OP179_02 Datasheet, PDF (14/16 Pages) Analog Devices – Rail-to-Rail High Output Current Operational Amplifiers

OP179/OP279
The crossover example frequency of 500 Hz can be shifted lower
or higher by frequency scaling of either resistors or capacitors. In
configuring the circuit for other frequencies, complementary LP/
HP action must be maintained between sections, and component
values within the sections must be in the same ratio. Table II
provides a design aid to adaptation, with suggested standard
component values for other frequencies.
Table II. RC Component Selection for Various Crossover
Frequencies
Crossover Frequency (Hz)
R1/C1 (U1A)*
R5/C3 (U1B)**
100
160 kΩ/0.01 µF
200
80.6 kΩ/0.01 µF
319
49.9 kΩ/0.01 µF
500
31.6 kΩ/0.01 µF
1k
16 kΩ/0.01 µF
2k
8.06 kΩ/0.01 µF
5k
3.16 kΩ/0.01 µF
10 k
1.6 kΩ/0.01 µF
Table notes (applicable for α = 2).
** For SK stage U1A: R1 = R2, and C1 = C2, etc.
** For MFB stage U1B: R6 = R5, R7 = R5/2, and C4 = 2C3.
References on Active Filters and Active Crossover Networks
1. Sallen, R.P.; Key, E.L., “A Practical Method of Designing
RC Active Filters,” IRE Transactions on Circuit Theory, Vol.
CT-2, March 1955.
2. Huelsman, L.P.; Allen, P.E., Introduction to the Theory and
Design of Active Filters, McGraw-Hill, 1980.
3. Zumbahlen, H., “Chapter 6: Passive and Active Analog
Filtering,” within 1992 Analog Devices Amplifier Applications
Guide.
4. Zumbahlen, H., “Speaker Crossovers,” within Chapter 8 of
1993 Analog Devices System Applications Guide.
5. Linkwitz, S., “Active Crossover Networks for Noncoincident
Drivers,” JAES, Vol. 24, #1, Jan/Feb 1976.
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REV. G