demo board quick start guide dc427 rms to dc converter 1 ltc1966 description demo board dc427 features the ltc1966 precision mi- cro-power true rms-to-dc converter. it incorporates a variety of passive components to support configurations for varied applications. two optional post-filters are in- cluded to improve averaging ripple and step response performance, as illustrated in the design cookbook sec- tion of the ltc1966 datasheet. the new ltc1966 is a patent-pending ? -based rms to dc converter that is simpler, more accurate, more flexi- ble, and lower power than conventional log-antilog rms-to-dc converters. the ltc1966 accepts single- ended or differential inputs with rail-to-rail common- mode range. one standout feature of the ltc1966 is its superior linearity, which allows hassle-free system cali- bration at any input voltage. quick start procedure table 1 shows the jumper positions and their respective effects. be sure that the jumpers are in the bold (default) positions. refer to figure 1 for the connection diagram and follow the procedure below: 1. connect the power supplies as shown. the power labels of v ss and v dd directly correspond to pins 4 and 7 of the ltc1966, respectively, and combinations other than 5v may be used, refer to the ltc1966 datasheet. 2. apply an input signal to convert from rms to dc to in1. any signal generator may be used; the ltc1966 works up to 1v peak with v dd = 5v. note: there is a 50 ? termination to ground on dc427, remove if driving with an op-amp. 3. observe the output with a dvm connected to termi- nals e4 and e7. note: the ltc1966 output impedance is high, and a 10m ? dvm input impedance will cause about ?1% gain error. 4. to use the output filters, reposition jp3 and observe the output at terminal e1 or e8. table 1: dc427 jumpers (default positions in bold) jumper setting effect top ltc1966 shutdown bottom ltc1966 always enabled jp1 removed ltc1966 controlled by e2 input to dc427 top in1 grounded jp2 bottom in1 active (j1 connected to pin 2) top ltc1966 connected to optional buff- ered post-filter right ltc1966 connected to output terminal e4, no filter jp3 bottom ltc1966 connected to optional dc- accurate post-filter top in2 active (j2 connected to pin 3) jp4 bottom in2 grounded installed outrtn (pin 6) grounded jp5 removed outrtn floating; drive with voltage at terminal e7
demo board quick start guide dc427 rms to dc converter 2 additional features although the dc427 demo board is ready to use out of the box (see ? quick start procedure ? above), it has fea- tures that you can access by adding, removing or chang- ing components on the board. here are some ways that you can change the configuration to take advantage of these features. differential inputs to drive the input differentially, move jumper jp4 from bottom to top. the ltc1966 will respond to the differ- ence of the signals. if two different frequencies are used, the vector sum results. averaging capacitors the board provides space for trying out different averag- ing (and filtering) capacitors. the space at c7b parallels c7a (the included 1 f, 16v metal film capacitor). the space has a footprint that will accommodate 2.5mm, 5mm, 7.5mm, and 10mm spaced through-hole leaded components as well as a large solder mask-free area for use with a wide variety of surface mount case sizes. try out the averaging capacitor you intend to use with the ltc1966 in dc427. raw output not buffered buffered and filtered output filtered output not buffered outrtn gnd e8 e7 e4 gnd e1 gnd + ? jp5 jp2 jp3 jp4 jp1 signal generator high impedance see text in 1 gnd in 2 gnd vss ( ? ) gnd vdd (+) gnd e2 pin 8, en j1 j2 ltc1966cms8 rms to dc converter demo DC427A linear technology (408) 432-1900 www.linear.com + ? + ? +5v ? 5v power supplies figure 1. proper measurement equipment setup
demo board quick start guide dc427 rms to dc converter 3 filter op amps likewise, the layout of the u2/u3 op amps includes ac- tive locations for sot-23, ms-8, so-8 and dip-8 single op amp packages. try out the op amp you intend to use in such filters using dc427. normally unused pins of the op amps (1, 5, and 8 in the 8-lead packages) are all tied in parallel, i.e. pin 8 of the dip is tied to pin 8 of the so and pin 8 of the ms. pin 5 of the sot-6 is tied to pin 5 of the other packages as well. if using any of these pins (for shutdown control, nulling, compensation, etc) the dip-8 through-hole pins will likely be the easiest place to connect to them. note: the ms-8 and dip-8 are located on the back (sol- der) side of the board. using the back side for these parts is not advised for production. ac coupling resistors r6 and r8 put 10k ? between the ltc1966 and the signals driving dc427. with 50 ? signal genera- tors, these are not needed, but they are helpful when driving dc427 with standard op amps whose output stages can get confused by the fast spikes of current drawn by the ltc1966's cmos inputs (described in the ltc1966 datasheet). another important reason for in- cluding r6/r8 is the ability to change one of them to a capacitor to provide ac coupling. select a 1206 case size capacitor as described in the ltc1966 datasheet. kelvin-sense points the ltc1966 has a typical conversion gain accuracy of 0.1%. measuring this accuracy can be difficult. the primary challenge is getting a known good accurate in- put signal to the ltc1966 without corrupting it with parasitics. in a 50 ? environment, even 0.05 ? in series will result in a 0.1% attenuation of the signal. of course many 50 ? terminators are 1% tolerance, including r7 &r9 on dc427. to compensate for these effects, the signal at the ltc1966 inputs can be kelvin-sensed. but parasitic capacitance can corrupt the ltc1966 sampling or the ltc1966 sampling can reduce the sensed signal level, depending on the exact impedance and parasitic levels. the preferred method is to sense at the outside of series feed resistors r6 and r8, at the dummy vias lo- cated above r6 and below r8. for a further discussion of the ltc1966 input sampling, refer to the ? input im- pedance ? information in the ? application information ? section of the ltc1966 datasheet. jacks and turrets connectors j1 and j2 allow installation of a bnc jack, such as connex type 112404. the various holes around the periphery of the board al- low the installation of turrets such as mill-max type 2501-2. however, the size and placement of the holes allow clip lead connections without installing the turrets. shutdown finally, by removing jumper jp1, the ltc1966 shdn pin may be driven. note: the lt1494 op-amps and the r1/r3 divider net- work will continue to draw current even when the ltc1966 is disabled. to measure the near-zero cur- rent of the ltc1966, remove zero- ? shunts r14 and r15. these can also be removed to power the optional filters with different supply voltages than the ltc1966.
5 5 4 4 3 3 2 2 1 1 d d c c b b a a en in 1 gn d in 2 vd d +2.7 gn d vss 0 -5.5 v 5.5v filtered output not buffered raw output not buffered out rtn buffered and filtered output opt . filter opt . filter on of f a dc4 27a wednesday, november 14, 2001 1 1 ltc1966cm s8 rms to dc converter june wu 5/1/01 j. petrofsky 5/1/01 size scale : cage cod e dwg n o rev sheet of filename: title cont ract no. approv als dat e drawn checked approved engineer designer technol ogy 1630 mccarthy blv d. milpitas , ca 95035 phone: (408)43 2-1900 fax: (408)434-0 507 vdd vdd vss vdd vss2 vss vdd2 vdd2 vdd2 vss2 vss2 vss vdd vdd2 c12 0.0 1uf j2 bn c r13 1k e8 c2 10 uf u1 ltc 1966cms8 8 2 3 1 4 6 5 7 enable in1 in2 gnd vss out rtn vout vdd jp5 c5 0. 01uf e2 c14 0.0 1uf c11 10 uf c1 3 0.1 uf r5 200 k r1 1.5 m r14 0 c7a 1. 0uf jp3 1 2 3 jp1 1 2 3 e9 e1 0 r4 681 k e1 1 e13 r2 1k e1 4 r1 2 27 4k e15 e16 e1 7 e18 c3 0. 22uf r6 10 k r3 1m c1 0 0.0 1uf r1 1 16 9k e1 9 e3 e20 c6 0.2 2uf r10 38. 3k c15 0.0 1uf c8 0. 1uf r15 0 e6 jp4 1 2 3 j1 bn c e5 r7 49. 9 c9 1. 0uf r9 49. 9 c7b (o pt) r8 10 k e1 - + v+ v- u3 lt 1494cs8 6 3 2 7 4 e4 e1 2 - + v+ v- u2 lt 1494cs8 6 2 3 7 4 c1 0.0 1uf jp2 1 2 3 e7 c4 0. 1uf
linear technology corporation ltc3411ems bill of material demo bd. #441a qty- 456 11/9/2004 12:04 pm item qty reference part description manufacture / part # 1 0 cbyp,cout2,cin2 (opt) cap., 0603 2 1 cc cap., x7r, 1000pf, 25v, 20% 0402 avx, 04023c102mat 3 1 cffw cap., npo, 10pf, 50v, 10% 0402 avx, 04025a100kat 4 1 cout1 cap., x5r, 22uf, 6.3v, 10% 1210 murata, grm32dr60j226ka01 5 1 cin1 cap., x5r, 10uf, 6.3v, 10% 1206 murata, grm31cr60j106kc01 6 0 cout4,cin3 (opt) cap., 6032, 7343 7 1 cout3 cap., x7r, 0.1uf, 16v, 20% 0603 avx, 0603yc104mat 8 1 cin4 cap., tant., 47uf, 16v, 20% 6032 avx, tajc476m016r 9 0 c1 (opt) cap., 402 10 0 d1 (opt) diode, sma 11 7 e1-e7 testpoint, turret, .094" mill-max, 2501-2 12 2 jp1,jp3 0.079 single row header 3 pin comm con, 2802s-03-g1 13 1 jp2 0.079x4 double row header comm con, 2202s-08-g1 14 3 jp1,jp2,jp3 shunt, comm con, ccij2mm-138g 15 1 l1 inductor, 2.2uh d52lc toko, a914byw-2r2m 16 1 rc res.,chip, 16.2k, 1/16w, 5%, 0402 aac, cr05-1622fm 17 1 r1 res.,chip, 10k, 1/16w, 5%, 0402 aac, cr05-103jm 18 1 rfb1 res.,chip, 887k, 1/16w, 1% 0402 aac, cr05-8873fm 19 1 rfb2 res.,chip, 698k, 1/16w, 1% 0402 aac, cr05-6983fm 20 1 rfb3 res.,chip, 412k, 1/16w, 1% 0402 aac, cr05-4123fm 21 1 rfb4 res.,chip, 280k, 1/16w, 1% 0402 aac, cr05-2803fm 22 0 rfb5 (opt) res., 1% 0402 23 1 rfilt res.,chip, 0, 1/16w, 0402 a ac, cj05-000m 24 1 rpg res.,chip, 100k, 1/16w, 5% 0402 aac, cr05-104jm 25 1 rse t res.,chip, 316k, 1/16w, 1% 0402 a ac, cr05-3163fm 26 0 rsw (opt) res., 0402 27 2 rs1,rs2 res.,chip, 1m, 1/16w, 5% 0402 aac, cr05-105jm 28 1 rsd res.,chip, 4.7m, 1/16w, 5% 0402 aac, cr05-475jm 29 1 u1 i.c., ltc3411, ms10 linearl, ltc3411ems 30 1 printed circuit boards demo board dc441a 31 1 stencil stencil dc441a 32 1 s / f s / frame, #10679, @ flairis 6-boards to alan 3/15/02 page 1 - of - 1
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