1/10 n low power consumption n short circuit protection n low distortion, low noise n high gain-bandwidth product n 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 compensa- tion allows stable operation as voltage follower in spite of its high gain-bandwidth product. the circuit presents very stable electrical charac- teristics over the entire supply voltage range, and is particularly intended for professional and tele- com applications (active filter, etc). order code n = dual in line package (dip) d = small outline package (so) - also available in tape & reel (dt) pin connections (top view) part number temperature range package nd ls204c 0c, +70c ls204i -40c, +105c example : LS204CN n dip8 (plastic package) d so8 (plastic micropackage) 1 2 3 45 6 7 8 - + - + output 1 inverting input 1 non-inverting input 1 v cc v cc output 2 inverting input 2 non-inverting input 2 - + high performance dual operational amplifier november 2001 ls204
ls204 2/10 schematic diagram (1/2 ls204) absolute maximum ratings symbol parameter value unit v cc supply voltage 18 v v i input voltage v cc v v id differential input voltage (v cc -1) v t oper operating temperature range ls204c ls204i 0 to +70 -40 to +105 c p tot power dissipation at t amb = 70c 1) 500 mw t j junction temperature 150 c t stg storage temperature range -65 to +150 c 1. power dissipation must be considered to ensure maximum junction temperature (tj) is not exceeded.
ls204 3/10 electrical characteristics v cc = 15v, t amb = 25c (unless otherwise specified) symbol parameter ls204i ls204c unit min. typ. max. min. typ. max. i cc supply current 0.7 1.2 0.8 1.5 ma i ib input bias current t amb = 25c t min < t op < t max 50 150 300 100 300 700 na r i input resistance (f = 1khz) 1 1 m w v io input offset voltage (r s 10k w ) t amb = 25c t min < t op < t max 0.5 2.5 3.5 0.5 3.5 5 mv dv io input offset voltage drift (r s 10k w ) t min < t op < t max 55 v/c i io input offset current t min < t op < t max 520 40 12 50 100 na di io input offset current drift t min < t op < t max 0.08 0.1 na/c i os output short-circuit current 23 23 ma a vd large signal voltage gain t min < t op < t max r l = 2k w v cc = 15v v cc = 4v 90 100 95 86 100 95 db gbp gain bandwith product (f =100khz) 1.8 3 1.5 2.5 mhz e n equivalent input noise voltage f = 1khz, r s = 100 w r s = 50 w r s = 1k w r s = 10k w 8 10 18 10 12 20 thd total harmonic distortion (f = 1khz, a v = 20db, r l = 2k w , v o = 2v pp ) 0.03 0.03 % v opp output voltage swing r l = 2k w v cc = 15v v cc = 4v 13 3 13 3 v v opp large signal voltage swing r l = 10k w , f = 10khz 28 28 vpp sr slew rate (r l = 2k w , unity gain) 0.8 1.5 1 v/ m s svr supply voltage rejection ratio t min < t op < t max 90 86 db cmr common mode rejection ratio v ic = 10v t min < t op < t max 90 86 db v o1 /v o2 channel separation (f= 1khz) 100 120 120 db nv hz ----------- -
ls204 4/10
ls204 5/10
ls204 6/10 application information: active low-pass filter butterworth the butterworth is a "maximally flat" amplitude re- sponse filter (figure 10) butterworth filters are used for filtering signals in data acquisition sys- tems to prevent aliasing errors in samples-data applications and for general purpose low-pass fil- tering. the cut-off frequency fc, is the frequency at which the amplitude response is down 3db. the attenu- ation 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 : q flattest possible amplitude response q excellent gain accuracy at low frequency end of passband bessel the bessel is a type of linear phase filter. be- cause of their linear phase characteristics, these filters approximate a constant time delay over a limited frequency range. bessel filters pass tran- sient 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. the maximum phase shift is radians where 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. other characteristics : q selectivity not as great as chebyschev or butterworth q very little overshoot response to step inputs q fast rise time chebyschev chebyschev filters have greater selectivity than ei- ther 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 : q greater selectivity q very non-linear phase response q 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. design of 2nd order active low pass filter (sallen and key configuration unity gain op-amp) n p C 2 ---------- - 2 pole 4 pole 6 pole 8 pole -3db frequency 0.77fc 0.67fc 0.57fc 0.50fc number of poles peak overshoot settling time (% of final value) % overshoot 1% 0.1% 0.01% butterworth 2 4 6 8 4 11 14 14 1.1fc sec. 1.7/fc 2.4/fc 3.1/fc 1.7fc sec. 2.8/fc 3.9s/fc 5.1/fc 1.9fc sec. 3.8/fc 5.0s/fc 7.1/fc bessel 2 4 6 8 0.4 0.8 0.6 0.1 0.8/fc 1.0/fc 1.3/fc 1.6/fc 1.4/fc 1.8/fc 2.1/fc 2.3/fc 1.7/fc 2.4/fc 2.7/fc 3.2/fc chebyschev (ripple 0.25db) 2 4 6 8 11 18 21 23 1.1/fc 3.0/fc 5.9/fc 8.4/fc 1.6/fc 5.4/fc 10.4/fc 16.4/fc - - - - chebyschev (ripple 1db) 2 4 6 8 21 28 32 34 1.6/fc 4.8/fc 8.2/fc 11.6/fc 2.7/fc 8.4/fc 16.3/fc 24.8/fc - - -
ls204 7/10 fixed r = r1 = r2, we have (see figure 12) figure 12 : filter configuration three parameters are needed to characterize the frequency and phase response of a 2nd order ac- tive filter: the gain (gv), the damping factio ( x ) or the q factor (q = 2 x ) 1 ), and the cuttoff frequency (fc). the higher order response are obtained with a se- ries of 2nd order sections. a simple rc section is introduced when an odd filter is required. the choice of x ' (or q factor) determines the filter response (see table 1). table 1 example figure 13 : 5th order low-pass filter (butterworth) with unity gain configuration c 1 = 1 r --- - z w c ------- c 2 = 1 r --- - 1 x w c ---------- - c2 r2 r1 vin c1 vout filter response x q cuttoff frequency fc bessel frequency at which phase shift is -90c butterworth frequency at which gv = -3db chebyschev frequency at which the amplitude response passes through specified max. ripple band and enters the stop bank. 3 2 ------- 1 3 ------- 2 2 ------- 1 2 ------- 2 2 ------- 1 2 ------- c2 r2 r1 c1 ri ci c4 r4 r3 c3
ls204 8/10 in the circuit of figure 13, for fc = 3.4khz and r i = r1 = r2 = r3 = 10k w , we obtain: the attenuation of the filter is 30db at 6.8khz and better than 60db at 15khz. 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 recipro- cal of the numbers in table 2. for fc = 5khz and ci = c1 = c2 = c3 = 1nf we obtain: table 2 : damping factor for low-pass butterworth filters figure 14 : 5th order high-pass filter (butterworth) with unity gain configuration ci = 1.354 1 r --- - 1 2 p fc ------------ = 6 . 3 3 n f c1 = 0.421 1 r --- - 1 2 p fc ------------ = 1 . 9 7 n f c2 = 1.753 1 r --- - 1 2 p fc ------------ = 8 . 2 0 n f c3 = 0.309 1 r --- - 1 2 p fc ------------ = 1 . 4 5 n f c4 = 3.325 1 r --- - 1 2 p fc ------------ = 1 5 . 14nf ri = 1 0.354 -------------- - 1 c --- - 1 2 p fc ------------ = 2 5 . 5 k w r1 = 1 0.421 -------------- - 1 c --- - 1 2 p fc ------------ = 7 5 . 6 k w r2 = 1 1.753 -------------- - 1 c --- - 1 2 p fc ------------ = 1 8 . 2 k w r3 = 1 0.309 -------------- - 1 c --- - 1 2 p fc ------------ = 103k w r4 = 1 3.325 -------------- - 1 c --- - 1 2 p fc ------------ = 9 . 6 k w order ci c1 c2 c3 c4 c5 c6 c7 c8 2 0.707 1.41 3 1.392 0.202 3.54 4 0.92 1.08 0.38 2.61 5 1.354 0.421 1.75 0.309 3.235 6 0.966 1.035 0.707 1.414 0.259 3.86 7 1.336 0.488 1.53 0.623 1.604 0.222 4.49 8 0.98 1.02 0.83 1.20 0.556 1.80 0.195 5.125 r2 c2 c1 r1 ri ci r4 c3 r3 c4
ls204 9/10 package mechanical data 8 pins - plastic package dimensions millimeters inches min. typ. max. min. typ. max. a 3.32 0.131 a1 0.51 0.020 b 1.15 1.65 0.045 0.065 b 0.356 0.55 0.014 0.022 b1 0.204 0.304 0.008 0.012 d 10.92 0.430 e 7.95 9.75 0.313 0.384 e 2.54 0.100 e3 7.62 0.300 e4 7.62 0.300 f 6.6 0260 i 5.08 0.200 l 3.18 3.81 0.125 0.150 z 1.52 0.060
ls204 10/10 package mechanical data 8 pins - plastic micropackage (so) dimensions millimeters inches min. typ. max. min. typ. max. a 1.75 0.069 a1 0.1 0.25 0.004 0.010 a2 1.65 0.065 a3 0.65 0.85 0.026 0.033 b 0.35 0.48 0.014 0.019 b1 0.19 0.25 0.007 0.010 c 0.25 0.5 0.010 0.020 c1 45 (typ.) d 4.8 5.0 0.189 0.197 e 5.8 6.2 0.228 0.244 e 1.27 0.050 e3 3.81 0.150 f 3.8 4.0 0.150 0.157 l 0.4 1.27 0.016 0.050 m 0.6 0.024 s 8 (max.) b e3 a a2 s l c e c1 a3 b1 a1 d m 8 5 1 4 f information furnished is believed to be accurate and reliable. however, stmicroelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result f rom its use. no license is granted by implication or otherwise under any patent or patent rights of stmicroelectronics. specificati ons mentioned in this publication are subject to change without notice. this publication supersedes and replaces all information previously supplied. stmicroelectronics products are not authorized for use as critical components in life support devices or systems without 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 - switzerland - united kingdom - united states ? http://www.st.com
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