swr200 swr200ds 1 description swr200 is a precision sine wave reference provid - ing an ultra stable sine wave output of +7.071 v at 0.05% initial accuracy and temperature coeffcient as low as 30 ppm/c over the full military temperature range. the extreme accuracy is made possible by a chopper-based agc circuit. the temperature charac - teristic of the chopper circuit compensates the typical nonlinearity of the internal dc zener reference, result - ing in a nearly linear amplitude-temperature character - istic. frequency of the swr200 is programmable with two external capacitors. the swr200 is available in a 14-pin bottom braze package. they are hermetically sealed and m ver - sions are screened for high reliability and quality. swr200 is well suited for any application requiring a stable sine wave source. the swr200 can be used as a reference source in precision sensing systems based on l vdt or r vdt position sensors. a programmable ac reference can be constructed using the swr200 as a reference for a high accuracy multiplying digital to analog converter. fea tures ? very high accuracy: +7.071 vrms 0.05% ? extremely low drift: 30 ppm/c (-55c to +125c) ? excellent stability: 10 ppm/1000 hrs. typical ? low distortion: 0.1% thd @ f = 3300 hz ? hermetic 14-pin ceramic dip ? military processing option applica tions ? transducer excitation ? high resolution servo systems ? high precision test and measurement instru - ments ? ac voltage standard ? l vdt or r vdt reference ? multiplying d/a reference +1 5 v - 1 5 v +1 5 v - 1 5 v +1 5 v - 1 5 v 3 +1 5 v 1 2 figure 1. block diagram precision sine wave reference swr200 p r o d u c t i n n o v a t i o n f r o m copyright ? cirrus logic, inc. 2009 (all rights reserved) http://www.cirrus.com aug 2009 apex ? swr200dsrevg p r o d u c t i n n o v a t i o n f r o m
swr200 2 swr200ds 1. characteristics and specifica tions electrical specifica tions v ps =15v, t = +25c, r l = 10k unless other wise noted. model SWR200C swr200m parameter min typ max min typ max units absolute maximum ra tings power supply 13.5 15 22 * * * v operating temperature -25 +85 -55 +125 oc storage temperature -65 +85 * * oc short circuit protection continuous * vrms output voltage 7.071 * v output voltage errors initial error 0.05 * % warmup drift 100 * v dc offset 3 * mv dc offset over temp. 3 18 * * v/ oc t min - t max 1 20.0 1 30.0 ppm/ oc long-term stability 10 * ppm/ oc output current range 10 * ma regula tion line 10 * ppm/v load 3 * ppm/ma power suppl y c urrents +ps 10.5 13 * * ma -ps 9.5 13 * * ma distortion 0.5 * % frequency range (f) f = 10 -5 c 1 c 2 ?f f vs. temperature .98 1 1.02 * * * hz 400 10k * * hz 15 * ppm/oc type output (typ.) temperature operating range package SWR200C +7.071v -25c to +85c dip swr200m +7.071v -55c to +125c dip selection guide hermetic 14-pin ceramic dip package style hc p r o d u c t i n n o v a t i o n f r o m
swr200 swr200ds 3 notes: * same as c models. 1. using the box method, the specifed value is the maximum deviation from the output voltage at +25c over the specifed operating temperature range. 2. the specifed values are unloaded. 3. pin 8 is internally connected to pin 7 and can be used as ref. gnd. 4. the frequency range can be extended to any desired lower value by using 2 external agc capacitors (see a n-3). 5. the increase in distrotion at lower frequencies can be eliminated by using external agc capacitors (see a n-3). 2. typical performance graphs t e m p e r atu r e o c swr2 0 0c v o u t v s . t e m per a t ure v o u t v s . t e m per a t ure % ? fre q . v s . temp. t e m p e r atu r e o c swr2 0 0m t e m p e r atu r e o c swr2 0 0c t e m p e r atu r e o c swr2 0 0m distor tion v s. te mp t em p erat u re o c distor tion v s. fr eque nc y fr e qu e n c y (hz ) n or m a l i z e d di s t o r t i o n v s. c 2/ c 1 c2/c 1 pow e r su pp l y c urr en t v s . t e m p. t em p erat u re o c ca se t e mp. ri se a b ove a m bien t v s. ou t p u t c u rr en t outpu t curre nt (m a ) j u n c t i on te m p . r i s e a b ove ca se t e mp. v s ou t p u t cu r ren t output curre nt (m a ) % ? fre q . v s . temp. 0 -20 15.6 20 -15.6 -50 50 35 0 -35 p r o d u c t i n n o v a t i o n f r o m
swr200 4 swr200ds 3. th eory of opera tion the following refers to the schematic in figure 1. a1 and a2 are connected as a phase-shift oscillator circuit with the frequency set by the external capacitors c1 and c2. q4 is included in the feedback loop of a1 as a gain control element. the oscillator output is fed to the chopper amplifer which develops an absolute value representation of the oscillator output. the chopper output is compared to a precision dc reference in integrator amplifer a3. this dc error signal is used ot control the gain setting fet q4. as in all precision zener based dc references, the drift of the zener becomes nonlinear at temperature extremes. the chopper amplifer drift characteristic is complementary to this nonlinearity and compensates for the reference drift. 4. applica tion informa tion figure 1 shows the connections for the sw r200 including the two frequency setting capacitors. the frequency is: f = 10 -5 c 1 c 2 the frequency stability is directly related to the stability of the capacitors, therefore stable capacitors like n po ce- ramic, or polycarbonate or polystyrene flm should be used. two separate ground pins are provided for accurate ground sensing. this minimizes errors due to drops in the ground pin which can become a signifcant source of error in sockets. the offset of the s w r200 is fully specifed for initial offset and drift and is low enough that it can normally be ne- glected. in applications which are especially sensitive to offset the output can be ac coupled. proper capacitor siz - ing and high impedance sensing will minimize errors due to capacitive coupling. extern al connections pin configura tion top vi e w s w r20 0 nc nc ou t p u t g nd s e n s e g n d nc nc nc c1 c1 -ps c2 +p s c2 p r o d u c t i n n o v a t i o n f r o m
|
