Electronic Components Datasheet Search |
|
UAF42AU Datasheet(PDF) 4 Page - Burr-Brown (TI) |
|
|
UAF42AU Datasheet(HTML) 4 Page - Burr-Brown (TI) |
4 / 6 page 4 At low frequencies, the value required for the frequency- setting resistors can be excessive. Resistor values above about 5M Ω can react with parasitic capacitance causing poor filter performance. When fO is below 10Hz, external capacitors must be added to keep the value of RF1 and RF2 below 5M Ω . When f O is in the range of about 10Hz to 32Hz, An external 5.49k Ω resistor, R 2A, is added in parallel with the internal resistor, R2, to reduce RF1 and RF2 by √10 and eliminate the need for external capacitors. At the other extreme, when fO is above 10kHz, R2A, is added in parallel with R2 to improve stability. External filter gain-set resistors, RG, are always required when using an inverting pole-pair configuration or when using a noninverting configuration with Q < 0.57. PP1 (Noninverting pole-pair subcircuit using internal gain- set resistor, R3)—See Figure 7. In the automatic topology selection mode, this configuration is used for all band-pass filter responses. This configuration allows the combination of unity pass-band gain and high Q (up to 400). Since no external gain-set resistor is required, external parts count is minimized. PP2 (Noninverting pole-pair subcircuit using an external gain-set resistor, RG)—See Figure 8. This configuration is used when the pole-pair Q is less than 0.57. PP3 (Inverting pole-pair subcircuit)—See Figure 9A. In the automatic topology selection mode, this configuration is used for the all-pole low-pass and high-pass filter responses. This configuration requires an external gain-set resistor, RG. With RG = 50kΩ, low-pass and high-pass gain are unity. PP4 (Noninverting pole-pair/zero subcircuit)—See Figure 10. In addition to a complex pole-pair, this configuration produces a j ω-axis zero (response null) by summing the low- pass and high-pass outputs using the auxiliary op amp, A4, in the UAF42. In the automatic topology selection mode, this configuration is used for all band-reject (notch) filter responses and Inverse Chebyshev filter types when Q > 0.57. This subcircuit option keeps external parts count low by using the internal gain-set resistor, R3. PP5 (Noninverting pole-pair/zero subcircuit)—See Figure 11. In addition to a complex pole-pair, this configuration produces a j ω-axis zero (response null) by summing the low- pass and high-pass outputs using the auxiliary op amp, A4, in the UAF42. In the automatic topology selection mode, this configuration is used for all band-reject (notch) filter responses and Inverse Chebyshev filter types when Q < 0.57. This subcircuit option requires an external gain-set resistor, RG. PP6 (Inverting pole-pair/zero subcircuit)—See Figure 12. In addition to a complex pole-pair, this configuration produces a j ω-axis zero (response null) by summing the low-pass and high-pass outputs using the auxiliary op amp, A4, in the UAF42. This subcircuit is only used when you override the automatic topology selection algorithm and specify the in- verting pole-pair topology. Then it is used for all band-reject (notch) filter responses and Inverse Chebyshev filter types. The program automatically places lower Q stages ahead of higher Q stages to prevent op amp output saturation due to gain peaking. Even so, peaking may limit input voltage to less than ±10V (V S = ±15V). The maximum input voltage for each filter design is shown on the filter block diagram. If the UAF42 is to be operated on reduced supplies, the maximum input voltage must be derated commensurately. To use the filter with higher input voltages, you can add an input attenuator. The program designs the simplest filter that provides the desired AC transfer function with a pass-band gain of 1.0V/V. In some cases the program cannot make a unity- gain filter and the pass-band gain will be less than 1.0V/V. In any case, overall filter gain is shown on the filter block diagram. If you want a different gain, you can add an additional stage for gain or attenuation as required. To build the filter, print-out the block diagram and compo- nent values. Consider one subcircuit at a time. Match the subcircuit type referenced on the component print-out to its corresponding circuit diagram—see the Filter Subcircuits section of this bulletin. The UAF42 Filter Component Values print-out has places to display every possible external component needed for any subcircuit. Not all of these components will be required for any specific filter design. When no value is shown for a component, omit the component. For example, the detailed schematic diagrams for complex pole-pair subcircuits show external capacitors in parallel with the 1000pF capacitors in the UAF42. No external capacitors are required for filters above approximately 10Hz. After the subcircuits have been implemented, connect them in series in the order shown on the filter block diagram. FILTER SUBCIRCUITS Filter designs consist of cascaded complex pole-pair and real-pole subcircuits. Complex pole pair subcircuits are based on the UAF42 state-variable filter topology. Six varia- tions of this circuit can be used, PP1 through PP6. Real pole sections can be implemented with the auxiliary op amp in the UAF42. High-pass (HP) and low-pass (LP) real-pole sections can be used. The subcircuits are referenced with a two or three letter abbreviation on the UAF42 Filter Compo- nent Values and Filter Block Diagram program outputs. Descriptions of each subcircuit follow: POLE-PAIR (PP) SUBCIRCUITS In general, all complex pole-pair subcircuits use the UAF42 in the state-variable configuration. The two filter parameters that must be set for the pole-pair are the filter Q and the natural frequency, fO. External resistors are used to set these parameters. Two resistors, RF1 and RF2, must be used to set the pole-pair fO. A third external resistor, RQ, is usually needed to set Q. |
Similar Part No. - UAF42AU |
|
Similar Description - UAF42AU |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.COM |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |