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1 lt1203/lt1205 150mhz video multiplexers n C 3db bandwidth: 150mhz n 0.1db gain flatness: 30mhz n channel-to-channel switching time: 25ns n turn-on/turn-off time: 25ns n high slew rate: 300v/ m s n disabled output impedance: 10m w n 50mv switching transient n channel separation at 10mhz: > 90db n differential gain: 0.02% n differential phase: 0.02 n wide supply range: 5v to 15v n output short-circuit protected n push-pull output s f ea t u re d u escriptio the lt1203 is a wideband 2-input video multiplexer designed for pixel switching and broadcast quality rout- ing. the lt1205 is a dual version that is configured as a 4-input, 2-output multiplexer. these multiplexers act as spdt video switches with 10ns transition times at toggle rates up to 30mhz. the C 3db bandwidth is 150mhz and 0.1db gain flatness is 30mhz. many parts can be tied together at their outputs by using the enable feature which reduces the power dissipation and raises the output impedance to 10m w . output capaci- tance when disabled is only 3pf and the lt1203 peaks less than 3db into a 50pf load. channel crosstalk and disable isolation are greater than 90db up to 10mhz. an on-chip buffer interfaces to fast ttl or cmos logic. switching transients are only 50mv with a 25ns duration. the lt1203 and lt1205 outputs are protected against shorts to ground. the lt1203/lt1205 are manufactured using linear technologys proprietary complementary bipolar process. the lt1203 is available in both the 8-lead pdip and so package while the lt1205 is available in the 16-lead narrow body so package. u a o pp l ic at i ty p i ca l +1 +1 +1 +1 lt1205 logic v + logic v out red v out green v out blue lt1203 ?ta01 en red 1 channel select red 2 green 1 green 2 blue 1 blue 2 v v v en v + +1 +1 lt1203 logic en v + high speed rgb mux large-signal response u s a o pp l ic at i n broadcast quality video multiplexing n picture-in-picture switching n hdtv n computer graphics n title generation n video crosspoint matrices n video routers
2 lt1203/lt1205 a u g w a w u w a r b s o lu t exi t i s supply voltage ...................................................... 18v signal input current (note 1) ............................ 20ma logic input current (note 2).............................. 50ma output short-circuit duration (note 3) ........ continuous specified temperature range (note 4) ....... 0 c to 70 c operating temperature range ............... C 40 c to 85 c storage temperature range ................ C 65 c to 150 c junction temperature (note 5) ............................ 150 c lead temperature (soldering, 10 sec)................. 300 c order part number lt1203cn8* lt1203cs8* s8 part marking 1203 *see note 4 consult factory for industrial and military grade parts. order part number lt1205cs* t jmax = 150 c, q ja = 100 c/w top view s package 16-lead plastic soic 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 v ino gnd v in1 v v in2 gnd v in3 v v + v out1 en1 logic 1 v + v out2 en2 logic 2 1 2 3 4 8 7 6 5 top view v in0 gnd v in1 v v + v out en logic n8 package 8-lead plastic dip s8 package 8-lead plastic soic t jmax = 150 c, q ja = 100 c/w (n) t jmax = 150 c, q ja = 150 c/w (s) wu u package / o rder i for atio symbol parameter conditions min typ max units v os output offset voltage any input selected l 10 30 mv output offset matching between outputs l 0.3 5 mv d v os / d t output offset drift l 40 m v/ c i in input current l 0.6 5 m a r in input resistance v s = 5v, v in = 2v l 15 m w v s = 15v, v in = 2v l 25 m w c in input capacitance input selected 2.6 pf input deselected 2.6 pf c out disabled output capacitance en pin voltage 0.8v 2.8 pf v in input voltage (note 1) v s = 5v l 2 2.8 v v s = 15v l 2 3.0 v psrr power supply rejection ratio v s = 4.5 to 15v l 60 70 db gain error v s = 15v, v in = 2v, r l = 1k l 24 % v s = 15v, v in = 2v, r l = 400 w l 610 % v s = 5v, v in = 2v, r l = 1k l 36 % e lectr ic al c c hara terist ics 0 c t a 70 c, 5v v s 15v, r l = 1k, pulse tested, en pin open or high, unless otherwise noted.
3 lt1203/lt1205 symbol parameter conditions min typ max units sr slew rate (note 6) 180 300 v/ m s fpbw full power bandwidth (note 7) v out = 2v p-p 28.6 47.7 mhz t sel channel-to-channel select time (note 8) r l = 10k 25 35 ns enable time (note 9) r l = 1k 25 35 ns disable time (note 9) r l = 1k 20 35 ns t r , t f small-signal rise and fall time v out = 250mv p-p , 10% to 90% 2.6 ns propagation delay v out = 250mv p-p 2.9 ns overshoot v out = 250mv p-p 5% crosstalk (note 10) r s = 10 w 90 db chip disabled crosstalk (note 10) r l = 10 w , en pin voltage 0.8v 110 db channel select output transient all v in = 0v 50 mv p-p t s settling time 1%, v out = 1v 30 ns differential gain (note 11) v s = 15v, r l = 10k 0.02 % differential phase (note 11) v s = 15v, r l = 10k 0.02 deg insertion loss r l = 100k, c l = 30pf, v out = 500mv p-p , f = 1mhz 0.02 db e lectr ic al c c hara terist ics 0 c t a 70 c, 5v v s 15v, r l = 1k, pulse tested, en pin open or high, unless otherwise noted. symbol parameter conditions min typ max units v out output voltage v s = 15v, v in = 2v, r l = 400 w l 1.8 1.90 v v s = 5v, v in = 2v, r l = 1k l 1.8 1.94 v overload swing (note 1) v s = 15v, v in = 5v l 0.9 1.5 v v s = 5v, v in = 5v l 0.9 1.5 v i out output current v s = 15v, v in = 2v, r l = 400 w l 4.5 4.75 ma v s = 5v, v in = 2v, r l = 1k l 1.8 2.00 ma r out enabled output resistance en pin voltage = 2v, v out = 2v, v s = 15v l 20 42 w disabled output resistance en pin voltage = 0.5v, v out = 2v, v s = 15v l 110 m w i s supply current (lt1203) en pin voltage = 2v l 10.0 14 ma en pin voltage = 0.5v l 5.8 8 ma supply current (lt1205) en pin voltage = 2v l 20.0 28 ma en pin voltage = 0.5v l 11.6 16 ma v il logic low logic pin l 0.8 v v ih logic high logic pin l 2v enable low en pin l 0.5 v enable high en pin l 2v i il digital input current low lt1203 pin 5, lt1205 pins 9, 13 = 0v l 1.5 6.5 m a i ih digital input current high lt1203 pin 5, lt1205 pins 9, 13 = 5v l 10 200 na i en enable pin current lt1203 pin 6, lt1205 pins 10, 14 l 20 80 m a cc hara terist ics ac t a = 25 c, v s = 15v, r l = 1k, en pin open or high, unless otherwise noted. the l denotes specifications which apply over the specified temperature range. note 1: the analog inputs (pins 1, 3 for the lt1203, pins 1, 3, 5, 7 for the lt1205) are protected against esd and overvoltage with internal scrs. for inputs 2.8v the scr will not fire. voltages above 2.8v will fire the scr and the dc current should be limited to 20ma. to turn off the scr the pin voltage must be reduced to less than 1v or the current reduced to less than 600 m a.
4 lt1203/lt1205 note 2: the digital inputs (pins 5, 6 for the lt1203, pins 9, 10, 13, 14 for the lt1205) are protected against esd and overvoltage with internal scrs. for inputs 6v the scr will not fire. voltages above 6v will fire the scr and the dc current should be limited to 50ma. to turn off the scr the pin voltage must be reduced to less than 2v or the current reduced to less than 10ma. note 3: a heat sink may be required depending on the power supply voltage. note 4: commercial grade parts are designed to operate over the temperature range of C 40 c to 85 c but are neither tested nor guaranteed beyond 0 c to 70 c. industrial grade parts specified and tested over C40 c to 85 c are available on special request, consult factory. note 5: t j is calculated from the ambient temperature t a and the power dissipation p d according to the following formulas: lt1203cn8: t j = t a + (p d 100 c/w) lt1203cs8: t j = t a + (p d 150 c/w) lt1205cs: t j = t a + (p d 100 c/w) note 6: slew rate is measured at 2.0v on a 2.5v output signal while operating on 15v supplies, r l = 1k. note 7: full power bandwidth is calculated from the slew rate measurement: fpbw = sr/2 p v peak note 8: for the lt1203, apply 1vdc to pin 1 and measure the time for the appearance of 0.5v at pin 7 when pin 5 goes from 5v to 0v. apply 1vdc to pin 1 and measure the time for disappearance of 0.5v at pin 7 when pin 5 goes from 0v to 5v. apply 1vdc to pin 3 and measure the time for the appearance of 0.5v at pin 7 when pin 5 goes from 0v to 5v. apply 1vdc to pin 3 and measure the time for disappearance of 0.5v at pin 7 when pin 5 goes from 5v to 0v. for the lt1205 the same test is performed on both muxs. note 9: for the lt1203, apply 1vdc to pin 1 and measure the time for the appearance of 0.5v at pin 7 when pin 6 goes from 0v to 5v. pin 5 voltage = 0v. apply 1vdc to pin 1 and measure the time for disappearance of 0.2v at pin 7 when pin 6 goes from 5v to 0v. pin 5 voltage = 0v. apply 1vdc to pin 3 and measure the time for the appearance of 0.5v at pin 7 when pin 6 goes from 0v to 5v. pin 5 voltage = 5v. apply 1vdc to pin 3 and measure the time for disappearance of 0.2v at pin 7 when pin 5 goes from 5v to 0v. pin 5 voltage = 5v. for the lt1205 the same test is performed on both muxs. note 10: v in = 0dbm (0.223v rms ) at 10mhz on one input with the other input selected and r s = 10 w . for disable crosstalk all inputs are driven simultaneously. in disable the output impedance is very high and signal couples across the package; the load impedance determines the crosstalk. note 11: differential gain and phase are measured using a tektronix tsg120 yc/ntsc signal generator and a tektronix 1780r video measurement set. the resolution of this equipment is 0.1% and 0.1 . ten identical muxs were cascaded giving an effective resolution of 0.01% and 0.01 . typical perfor a ce characteristics wu logic en v out 01v in0 11v in1 0 0* high z out 1 0 high z out *must be 0.5v truth table frequency (mhz) 1 ? gain (db) phase (deg) 0 1 2 3 10 100 1000 lt1203/05 ?tpc02 ? ? ? ? 4 5 120 100 ?0 ?0 ?0 140 160 180 200 ?0 0 v s = ?5v t a = 25? r l = frequency (mhz) 1 ? gain (db) phase (deg) 0 1 2 3 10 100 1000 lt1203/05 ?tpc01 ? ? ? ? 4 5 120 100 ?0 ?0 ?0 140 160 180 200 ?0 0 v s = 5v t a = 25? r l = 5v frequency response 15v frequency response
5 lt1203/lt1205 typical perfor a ce characteristics wu frequency response with capacitive loads disable rejection vs frequency crosstalk rejection vs frequency output impedance (enabled) vs frequency crosstalk rejection vs frequency supply voltage (?) 0 frequency (mhz) 160 180 18 lt1203/05 ?tpc03 140 120 2 6 8 10 12 14 16 4 200 t a = 25? r l = 10k peaking 0.5db frequency (mhz) 1 ? gain (db) ? ? 1 3 10 100 lt1203/05 ?tpc04 ? ? 0 2 4 5 v s = ?5v t a = 25? r l = c l = 100pf c l = 50pf c l = 20pf c l = 10pf frequency (mhz) 1 110 crosstalk rejection (db) 100 ?0 ?0 ?0 ?0 10 100 lt1203/05 ?tpc05 ?0 ?0 ?0 v s = ?5v t a = 25? r l = r s = 0 w r s = 10 w r s = 37.5 w r s = 75 w frequency (mhz) 1 110 crosstalk rejection (db) 100 ?0 ?0 ?0 ?0 10 100 lt1203/05 ?tpc06 ?0 ?0 ?0 t a = 25? r s = 0 w r l = v s = 5v v s = ?5v frequency (mhz) 1 ?0 ?0 ?0 ?00 ?10 ?20 disable rejection (db) ?0 ?0 ?0 ?0 10 100 lt1203/05 ?tpc07 ?0 v s = ?5v t a = 25? r l = r l = 1k r l = 100 w r l = 10 w frequency (mhz) 0 30 20 10 70 60 50 40 lt1203/05 ?tpc08 power supply rejection ratio (db) 1 100 10 v s = ?5v t a = 25? r l = r s = 0 w psrr +psrr supply current vs supply voltage (enabled) supply current vs supply voltage (disabled) frequency (hz) 20 output impedance ( w ) 40 30 60 80 100 10k 1m 100m 10m lt1203/05 ?tpc09 10 100k v s = ?5v t a = 25? supply voltage (v) 0 7.6 supply current (ma) 8.4 9.6 4 8 10 18 lt1203/05 ?tpc10 8.0 9.2 8.8 26 12 14 16 lt1203 r l = 125 25 55 supply voltage (v) 0 4.4 supply current (ma) 4.8 4 8 10 18 lt1203/05 ?tpc11 4.6 5.2 5.0 26 12 14 16 125 25 lt1203 r l = 55 C 3db bandwidth vs supply voltage power supply rejection ratio vs frequency
6 lt1203/lt1205 typical perfor a ce characteristics wu temperature (?) ?0 5 6 8 25 75 lt 1203/05 ?tpc12 4 3 ?5 0 50 100 125 2 1 7 gain error (%) v s = ?5v v in = 2v to 2v r l = 400 w r l = 1k gain error vs temperature input voltage (v) ? input bias current ( m a) 0.4 0.6 0.8 4 lt1203/05 ?tpc13 0.2 0 0.4 ? 0 2 0.2 1.2 1.0 ? ? 1 3 125? 25? 55? v s = ?5v r l = input voltage (v) ? output voltage (v) 2 4 3 lt1203/05 ?tpc14 0 ? ? ? ? 1 5 1 3 ? ? 2 ? ? 0 4 v s = ?5v t a = 25? r l = 1k output voltage vs input voltage small-signal rise time r l = 1k v in0 to v in1 select time v in1 to v in0 select time settling time to 1mv and 10mv vs output step settling time (ns) 0 output step (v) 1.0 2.0 400 lt1203/05 ?tpc15 0 1.0 2.0 100 200 300 500 0.5 1.5 0.5 1.5 10mv 10mv 1mv 1mv v s = ?5v r l = 1k lt1203/05 ? tpc16 v s = 15v r l = 10k lt1203/05 ? tpc17 lt1203/05 ? tpc18 v s = 15v r l = 10k logic (pin 5) v out (pin 7) logic (pin 5) v out (pin 7) input bias current vs input voltage v ino = 1v v in1 = 0v v ino = 1v v in1 = 0v
7 lt1203/lt1205 typical perfor a ce characteristics wu channel 1 disable v s = 15v r l = 1k lt1203/05 ? tpc19 v s = 15v r l = 1k channel 1 enable lt1203/05 ? tpc20 input protection the logic inputs have esd protection ( 3 2kv) and short- ing them to 12v or 15v will cause excessive current to flow. limit the current to less than 50ma when driving the logic above 6v. the analog inputs are protected against esd and overvoltage with internal scrs. for inputs 3 2.8v the scrs will fire and the dc current should be limited to 20ma. power supplies the lt1203/lt1205 will operate from 5v (10v total) to 15v (30v total) and is specified over this range. charac- teristics change very little over this voltage range. it is not necessary to use equal value supplies however, the output offset voltage will change. the offset will change about 300 m v per volt of supply mismatch. the lt1203/lt1205 have a very wide bandwidth yet are tolerant of power supply bypassing. the power supplies should be by- passed with a 0.1 m f or 0.01 m f ceramic capacitor within 0.5 inch of the part. circuit layout use a ground plane to ensure a low impedance ground is available throughout the pcb layout. separate the inputs u s a o pp l ic at i wu u i for atio lt1203 channel-to-channel switching transient with ground plane to ensure high channel separation. for minimum peaking, maximum bandwidth and maximum gain flatness sockets are not recommended because they can add considerable stray inductance and capacitance. if a socket must be used, use a low profile, low capacitance socket such as the samtec iso-308. switching transients the lt1203/lt1205 use input buffers to ensure switching transients do not couple to other video equipment sharing the input line. output switching transients are about 50mv p-p with a 20ns duration and input transients are output 50mv/div input 20mv/div logic (pin 5) r s = 50 w lt1203/05 ? ai01 v ino = 1v v in1 = 0v v ino = 1v v in1 = 0v en (pin 6) v out (pin 7) v out (pin 7) en (pin 6)
8 lt1203/lt1205 u s a o pp l ic at i wu u i for atio cmos mux channel-to-channel switching transient output 1v/div lt1203/05 ? ai02 r s = 50 w note: 50 times larger than lt1203 transient lt1203/05 ? ai03 output (pin 7) channel 1 = 0v channel 2 = 2mhz sinewave logic (pin 5) lt1203 switching inputs only 10mv p-p . a photo of the switching transients from a cmos mux shows glitches to be 50 times larger than on the lt1203. also shown is the output of the lt1203 switching on and off a 2mhz sinewave cleanly and without abnormalities. pixel switching the multiplexers are fabricated on ltc's complementary bipolar process to attain fast switching speed, high band- width, and a wide supply voltage range compatible with traditional video systems. channel-to-channel switching time and enable time are both 25ns, therefore delay is the same when switching between channels or between ics. to demonstrate the switching speed of the lt1203/lt1205 the rgb mux of figure 1 is used to switch rgb worksta- tion inputs with a 22ns pixel width. figure 2a is a photo showing the workstation output and rgb mux output. the slight rise time degradation at the rgb mux output is due to the bandwidth of the lt1260 current feedback amplifier used to drive the 75 w cable. in figure 2b, the lt1203 switches to an input at zero at the end of the first pixel and removes the following pixels. +1 1 2 3 4 5 6 7 8 16 15 14 13 1 2 3 4 8 7 6 5 12 1 16 15 14 13 12 11 10 9 2 3 4 5 6 7 8 lt1260 11 10 9 +1 +1 +1 lt1205 lt1203/05 ? f01 +1 +1 lt1203 r4 75 w j4 green 2 j7 logic r6 75 w c1 0.1 m f c2 0.1 m f c3 4.7 m f c4 4.7 m f j6 blue 2 r8* 10k r13 1.5k r15 1.5k r9* 10k *optional r14 1.5k r7* 10k r5 75 w j5 blue 1 r3 75 w j3 green 1 r2 75 w j2 red 2 r1 75 w j1 red 1 + + + r12 1.5k r10 1.5k v + v r11 1.5k r g b + + gnd j8 enable j9 red j10 green j11 blue r16 75 w r17 75 w r18 75 w figure 1. rgb mux input 1v/div logic control
9 lt1203/lt1205 workstation output lt1203/05 ? f02a figure 2a. workstation and rgb mux output lt1203/05 ? f02b figure 2b. rgb mux output switched to ground after one pixel u s a o pp l ic at i wu u i for atio frequency (mhz) 1 ? gain (db) ? 0 1 2 10 100 1000 lt1203/05 ?f04 ? ? 3 4 g r, b v s = ?5v r l = 150 w r f = r g = 1.3k input expansion the output impedance of the lt1203/lt1205 is typically 20 w when enabled and 10m w when disabled or not selected. this high disabled output impedance allows the output of many lt1205s to be shorted together to form large crosspoint arrays. with their outputs shorted to- gether, shoot-through current is low because the on channel is disabled before the off channel is activated. enable ic #1 timing and supply current waveforms enable ic #2 v out 1v/div i s 10ma/div 5v/div 5v/div lt1203/05 ? ai04 four lt1205s are used in figure 5 to form a 16-to-1 multiplexer which is very space efficient and uses only six so packages. in this application 15 switches are turned off and only one is active. an attenuator is formed by the 15 deselected switches and the active device which has an figure 4. rgb mux frequency response of demonstration board #041 rgb mux output workstation output rgb mux output demonstration board a demonstration board (#041) of the rgb mux in figure 1 has been fabricated and its layout is shown in figure 3. the small-signal bandwidth of the rgb mux is set by the bandwidth of the lt1260. the stray capacitance of the surface mount feedback resistors r f and r g restricts the C 3db bandwidth to about 95mhz. the bandwidth can be improved by about 20% using the through-hole lt1260 and components. a frequency response plot in figure 4 shows that the r, g, and b amplifiers have slightly different frequency responses. the difference in the g amplifier is due to different output trace routing to feedback resistor r13.
10 lt1203/lt1205 (408) 432-1900 lt1203/lt1205 fast switching rgb multiplexer demo board r9 r8 c2 c1 r15 c4 b g r r1 r2 g1 g2 b1 b2 r14 r11 u3 u1 u2 r10 041a enable logic r16 r18 r17 c3 gnd v + v r13 r12 r7 r1 r2 r3 r4 r5 r6 copywrite '93 made in usa lt1205/03 ?f03 figure 3. demo board #041 layout
11 lt1203/lt1205 u s a o pp l ic at i wu u i for atio +1 +1 +1 +1 u1 lt1205 16 9 10 11 12 13 14 15 c2 0.1 m f c7 0.1 m f 1 r1 75 w c1 0.1 m f 8 7 6 5 4 3 2 +1 +1 +1 +1 u2 lt1205 16 9 10 11 12 13 14 15 1 8 7 6 5 4 3 2 1 5v 8 16 4 5 6 a b c d en 3 2 15 7 2 3 7 4 6 output optional r x 10k 9 10 11 12 13 14 a g2a g2b g1 c b y0 y7 y6 y5 y4 y3 y2 y1 +1 +1 +1 +1 u3 lt1205 16 9 10 11 12 13 14 15 1 8 7 6 5 4 3 2 +1 +1 +1 u4 lt1205 16 9 lt1203/05 ?f05 10 11 12 13 14 15 1 8 ch15 ch0 7 6 5 4 3 2 gnd 15v 15v r f 1.6k r g 1.6k r s 75 w c5 4.7 m f + c6 4.7 m f + + u6 lt1252 u5 74hct238 r16 75 w c4 0.1 m f c3 0.1 m f +1 d x l l l l l l l l h h h h h h h h c x l l l l h h h h l l l l h h h h b x l l h h l l h h l l h h l l h h a x l h l h l h l h l h l h l h l h l h h h h h h h h h h h h h h h h off ch0 ch1 ch2 ch3 ch4 ch5 ch6 ch7 ch8 ch9 ch10 ch11 ch12 ch13 ch14 ch15 select logic truth table output enable en figure 5. 16-to-1 multiplexer and truth table
12 lt1203/lt1205 output impedance of only 25 w at 10mhz. this attenuator is responsible for the outstanding all hostile crosstalk rejection of 90db at 10mhz with 15 input signals. several suggestions to attain this high rejection include: 1. mount the feedback resistors for the surface mount lt1252 on the back side of the pc board. 2. keep the feedback trace (pin 3) of the lt1252 as short as possible. 3. route v + and v C for the lt1205s on the component (top) side and under the devices (between inputs and outputs). 4. use the backside of the pc board as a solid ground plane. connect the lt1205 device grounds and by- pass capacitors grounds as vias to the backside ground plane. u s a o pp l ic at i wu u i for atio 16-to-1 mux, switching lt1205 enable lines 1v 0v 0v r f = r g = 1.6k r l = 100 w v in4 = 0v v in0 = 1v lt1203/05 ? ai05 16-to-1 multiplexer all hostile crosstalk rejection 16-to-1 mux response frequency (mhz) 1 gain (db) ? ? ? 0 10 100 lt1203/05 ?ai07 2 v s = ?5v r l = 100 w r f = r g = 1.6k each off switch has 2.8pf of output capacitance and 15 off switches tied together represent a 48pf load to the one active switch. in this case the active device will peak about 3db at 50mhz. an attribute of current feedback amplifiers is that the bandwidth can easily be adjusted by changing the feedback resistors, and in this application the lt1252s bandwidth is reduced to about 60mhz using 1.6k feedback resistors. this has the effect of reducing the peaking in the mux to 0.25db and flattening the response to 0.05db at 30mhz. 4 4 crosspoint the compact high performance 4 4 crosspoint shown in figure 6 uses four lt1205s to route any input to any or all outputs. the complete crosspoint uses only six so pack- ages and less than six square inches of pc board space. the lt1254 quad current feedback amplifier serves as a cable driver with a gain of 2. a 5v supply is used to ensure that the maximum 150 c junction temperature of the lt1254 is not exceeded in the so package. with this supply voltage the crosspoint can operate at a 70 c ambient temperature and drive 2v (peak or dc) into a double-terminated 75 w video cable. the feedback resis- tors of these output amplifiers have been optimized for this supply voltage. the C 3db bandwidth of the crosspoint is over 100mhz with only 0.8db of peaking. all hostile crosstalk rejection is 85db at 10mhz when a shorted input is routed to all outputs. to obtain this level of performance it is necessary to follow techniques similar to select line c frequency (mhz) 1 ?20 hostile crosstalk rejection (db) ?00 ?0 ?0 ?0 10 100 lt1203/05 ?ai06 ?0 v s = ?5v r s = 10 w r l = 100 w 5v
13 lt1203/lt1205 +1 +1 +1 +1 u1 lt1205 16 9 10 11 12 13 14 15 c2 0.1 m f 1 r1 75 w c1 0.1 m f 8 7 6 5 4 3 2 +1 +1 +1 +1 u2 lt1205 16 9 10 11 12 13 14 15 1 8 7 6 5 4 3 2 10 9 8 4 11 output 2 j7 +1 +1 +1 +1 u3 lt1205 16 u5 74hc04 9 10 11 12 13 14 15 1 8 7 6 5 4 3 2 +1 +1 +1 u4 lt1205 16 9 a lt1203/05 ?f06 10 11 12 13 14 15 1 8 ch3 j4 ch0 j1 7 6 5 4 3 2 r2 75 w ch1 j2 r3 75 w ch2 j3 gnd b 5v ?v r13 820 w r14 820 w c6 4.7 m f r19 75 w c5 4.7 m f r7 10k + r4 75 w c4 0.1 m f select logic output 0 ab select logic output 1 ab select logic output 2 ab select logic output 3 c3 0.1 m f +1 a l l h h b l h l h ch0 ch1 ch2 ch3 select logic truth table input channel u6 c lt1254 12 13 14 output 3 j8 r15 820 w r16 820 w r20 75 w r8 10k + u6 d lt1254 5 6 7 output 1 j6 r11 820 w r12 820 w r18 75 w r6 10k + u6 b lt1254 3 2 1 output 0 j5 r9 820 w r10 820 w r17 75 w + u6 a lt1254 + + r5 10k figure 6. 4 4 crosspoint and truth table u s a o pp l ic at i wu u i for atio
14 lt1203/lt1205 u s a o pp l ic at i wu u i for atio those used in the 16-to-1 crosspoint with one additional suggestion: surround the lt1205 output traces by ground plane and route them away from the (C) inputs of the other three lt1254s. each pair of logic inputs labeled select logic output is used to select a particular output. the truth table is used to select the desired input and is applied to each pair of logic inputs. for example, to route channel 1 input to output 3, the 4th pair of logic inputs labeled select logic output 3 is coded a = low and b = high. to route channel 3 input to all outputs, set all eight logic inputs high. channel 3 is the default input with all logic inputs open. to shut off all channels a pair of lt1259s can be substituted for the lt1254. the lt1259 is a dual current feedback amplifier with a shutdown pin that reduces the supply current to 0 m a. response of all four inputs for the 4 4 crosspoint frequency (mhz) 1 gain (db) 2 0 ? ? ? ? 10 100 lt1203/05 ?ai08 200 v s = 5v r f = r g = 820 w r l = 100 w lt1203/05 ? ai10 channel 0 = 1v channel 2 = 0v 4 4 crosspoint, switching channel 0 to channel 2 input a of select logic output 0 5v 0v 4 4 crosspoint, all hostile rejection frequency (mhz) 1 120 hostile crosstalk rejection (db) 100 ?0 ?0 ?0 10 100 v s = 5v r l = 100 w r s = 0 w lt1203/05 ?ai09
15 lt1203/lt1205 off in 0 gnd logic enable v lt1203/05 ?ss v + out in 1 ?v 2v v v v + v + logic si plified sche atic ww information furnished by linear technology corporation is believed to be accurate and reliable. however, no responsibility is assumed for its use. linear technology corporation makes no represen- tation that the interconnection of its circuits as described herein will not infringe on existing patent rights. dimensions in inches (millimeters) unless otherwise noted. package descriptio u n8 package 8-lead plastic dip n8 0392 0.045 ?0.015 (1.143 ?0.381) 0.100 ?0.010 (2.540 ?0.254) 0.065 (1.651) typ 0.045 ?0.065 (1.143 ?1.651) 0.130 ?0.005 (3.302 ?0.127) 0.020 (0.508) min 0.018 ?0.003 (0.457 ?0.076) 0.125 (3.175) min 12 3 4 87 6 5 0.250 ?0.010 (6.350 ?0.254) 0.400 (10.160) max 0.009 ?0.015 (0.229 ?0.381) 0.300 ?0.320 (7.620 ?8.128) 0.325 +0.025 0.015 +0.635 0.381 8.255 ()
16 lt1203/lt1205 package descriptio u dimensions in inches (millimeters) unless otherwise noted. s8 package 8-lead plastic soic 1 2 3 4 0.150 ?0.157* (3.810 ?3.988) 8 7 6 5 0.189 ?0.197* (4.801 ?5.004) 0.228 ?0.244 (5.791 ?6.197) 0.016 ?0.050 0.406 ?1.270 0.010 ?0.020 (0.254 ?0.508) 45 0 8?typ 0.008 ?0.010 (0.203 ?0.254) so8 0294 0.053 ?0.069 (1.346 ?1.752) 0.014 ?0.019 (0.355 ?0.483) 0.004 ?0.010 (0.101 ?0.254) 0.050 (1.270) bsc *these dimensions do not include mold flash or protrusions. mold flash or protrusions shall not exceed 0.006 inch (0.15mm). 0.016 ?0.050 0.406 ?1.270 0.010 ?0.020 (0.254 ?0.508) 45 0??8?typ 0.008 ?0.010 (0.203 ?0.254) 1 2 3 4 5 6 7 8 0.150 ?0.157* (3.810 ?3.988) 16 15 14 13 0.386 ?0.394* (9.804 ?10.008) 0.228 ?0.244 (5.791 ?6.197) 12 11 10 9 so16 0893 0.053 ?0.069 (1.346 ?1.752) 0.014 ?0.019 (0.355 ?0.483) 0.004 ?0.010 (0.101 ?0.254) 0.050 (1.270) typ *these dimensions do not include mold flash or protrusions. mold flash or protrusions shall not exceed 0.006 inch (0.15mm). s package 16-lead plastic soic ? linear technology corporation 1994 lt/gp 0494 10k ? printed in usa linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7487 (408) 432-1900 l fax : (408) 434-0507 l telex : 499-3977

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