LMV321M7SLASHNOPB datasheet(20/44 Pages) TI1

Part #	LMV321M7/NOPB

Description	Single/Dual/Quad General Purpose, Low Voltage, Rail-to-Rail Output Operational Amplifiers

PDF	44 Pages

Scroll/Zoom	100%

Manufacturer	TI1 [Texas Instruments]

Direct Link	http://www.ti.com

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20 / 44 page

LMV321-N, LMV321-N-Q1, LMV358-N, LMV358-N-Q1

LMV324-N, LMV324-N-Q1

SNOS012I – AUGUST 2000 – REVISED FEBRUARY 2013

www.ti.com

(3)

Figure 61. Sallen-Key 2nd-Order Active Low-Pass Filter

The following paragraphs explain how to select values for R1, R2, R3, R4, C1, and C 2 for given filter requirements,

such as ALP, Q, and fc.

The standard form for a 2nd-order low pass filter is

(4)

where

Q: Pole Quality Factor

ωC: Corner Frequency

A comparison between Equation 3 and Equation 4 yields

(5)

(6)

To reduce the required calculations in filter design, it is convenient to introduce normalization into the

components and design parameters. To normalize, let

ωC = ωn = 1 rad/s, and C1 = C2 = Cn = 1F, and substitute

these values into Equation 5 and Equation 6. From Equation 5, we obtain

(7)

From Equation 6, we obtain

(8)

For minimum DC offset, V+ = V−, the resistor values at both inverting and non-inverting inputs should be equal,

which means

(9)

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Product Folder Links: LMV321-N LMV321-N-Q1 LMV358-N LMV358-N-Q1 LMV324-N LMV324-N-Q1

LMV321M7/NOPB Datasheet(PDF) 20 Page - Texas Instruments