the GB4600 is a high per for mance, monolithic unity gain video buf fer made on gennum's pr oprietar y lsi pr ocess. the device featur es a stable wideband topology capable of driving high capacitance video busses. optimal system power/bandwidth can be achieved by using the high/low curr ent mode select ( i -set). in addition, the GB4600 can be disabled by taking the enable pin to gr ound. the enable input is ttl and 5 v cmos compatible. the GB4600 operates fr om 4.5 to 5.5 v power supplies and typically draws 30 ma of curr ent when i -set is not connected. the supply curr ent dr ops by appr oximately 50% when i -set is dir ectly connected to v ee . a typical application for the GB4600 is inter facing gennum's wide range of video cr osspoint switches. the 8 pin soic packaging is ideally suited for space r estricted boar d ? input and output b uff er ing in wide crosspoint matr ices ? inter-board video signal b uff er ing ? inter-system video signal b uff er ing ordering informa tion par t number package t emperatur e range GB4600-cka 8 soic 0 to 70 c fea tures da t a sheet ? wideband, unity gain, stab le operation ( 0.1 db at 100 mhz when c l = 27 pf) (full po wer bw = 120 mhz when c l = 47 pf). ? selectab le high and lo w current operating modes ( i l = 10 ma or i l = 20 ma) ? drives high capacitance loads (c l = 180 pf) to 70 mhz at -3 db. ? e xtremel y lo w diff erential phase and gain ? con venient 8 pin soic pac ka ging ? 100 m w disab led po wer consumption gennum corpora tion p .o. box 489, stn a, burlington, ontario, canada l7r 3y3 tel. (905) 632-2996 fax: (905) 632-5946 japan branch: a-302, miyamae v illage, 2-10-42, miyamae, suginami-ku, t okyo 168, japan tel. (03) 3334-7700 fax. (03) 3247-8839 applica tions description a v ailable p ackaging pin connections 8 pin soic i -set nc input output 3 48 5 1 gnd enable v ee 26 v cc 7 GB4600 monolithic unity gain v ideo buf fer document no. 13421 - 5 1 2 3 4 8 7 6 5 revision date: februar y 2003 functional block diagram video switch enable input output enable current set i -set layouts.
2 p arameter v alue supply v oltage 7.5 v operating t emperatur e range 0 c to 70 c storage t emperatur e range -65 c to 150 c lead t emperatur e (soldering 10 sec.) 260 c analog input v oltage -5.5 v v in 5.5 v logic input v oltage -0.5 v v l 5.5 v absolute maximum ra tings p arameter symbol conditions min. typ . max. units supply v oltage v s 4.5 5.0 5.5 v supply curr ent i + -3 0 3 7 m a i - -3 0 3 7 m a i + r-set = 0 w -1 6 2 0 m a i - r-set = 0 w -1 6 2 0 m a i + (of f) enable = 0 - 0 - m a i - (of f) enable = 0 - 16 50 m a analog output v oltage v out unclipped extr emes -1.8 - 2.2 v analog input bias curr ent i v bias -1 2 - m a output of fset v oltage v os t a = 25 c- 5 - 1 5 m v output of fset v oltage drift d v os - 5 0 100 m v/ c chip enable time t on - 100 - n s chip disable time t off -1 - m s logic input thr esholds v ih 2.0 - - v v il - - 0.8 v enable bias curr ent i bias enable = 0, t a = 25 c - - 5.0 m a inser tion loss i.l. ? = 100 khz, t a = 25 c - -0.04 - db fr equency response ( 0.1db) f .r. v in = 1 v p-p c l = 27 pf - 100 - mhz full power (-3db) fpbw v in = 1 v p-p, - 120 - mhz input resistance r in 1.0 3.0 - m w input capacitance c in - 1.1 - p f output resistance r out -2 - w output capacitance c out -5 - p f dif fer ential gain dg ? = 3.58 mhz - 0.02 - % dif fer ential phase dp ? = 3.58 mhz - 0.02 - deg of f isolation at 30 mhz v in = 1 v p-p 75 80 - d b +sr r-set = 0 ( i minimum) - 250 - v / m s v in = 3 v p-p, c l = 100 pf -sr r s = 12 w - 100 - v / m s +sr v in = 3 v p-p, c l = 100 pf - 350 - v/ m s -sr r s = 12 w - 170 - v / m s slew rate logic st a tic dc suppl y dynamic electrical characteristics v s = 5 v , t a = 0 to 70 c, r l = 10k w , c l = 47 pf , r- set = open cir cuit unless otherwise shown. ca ution electr ost a tic sensitive devices do no t open p a cka ges or handle except a t a st a tic-free w orkst a tion 13421 - 5
3 7 4 8 2 5 75 GB4600 3 1 r s video input 0.1 5 10 k -5v +5v 0.1 chip enable -5v r l min. max. 0.1 -5v 1 +5v 0.1 4 video out (75 ) 10 k 0.1 i -set 8 c l w comlinear clc110 the cir cuit shown above uses the GB4600 as an input buf fer driving several gx4201 video cr osspoint ics. the GB4600 is capable of driving loads up to 100 pf to a -3 db bandwidth of 80 mhz. for lighter loads, the bandwidth is extended to over 100 mhz. capacitor c l is used to shape the r esponse in conjunction with the 27 w series r esistor fr om pin 4. the value shown will give a -1 db r esponse at 100 mhz with a total load capacitance (fixed plus actual) of 47 pf . in or der to disable the GB4600, pin 1 is driven fr om the t all y outputs of the gx4201s. when all cr osspoints ar e off , the voltage on pin 1 will be 0 volts, disabling the GB4600. whenever any cr osspoint is selected, the voltage on pin 1 rises to +5 volts and tur ns on the buf fer . this configuration minimizes the curr ent drain when a gr oup of cr osspoints ar e tur ned of f. for other applications, the enable input on the GB4600 may be contr olled by any ttl or 5 volt cmos device. a unique featur e of the GB4600 is that its curr ent drain can be r educed by adjusting the value of the r esistor on the i -set input, pin 5. if r-set is made zer o ohms (a dir ect connection to -v ee ) then the supply curr ent dr ops 50% fr om 36 ma to 18 ma. a r educed curr ent will r educe the bandwidth as shown in figur e 3. for values of r s = 27 w and c l = 47 pf , the -1 db bandwidth shrinks fr om 100 mhz at maximum curr ent to 80 mhz at minimum curr ent. as with any high fr equency cir cuit, car eful boar d layout with ample gr ound plane is critical. all r esistors ar e in ohms, all capacitors in micr ofarads unless otherwise stated all r esistors ar e in ohms, all capacitors in micr ofarads unless otherwise stated test circuit * the curr ent will be maximum if the pin 5 is left open cir cuit. any value of r esistance fr om pin 5 to -v ee will r educe the curr ent. the minimum curr ent (50% of max.) will occur when r-set = 0 w . typical applica tion circuit 7 4 8 2 5 75 GB4600 3 1 27 video input gx4201 0.1 gx4201 gx4201 video out video out video out t all y out t all y out t all y out 10k -5v -5v +5v 0.1 c l * r-set 13421 - 5
4 typical performance cur ves for the GB4600 0.05 0.04 0.03 0.02 0.01 0 1.5 1.0 0.5 0 -0.5 -1.0 -1.5 -2.0 -2.5 -3.0 -3.5 10 200 1 100 v in = 1v p-p c l = 47pf r s = 12 w v in = 1v p-p r s = 18 w c l = 100pf v blanking = 0v v luminence = 0.714v v in = 40 ire frequency (mh z ) fig. 3 i -set bandwidth vs f requency fig. 1 off - isolation vs f requency 1 1 0 100 300 40 50 60 70 80 90 100 1.5 1.0 0.5 0 -0.5 -1.0 -1.5 -2.0 -2.5 -3.0 -3.5 10 100 200 frequency (mhz) dg dp dg/dp 100 frequency (mhz) 1 10 1 3 5 10 frequency (mhz) i set = max. i set = min. off isola tion (db) gain ( d b) gain ( d b) v in = 1v p-p r s = 27 w r-set ( w ) fig. 2 full p o w er bandwidth (100 pf) vs f requency fig. 4 diff erential gain and phase vs f requency fig. 5 soic der ating cur v es 100 1k 10k 1m ambient tempera ture ( o c) (still air) 80 75 70 65 60 55 50 45 40 v s = 5.0v v s = 5.3v v s = 5.5v document identifica tion da t a sheet the pr oduct is in pr oduction. gennum r eserves the right to make changes at any time to impr ove r eliability , function or design, in or der to pr ovide the best pr oduct possible. gennum corporation assumes no r esponsibility for the use of any cir cuits described her ein and makes no r epr esentations that they ar e fr ee fr om patent infringement. ? copyright may 1991 gennum corporation. all rights r eserved. printed in canada. revision no tes: 13421 - 5 remove r efer ence to dip package. remove associated par t number fr om dip package.
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