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LT6559 1 6559f typical application features applications description low cost 5v/?v 300mhz triple video ampli er in 3mm 3mm qfn the lt ? 6559 is a low cost, high speed, triple ampli? er that has been optimized for excellent video performance on a single 5v supply, yet ? ts in the small footprint of a 3mm 3mm qfn package. with a C3db bandwidth of 300mhz, a 0.1db bandwidth of 150mhz, and a slew rate of 800v/s, the LT6559s dynamic performance is an excellent match for high speed rgb or yp b p r video applications. for multiplexing applications such as kvm switches or selectable video inputs, each channel has an independent high speed enable/disable pin. each ampli? er will turn on in 30ns and off in 40ns. when enabled, each ampli? er draws 3.9ma from a 5v supply. the LT6559 operates on a single supply voltage ranging from 4v to 12v, and on split supplies ranging from 2v to 6v. the LT6559 comes in a compact 16-lead 3mm 3mm qfn package, and operates over a C40c to 85c temperature range. the LT6559 is manufactured on linear technologys proprietary complementary bipolar process. 3-input video mux cable driver 300mhz bandwidth on single 5v and 5v (a v = 1, 2 and C1) 0.1db gain flatness: 150mhz (a v = 1, 2 and C1) high slew rate: 800v/s wide supply range: 2v to 6v (dual supply) 4v to 12v (single supply) 80ma output current low supply current: 3.9ma/ampli? er shutdown mode fast turn-on time: 30ns fast turn-off time: 40ns small 0.75mm tall 16-lead 3mm 3mm qfn package rgb/yp b p r cable drivers lcd projectors kvm switches a/v receivers mux ampli? ers composite video cable drivers adc drivers time (10ns/div) output 200mv/div 6559 ta02 r l = 100 ? r f = r g = 301 ? f = 10mhz square wave response , lt, ltc and ltm are registered trademarks of linear technology corporation. all other trademarks are the property of their respective owners. 5v ?v 5v ?v + 1/3 LT6559 r g 182 ? r f 301 ? a en a v in a + 1/3 LT6559 r g 182 ? r f 301 ? en b v in b b c channel select 100 ? 100 ? 5v ?v + 1/3 LT6559 r g 182 ? en c v in c 100 ? 75 ? v out 75 ? cable 6559 ta01 r f 301 ?
LT6559 2 6559f package/order information absolute maximum ratings total supply voltage (v + to v C ) ..............................12.6v 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) C40c to 85c speci? ed temperature range (note 4) .. C40c to 85c storage temperature range .................. C65c to 125c junction temperature (note 5) ............................ 125c (note 1) 16 17 15 14 13 5 6 7 8 top view ud package 16 - lead (3mm 3mm) plastic qfn 9 10 11 12 4 3 2 1 *gnd ?n g +in g *gnd v + en g out g v +in r ?n r en r out r +in b ?n b en b out b t jmax = 125c, ja = 68c/w, jc = 4.2c/w exposed pad (pin 17) is v C , must be soldered to the pcb order part number ud part marking LT6559cud lchg order options tape and reel: add #tr lead free: add #pbf lead free tape and reel: add #trpbf lead free part marking: http://www.linear.com/leadfree/ consult ltc marketing for parts speci? ed with wider operating temperature ranges. * ground pins are not internally connected. for best channel isolation, connect to ground. the o denotes speci? cations which apply over the speci? ed operating temperature range, otherwise speci? cations are at t a = 25c. for each ampli? er: v cm = 2.5v, v s = 5v, ? e ? n = 0v, pulse tested, unless otherwise noted. (note 4) 5v electrical characteristics symbol parameter conditions min typ max units v os input offset voltage o 1.5 10 12 mv mv v os / t input offset voltage drift o 15 v/c i in + noninverting input current o 10 25 30 a a i in C inverting input current o 10 60 70 a a e n input noise voltage density f = 1khz, r f = 1k, r g = 10 , r s = 0 4.5 nv/ ? h ? z +i n noninverting input noise current density f = 1khz 6 pa/ ? h ? z Ci n inverting input noise current density f = 1khz 25 pa/ ? h ? z r in input resistance v in = 1v 0.14 m c in input capacitance ampli? er enabled ampli? er disabled 2.0 2.5 pf pf c out output capacitance ampli? er disabled 8.5 pf v inh input voltage range, high 3.5 4.0 v v inl input voltage range, low 1.0 1.5 v v outh maximum output voltage swing, high r l = 100k 4.1 4.15 v v outl maximum output voltage swing, low r l = 100k 0.85 0.9 v v outh maximum output voltage swing, high r l = 150 r l = 150 3.85 3.65 3.95 v v
LT6559 3 6559f the denotes speci? cations which apply over the speci? ed operating temperature range, otherwise speci? cations are at t a = 25c. for each ampli? er: v cm = 0v, v s = 5v, e n = 0v, pulse tested, unless otherwise noted. (note 4) 5v electrical characteristics symbol parameter conditions min typ max units v os input offset voltage 1.5 10 mv 6 v os / 6 t input offset voltage drift 15 v/c i in + noninverting input current 10 25 a i in C inverting input current 10 60 a e n input noise voltage density f = 1khz, r f = 1k, r g = 10 1 , r s = 0 1 4.5 nv/ h z +i n noninverting input noise current density f = 1khz 6 pa/ h z Ci n inverting input noise current density f = 1khz 25 pa/ h z r in input resistance v in = 3.5v 1 m 1 c in input capacitance ampli? er enabled ampli? er disabled 2.0 2.5 pf pf c out output capacitance ampli? er disabled 8.5 pf v inh input voltage range, high v s = 5v 3.5 4.0 v v inl input voltage range, low C4.0 C3.5 v v outh maximum output voltage swing, high r l = 100k 4.0 4.2 v the denotes speci? cations which apply over the speci? ed operating temperature range, otherwise speci? cations are at t a = 25c. for each ampli? er: v cm = 2.5v, v s = 5v, e n = 0v, pulse tested, unless otherwise noted. (note 4) 5v electrical characteristics symbol parameter conditions min typ max units v outl maximum output voltage swing, low r l = 150 1 r l = 150 1 1.05 1.15 1.35 v v cmrr common mode rejection ratio v cm = 1.5v to 3.5v 40 50 db psrr power supply rejection ratio v s = 2v to 5v, e n = v C 56 70 db r ol transimpedance, 6 v out / 6 i in C v out = 1.5v to 3.5v, r l = 150 40 80 k 1 i out maximum output current r l = 0 1 65 ma i s supply current per ampli? er 3.9 6.1 ma disable supply current per ampli? er e n pin voltage = 4.5v, r l = 150 1 0.1 100 a i e n enable pin current 30 a sr slew rate (note 6) a v = 10, r l = 150 1 , v s = 5v 500 v/s t on turn-on delay time (note 7) r f = r g = 301 1 , r l = 150 1 , v s = 5v 30 75 ns t off turn-off delay time (note 7) r f = r g = 301 1 , r l = 150 1 , v s = 5v 40 100 ns t r , t f small-signal rise and fall time r f = r g = 301 1 , r l = 150 1 , v out = 1v p-p , v s = 5v 1.3 ns t pd propagation delay r f = r g = 301 1 , r l = 150 1 , v out = 1v p-p , v s = 5v 2.5 ns os small-signal overshoot r f = r g = 301 1 , r l = 150 1 , v out = 1v p-p , v s = 5v 10 % t s settling time 0.1%, a v = C1v, r f = r g = 301 1 , r l = 150 1 , v s = 5v 25 ns dg differential gain (note 8) r f = r g = 301 1 , r l = 150 1 , v s = 5v 0.13 % dp differential phase (note 8) r f = r g = 301 1 , r l = 150 1 , v s = 5v 0.10 deg
LT6559 4 6559f note 1: stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. exposure to any absolute maximum rating condition for extended periods may affect device reliability and lifetime. note 2: this parameter is guaranteed to meet speci? ed 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 ampli? ers have their outputs short circuited. note 4: the LT6559 is guaranteed to meet speci? ed performance from 0c to 70c and is designed, characterized and expected to meet these extended temperature limits, but is not tested or qa sampled at C40c and 85c. note 5: t j is calculated from the ambient temperature t a and the power dissipation p d according to the following formula: t j = t a + (p d ? 68c/w) note 6: at 5v, slew rate is measured at 2v on a 3v output signal. at 5v, slew rate is measured from 2v to 3v on a 1.5v to 3.5v output signal. slew rate is 100% production tested at 5v for both the rising and falling edge of the b channel. the slew rate of the r and g channels is guaranteed through design and characterization. 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 speci? cation 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 ampli? er stages were cascaded giving an effective resolution of 0.01% and 0.01. note 9: the LT6559 is guaranteed functional over the operating temperature range of C40c to 85c. typical ac performance v s (v) a v r l ( )r f ( )r g ( ) small signal C3db bw (mhz) small signal 0.1db bw (mhz) small signal peaking (db) 5, 5 1 150 365 - 300 150 0.05 5, 5 2 150 301 301 300 150 0 5, 5 C1 150 301 301 300 150 0 symbol parameter conditions min typ max units v outl maximum output voltage swing, low r l = 100k C4.2 C4.0 v v outh maximum output voltage swing, high r l = 150 r l = 150 3.4 3.2 3.6 v v v outl maximum output voltage swing, low r l = 150 r l = 150 C3.6 C3.4 C3.2 v v cmrr common mode rejection ratio v cm = 3.5v 42 52 db psrr power supply rejection ratio v s = 2v to 5v, ? e ? n = v C 56 70 db r ol transimpedance, v out / i in C v out = 2v, r l = 150 40 100 k i out maximum output current r l = 0 100 ma i s supply current per ampli? er v out = 0v o 4.6 6.5 ma disable supply current per ampli? er ? e ? n pin voltage = 4.5v, r l = 150 0.1 100 a i ? e ? n enable pin current 30 a sr slew rate (note 6) a v = 10, r l = 150 500 800 v/s t on turn-on delay time (note 7) r f = r g = 301 , r l = 150 30 75 ns t off turn-off delay time (note 7) r f = r g = 301 , r l = 150 40 100 ns t r , t f small-signal rise and fall time r f = r g = 301 , r l = 150 , v out = 1v p-p 1.3 ns t pd propagation delay r f = r g = 301 , r l = 150 , v out = 1v p-p 2.5 ns os small-signal overshoot r f = r g = 301 , r l = 150 , v out = 1v p-p 10 % t s settling time 0.1%, a v = C1, r f = r g = 301 , r l = 150 25 ns dg differential gain (note 8) r f = r g = 301 , r l = 150 0.13 % dp differential phase (note 8) r f = r g = 301 , r l = 150 0.10 deg the o denotes speci? cations which apply over the speci? ed operating temperature range, otherwise speci? cations are at t a = 25c. for each ampli? er: v cm = 0v, v s = 5v, ? e ? n = 0v, pulse tested, unless otherwise noted. (note 4) 5v electrical characteristics
LT6559 5 6559f frequency (hz) gain (db) 4 2 0 ? ? 6559 g01 1m 10m 100m 1g v s = 5v v in = ?0dbm r f = 365 ? r l = 150 ? frequency (hz) gain (db) 10 8 6 4 2 6559 g02 1m 10m 100m 1g v s = 5v v in = ?0dbm r f = r g = 301 ? r l = 150 ? frequency (hz) gain (db) 4 2 0 ? ? 6559 g03 1m 10m 100m 1g v s = 5v v in = ?0dbm r f = r g = 301 ? r l = 150 ? time (5ns/div) output (1v/div) 6559 g04 v s = 5v v in = 2.5v r f = 365 ? r l = 150 ? time (5ns/div) output (1v/div) 6559 g05 v s = 5v v in = 1.25v r f = r g = 301 ? r l = 150 ? time (5ns/div) output (1v/div) 6559 g06 v s = 5v v in = 2.5v r f = r g = 301 ? r l = 150 ? frequency (khz) 90 distortion (db) 80 60 40 30 1 100 1000 100000 6559 g07 100 10 10000 50 70 110 hd2 hd3 t a = 25 c r f = r g = 301 ? r l = 150 ? v s = 5v v out = 2vpp frequency (mhz) 1 2 output voltage (v p-p ) 3 4 5 6 8 10 100 6559 g08 7 a v = +1 a v = +2 t a = 25 c r f = 301 ? r l = 150 ? v s = 5v frequency (hz) 20 psrr (db) 40 50 70 80 10k 1m 10m 100m 6559 g09 0 100k 60 30 10 + psrr psrr t a = 25 c r f = r g = 301 ? r l = 150 ? a v = +2 typical performance characteristics closed-loop gain vs frequency (a v = 1) closed-loop gain vs frequency (a v = 2) closed-loop gain vs frequency (a v = C1) large-signal transient response (a v = 1) large-signal transient response (a v = 2) large-signal transient response (a v = C1) 2nd and 3rd harmonic distortion vs frequency maximum undistorted output voltage vs frequency psrr vs frequency
LT6559 6 6559f typical performance characteristics input voltage noise and current noise vs frequency output impedance vs frequency output impedance (disabled) vs frequency maximum capacitive load vs feedback resistor capacitive load vs output series resistor supply current per ampli? er vs supply voltage output voltage swing vs temperature enable pin current vs temperature positive supply current per ampli? er vs temperature frequency (hz) 10 input noise (nv/ hz or pa/ hz) 10 100 1000 30 100 300 1k 3k 10k 30k 100k 6559 g10 1 ?n +in en frequency (hz) 10k 0.01 output impedance ( ? ) 1 100 1m 10m 100k 100m 6559 g11 0.1 10 r f = r g = 301 ? a v = +2 v s = 5v frequency (hz) 100k 100 output impedance (disabled) ( ? ) 1k 10k 100k 1m 10m 100m 6559 g12 r f = 365 ? a v = +1 v s = 5v feedback resistance ( ? ) 300 1 capacitive load (pf) 10 100 1000 900 1500 2100 2700 3300 6559 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 6559 g14 30 r f = r g = 301 ? v s = 5v overshoot < 2% supply voltage ( v) 0 0 supply current (ma) 1 3 4 5 2 4 59 6559 g15 2 13 6 7 8 6 en = v en = 0v ambient temperature ( c) ?0 ? output voltage swing (v) ? ? ? 0 5 2 0 50 75 6559 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 6559 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 6559 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
LT6559 7 6559f ambient temperature ( c) ?0 input offset voltage (mv) 2.5 25 6559 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 6559 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 6559 g21 ?00 1m r f = r g = 301 ? r l = 150 ? a v = +2 r g b | t pd = 2.5ns | 6559 g22 time (500ps/div) a v = + 2 r l = 150 ? r f = r g = 301 ? input 100mv/div output 200mv/div frequency (hz) ?0 all hostile crosstalk (db) ?0 ?0 ?0 ?0 ?0 ?0 ?0 ?0 100k 10m 100m 500m 6559 g24 ?00 ?10 1m r f = r g = 301 ? r l = 150 ? a v = +2 r g b | t r = 1.3ns | 6559 g23 time (500ps/div) a v = + 2 r l = 150 ? r f = r g = 301 ? v out 200mv/div os = 10% | | typical performance characteristics input offset voltage vs temperature input bias currents vs temperature all hostile crosstalk all hostile crosstalk (disabled) propagation delay rise time and overshoot
LT6559 8 6559f pin functions gnd (pins 1, 4): ground. not connected internally. Cin g (pin 2): inverting input of g channel ampli? er. +in g (pin 3): noninverting input of g channel ampli? er. +in b (pin 5): noninverting input of b channel ampli? er. Cin b (pin 6): inverting input of b channel ampli? er. ? e ? n b (pin 7): b channel enable pin. logic low to enable. out b (pin 8): b channel output. v C (pin 9): negative supply voltage, usually ground or C5v. out g (pin 10): g channel output. ? e ? n g (pin 11): g channel enable pin. logic low to enable. v + (pin 12): positive supply voltage, usually 5v. out r (pin 13): r channel output. ? e ? n r (pin 14): r channel enable pin. logic low to enable. Cin r (pin 15): inverting input of r channel ampli? er. +in r (pin 16): noninverting input of r channel ampli? er. exposed pad (pin 17): v C . must be soldered to the pcb. applications information feedback resistor selection the small-signal bandwidth of the LT6559 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. optimized for 5v and single-supply 5v operation, the LT6559 has a C3db bandwidth of 300mhz at gains of +1, C1, or +2. refer to the resistor selection guide in the typical ac performance table. capacitance on the inverting input current feedback ampli? ers require resistive feedback from the output to the inverting input for stable operation. take care to minimize the stray capacitance between the output and the inverting input. capacitance on the inverting input to ground will cause peaking in the frequency response and overshoot in the transient response. capacitive loads the LT6559 can drive many capacitive loads directly when the proper value of feedback resistor is used. the required value for the feedback resistor will increase as load ca- pacitance increases and as closed-loop gain decreases. alternatively, a small resistor (5 to 35 ) can be put in series with the output to isolate the capacitive load from the ampli? er output. this has the advantage that the ampli- ? er bandwidth is only reduced when the capacitive load is present. the disadvantage is that the gain is a function of the load resistance. power supplies the LT6559 will operate from single or split supplies from 2v (4v total) to 6v (12v 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 600v per volt of supply mismatch. the inverting bias current will typically change about 2a per volt of supply mismatch. slew rate unlike a traditional voltage feedback op amp, the slew rate of a current feedback ampli? er is dependent on the ampli? er gain con? guration. in a current feedback ampli- ? er, 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 LT6559 is approximately 600v/s and is set by internal currents and capacitances. the output slew rate is set by the value of the feedback resistor and
LT6559 9 6559f applications information internal capacitance. at a gain of 2 with 301 feedback and gain resistors and 5v supplies, the output slew rate is typically 800v/s. larger feedback resistors will reduce the slew rate as will lower supply voltages. enable/disable each ampli? er of the LT6559 has a unique high imped- ance, zero supply current mode which is controlled by its own ? e ? n pin. these ampli? ers are designed to operate with cmos logic; the ampli? ers draw 0.1a of current when these pins are high or ? oated. to activate each ampli? er, its ? e ? n pin is normally pulled to a logic low. however, sup- ply current will vary as the voltage between the v + supply and ? e ? n is varied. as seen in figure 1, +i s does vary with (v + C v ? e ? n ), particularly when the voltage difference is less than 3v. for normal operation, it is important to keep the ? e ? n pin at least 3v below the v + supply. if a v + of less than 3v is used, for the ampli? er to remain enabled at all times the ? e ? n pin should be tied to the v C supply. the enable pin current is approximately 30a when activated. if using cmos open-drain logic, an external 1k pull-up resistor is recommended to ensure that the LT6559 remains disabled regardless of any cmos drain-leakage currents. 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 the input voltage range has not been properly considered. v + ?v en (v) 0 0 +i s (ma) 0.5 1.5 2.0 2.5 5.0 3.5 2 4 5 6559 f01 1.0 4.0 4.5 3.0 1 3 6 7 t a = 25 c v + = 5v v = 5v v = 0v figure 1. +i s vs (v + C v ? e ? n ) the enable/disable times are very fast when driven from standard 5v cmos logic. each ampli? er 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). figure 2. ampli? er enable time, a v = 2 figure 3. ampli? er disable time, a v = 2 2v 0v 5v 0v output 6559 f02 v s = 5v v in = 1v r f = 301 ? r g = 301 ? r l = 100 ? en 6559 f03 v s = 5v v in = 1v r f = 301 ? r g = 301 ? r l = 100 ? 2v 0v 5v 0v output en
LT6559 10 6559f typical applications 3-input video mux cable driver the application on the ? rst 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 . in this circuit the ac- tive ampli? er is loaded by the sum of r f and r g of each disabled ampli? er. resistor values have been chosen to keep the total back termination at 75 while maintaining a gain of 1 at the 75 load. the switching time between any two channels is approximately 32ns when both enable pins are driven (figure 5). when building the board, care was taken to minimize trace lengths at the inverting inputs. the ground plane was also pulled a few millimeters away from r f and r g on both sides of the board to minimize stray capacitance. using the LT6559 to drive lcd displays driving a variety of xga and uxga lcd displays can be a dif? cult problem because they are usually a capacitive load of over 300pf, and require fast settling. the LT6559 is particularly well suited for driving these lcd displays because it can drive large capacitive loads with a small series resistor at the output, minimizing settling time. as seen in figure 6, at a gain of +3 with a 16.9 output series resistor and a 330pf load, the LT6559 is capable of settling to 0.1% in 30ns for a 6v step. figure 4. square wave response figure 5. 3-input video mux switching response (a v = 2) figure 6. large-signal pulse response output 200mv/div 6559 f04 r l = 150 ? r f = r g = 301 ? f = 10mhz 5ns/div output 6559 f05 v s = 5 v ina = v inb = 2v p-p at 3.58mhz 20ns/div en a en b 6559 f06 v s = 5 r f = 301 ? 20ns/div v in v out r g = 150 ? r s = 16.9 ? c l = 330pf
LT6559 11 6559f typical applications buffered rgb to yp b p r conversion an LT6559 and an lt1395 can be used to map rgb signals into yp b p r component video as shown in figure 7. the lt1395 performs a weighted inverting addition of all three inputs. the lt1395 output includes an ampli? cation of the r input by: ? =? 324 107 030 . . k the ampli? cation of the g input is by: ? =? 324 549 059 . finally, the b input is ampli? ed by: ? =? 324 294 011 . . k therefore, the lt1395 output is: C 0.3r C 0.59g C 0.11b = Cy. this output is further scaled and inverted by C301/150 = C2 by LT6559 section a2, thus producing 2y. with the division by two that occurs due to the termination resistors, the desired y signal is generated at the load. the LT6559 section a1 provides a gain of 2 for the r sig- nal, and performs a subtraction of 2y from the section a2 output. the output resistor divider provides a scaling factor of 0.71 and forms the 75 back-termination resistance. thus, the signal seen at the terminated load is the desired 0.71(r C y) = p r . the LT6559 section a3 provides a gain of 2 for the b signal, and also performs a subtraction of 2y from the section a2 output. the output resistor divider provides a scaling factor of 0.57 and forms the 75 back-termination resistance. thus the signal seen at the terminated load is the desired 0.57(b C y) = p b . for this circuit to develop a normal sync on the y signal, a normal sync must be inserted on each of the r, g, and b inputs. alternatively, additional circuitry could be added to inject sync directly at the y output with controlled cur- rent pulses. figure 7. rgb to yp b p r conversion + lt1395 + a2 1/3 LT6559 + a1 1/3 LT6559 324 ? 150 ? 301 ? 75 ? 2.94k 549 ? r11 80.6 ? r g b r12 86.6 ? r13 76.8 ? all resistors 1% v s = 3v to 5v y 1.07k 75 ? sources 301 ? 301 ? 301 ? 301 ? 133 ? p b 174 ? 105 ? p r 261 ? 6559 f07 + a3 1/3 LT6559 y = 0.30r + 0.59g + 0.11b p b = 0.57 (b ?y) p r = 0.71 (r ?y)
LT6559 12 6559f typical applications yp b p r to rgb conversion two LT6559s can be used to map the yp b p r component video into the rgb color space as shown in figure 8. the y input is properly terminated with 75 and buffered with a gain of 2 by ampli? er a2. the p r input is terminated and buffered with a gain of 2.8 by ampli? er a1. the p b input is terminated and buffered with a gain of 3.6 by ampli? er a3. ampli? er b1 performs an equally weighted addition of ampli? ers a1 and a2 outputs, thereby producing 2(y + 1.4p r ), which generates the desired r signal at the terminated load due to the voltage division by 2 caused by the termination resistors. ampli? er b3 forms the equally weighted addition of ampli? ers a2 and a3 outputs, thereby producing 2(y + 1.8p b ), which generates the desired b signal at the terminated load. ampli? er b2 performs a weighted summation of all three inputs. the p b signal is ampli? ed overall by: ? =? 301 154 36 2 034 . ? ( . ) k the p r signal is ampli? ed overall by: ? =? 301 590 28 2 071 ? ( . ) the y signal is ampli? ed overall by: 1 1 698 1 301 590 1 54 221 k kk + += || . ?) therefore the ampli? er b2 output is: 2(y C 0.34p b C 0.71p r ) which generates the desired g signal at the terminated load. the sync present on the y input is reconstructed on all three r, g, and b outputs. figure 8. yp b p r to rgb conversion r = y + 1.40p r g = y ?0.34p b 0.71 p r b = y + 1.77p b all resistors 1% v s = 3v to 5v + a1 1/3 LT6559 75 ? 301 ? 165 ? p r + a2 1/3 LT6559 75 ? 301 ? 301 ? y + a3 1/3 LT6559 75 ? 301 ? 118 ? p b + b1 1/3 LT6559 1k 301 ? 301 ? r 75 ? 1k 1k + b2 1/3 LT6559 + b3 1/3 LT6559 301 ? 301 ? b 75 ? 1k 1k 301 ? 590 ? g 75 ? 698 ? 1.54k 6559 f08
LT6559 13 6559f typical applications application (demo) boards the dc1063a demo board has been created for evaluating the LT6559 and is available directly from linear technol- ogy. it has been designed as an rgb video buffer/cable driver, using standard vga 15-pin d-sub (hd-15) con- nectors for input and output signals. all sync signals are also passed directly from the input to the output, so the LT6559s performance can be determined by applying a 5v supply to the dc1063a demo board and then inserting the board between a computers analog video output and a monitor. schematics for the dc1063a demo board can be found on the back page of this datasheet. as seen in the dc1063a schematic, each ampli? er is con- ? gured in a gain of 2, with a 75 back-termination resulting in a ? nal gain of 1. each input is properly terminated for 75 input impedance with ac coupling capacitors at each input and output. additionally, for proper operation, the positive input of each ampli? er is biased to mid-supply with a high impedance resistor divider. as seen below, the dc1063a is a 2-sided board. 6559 f10 figure 9. dc1063a component locator figure 10. dc1063a top side figure 11. dc1063a bottom side 6559 f11 6559 f09
LT6559 14 6559f simplified schematic en +in ?n out v + v 6559 ss , each ampli? er
LT6559 15 6559f 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 representa- tion that the interconnection of its circuits as described herein will not infringe on existing patent rights. package description 3.00 0.10 (4 sides) recommended solder pad pitch and dimensions 1.45 0.05 (4 sides) note: 1. drawing conforms to jedec package outline mo-220 variation (weed-2) 2. drawing not to scale 3. all dimensions are in millimeters 4. dimensions of exposed pad on bottom of package do not include mold flash. mold flash, if present, shall not exceed 0.15mm on any side 5. exposed pad shall be solder plated 6. shaded area is only a reference for pin 1 location on the top and bottom of package pin 1 top mark (note 6) 0.40 0.10 bottom view?xposed pad 1.45 0.10 (4-sides) 0.75 0.05 r = 0.115 typ 0.25 0.05 1 pin 1 notch r = 0.20 typ or 0.25 45 chamfer 15 16 2 0.50 bsc 0.200 ref 2.10 0.05 3.50 0.05 0.70 0.05 0.00 ?0.05 (ud16) qfn 0904 0.25 0.05 0.50 bsc package outline ud package 16-lead plastic qfn (3mm 3mm) (reference ltc dwg # 05-08-1691)
LT6559 16 6559f linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 fax: (408) 434-0507 www.linear.com linear technology corporation 2006 lt 0606 ? printed in usa related parts typical application 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 ampli? er cascadable enable 64:1 multiplexing lt1395/lt1396/lt1397 single/dual/quad current feedback ampli? ers 400mhz bandwidth, 0.1db flatness >100mhz lt1399 300mhz triple current feedback ampli? er 0.1db gain flatness to 150mhz, shutdown 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 low distortion, low noise lt6550/lt6551 3.3v triple and quad video buffers 110mhz gain of 2 buffers in ms package lt6553 650mhz gain of 2 triple video ampli? er lt6554 650mhz gain of 1 triple video ampli? er same pinout as the lt6553 but optimized for high impedance loads lt6555 650mhz gain of 2 triple 2:1 video multiplexor lt6556 750mhz gain of 1 triple 2:1 video multiplexor same pinout as the lt6553 but optimized for high impedance loads lt6557 500mhz gain of 2 single-supply triple video ampli? er optimized for single 5v supply, 2200v/s slew rate, input bias contr ol lt6558 550mhz gain of 1 single-supply triple video ampli? er optimized for single 5v supply, 2200v/s slew rate, input bias contr ol dc1063a demo circuit schematic video in j1 hd-15-m c1 22 f + + + 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 2 3 h sync v sync video out j2 hd-15-f enable jp1 2mm green blue red 1 2 3 u1:b LT6559 u1:a LT6559 u1:c LT6559 c4 22 f c5 22 f c3 22 f c6 22 f c2 22 f c7 220 f c8 220 f c11 4.7 f c10 100nf r3 78.7 ? r9 3.32k r2 78.7 ? r7 3.32k r13 301 ? r6 3.32k r12 301 ? r4 3.32k r10 301 ? r5 3.32k r11 301 ? r1 78.7 ? r15 301 ? r18 75 ? r8 3.32k r14 301 ? r17 75 ? r16 75 ? c9 220 f e1 5v e2 ground 1 4 5 6 7 8 9 10 11 12 13 14 15 2 3 8 9 9 9 10 6559 ta03 12 13 11 12 7 5 6 12 14 15 16 + + + +

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