quick start guide for demonstration circuit 566 digitally controlled programmable gain amplifier 1 ltc6910 description demonstration circuits 566a-a, -b and -c, feature the easy to use, rail-to-rail input and output ltc6910 se- ries of low noise programmable gain amplifier (pga) parts. the inverting gain is set by changing the positions of three onboard jumpers: g0, g1 and g2 to set the 3-bit programming code. demo circuit 566a- a is for the ltc6910?1 with gains of 0, 1, 2, 5, 10, 20, 50, 100 v/v. demo circuit 566a-b is for the ltc6910?2 with gains of 1, 2, 4, 8, 16, 32, and 64 v/v. demo circuits 566a-c is for the ltc6910?3 with gains of 1, 2, 3, 4, 5, 6 and 7 v/v. all three-demo boards have input jumpers to select between ac or dc coupling of the input, and a jumper to select operation with a single or dual supply. typi- cal applications include data acquisition systems, dy- namic gain changing, automatic ranging circuits and automatic gain control. the ltc6910 family can op- erate from single or split supplies from 2.7v to 10.5v total between v+ and v-. design files for this circuit board are available. call the ltc factory. table 1. performance summary (t a = 25c) parameter condition value supply voltage range v+ to v? 2.7v to 10.5v gain accuracy gain dependent (see data sheet) typical 0.05db at gain = 1 and 0.4 db at gain = 100 vs = 2.5v, v out = 1.4v 12v/s slew rate vs = 5v, v out = 1.4v 16v/s frequency (hz) 10 gain (db) 30 50 0 20 40 100 10k 100k 1m 10m 6910 g02 ?10 1k gain of 100 (digital input 111) gain of 1 (digital input 001) gain of 2 (digital input 010) gain of 5 (digital input 011) gain of 10 (digital input 100) gain of 20 (digital input 101) gain of 50 (digital input 110) v s = 10v, v in = 5mv rms figure 1. ltc6910-1 frequency re- sponse frequency (hz) 10 gain (db) 30 50 0 20 40 100 1k 100k 1m 10m 69102 ta02 ?10 10k v s = 5v v in = 10mv rms gain of 64 gain of 32 gain of 16 gain of 4 gain of 8 gain of 2 gain of 1 figure 2. ltc6910-2 frequency re- sponse frequency (hz) 0 gain (db) 10 20 ?5 5 15 1k 100 100k 1m 10m 69103 ta02 ?10 10k gain of 7 gain of 6 gain of 5 gain of 4 gain of 3 gain of 2 gain of 1 v s = 5v v in = 10mv rms figure 3. ltc6910-3 frequency re- sponse
quick start guide for demonstration circuit 566 digitally controlled programmable gain amplifier 2 figure 4. proper measurement equipment setup quick start procedure the 566 family of demonstration boards allow for easy evaluation of the performance of the ltc6910 series of pgas. refer to figure 4 for proper meas- urement equipment setup and follow the procedure given below: 1. place jumpers in the following positions: single for single supply dual for dual supply dc for dc coupling ac for ac coupling f ?3db = 1/(2 c 7 r input ) c 7 = 10f, r input is the nominal input im- pedance and depends on the gain setting, see table 2, 3, or 4. the jumper settings given in this procedure set the gain to a value of ?1 (the ltc6910-x is an inverting amplifier), for other gain values refer to gain table 2, 3 or 4 which matches the demo circuit, 566-a, - b, or -c. to set the gain to a value of ?1 set: g0: set to logic 1 g1: set to logic 0 g2: set to logic 0 2. with the power off, connect the input power supply to v+, v- and agnd as required. note: make sure that the input voltage does not exceed 11v total between v+ and v?. 3. set a function generator to output a 1khz 1v p?p signal. 4. set the input jumper to give the desired input cou- pling, ac or dc. supply jumper: input jumper (in):
quick start guide for demonstration circuit 566 digitally controlled programmable gain amplifier 3 5. turn on the power supply and connect the signal generator to the in bnc, or turrets as shown in figure 4. 6. monitor the output (bnc or test point) with an os- cilloscope to observe a 1khz 1v p?p signal. 7. using tables 2, 3 or 4 set the gain as desired and set the input to within the nominal linear input range. example: for a dual 5v supply operation and a gain equal to five, the input to an ltc6910-1 should be set equal to or less than 2v p-p (see table 2). table 2. dc566a?a gain settings and properties ltc6910-1 nominal voltage gain nominal linear input range (v p?p ) g2 g1 g0 volts/volt (db) dual 5v supply single 5v supply single 3v supply nominal input impedance (k ? ) 1 0 0 0 -120 10 5 3 open 0 0 1 -1 0 10 5 3 10 0 1 0 -2 6 5 2.5 1.5 5 0 1 1 -5 14 2 1 0.6 2 1 0 0 ?10 20 1 0.5 0.3 1 1 0 1 -20 26 0.5 0.25 0.15 1 1 1 0 -50 34 0.2 0.1 0.06 1 1 1 1 -100 40 0.1 0.05 0.3 1
quick start guide for demonstration circuit 566 digitally controlled programmable gain amplifier 4 table 3. dc566a?b gain settings and properties ltc6910-2 table 4. dc566a?c gain settings and properties ltc6910-3 nominal voltage gain nominal linear input range (v p?p ) g2 g1 g0 volts/volt (db) dual 5v supply single 5v supply single 3v supply nominal input impedance (k) 1 0 0 0 -120 10 5 3 open 0 0 1 -1 0 10 5 3 10 0 1 0 -2 6 5 2.5 1.5 5 0 1 1 -4 12 2.5 1.25 0.75 2.5 1 0 0 -8 18.06 125 0.625 0.375 1.25 1 0 1 -16 24.08 0.625 0.313 0.188 1.25 1 1 0 -32 30.1 0.313 0.156 0.094 1.25 1 1 1 -64 36.12 0.156 0.078 0.047 1.25 nominal voltage gain nominal linear input range (v p?p ) g2 g1 g0 volts/volt (db) dual 5v supply single 5v supply single 3v supply nominal input impedance (k) 1 0 0 0 -120 10 5 3 open 0 0 1 -1 0 10 5 3 10 0 1 0 -2 6 5 2.5 1.5 5 0 1 1 -3 9.5 3.33 1.67 1 3.3 1 0 0 -4 12 2.5 1.25 0.75 2.5 1 0 1 -5 14 2 1 0.6 2 1 1 0 -6 15.6 1.67 0.83 0.5 1.7 1 1 1 -7 16.9 1.43 0.71 0.43 1.4
quick start guide for demonstration circuit 566 digitally controlled programmable gain amplifier 5
linear technology corporation ltc6910-3cts8 parts list DC566A-C rev 2 1/21/2003 item qty ref desc part number 1 3 c1,c2,c3 cap, x7r 0.1uf 16v 10% 0603 avx 0603yc104kat 1 c3 cap, x5r 1uf 10v 10% 0603 avx 0603zd105kat 2 2 c5,c4 cap, x5r 4.7uf 16v 20% 1206 taiyo yuden emk316bj475ml-t 3 0 c6 cap, 0603 option option 4 1 c7 cap, x7r 10uf 10v 20% 1210 taiyo yuden lmk325bj106mn-t 5 5 jp1,jp2,jp3,jp4,jp5 header, 3pin, 2mm comm con 2802s-03g2 6 2 j2,j1 conn, bnc,5 pins connex 112404 7 1 r1 res, 0 ohm jumper 1/16w 0603 aac cj06-000 8 11 tp0-tp7,tp9,tp12,tp13 turret mill max2501-2 9 1 u1 ic, ltc6910-3cts8 linear tech ltc6910-3cts8 10 5 jp1,jp2,jp3,jp4,jp5 shunt, 2 pins 2mm comm con ccij2mm-138g 3 r2,r3,r4 res, 100k ohms 5% 1/16w 0805 aac cr10-104jm 1 of 1
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