LMC7101_15 Datasheet, PDF (24/33 Pages) Texas Instruments – LMC7101, LMC7101Q-Q1 Tiny Low-Power Operational Amplifier With Rail-to-Rail Input and Output

LMC7101, LMC7101Q-Q1
SNOS719G – SEPTEMBER 1999 – REVISED SEPTEMBER 2015
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Typical Application (continued)
8.2.1 Design Requirements
For this example application, the supply voltage is 5 V, and 100 × ±5% of noninverting gain is necessary. The
signal input impedance is approximately 10 kΩ.
8.2.2 Detailed Design Procedure
Use the equation for a noninverting amplifier configuration; G = 1 + R2 / R1, set R1 to 10 kΩ, and R2 to 99 × the
value of R1, which would be 990 kΩ. Replacing the 990-kΩ resistor with a more readily available 1-MΩ resistor
will result in a gain of 101, which is within the desired gain tolerance. 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 must not
approach 180° because this is the situation of conditional stability. The most critical case occurs when the
attenuation of the feedback network is zero.
8.2.3 Application Curve
VDD
Gain = 1 + R₂/R₁
= 101 (as shown)
V_IN (mV)
Figure 67. Output Response
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