LS204 HIGH PERFORMANCE DUAL OPERATIONAL AMPLIFIER ■ LOW POWER CONSUMPTION ■ SHORT CIRCUIT PROTECTION ■ LOW DISTORTION, LOW NOISE ■ HIGH GAIN-BANDWIDTH PRODUCT ■ HIGH CHANNEL SEPARATION N DIP8 (Plastic Package) 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 (active filter, etc). D SO8 (Plastic Micropackage) PIN CONNECTIONS (top view) ORDER CODE Package Part Number Temperature Range N LS204C 0°C, +70°C LS204I -40°C, +105°C Example : LS204CN • • D • • Output1 1 Inverting input 1 2 - Non-invertinginput 1 3 + V CC - 4 8 VCC+ 7 Output2 - 6 Invertinginput 2 + 5 Non-invertinginput 2 N = Dual in Line Package (DIP) D = Small Outline Package (SO) - also available in Tape & Reel (DT) November 2001 1/10 LS204 SCHEMATIC DIAGRAM (1/2 LS204) ABSOLUTE MAXIMUM RATINGS Symbol Unit Supply voltage ±18 V Input Voltage ±VCC V Vid Differential Input Voltage ±(VCC -1) V 0 to +70 -40 to +105 °C Toper 2/10 Value Vi V CC 1. Parameter Operating Temperature Range LS204C LS204I Ptot Power Dissipation at Tamb = 70°C 1) 500 mW TJ Junction Temperature 150 °C Tstg Storage Temperature Range -65 to +150 °C Power dissipation must be considered to ensure maximum junction temperature (Tj) is not exceeded. LS204 ELECTRICAL CHARACTERISTICS VCC = ±15V, T amb = 25°C (unless otherwise specified) LS204I Symbol LS204C Parameter Unit Min. Typ. Max. Min. Typ. Max. Icc Supply Current 0.7 1.2 0.8 1.5 mA Iib Input Bias Current Tamb = 25°C Tmin < Top < Tmax 50 150 300 100 300 700 nA Ri Input Resistance (f = 1kHz) 1 V io Input Offset Voltage (Rs ≤ 10kΩ) Tamb = 25°C Tmin < Top < Tmax DV io Input Offset Voltage Drift (Rs ≤ 10kΩ) Tmin < Top < Tmax Iio Input Offset Current Tmin < Top < Tmax DI io Input Offset Current Drift Tmin < Top < Tmax Ios Output Short-circuit Current Avd Large Signal Voltage Gain Tmin < Top < Tmax RL = 2kΩ VCC = ±15V VCC = ±4V GBP en 0.5 2.5 3.5 0.5 5 5 Gain Bandwith Product (f =100kHz) 1 20 40 12 50 100 nA nA/°C 23 23 mA 86 100 95 1.8 3 1.5 2.5 8 10 18 10 12 20 0.03 0.03 Total Harmonic Distortion (f = 1kHz, Av = 20dB, RL = 2kΩ, V o = 2Vpp) ±Vopp Output Voltage Swing R L = 2kΩ Vopp Large Signal Voltage Swing R L = 10kΩ, f = 10kHz SR Slew Rate (RL = 2kΩ, unity gain) 0.8 SVR Supply Voltage Rejection Ratio Tmin < Top < Tmax 90 86 CMR Common Mode Rejection Ratio Vic = ±10V Tmin < Top < Tmax 90 86 Vo1/Vo2 Channel Separation (f= 1kHz) µV/°C 0.1 100 95 ±13 mV 0.08 THD VCC = ±15V VCC = ±4V 3.5 5 5 90 Equivalent Input Noise Voltage f = 1kHz, Rs = 100Ω R s = 50Ω R s = 1kΩ R s = 10kΩ MΩ ±3 ±13 ±3 dB MHz nV -----------Hz % V 28 28 Vpp 1.5 1 V/µs dB dB 100 120 120 dB 3/10 LS204 4/10 LS204 5/10 LS204 APPLICATION INFORMATION: Active low-pass filter BUTTERWORTH The Butterworth is a ”maximally flat” amplitude response filter (figure 10) Butterworth filters are used for filtering signals in data acquisition systems to prevent 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 3dB. The attenuation rate beyond the cutoff frequency is n6 dB per octave of frequency where n is the order (number of poles) of the filter. Other characteristics : ❑ Flattest possible amplitude response ❑ Excellent gain accuracy at low frequency end of passband BESSEL The Bessel is a type of “linear phase” filter. Because of their linear phase characteristics, these filters approximate a constant time delay over a limited frequency range. Bessel filters pass transient waveforms with a minimum of distortion. They are also used to provide time delays for low pass filtering of modulated waveforms and as a “running average” type filter. n π radians where The maximum phase shift is –---------2 n is the order (number of poles) of the filter. The cut-off frequency fc, is defined as 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. The following table can be used to obtain the -3dB frequency of the filter. -3dB Frequency 2 Pole 4 Pole 6 Pole 8 Pole 0.77fc 0.67fc 0.57fc 0.50fc Other characteristics : ❑ Selectivity not as great as Chebyschev or Butterworth ❑ Very little overshoot response to step inputs ❑ Fast rise time CHEBYSCHEV Chebyschev filters have greater selectivity than either Bessel ro Butterworth at the expense of ripple in the passband (figure 11). Chebyschev filters are normally designed with peak-to-peak ripple values from 0.2dB to 2dB. Increased ripple in the passband allows increased attenuation above the cut-off frequency. The cut-off frequency is defined as the frequency at which the amplitude response passes through the specificed maximum ripple band and enters the stop band. Other characteristics : ❑ Greater selectivity ❑ Very non-linear phase response ❑ High overshoot response to step inputs The table below shows the typical overshoot and setting time response of the low pass filters to a step input. Number of Poles Butterworth Bessel Chebyschev (ripple ±0.25dB) Chebyschev (ripple ±1dB) 2 4 6 8 2 4 6 8 2 4 6 8 2 4 6 8 Peak Overshoot Settling Time (% of final value) % Overshoot ±1% ±0.1% ±0.01% 4 11 14 14 0.4 0.8 0.6 0.1 11 18 21 23 21 28 32 34 1.1Fc sec. 1.7/fc 2.4/fc 3.1/fc 0.8/fc 1.0/fc 1.3/fc 1.6/fc 1.1/fc 3.0/fc 5.9/fc 8.4/fc 1.6/fc 4.8/fc 8.2/fc 11.6/fc 1.7Fc sec. 2.8/fc 3.9S/fc 5.1/fc 1.4/fc 1.8/fc 2.1/fc 2.3/fc 1.6/fc 5.4/fc 10.4/fc 16.4/fc 2.7/fc 8.4/fc 16.3/fc 24.8/fc 1.9Fc sec. 3.8/fc 5.0S/fc 7.1/fc 1.7/fc 2.4/fc 2.7/fc 3.2/fc - Design of 2nd order active low pass filter (Sallen and Key configuration unity gain op-amp) 6/10 - LS204 Fixed R = R1 = R2, we have (see figure 12) 1 ζ C 1 = ---- ------R ωc 1 1 C 2 = ---- ----------R ξ ωc Figure 12 : Filter Configuration C2 R1 R2 Vin Vout C1 Three parameters are needed to characterize the frequency and phase response of a 2nd order active filter: the gain (Gv), the damping factio (ξ) or the Q factor (Q = 2 ξ)1), and the cuttoff frequency (fc). The higher order response are 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 1). Table 1 ξ Q Bessel 3 ------2 1 ------3 Frequency at which Phase Shift is -90°C Butterworth 2 ------2 1 ------2 Frequency at which Gv = -3dB Chebyschev 2 ------2 1 ------2 Filter Response Cuttoff Frequency fc Frequency at which the amplitude response passes through specified max. ripple band and enters the stop bank. EXAMPLE Figure 13 : 5th Order Low-pass Filter (Butterworth) with Unity Gain configuration C2 Ri R1 C4 R2 R3 Ci R4 C1 C3 7/10 LS204 In the circuit of figure 13, for fc = 3.4kHz and Ri = R1 = R2 = R3 = 10kΩ, we obtain: 1 1 Ci = 1.354 ---- ------------ = 6.33nF R 2π f c The same method, referring to table 2 and figure 14 is used to design high-pass filter. In this case the damping factor is found by taking the reciprocal of the numbers in table 2. For fc = 5kHz and Ci = C1 = C2 = C3 = 1nF we obtain: 1 1 C1 = 0.421 ---- ------------ = 1.97nF R 2π fc 1 1 1 Ri = --------------- ---- ------------ = 25.5k Ω 0.354 C 2π fc 1 1 C2 = 1.753 ---- ------------ = 8.20nF R 2π fc 1 1 1 R1 = --------------- ---- ------------ = 75.6kΩ 0.421 C 2π fc 1 1 C3 = 0.309 ---- ------------ = 1.45nF R 2π fc 1 1 1 R2 = --------------- ---- ------------ = 18.2kΩ 1.753 C 2π fc 1 1 C4 = 3.325 ---- ------------ = 15.14nF R 2π fc 1 1 1 R3 = --------------- ---- ------------ = 103kΩ 0.309 C 2π fc The attenuation of the filter is 30dB at 6.8kHz and better than 60dB at 15kHz. 1 1 1 R4 = --------------- ---- ------------ = 9.6kΩ 3.325 C 2π fc Table 2 : Damping Factor for Low-pass Butterworth Filters Order Ci 2 3 1.392 4 5 1.354 6 7 1.336 8 C1 C2 C3 C4 0.707 1.41 0.202 3.54 0.92 C5 C6 1.08 0.38 2.61 0.421 1.75 0.309 3.235 0.966 1.035 0.707 1.414 0.259 3.86 0.488 1.53 0.623 1.604 0.222 4.49 0.98 1.02 0.83 1.20 0.556 1.80 Figure 14 : 5th Order High-pass Filter (Butterworth) with Unity Gain configuration R2 Ci C1 R4 C2 C3 Ri 8/10 C4 R1 R3 C7 C8 0.195 5.125 LS204 PACKAGE MECHANICAL DATA 8 PINS - PLASTIC PACKAGE Millimeters Inches Dimensions Min. A a1 B b b1 D E e e3 e4 F i L Z Typ. Max. Min. 3.32 0.51 1.15 0.356 0.204 0.020 0.045 0.014 0.008 0.065 0.022 0.012 0.430 0.384 0.313 2.54 7.62 7.62 3.18 Max. 0.131 1.65 0.55 0.304 10.92 9.75 7.95 Typ. 0.100 0.300 0.300 6.6 0260 5.08 3.81 1.52 0.200 0.150 0.060 0.125 9/10 LS204 PACKAGE MECHANICAL DATA 8 PINS - PLASTIC MICROPACKAGE (SO) s b1 b a1 A a2 C c1 a3 L E e3 D M 5 1 4 F 8 Millimeters Inches Dimensions Min. A a1 a2 a3 b b1 C c1 D E e e3 F L M S Typ. Max. 0.65 0.35 0.19 0.25 1.75 0.25 1.65 0.85 0.48 0.25 0.5 4.8 5.8 5.0 6.2 0.1 Min. Typ. Max. 0.026 0.014 0.007 0.010 0.069 0.010 0.065 0.033 0.019 0.010 0.020 0.189 0.228 0.197 0.244 0.004 45° (typ.) 1.27 0.050 3.81 3.8 0.4 0.150 4.0 1.27 0.6 0.150 0.016 0.157 0.050 0.024 8° (max.) Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibil ity for the consequences of use of such information nor for any infring ement of patents or other righ ts of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications mentioned in this publication are subject to change witho ut notice. This publ ication supersedes and replaces all information previously supplied. STMicroelectronics products are not authorized for use as critical components in life suppo rt devices or systems withou t express written approval of STMicroelectronics. The ST logo is a registered trademark of STMicroelectronics 2001 STMicroelectronics - Printed in Italy - All Rights Reserved STMicroelectronics GROUP OF COMPANIES Australia - Brazil - Canada - China - Finland - France - Germany - Hong Kong - India - Israel - Italy - Japan - Malaysia Malta - Morocco - Singapore - Spain - Sweden - Swit zerland - United Kingdom - United States http://www. st.com 10/10