LM124-N, LM224-N

LM2902-N, LM324-N

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SNOSC16D – MARCH 2000 – REVISED JANUARY 2015

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Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component

specification, and TI does not warrant its accuracy or completeness. TI’s customers are

responsible for determining suitability of components for their purposes. Customers should

validate and test their design implementation to confirm system functionality.

8.1 Application Information

The LM124 series of amplifiers is specified for operation from 3 V to 32 V (±1.5 V to ±16 V). Many of the

specifications apply from –40°C to 125°C. Parameters that can exhibit significant variance with regards to

operating voltage or temperature are presented in Typical Characteristics.

8.2 Typical Applications

Figure 15 emphasizes operation on only a single power supply voltage. If complementary power supplies are

available, all of the standard op amp circuits can be used. In general, introducing a pseudo-ground (a bias

application circuits are shown which take advantage of the wide input common-mode voltage range which

includes ground. In most cases, input biasing is not required and input voltages which range to ground can easily

be accommodated.

8.2.1 Non-Inverting DC Gain (0 V Input = 0 V Output)

Figure 15. Non-Inverting Amplifier with G=100

8.2.1.1 Design Requirements

For this example application, the required signal gain is a non-inverting 100x±5% with a supply voltage of 5 V.

8.2.1.2 Detailed Design Procedure

Using the equation for a non-inverting gain configuration, Av = 1+R2/R1. Setting the R1 to 10 k

Ω, R2 is 99 times

larger than R1, which is 990 k

Ω. A 1MΩ is more readily available, and provides a gain of 101, which is within the

desired specification.

The gain-frequency characteristic of the amplifier and its feedback network must be such that oscillation does not

occur. To meet this condition, the phase shift through amplifier and feedback network must never exceed 180°

for any frequency where the gain of the amplifier and its feedback network is greater than unity. In practical

applications, the phase shift should not approach 180° since this is the situation of conditional stability. Obviously

the most critical case occurs when the attenuation of the feedback network is zero.

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