gain

setting without introducing any short-term or long-term errors. For example, when set to a closed-loop gain

of 100 as the analog input amplifier for a 12-bit A/D converter, the overall conversion error over full

operation temperature and 30 years life of the part (operating at 50°C) would be less than 5 LSBs.

B)

Fast large-signal settling time to 0.01% of final value (1.4

μs) allows 12 bit accuracy at 100 KHZ or more

sampling rate.

C)

No flicker (1/f) noise means unsurpassed data accuracy over any measurement period of time, no matter

how long. Consider the following op amp performance, based on a typical low-noise, high-performance

commercially-available device, for comparison:

Op amp flatband noise = 8nV/

√Hz

1/f corner frequency = 100 Hz

AV = 2000

Measurement time = 100 sec

Bandwidth = 2 Hz

This example will result in about 2.2 mVPP (1.9 LSB) of output noise contribution due to the op amp alone,

compared to about 594

μVPP (less than 0.5 LSB) when that op amp is replaced with the LMP2012 which

has no 1/f contribution. If the measurement time is increased from 100 seconds to 1 hour, the

improvement realized by using the LMP2012 would be a factor of about 4.8 times (2.86 mVPP compared to

596

μV when LMP2012 is used) mainly because the LMP2012 accuracy is not compromised by increasing

the observation time.

D)

Rail-to-Rail output swing maximizes the ADC dynamic range in 5-Volt single-supply converter applications.

Below are some typical block diagrams showing the LMP2012 used as an ADC amplifier (Figure 8 and

Figure 9).

Figure 9.

RADIATION ENVIRONMENTS

Careful consideration should be given to environmental conditions when using a product in a radiation

environment.

TOTAL IONIZING DOSE

Radiation hardness assured (RHA) products are those part numbers with a total ionizing dose (TID) level

specified in the Ordering Information table on the front page. Testing and qualification of these products is done

on a wafer level according to MIL-STD-883G, Test Method 1019.7, Condition A and the “Extended room

temperature anneal test” described in section 3.11 for application environment dose rates less than 0.082

rad(Si)/s. Wafer level TID data are available with lot shipments.

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