LS204_08 STMICROELECTRONICS | Alldatasheet
Document overview
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Technical content
Features
■ Low power consumption ■ Short-circuit protection ■ Low distortion, low noise ■ High gain-bandwidth product ■ High channel separation
Description
The LS204 is a high performance dual operational amplifier with frequency and phase compensation built into the chip. The internal phase compensation allows stable operation as voltage follower in spite of its high gain-bandwidth product. The circuit presents very stable electrical characteristics over the entire supply voltage range, and is particularly intended for professional and telecom applications (such as active filtering). + - Output 1 Inverting input 1 Non-inverting input 1 VCC VCC Output 2 Inverting input 2 Non-inverting input 2- N DIP8 (Plastic package) D SO-8 (Plastic micro package) Pin connections (top view)
1 Circuit schematics
Figure 1. Schematic diagram (1/2 LS204)
2 Absolute maximum ratings and operating conditions
Table 1. Absolute maximum ratings
- All voltage values, except differential vo ltage, are with respect to the zero reference level (ground) of the supply voltages
- The magnitude of the input voltage must never exceed the magnit ude of the supply voltage or 15 volts, whichever is less.
- Differential voltages are the non-inverting input term inal with respect to the inverting input terminal.
- Short-circuits can c ause excessive heating and destructive dissipation. Values are typical.
- The output may be shorted to ground or to either supply. Temperature and/or supply voltages must be limited to ensure
that the dissipation rating is not exceeded.
- Human body model: A 100 pF capacitor is charged to the specified voltage, then discharged through a 1.5 kΩ resistor
between two pins of the device. This is done for all couples of connected pin combinations while the other pins are floating.
- Machine model: A 200 pF capacitor is c harged to the specified voltage, then discharged directly between two pins of the
while the other pins are floating.
- Charged device model: all pins and the pac kage are charged together to the specified voltage and then discharged directly
to the ground through only one pin. This is done for all pins. Table 2. Operating conditions
3 Electrical characteristics
Table 3. Electrical characteristics at V CC = ±15 V, Tamb = +25° C (unless otherwise specified)
4 Application information for active low-pass filters
4.1 Butterworth
The Butterworth is a "maximally flat" amplitude response filter (Figure 11). aliasing errors in samples-data applications and for general purpose low-pass filtering. The cut-off frequency, Fc, is the frequency at which the amplitude response is down 3 dB. is the order (number of poles) of the filter.
- Flattest possible amplitude response
- Excellent gain accuracy at low frequency end of passband
4.2 Bessel
The Bessel is a type of “linear phase” filter. waveforms and as a “running average” type filter. the frequency at which the phase shift is one half of this value. For accurate delay, the cut-off frequency should be twice the maximum signal frequency. Table 4 can be used to obtain the -3 dB frequency of the filter.
- Selectivity not as great as Chebyschev or Butterworth
- Very little overshoot response to step inputs
- Fast rise time
4.3 Chebyschev
of ripple in the passband (Figure 12). Table 4. -3 dB frequency of the filter
2 Poles 4 Poles 6 Poles 8 Poles
Increased ripple in the passband allows increased attenuation above the cut-off frequency. through the specified maximum ripple band and enters the stop band.
- Greater selectivity
- Very non-linear phase response
- High overshoot response to step inputs Table 5 shows the typical overshoot and setting time response of the low pass filters to a step input.
4.4 Design of 2nd order active low pass filter (Sallen and Key
Table 5. Overshoot and setting time response of low pass filters to step input
Figure 13. Filter configuration
- the gain (Gv),
- the damping factor (ξ ) or the Q factor (Q = 2 ξ )1),
- the cut-off frequency (Fc). The higher order response is obtained with a series of 2nd order sections. A simple RC section is introduced when an odd filter is required. The choice of ξ (or Q factor) determines the filter response (see Table 6).
Table 6. Filter response to ξ or Q factor specified max. ripple band and enters the stop bank.
4.5 Example
Figure 14. 5th order low-pass filter (Butterworth) with unity gain configuration The attenuation of the filter is 30 dB at 6.8 kHz and better than 60 dB at 15 kHz. The same method, referring to Table 7 and Figure 15 is used to design high-pass filters. In this case the damping factor is found by taking the reciprocal of the numbers in Ta bl e 7. Figure 15. 5th order high-pass filter (Butterworth) with unity gain configuration
Table 7. Damping factor for low-pass Butterworth filters
5 Package information
In order to meet environmental requirements, STMicroelectronics offers these devices in ECOPACK® packages. These packages have a lead-free second level interconnect. The category of second level interconnect is marked on the package and on the inner box label, in compliance with JEDEC Standard JESD97. The maximum ratings related to soldering conditions are also marked on the inner box label. ECOPACK is an STMicroelectronics trademark. ECOPACK specifications are available at: www.st.com
5.1 DIP8 package information
Figure 16. DIP8 package mechanical drawing Table 8. DIP8 package mechanical data
5.2 SO-8 package information
Figure 17. SO-8 package mechanical drawing Table 9. SO-8 package mechanical data
6 Ordering information
7 Revision history
Table 10. Order codes
- Qualification and characterizati on according to AEC Q100 and Q003 or equivalent, advanced screening
according to AEC Q001 & Q 002 or equivalent are on-going. Table 11. Document revision history 29-Nov-2001 1 Initial release. 4-Jun-2008 2 Updated document format. Added automotive grade order codes.