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1 lt1398/lt1399/lt1399hv sn13989 13989fas low cost dual and triple 300mhz current feedback amplifiers with shutdown 3-input video mux cable driver the lt ? 1399 and lt1399hv contain three independent 300mhz current feedback amplifiers, each with a shut- down pin. the lt1399hv is a higher voltage version of the lt1399. the lt1398 is a two amplifier version of the lt1399. the lt1398/lt1399 operate on all supplies from a single 4v to 6v. the lt1399hv operates on all supplies from 4v to 7.5v. each amplifier draws 4.6ma when active. when disabled each amplifier draws zero supply current and its output be- comes high impedance. the amplifiers turn on in only 30ns and turn off in 40ns, making them ideal in spread spectrum and portable equipment applications. the lt1398/lt1399/lt1399hv are manufactured on lin- ear technologys proprietary complementary bipolar pro- cess. the lt1399/lt1399hv are pin-for-pin upgrades to the lt1260 optimized for use on 5v/ 7.5v supplies. n 300mhz bandwidth on 5v (a v = 1, 2 and C1) n 0.1db gain flatness: 150mhz (a v = 1, 2 and C1) n completely off in shutdown, 0 m a supply current n high slew rate: 800v/ m s n wide supply range: 2v(4v) to 6v(12v) (lt1398/lt1399) 2v (4v) to 7.5v (15v) (lt1399hv) n 80ma output current n low supply current: 4.6ma/amplifier n fast turn-on time: 30ns n fast turn-off time: 40ns n 16-pin narrow so/narrow ssop packages n rgb cable drivers n lcd drivers n spread spectrum amplifiers n mux amplifiers n composite video cable drivers n portable equipment , ltc and lt are registered trademarks of linear technology corporation. square wave response output 200mv/div time (10ns/div) 1398/99 ta02 r l = 100 w r f = r g = 324 w f = 10mhz features descriptio u applicatio s u typical applicatio u + 1/3 lt1399 r g 200 w r f 324 w a en a v in a + 1/3 lt1399 r g 200 w r f 324 w en b v in b bc channel select 97.6 w 97.6 w + 1/3 lt1399 r g 200 w r f 324 w en c v in c 97.6 w 75 w v out 75 w cable 1399 ta01
2 lt1398/lt1399/lt1399hv sn13989 13989fas the l denotes specifications which apply over the specified operating temperature range, otherwise specifications are at t a = 25 c. for each amplifier: v cm = 0v, v s = 5v, en = 0v, pulse tested, unless otherwise noted. (note 4) a u g w a w u w a r b s o lu t exi t i s (note 1) total supply voltage (v + to v C ) lt1398/lt1399 ................................................ 12.6v lt1399hv ....................................................... 15.5v input current (note 2) ....................................... 10ma output current ................................................. 100ma differential input voltage (note 2) ........................... 5v output short-circuit duration (note 3) ........ continuous operating temperature range (note 9) ... C 40 c to 85 c specified temperature range (note 4) .. 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 wu u package / o rder i for atio order part number lt1399cgn lt1399cs lt1399hvcs lt1399ign lt1399is t jmax = 150 c, q ja = 120 c/w (gn) t jmax = 150 c, q ja = 100 c/w (s) *ground pins are not internally connected. for best channel isolation, connect to ground. consult factory for parts specified w ith wider operating temperature ranges. order part number lt1398cs t jmax = 150 c, q ja = 100 c/w 1 2 3 4 5 6 7 8 top view 16 15 14 13 12 11 10 9 in a +in a *gnd *gnd *gnd *gnd +in b in b en a out a v + gnd* gnd* v out b en b a s package 16-lead plastic so b e lectr ic al c c hara terist ics symbol parameter conditions min typ max units v os input offset voltage 1.5 10 mv l 12 mv d v os / d t input offset voltage drift l 15 m v/ c i in + noninverting input current 10 25 m a l 30 m a i in C inverting input current 10 50 m a l 60 m a e n input noise voltage density f = 1khz, r f = 1k, r g = 10 w , r s = 0 w 4.5 nv/ ? hz +i n noninverting input noise current density f = 1khz 6 pa/ ? hz Ci n inverting input noise current density f = 1khz 25 pa/ ? hz r in input resistance v in = 3.5v l 0.3 1 m w c in input capacitance amplifier enabled 2.0 pf amplifier disabled 2.5 pf c out output capacitance amplifier disabled 8.5 pf v inh input voltage range, high v s = 5v l 3.5 4.0 v v s = 5v, 0v 4.0 v 1 2 3 4 5 6 7 8 top view 16 15 14 13 12 11 10 9 in r +in r *gnd in g +in g *gnd +in b in b en r out r v + en g out g v out b en b r g s package 16-lead plastic so gn package 16-lead plastic ssop b gn part marking 1399 1399i (lt1398/lt1399)
3 lt1398/lt1399/lt1399hv sn13989 13989fas e lectr ic al c c hara terist ics symbol parameter conditions min typ max units v inl input voltage range, low v s = 5v l C 3.5 C 4.0 v v s = 5v, 0v 1.0 v v outh maximum output voltage swing, high v s = 5v, r l = 100k 3.9 4.2 v v s = 5v, r l = 100k l 3.7 v v s = 5v, 0v; r l = 100k 4.2 v v outl maximum output voltage swing, low v s = 5v, r l = 100k C 3.9 C 4.2 v v s = 5v, r l = 100k l C 3.7 v v s = 5v, 0v; r l = 100k 0.8 v v outh maximum output voltage swing, high v s = 5v, r l = 150 w 3.4 3.6 v v s = 5v, r l = 150 w l 3.2 v v s = 5v, 0v; r l = 150 w 3.6 v v outl maximum output voltage swing, low v s = 5v, r l = 150 w C 3.4 C 3.6 v v s = 5v, r l = 150 w l C 3.2 v v s = 5v, 0v; r l = 150 w 0.6 v cmrr common mode rejection ratio v cm = 3.5v l 42 52 db Ci cmrr inverting input current v cm = 3.5v 10 16 m a/v common mode rejection v cm = 3.5v l 22 m a/v psrr power supply rejection ratio v s = 2v to 5v, en = v C l 56 70 db +i psrr noninverting input current v s = 2v to 5v, en = v C 12 m a/v power supply rejection l 3 m a/v Ci psrr inverting input current v s = 2v to 5v, en = v C l 27 m a/v power supply rejection a v large-signal voltage gain v out = 2v, r l = 150 w 50 65 db r ol transimpedance, d v out / d i in C v out = 2v, r l = 150 w 40 100 k w i out maximum output current r l = 0 w l 80 ma i s supply current per amplifier v out = 0v l 4.6 6.5 ma disable supply current per amplifier en pin voltage = 4.5v, r l = 150 w l 0.1 100 m a i en enable pin current 30 110 m a l 200 m a sr slew rate (note 6) a v = 10, r l = 150 w 500 800 v/ m s t on turn-on delay time (note 7) r f = r g = 324 w , r l = 100 w 30 75 ns t off turn-off delay time (note 7) r f = r g = 324 w , r l = 100 w 40 100 ns t r , t f small-signal rise and fall time r f = r g = 324 w , r l = 100 w , v out = 1v p-p 1.3 ns t pd propagation delay r f = r g = 324 w , r l = 100 w , v out = 1v p-p 2.5 ns os small-signal overshoot r f = r g = 324 w , r l = 100 w , v out = 1v p-p 10 % t s settling time 0.1%, a v = C 1, r f = r g = 309 w , r l = 150 w 25 ns dg differential gain (note 8) r f = r g = 324 w , r l = 150 w 0.13 % dp differential phase (note 8) r f = r g = 324 w , r l = 150 w 0.10 deg the l denotes specifications which apply over the specified operating temperature range, otherwise specifications are at t a = 25 c. for each amplifier: v cm = 0v, v s = 5v, en = 0v, pulse tested, unless otherwise noted. (note 4) (lt1398/lt1399)
4 lt1398/lt1399/lt1399hv sn13989 13989fas the l denotes specifications which apply over the specified operating temperature range, otherwise specifications are at t a = 25 c. for each amplifier: v cm = 0v, v s = 7.5v, en = 0v, pulse tested, unless otherwise noted. (note 4) e lectr ic al c c hara terist ics symbol parameter conditions min typ max units v os input offset voltage 1.5 10 mv l 12 mv d v os / d t input offset voltage drift l 15 m v/ c i in + noninverting input current 10 25 m a l 30 m a i in C inverting input current 10 50 m a l 60 m a e n input noise voltage density f = 1khz, r f = 1k, r g = 10 w , r s = 0 w , v s = 5v 4.5 nv/ ? hz +i n noninverting input noise current density f = 1khz, v s = 5v 6 pa/ ? hz Ci n inverting input noise current density f = 1khz, v s = 5v 25 pa/ ? hz r in input resistance v in = 6v l 0.3 1 m w c in input capacitance amplifier enabled 2.0 pf amplifier disabled 2.5 pf c out output capacitance amplifier disabled 8.5 pf v inh input voltage range, high v s = 7.5v l 6 6.5 v v s = 7.5v, 0v 6.5 v v inl input voltage range, low v s = 7.5v l C6 C6.5 v v s = 7.5v, 0v 1.0 v v outh maximum output voltage swing, high v s = 7.5v, r l = 100k 6.4 6.7 v v s = 7.5v, r l = 100k l 6.1 v v s = 7.5v, 0v; r l = 100k 6.7 v v outl maximum output voltage swing, low v s = 7.5v, r l = 100k C 6.4 C 6.7 v v s = 7.5v, r l = 100k l C 6.1 v v s = 7.5v, 0v; r l = 100k 0.8 v v outh maximum output voltage swing, high v s = 7.5v, r l = 150 w 5.4 5.8 v v s = 7.5v, r l = 150 w l 5.1 v v s = 7.5v, 0v; r l = 150 w 5.8 v v outl maximum output voltage swing, low v s = 7.5v, r l = 150 w C 5.4 C 5.8 v v s = 7.5v, r l = 150 w l C 5.1 v v s = 7.5v, 0v; r l = 150 w 0.6 v cmrr common mode rejection ratio v cm = 6v l 42 52 db Ci cmrr inverting input current v cm = 6v 10 16 m a/v common mode rejection v cm = 6v l 22 m a/v psrr power supply rejection ratio v s = 2v to 7.5v, en = v C l 56 70 db +i psrr noninverting input current v s = 2v to 7.5v, en = v C 12 m a/v power supply rejection l 3 m a/v Ci psrr inverting input current v s = 2v to 7.5v, en = v C l 27 m a/v power supply rejection a v large-signal voltage gain v out = 4.5v, r l = 150 w 50 65 db r ol transimpedance, d v out / d i in C v out = 4.5v, r l = 150 w 40 100 k w i out maximum output current r l = 0 w l 80 ma i s supply current per amplifier v out = 0v l 4.6 7 ma disable supply current per amplifier en pin voltage = 7v, r l = 150 w l 0.1 100 m a i en enable pin current 30 110 m a l 200 m a (lt1399hv)
5 lt1398/lt1399/lt1399hv sn13989 13989fas the l denotes specifications which apply over the specified operating temperature range, otherwise specifications are at t a = 25 c. for each amplifier: v cm = 0v, v s = 7.5v, en = 0v, pulse tested, unless otherwise noted. (note 4) e lectr ic al c c hara terist ics symbol parameter conditions min typ max units sr slew rate (note 6) a v = 10, r l = 150 w , v s = 5v 500 800 v/ m s t on turn-on delay time (note 7) r f = r g = 324 w , r l = 100 w , v s = 5v 30 75 ns t off turn-off delay time (note 7) r f = r g = 324 w , r l = 100 w , v s = 5v 40 100 ns t r , t f small-signal rise and fall time r f = r g = 324 w , r l = 100 w , v out = 1v p-p , 1.3 ns v s = 5v t pd propagation delay r f = r g = 324 w , r l = 100 w , v out = 1v p-p , 2.5 ns v s = 5v os small-signal overshoot r f = r g = 324 w , r l = 100 w , v out = 1v p-p ,10% v s = 5v t s settling time 0.1%, a v = C 1v, r f = r g = 309 w , r l = 150 w ,25ns v s = 5v dg differential gain (note 8) r f = r g = 324 w , r l = 150 w , v s = 5v 0.13 % dp differential phase (note 8) r f = r g = 324 w , r l = 150 w , v s = 5v 0.10 deg note 1: absolute maximum ratings are those values beyond which the life of a device may be impaired. note 2: this parameter is guaranteed to meet specified performance through design and characterization. it has not been tested. note 3: a heat sink may be required depending on the power supply voltage and how many amplifiers have their outputs short circuited. note 4: the lt1398c/lt1399c/lt1399hvc are guaranteed to meet specified performance from 0 c to 70 c and are designed, characterized and expected to meet these extended temperature limits, but are not tested or qa sampled at C 40 c and 85 c. the lt1399i is guaranteed to meet specified performance from C40 c to 85 c. note 5: t j is calculated from the ambient temperature t a and the power dissipation p d according to the following formula: lt1398cs, lt1399cs, lt1399is, lt1399hvcs: t j = t a + (p d ? 100 c/w) lt1399cgn, lt1399ign: t j = t a + (p d ? 120 c/w) note 6: slew rate is measured at 2v on a 3v output signal. note 7: turn-on delay time (t on ) is measured from control input to appearance of 1v at the output, for v in = 1v. likewise, turn-off delay time (t off ) is measured from control input to appearance of 0.5v on the output for v in = 0.5v. this specification is guaranteed by design and characterization. note 8: differential gain and phase are measured using a tektronix tsg120yc/ntsc signal generator and a tektronix 1780r video measurement set. the resolution of this equipment is 0.1% and 0.1 . ten identical amplifier stages were cascaded giving an effective resolution of 0.01% and 0.01 . note 9: the lt1398c, lt1398i, lt1399c, lt1399i, lt1399hvc and lt1399hvi are guaranteed functional over the operating temperature range of C40 c to 85 c. small signal small signal small signal v s (v) a v r l ( w )r f ( w )r g ( w ) C 3db bw (mhz) 0.1db bw (mhz) peaking (db) 5 1 100 365 C 300 150 0.05 5 2 100 324 324 300 150 0 5 C 1 100 309 309 300 150 0 typical ac perfor a ce w u (lt1399hv)
6 lt1398/lt1399/lt1399hv sn13989 13989fas closed-loop gain vs frequency (a v = 1) 4 2 0 C2 C4 gain (db) 1m 10m 1g 100m frequency (hz) v s = 5v v in = C10dbm r f = 365 w r l = 100 w 1398/99 g01 closed-loop gain vs frequency (a v = C 1) v s = 5v v in = C10dbm r f = r g = 309 w r l = 100 w 1398/99 g03 4 2 0 C2 C4 gain (db) 1m 10m 1g 100m frequency (hz) closed-loop gain vs frequency (a v = 2) v s = 5v v in = C10dbm r f = r g = 324 w r l = 100 w 10 8 6 4 2 gain (db) 1m 10m 1g 100m frequency (hz) 1398/99 g02 large-signal transient response (a v = C 1) output (1v/div) time (5ns/div) v s = 5v v in = 2.5v r f = r g = 309 w r l = 100 w 1398/99 g06 large-signal transient response (a v = 2) output (1v/div) time (5ns/div) v s = 5v v in = 1.25v r f = r g = 324 w r l = 100 w 1398/99 g05 large-signal transient response (a v = 1) output (1v/div) time (5ns/div) v s = 5v v in = 2.5v r f = 365 w r l = 100 w 1398/99 g04 cc hara terist ics uw a t y p i ca lper f o r c e psrr vs frequency maximum undistorted output voltage vs frequency 2nd and 3rd harmonic distortion vs frequency frequency (khz) 90 distortion (db) 80 60 40 30 1 100 1000 100000 1398/1399 g07 100 10 10000 50 70 110 hd2 hd3 t a = 25 c r f = r g = 324 r l = 100 v s = 5v v out = 2vpp frequency (mhz) 1 2 output voltage (v p-p ) 3 4 5 6 8 10 100 1398/1399 g08 7 a v = +1 a v = +2 t a = 25 c r f = 324 r l = 100 v s = 5v frequency (hz) 20 psrr (db) 40 50 70 80 10k 1m 10m 100m 1398/1399 g09 0 100k 60 30 10 + psrr psrr t a = 25 c r f = r g = 324 r l = 100 a v = +2
7 lt1398/lt1399/lt1399hv sn13989 13989fas cc hara terist ics uw a t y p i ca lper f o r c e input voltage noise and current noise vs frequency frequency (hz) 10 input noise (nv/ hz or pa/ hz) 10 100 1000 30 100 300 1k 3k 10k 30k 100k 1398/1399 g10 1 ?n +in en frequency (hz) 10k 0.01 output impedance ( ) 1 100 1m 10m 100k 100m 1398/1399 g11 0.1 10 r f = r g = 324 r l = 50 a v = +2 v s = 5v frequency (hz) 100k 100 output impedance (disabled) ( ) 1k 10k 100k 1m 10m 100m 1398/1399 g12 r f = 365 a v = +1 v s = 5v output impedance vs frequency output impedance (disabled) vs frequency maximum capacitive load vs feedback resistor capacitive load vs output series resistor supply current vs supply voltage feedback resistance ( ) 300 1 capacitive load (pf) 10 100 1000 900 1500 2100 2700 3300 1398/1399 g13 r f = r g a v = +2 v s = 5v peaking 5db capacitive load (pf) 10 0 output series resistance ( ) 10 20 40 100 1000 1398/1399 g14 30 r f = r g = 324 v s = 5v overshoot < 2% supply voltage ( v) 0 0 supply current (ma) 1 3 4 5 2 4 59 1398/1399 g15 2 13 6 7 8 6 en = v en = 0v output voltage swing vs temperature enable pin current vs temperature positive supply current per amplifier vs temperature ambient temperature ( c) ?0 ? output voltage swing (v) ? ? ? 0 5 2 0 50 75 1398/1399 g16 ? 3 4 1 ?5 25 100 125 r l = 150 r l = 100k r l = 150 r l = 100k ambient temperature ( c) ?0 ?0 ?0 ?0 25 75 1398/1399 g17 ?0 ?0 ?5 0 50 100 125 ?0 ?0 ?0 enable pin current ( a) v s = 5v en = 0v en = 5v ambient temperature ( c) ?0 positive supply current per amplifier (ma) 4.75 25 1398/1399 g18 4.00 3.50 ?5 0 50 3.25 3.00 5.00 4.50 4.25 3.75 75 100 125 en = 5v en = 0 v s = 5v
8 lt1398/lt1399/lt1399hv sn13989 13989fas cc hara terist ics uw a t y p i ca lper f o r c e input offset voltage vs temperature input bias currents vs temperature all hostile crosstalk propagation delay rise time and overshoot all hostile crosstalk (disabled) ambient temperature ( c) ?0 input offset voltage (mv) 2.5 25 1398/1399 g19 1.0 0 ?5 0 50 0.5 1.0 3.0 2.0 1.5 0.5 75 100 125 v s = 5v ambient temperature ( c) ?0 6 9 i b + i b 15 25 75 1398/99 g20 3 0 ?5 0 50 100 125 ? ? 12 input bias current ( a) v s = 5v frequency (hz) ?0 all hostile crosstalk (db) ?0 0 ?0 ?0 ?0 ?0 ?0 ?0 ?0 100k 10m 100m 500m 1398/1399 g21 ?00 1m r f = r g = 324 r l = 100 a v = +2 r g b input 100mv/div output 200mv/div t pd = 2.5ns time (500ps/div) a v = +2 r l = 100 w r f = r g = 324 w v out 200mv/div os = 10% t r = 1.3ns time (500ps/div) a v = +2 r l = 100 w r f = r g = 324 w frequency (hz) ?0 all hostile crosstalk (db) ?0 ?0 ?0 ?0 ?0 ?0 ?0 ?0 100k 10m 100m 500m 1398/1399 g24 ?00 ?10 1m r f = r g = 324 r l = 100 a v = +2 r g b 1398/1399 g22 1398/1399 g23
9 lt1398/lt1399/lt1399hv sn13989 13989fas pi n fu n ctio n s uuu lt1399, lt1399hv C in r (pin 1): inverting input of r channel amplifier. + in r (pin 2): noninverting input of r channel amplifier. gnd (pin 3): ground. not connected internally. C in g (pin 4): inverting input of g channel amplifier. + in g (pin 5): noninverting input of g channel amplifier. gnd (pin 6): ground. not connected internally. + in b (pin 7): noninverting input of b channel amplifier. C in b (pin 8): inverting input of b channel amplifier. en b (pin 9): b channel enable pin. logic low to enable. out b (pin 10): b channel output. v C (pin 11): negative supply voltage, usually C 5v. out g (pin 12): g channel output. en g (pin 13): g channel enable pin. logic low to enable. v + (pin 14): positive supply voltage, usually 5v. out r (pin 15): r channel output. en r (pin 16): r channel enable pin. logic low to enable. take care to minimize the stray capacitance between the output and the inverting input. capacitance on the invert- ing input to ground will cause peaking in the frequency response (and overshoot in the transient response). capacitive loads the lt1398/lt1399/lt1399hv can drive many capaci- tive loads directly when the proper value of feedback resistor is used. the required value for the feedback resistor will increase as load capacitance increases and as closed-loop gain decreases. alternatively, a small resistor (5 w to 35 w ) can be put in series with the output to isolate the capacitive load from the amplifier output. this has the advantage that the amplifier bandwidth is only reduced when the capacitive load is present. the disadvantage is that the gain is a function of the load resistance. u s a o pp l ic at i wu u i for atio feedback resistor selection the small-signal bandwidth of the lt1398/lt1399/ lt1399hv is set by the external feedback resistors and the internal junction capacitors. as a result, the bandwidth is a function of the supply voltage, the value of the feedback resistor, the closed-loop gain and the load resistor. the lt1398/lt1399 have been optimized for 5v supply operation and have a C 3db bandwidth of 300mhz at a gain of 2. the lt1399hv provides performance similar to the lt1399. please refer to the resistor selection guide in the typical ac performance table. capacitance on the inverting input current feedback amplifiers require resistive feedback from the output to the inverting input for stable operation. lt1398 C in a (pin 1): inverting input of a channel amplifier. + in a (pin 2): noninverting input of a channel amplifier. gnd (pins 3, 4, 5, 6): ground. not connected internally. + in b (pin 7): noninverting input of b channel amplifier. C in b (pin 8): inverting input of b channel amplifier. en b (pin 9): b channel enable pin. logic low to enable. out b (pin 10): b channel output. v C (pin 11): negative supply voltage, usually C 5v. gnd (pins 12, 13): ground. not connected internally. v + (pin 14): positive supply voltage, usually 5v. out a (pin 15): a channel output. en a (pin 16): a channel enable pin. logic low to enable.
10 lt1398/lt1399/lt1399hv sn13989 13989fas u s a o pp l ic at i wu u i for atio power supplies the lt1398/lt1399 will operate from single or split supplies from 2v (4v total) to 6v (12v total). the lt1399hv will operate from single or split supplies from 2v (4v total) to 7.5v (15v total). it is not necessary to use equal value split supplies, however the offset voltage and inverting input bias current will change. the offset voltage changes about 600 m v per volt of supply mis- match. the inverting bias current will typically change about 2 m a per volt of supply mismatch. slew rate unlike a traditional voltage feedback op amp, the slew rate of a current feedback amplifier is not independent of the amplifier gain configuration. in a current feedback ampli- fier, both the input stage and the output stage have slew rate limitations. in the inverting mode, and for gains of 2 or more in the noninverting mode, the signal amplitude between the input pins is small and the overall slew rate is that of the output stage. for gains less than 2 in the noninverting mode, the overall slew rate is limited by the input stage. the input slew rate of the lt1398/lt1399/lt1399hv is approximately 600v/ m s and is set by internal currents and capacitances. the output slew rate is set by the value of the feedback resistor and internal capacitance. at a gain of 2 with 324 w feedback and gain resistors and 5v supplies, the output slew rate is typically 800v/ m s. larger feedback resistors will reduce the slew rate as will lower supply voltages. enable/ disable each amplifier of the lt1398/lt1399/lt1399hv has a unique high impedance, zero supply current mode which is controlled by its own en pin. these amplifiers are designed to operate with cmos logic; the amplifiers draw zero current when these pins are high. to activate each amplifier, its en pin is normally pulled to a logic low. however, supply current will vary as the voltage between the v + supply and en is varied. as seen in figure 1, +i s does vary with (v + C v en ), particularly when the voltage difference is less than 3v. for normal operation, it is important to keep the en pin at least 3v below the v + supply. if a v + of less than 3v is desired, and the amplifier will remain enabled at all times, then the en pin should be tied to the v C supply. the enable pin current is approxi- mately 30 m a when activated. if using cmos open-drain logic, an external 1k pull-up resistor is recommended to ensure that the lt1399 remains disabled in spite of any cmos drain-leakage currents. figure 1. + i s vs (v + C v en ) v + ?v en (v) 0 0 +i s (ma) 0.5 1.5 2.0 2.5 5.0 3.5 2 4 5 1398/99 f01 1.0 4.0 4.5 3.0 1 3 6 7 t a = 25 c v + = 5v v = 5v v = 0v figure 2. amplifier enable time, a v = 2 v s = 5v v in = 1v r f = 324 w r g = 324 w r l = 100 w 1398/99 f02 output en figure 3. amplifier disable time, a v = 2 v s = 5v v in = 1v r f = 324 w r g = 324 w r l = 100 w 1398/99 f03 output en
11 lt1398/lt1399/lt1399hv sn13989 13989fas u s a o pp l ic at i wu u i for atio the enable/disable times are very fast when driven from standard 5v cmos logic. each amplifier enables in about 30ns (50% point to 50% point) while operating on 5v supplies (figure 2). likewise, the disable time is approxi- mately 40ns (50% point to 50% point) (figure 3). differential input signal swing to avoid any breakdown condition on the input transis- tors, the differential input swing must be limited to 5v. in normal operation, the differential voltage between the input pins is small, so the 5v limit is not an issue. in the disabled mode however, the differential swing can be the same as the input swing, and there is a risk of device breakdown if input voltage range has not been properly considered. 3-input video mux cable driver the application on the first page of this data sheet shows a low cost, 3-input video mux cable driver. the scope photo below (figure 4) displays the cable output of a 30mhz square wave driving 150 w . in this circuit the active amplifier is loaded by the sum of r f and r g of each disabled amplifier. resistor values have been chosen to keep the total back termination at 75 w while maintaining a gain of 1 at the 75 w load. the switching time between any two channels is approximately 32ns when both enable pins are driven. when building the board, care was taken to minimize trace lengths at the inverting input. the ground plane was also pulled away from r f and r g on both sides of the board to minimize stray capacitance. figure 5. 3-input video mux switching response (a v = 2) v s = 5v 20ns/div v ina = v inb = 2v p-p at 3.58mhz 1398/99 f05 en a en b output using the lt1399 to drive lcd displays driving the current crop of xga and uxga lcd displays can be a difficult problem because they require drive voltages of up to 12v, are usually a capacitive load of over 300pf, and require fast settling. the lt1399hv is par- ticularly well suited for driving these lcd displays be- cause it is capable of swinging more than 6v on 7.5v supplies, and it can drive large capacitive loads with a small series resistor at the output, minimizing settling time. as seen in figures 6 and 7, at a gain of +3 with a 16.9 w output series resistor and a 330pf load, the lt1399hv is capable of settling to 0.1% in 30ns for a 6v step. similarly, a 12v output step settles in 70ns. figure 6. lt1399/lt1399hv large-signal pulse response v in v out v s = 5v 20ns/div r f = 324 w r g = 162 w r s = 16.9 w c l = 330pf 1398/99 ai06 figure 4. square wave response output 200mv/div 5ns/div 1398/99 f04 r l = 150 w r f = r g = 324 w f = 10mhz
12 lt1398/lt1399/lt1399hv sn13989 13989fas u s a o pp l ic at i wu u i for atio buffered rgb to color-difference matrix two lt1398s can be used to create buffered color- difference signals from rgb inputs (figure 8). in this application, the r input arrives via 75 w coax. it is routed to the noninverting input of lt1398 amplifier a1 and to a 1082 w resistor r8. there is also an 80.6 w termination + a2 1/2 lt1398 + b1 1/2 lt1398 + a1 1/2 lt1398 r7 324 r6 162 r5 324 r10 2940 r9 549 r11 80.6 r g b r12 86.6 r13 76.8 all resistors 1% v s = 5v r8 1082 75 sources r1 324 r2 324 r4 324 r3 324 b-y y r-y 1398/99 f08 + b2 1/2 lt1398 resistor r11, which yields a 75 w input impedance at the r input when considered in parallel with r8. r8 connects to the inverting input of a second lt1398 amplifier (a2), which also sums the weighted g and b inputs to create a C0.5 ? y output. lt1398 amplifier b1 then takes the C0.5 ? y output and amplifies it by a gain of C2, resulting in the y output. amplifier a1 is configured in a noninvert- ing gain of 2 with the bottom of the gain resistor r2 tied to the y output. the output of amplifier a1 thus results in the color-difference output r-y. the b input is similar to the r input. it arrives via 75 w coax, and is routed to the noninverting input of lt1398 amplifier b2, and to a 2940 w resistor r10. there is also a 76.8 w termination resistor r13, which yields a 75 w input impedance when considered in parallel with r10. r10 also connects to the inverting input of amplifier a2, adding the b contribution to the y signal as discussed above. amplifier b2 is configured in a noninverting gain of 2 configuration with the bottom of the gain resistor r4 tied to the y output. the output of amplifier b2 thus results in the color-difference output b-y. figure 7. lt1399hv output voltage swing v in v out v s = 7.5v 50ns/div r f = 324 w r g = 162 w r s = 16.9 w c l = 330pf 1398/99 f07 figure 8. buffered rgb to color-difference matrix
13 lt1398/lt1399/lt1399hv sn13989 13989fas u s a o pp l ic at i wu u i for atio the g input also arrives via 75 w coax and adds its contribution to the y signal via a 549 w resistor r9, which is tied to the inverting input of amplifier a2. there is also an 86.6 w termination resistor r12, which yields a 75 w termination when considered in parallel with r9. using superposition, it is straightforward to determine the output of amplifier a2. although inverted, it sums the r, g and b signals in the standard proportions of 0.3r, 0.59g and 0.11b that are used to create the y signal. amplifier b1 then inverts and amplifies the signal by 2, resulting in the y output. buffered color-difference to rgb matrix the lt1399 can be used to create buffered rgb outputs from color-difference signals (figure 9). the r output is a back-terminated 75 w signal created using resistor r5 and lt1399 amplifier a1 configured for a gain of +2 via 324 w resistors r3 and r4. the noninverting input of amplifier a1 is connected via 1k resistors r1 and r2 to the y and r-y inputs respectively, resulting in cancella- tion of the y signal at the amplifier input. the remaining r signal is then amplified by a1. the b output is also a back-terminated 75 w signal created using resistor r16 and amplifier a3 configured for a gain of +2 via 324 w resistors r14 and r15. the noninverting input of amplifier a3 is connected via 1k resistors r12 and r13 to the y and b-y inputs respec- tively, resulting in cancellation of the y signal at the amplifier input. the remaining b signal is then amplified by a3. the g output is the most complicated of the three. it is a weighted sum of the y, r-y and b-y inputs. the y input is attenuated via resistors r6 and r7 such that amplifier a2s noninverting input sees 0.83y. using superposition, we can calculate the positive gain of a2 by assuming that r8 and r9 are grounded. this results in a gain of 2.41 and a contribution at the output of a2 of 2y. the r-y input is amplified by a2 with the gain set by resistors r8 and r10, giving an amplification of C1.02. this results in a contri- bution at the output of a2 of 1.02y C 1.02r. the b-y input is amplified by a2 with the gain set by resistors r9 and r10, giving an amplification of C 0.37. this results in a contribution at the output of a2 of 0.37y C 0.37b. if we now sum the three contributions at the output of a2, we get: a2 out = 3.40y C 1.02r C 0.37b it is important to remember though that y is a weighted sum of r, g and b such that: y = 0.3r + 0.59g + 0.11b if we substitute for y at the output of a2 we then get: a2 out = (1.02r C 1.02r) + 2g + (0.37b C 0.37b) = 2g the back-termination resistor r11 then halves the output of a2 resulting in the g output. + a2 1/3 lt1399 r7 1k b-y r-y y r10 324 r11 75 r6 205 r2 1k r1 1k r8 316 r9 845 + a3 1/3 lt1399 r14 324 b g r16 75 r12 1k r13 1k r15 324 all resistors 1% v s = 5v + a1 1/3 lt1399 r3 324 r r5 75 r4 324 1398/99 f09 figure 9. buffered color-difference to rgb matrix
14 lt1398/lt1399/lt1399hv sn13989 13989fas si plified sche atic ww , each amplifier en +in ?n out v + v 1398/99 ss
15 lt1398/lt1399/lt1399hv sn13989 13989fas s package 16-lead plastic small outline (narrow 0.150) (ltc dwg # 05-08-1610) dimensions in inches (millimeters) unless otherwise noted. package descriptio u gn package 16-lead plastic ssop (narrow 0.150) (ltc dwg # 05-08-1641) 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. gn16 (ssop) 0398 * dimension does not include mold flash. mold flash shall not exceed 0.006" (0.152mm) per side ** dimension does not include interlead flash. interlead flash shall not exceed 0.010" (0.254mm) per side 12 3 4 5 6 7 8 0.229 ?0.244 (5.817 ?6.198) 0.150 ?0.157** (3.810 ?3.988) 16 15 14 13 0.189 ?0.196* (4.801 ?4.978) 12 11 10 9 0.016 ?0.050 (0.406 ?1.270) 0.015 0.004 (0.38 0.10) 45 0 ?8 typ 0.007 ?0.0098 (0.178 ?0.249) 0.053 ?0.068 (1.351 ?1.727) 0.008 ?0.012 (0.203 ?0.305) 0.004 ?0.0098 (0.102 ?0.249) 0.025 (0.635) bsc 0.009 (0.229) ref 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 s16 0695 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 dimension does not include mold flash. mold flash shall not exceed 0.006" (0.152mm) per side dimension does not include interlead flash. interlead flash shall not exceed 0.010" (0.254mm) per side * **
16 lt1398/lt1399/lt1399hv sn13989 13989fas part number description comments lt1203/lt1205 150mhz video multiplexers 2:1 and dual 2:1 muxs with 25ns switch time lt1204 4-input video mux with current feedback amplifier cascadable enable 64:1 multiplexing lt1227 140mhz current feedback amplifier 1100v/ m s slew rate, shutdown mode lt1252/lt1253/lt1254 low cost video amplifiers single, dual and quad current feedback amplifiers lt1259/lt1260 dual/triple current feedback amplifier 130mhz bandwidth, 0.1db flatness >30mhz lt1395/lt1396/lt1397 single/dual/quad current feedback amplifiers 400mhz bandwidth, 0.1db flatness >100mhz lt1675/lt1675-1 triple/single 2:1 buffered video mulitplexer 2.5ns switching time, 250mhz bandwidth lt1806/lt1807 single/dual 325mhz rail-to-rail in/out op amp low distortion, low noise lt1809/lt1810 single/dual 180mhz rail-to-rail in/out op amp 350v/ m s, low distortion ? linear technology corporation 1998 lt/tp 0501 2k rev a ? printed in usa u a o pp l ic at i ty p i ca l linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 l fax: (408) 434-0507 l www.linear-tech.com related parts single supply rgb video amplifier the lt1399 can be used with a single supply voltage of 6v or more to drive ground-referenced rgb video. in figure 10, two 1n4148 diodes d1 and d2 have been placed in series with the output of the lt1399 amplifier a1 but within the feedback loop formed by resistor r8. these diodes effectively level-shift a1s output down- ward by 2 diodes, allowing the circuit output to swing to ground. amplifier a1 is used in a positive gain configuration. the feedback resistor r8 is 324 w . the gain resistor is created from the parallel combination of r6 and r7, giving a thevenin equivalent 80.4 w connected to 3.75v. this gives an ac gain of + 5 from the noninverting input of amplifier a1 to the cathode of d2. however, the video input is also attenuated before arriving at a1s positive input. assuming a 75 w source impedance for the signal driving v in , the thevenin equivalent signal arriving at a1s positive input is 3v + 0.4v in , with a source imped- ance of 714 w . the combination of these two inputs gives an output at the cathode of d2 of 2 ? v in with no additional dc offset. the 75 w back termination resistor r9 halves the signal again such that v out equals a buffered version of v in . it is important to note that the 4.7 m f capacitor c1 has been added to provide enough current to maintain the voltage drop across diodes d1 and d2 when the circuit output drops low enough that the diodes might otherwise reverse bias. this means that this circuit works fine for continuous video input, but will require that c1 charge up after a period of inactivity at the input. + a1 1/3 lt1399 d1 1n4148 c1 4.7 f d2 1n4148 r9 75 r8 324 v s 6v to 12v r7 324 r5 2.32 r4 75 v in r2 1300 r1 1000 5v r6 107 r3 160 v out 1398/99 f10 video source 75 figure 10. single supply rgb video amplifier (1 of 3 channels)

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