$ (+) input hi (C) input lo analog common reference out reference in +5v supply r1 dp 1 dp 2 dp 3 6 5 4 11 12 10 8 7 1 3 dc/dc converter 2 5v return +5v C5v r2 ?+2.0v data 909k v+ vC a/d converter 0 vdc 0.01 f 9 display enable +5v r2 is not used on 200mv (-0) models or 2v (-1) models. r2 = 100k on 20v (-2) models and 9.1k on 200v (-3) models. only used on 200mv (-0) and 2v (-1) models. display test/hold 11 pin 9 is display test on all but eight models. on those models (-h option), it is display hold. 1 2 3 2 1 3 for full details go to www.murata-ps.com/rohs www.murata-ps.com www.murata-ps.com/support dms-20pc series 3? digit, led display, low-cost, subminiature digital panel voltmeters mpm_dms_20pc.d07 page 1 of 6 dms-20pc series, 3? digit, led display, digital panel voltmeters combine a preci- sion a/d converter; a factory-trimmed, highly stable, voltage reference; and a large (0.37"/9.4mm), easy-to-read led display in a single package that is only slightly larger than the display itself. displays are offered in either red, orange, amber, yellow, green or blue colors. high-intensity and low-power (35mw total) red leds are also optional. these low-cost meters are fully self-contained and fully functional. their subminiature (1.38" x 0.88" x 0.48"), epoxy-encapsulated cases incorporate built-in color ? lters and bezels; are moisture and vibration proof; and function well in the harshest environments. their 12-pin, dual-in-line con? guration offers component-like, plug-in convenience and maximum versatility. operating temperature range is 0 to +60c. the meters come with one of four, differential, input voltage ranges: 200mv, 2v 20v or 200v. input impedance is a minimum 800k. cmrr is typically 86db (dc to 60hz), and cmv is 2v. input overvoltage protection (on the non-inverting input) is 250v. devices are fully calibrated at the factory to an accuracy of 1 count (0.05% of full scale range) and never require calibration or adjustment. a display enable function permits the display to be disabled for "power-down" operation. all models have a display test function. standard red led models offer an optional display hold function. small size, low cost and adjustment-free reliability make the dms-20pc series the best choice for all your 3? digit, led, dpm applications. features lowest-cost led meters subminiature size: 1.38" x 0.88" x 0.48" (35mm x 22mm x 12mm) large (0.37"/9.4mm) led display choice of 6 led colors high-intensity or low-power (7ma) red leds optional epoxy-encapsulated, 12-pin dip package with built-in color ? lter and bezel 4 differential input voltage ranges factory calibrated, 1 count accuracy single +5v power supply user-selectable decimal point placement display enable function for "power-down" mode display test and hold (optional) functions 0 to +60c temperature range simplified schematic diagram figure 1. dms-20pc series simpli? ed schematic new low-power blue and green leds
? applies for transient or continuous overvoltages applied to (+) input hi (pin 11) with (C) input lo (pin 12) properly connected. pin 12 is not overvoltage protected (see figure 1). voltages applied to pin 12 should not exceed the supply voltage. ? see technical notes. ? the display hold function is optional on standard red and green led models only. leave blank for standard models. add -h for display hold option (available on standard red and green led models only). dms-20pc - 1 - rs -c led color: as = standard amber bs = standard blue gs = standard green os = standard orange rs = standard red ys = standard yellow rh = high-intensity red rl = low-power red bl = low-power blue pgl = low-power green accessories: dms-20-cp panel cutout punch dms-bzl3-c dms-20 bezel assembly dms-bzl4-c dms-20 bezel assembly with sealing gasket dms-eb2-c application/evaluation board with standard molex connector, decimal point solder pads and attenuation resistor pads. input range: 0 = 200mv 1 = 2v 2 = 20v 3 = 200v a panel-mount retaining clip is supplied with each model. 1. reference output (pin 8) and input (pin 7) : pin 8 is a precision reference actively trimmed at the factory. in normal operation, pin 8 must be tied to pin 7 to achieve all listed accuracy and drift speci? ca- tions. 2. analog common (pin 10) : this pin is connected to an internal, low-noise, "relative" ground. it is used in certain differential and "? oating" measurements as described in the applications section of this data sheet and ap note 3 of the datel panel meter catalog. pin 10 should not be connected to pin 3 (5v return) or to your systems analog ground. 3. decimal point placement : the location of the decimal point is user- selectable, and the decimal point control pins (dp1-dp3) are active low functions. select the appropriate decimal point by tying the appropriate pin (pin 4, 5 or 6) to pin 3 (5v return). unused decimal point location pins should be left open. hard wiring is preferable, however, you can use logic gates to exercise dynamic control over the location of the decimal point if the following drive conditions are met: model applied "0" voltage load current* dms-20pc-x-xl +0.05v max. 0.7ma max. all others +0.4v max. 6ma max. * the driving gates must be able to sink this much current analog inputs min. typ. max. units full scale input range: dms-20pc-0 C 200 C mv dms-20pc-1 C 2 C volts dms-20pc-2 C 20 C volts dms-20pc-3 C 200 C volts input impedence: dms-20pc-0, -1 C 1000 C m dms-20pc-2, -3 C 1 C m overvoltage protection ? C C 250 volts common mode voltage range C C 2 volts cmrr (dc to 60hz) C86Cdb performance sampling rate 2.5 reading per second accuracy (3 minute warm-up): dms-20pc-0 (vin = +0.19v) C 1 3 counts dms-20pc-1 (vin = +1.9v) C 1 3 counts dms-20pc-2 (vin = +19v) C 2 3 counts dms-20pc-3 (vin = +190v) C 2 3 counts zero reading (vin = 0 volts) C001 000 001 temperature drift (0 = +60c) C 0.2 0.4 cnts/c power supply requirements supply voltage +4.75 +5.00 +5.25 volts supply current: dms-20pc-x-rl C +7 +12 ma dms-20pc-x-bl & -pgl C +12 +17 ma dms-20pc-x-rs, -rh C +60 +90 ma dms-20pc-x-rs-h C +60 +90 ma dms-20pc-x-bs C +75 +100 ma dms-20pc-x-gs-h C +90 +120 ma dms-20pc-x-as, -gs, -os, -ys C +90 +120 ma display display type and size 3? digit, 0.37"/9.4mm high led polarity indication autopolarity ("C" for negative vin) overrange indication "C1_ _ _ " for negative inputs "1_ _ _ " for positive inputs physical/environmental operating temperature 0 C +60 c storage temperature C20 C +75 c humidity (non-condensing) 0 C 95 % case material polycarbonate weight 0.4 ounces (11 grams) performance/functional speci? cations typical at t a = +25c and supply voltage = +5v using the single-ended input circuit, unless otherwise noted. ordering information rohs compliant parts: add "-c" suf? x to part number. add -c for rohs www.murata-ps.com/support dms-20pc series 3? digit, led display, low-cost, subminiature digital panel voltmeters mpm_dms_20pc.d07 page 2 of 6 technical notes
4. display test/hold (pin 9) function : pin 9 is a dual-function pin. on all standard models (without "-h" suf? x), tying pin 9 to pin 1 (+5v supply) activates the meter's display test feature. all display segments, except the decimal points, will be illuminated. the display will show "1888" ("C1888" if a negative input signal is present). do not leave the meter in the test mode for more than 10 seconds as this will cause the meter's operating temperature to rise and possibly affect its performance. pin 9 must be left open when the test function is not being used. on models with the "-h" suf? x (dms-20pc-1-rs-h for example), pin 9 serves as a display hold control pin. tying pin 9 to +5v supply (pin 1) on these models will hold or "freeze" the current display read- ing inde? nitely. pin 9 must also be left open when the hold function is not being used. after disabling display hold, allow the meter a full 10 seconds to resume normal calibrated operation before holding a new reading. the display test or display hold pin should normally be con- nected, via a selector switch, to pin 1 (+5v supply). if automatic, logic-controlled operation is desired, only pnp or mosfet transis- tors should be used. the base or gate of these transistors should be driven suf? ciently hard to bring pin 9 within 0.05v of +5v supply. 5. display enable (pin 2) function : on all models, tying pin 2 to pin 1 (+5v supply) applies full power to the led display. this is the normal mode of operating the meter. leaving display enable open (no connection), only turns off the led display. the meter's analog- to-digital converter continues to sample the input signal. total current consumption with the display off is approximately 400a (0.4ma). this is a very useful feature if the meter is used in battery-powered equipment. with the exception of the low-power red led models (dms-20pc-x- rl), a regulated voltage lower than +5v supply can be used to dim the display intensity. display intensity control is best performed with the high brightness, red led, dms-20pc-x-rh model. all low-power red led models must have display enable tied directly to pin 1 (+5v supply). voltages applied to display enable must never be greater than +5v supply. 6. gain adjust : there is a gain-adjust potentiometer on the back of each meter. it has approximately 50 counts (2.5%) range of adjustment. since these devices essentially have no zero/offset errors, a gain adjustment is effectively an overall accuracy adjust- ment. though they may be performed at any point (except zero), accuracy adjustments are most effective when performed with higher level input signals. the circuit shown in figure 10 provides 10% range of adjustment. 7. soldering methods : all models in the dms-20pc series easily with- stand most common wave soldering operations. we recommend, however, that you evaluate the effects your particular soldering techniques may have on the meters plastic case and high-precision electrical performance. we recommend the use of no-clean solders. 8. suggested mating connectors: panel mounted: connector housing datel p/n 4320-01069-0 terminal type datel p/n 4400-01032-0 crimping tool datel p/n 39-2099000 wire size 22 to 26 awg insulation diameter 0.062" (1.57mm) maximum stripping length 0.100 to 0.125" (2.54 to 3.17mm) board mounted: socket datel p/n 4320-01074-0 figure 2. single-ended input con? guration dms-20pc meters are highly versatile devices that can be used in hundreds of applications. the application circuits chosen for this section are ones that have historically received many inquiries. the schematic in figure 1 shows that the meter's high-impedance input consists of an op amp powered from a 5vdc power supply (the C5v is internally generated). one can easily see why input signals applied to (C) input lo and (+) input hi have to be kept within the power supply rails of 5v. also note that only pin 11 has a current-limiting 909k series resistor. high input voltages that have a common ground with pin 3 (5v return) should only be applied to pin 11 ((+) input hi) and never to pin 12. in these high-voltage cases, pin 12 should always be tied to pin 3 (5v return). the schematic also shows that pin 3 is the meter's zero-volt reference point regardless of the type of power or signal source used. this is an important point to keep in mind when a digital or analog multimeter is used to make system measurements. the multimeter's negative lead (usually the black one) must be connected to pin 3 (5v return). 1. single-ended input con? gurations : true single-ended measure- ments can be made with any dms-20pc meter. the circuit of figure 2 avoids problems normally associated with ground-loop currents. separate ground runs should be used for 5v return (pin 3) and (C) input lo (pin 12). 1 12 3 +5v sup (C) in lo 5v ret 85-264vac 11 (+) in hi 6 dp1 + C ac to dc converter v in dms-20pc-1 7 ref out ref in 8 2 display enable www.murata-ps.com/support dms-20pc series 3? digit, led display, low-cost, subminiature digital panel voltmeters mpm_dms_20pc.d07 page 3 of 6 applications
figure 3. differential input con? guration r2 r1 + r2 x v in = reading 50k < r1 + r2 < 10m figure 6. floating input measurements (alternate con? guration) figure 5. floating input measurements figure 4. input attenuation circuit r shunt = r1 = v fsr /i fsr where: v fsr = full scale reading (in volts) i fsr = relative full scale current (in amps) 2. differential input con? gurations : differential measurements can be made with all dms-20pc meters. figure 3, though not a practical real-world application, uses a voltage divider to demonstrate the concept of a differential input signal. be care- ful not to exceed the 2v common mode voltage limitation for 5v-powered meters. 3. engineering scaling : for measuring voltages greater than the full scale input range of a given meter, the input signal must be attenuated. a simple voltage divider (similar to that shown in figure 4) will scale the input to within the range of the selected meter. r1 and r2 should be precision, 1%, metal-? lm resistors with absolute tcr's less than 50ppm/c. see ap note 4 for more information on engineering scaling. 4. floating signal source measurements : floating signals can be measured using the circuits shown in figures 5 and 6. connecting pin 10 (analog common) or pin 3 (5v return) to (C) input lo (pin 12) provides the reference point for the meters input. a "? oating" input is a signal that has no galvanic connection to the meter's power supply. in the ? gures below, the 1.5v battery illustrates a true ? oating input. 5. process control (4-to-20ma) measurements : in many common process-control applications, a 4-to-20ma current loop is used to transmit information. because dms-20pc meters have such high input impedance, a simple shunt resistor across the meter's input can be used to convert the loop current to a voltage. see figure 7. the value of the shunt resistor is a function of the scaling require- ments of the particular application and can be calculated using the following equation: 1 12 3 +5v sup (C) in lo 5v ret 11 (+) in hi 6 ac to dc converter dms-20pc-1 r2 r1 r3 1k 1k 1k 8 7 ref in dp1 ref out 2 display enable 85-264vac dms-20pc-1 r2 11 12 (+) in hi (C) in lo v in r1 + C 13 +5v sup 5v ret ac to dc converter 8 7 ref out ref in 2 display enable 85-264vac 13 +5v sup 6 dp1 ac to dc converter dms-20pc-1 12 (C) in lo 11 (+) in hi 1.5v cell + C 8 7 ref out ref in 2 display enable 5v ret 85-264vac dms-20pc-1 12 (C) in lo 10 ana comm 11 (+) in hi 1.5v cell + C 8 7 ref out ref in 13 +5v sup 6 dp1 ac to dc converter 2 display enable 5v ret 85-264vac www.murata-ps.com/support dms-20pc series 3? digit, led display, low-cost, subminiature digital panel voltmeters mpm_dms_20pc.d07 page 4 of 6 applications
http://www.murata-ps.com/data/meters/dms-an6.pdf figure 10. external gain adjustment figure 8. 4.5-18v power supply monitor figure 9. basic dc ammeter circuit figure 7. 4-to-20ma current loop operation to calibrate the circuit of figure 7, perform the following: 1. with 4ma applied, adjust the 50k potentiometer (r2) to display a reading of "000" (assuming that is the desired reading). 2. with 20ma applied, adjust the gain-adjust potentiometer on the back of the meter to display a reading of "1000". for different full scale readings, alter the value of r shunt accordingly. the lm-2931 was chosen because it has the following on-chip protection features: reverse polarity, short circuit and thermal runaway. when using other, higher-power, dms-20pc models with three-terminal regulators, be sure to consult the regula- tor manufacturer's data sheet to ensure the regulator is being utilized safely and correctly. 7. digital ammeter: digital ammeters are ? nding ever-increasing usage because analog-style ammeters (moving-vane types) now cost roughly the same as their digital counterparts. addi- tionally, analog ammeters are not nearly as rugged as modern digital panel voltmeters. figure 9 illustrates a typical ammeter application. the circuit uses a 200mv input meter the preferred range for most ammeters to measure the voltage developed across a 0.1 current shunt. the circuit shown represents a basic ammeter connection diagram. click here to view a detailed application note describing digital dc ammeters. 8. external gain adjustment : connect reference out (pin 8) to reference in (pin 7) for normal, factory calibrated, operation. use the circuit shown in figure 10 for applications needing external gain adjustment. calibration is performed with a precise, near-full-scale, input voltage. 6. power supply monitoring: one of the most common digital panel meter applications involves monitoring the output voltage of the system power supply often this supply also powers the meter itself. the low-power, red led dms-20pc-2-rl can be con? gured to allow power supply monitoring over the range of 4.5-18vdc. the circuit in figure 8 uses a low-drop-out, three-ter- minal regulator (lm-2931z-5, available from national semicon- ductor) to provide regulated 5v-power to the meter. example: for a meter with a 2v full scale input (1.999 full scale reading) and a desired display reading of "1000" (with an input of 20ma), v fsr = 1.000 volts r shunt = 1.000v/(0.020 C 0.004)a r shunt = 1.000v/0.016a = 62.5 ohms 13 +5v sup 5v ret ac to dc converter dms-20pc-1 12 (C) in lo 10 ana comm 11 (+) in hi r1 + C 4-20ma 50k r2 8 7 ref out ref in 2 display enable 85-264vac 5 78 + C dms-20pc-2-rl 12 11 1 4.5 - 18vdc lm2931z-5 gnd in out +5v sup 3 dp2 ref in ref out (C) in lo 5v ret 2 disp en (+) in hi 22f 10v + 6 3 + C dms-20pc-0 11 0.150v 1 1.5 amp (load current) 5vdc 7 8 +5v sup 5v ret dp1 (+) in hi ref out ref in 2 disp en 0.1w r shunt load (3.3 ) 12 (C) in lo w 12 voltage calibrator out 10 (+) in hi (C) in lo ana comm = 10 to 20 turns 7 ref in 11 732, 1% 8.06k, 1% 5v ret connections for 2v, 20v and 200v models connections for 200mv models com 17.4k, 1% 2k 24.3k, 1% 3 12 dms-20pc-1 8 nc 200 +5v in 1 1 1 1 www.murata-ps.com/support dms-20pc series 3? digit, led display, low-cost, subminiature digital panel voltmeters mpm_dms_20pc.d07 page 5 of 6 applications
mechanical dimensions: inches (mm) tolerances: 2 pl dec 0.02 (0.51) 3 pl dec 0.010 (0.254) lead dimensions: 0.025 (0.635) x 0.025 (0.635) nominal recommended pc board finished hole diameter: 0.042 0.003 (1.067 0.076) made in usa dms-20pc-x-xx front view dp1 dp2 dp3 pin #1 identifier +5v supply display enable 5v return dp3 dp2 dp1 1 2 3 4 5 6 (C) input lo (+) input hi analog common display test/hold reference out reference in 12 11 10 9 8 7 0.80 (20.3) 0.15 (3.8) typ. 0.50 (12.7) 0.10 (2.5) typ. 0.040 (1.02) 0.040 (1.02) 1.10 (27.9) 0.10 (2.5) typ. 0.25 (6.4) typ. 0.475 (12.07) 0.040 (1.02) 1.30 (33.0) 1.38 (35.1) 0.88 (22.4) ? ? 0.170 (4.32) 0.150 (3.81) pin 1 0.125 (3.175) diameter (use only when pc board mounting) calibration potentiometer hole location ?? ? ? bezel panel #2-56 insert 0.156 (3.96) deep front view 1.280 (32.51) 0.187 (4.75) 1.826 (46.38) 0.838 (21.29) 1.626 (41.30) 1.07 (27.18) internal corner radii: 0.032 (0.81) max. 0.093 (2.362) dia (4 required) 0.116 (2.95) 1.336 (33.93) 0.145 (3.68) panel cutout murata power solutions, inc. makes no representation that the use of its products in the circuits described herein, or the use of other technical information contained herein, will not infringe upon existing or future patent rights. the descriptions contained her ein do not imply the granting of licenses to make, use, or sell equipment constructed in accordance therewith. speci? cations are subject to cha nge without notice. ? 2011 murata power solutions, inc. www.murata-ps.com/support murata power solutions, inc. 11 cabot boulevard, mans? eld, ma 02048-1151 u.s.a. iso 9001 and 14001 registered dms-20pc series 3? digit, led display, low-cost, subminiature digital panel voltmeters mpm_dms_20pc.d07 page 6 of 6 mechanical specifications bezel installation and recommended drill and panel cutout
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