DATEL DMS-20PC Series 3½ Digit LED Display Low-Cost Subminiature Digital Panel Voltmeters handbook
Contents
1. 7 REF IN DATEL 85 264Vac DMS PS1 CM AC to DC Converter Figure 5 Floating Input Measurements 5V Powered Models id DMS 20LCD 1 9 IN HI 10 ANA COMM 12 9V BATTERY 1 5V _ CELL J Tip Figure 6 Floating Input Measurements 9V Powered Models 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 20LCD 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 3 DIGIT LCD DISPLAY DIGITAL PANEL VOLTMETERS DMS 20LCD Applications function of the scaling requirements of the particular application and can be calculated using the following equation Rshunt R1 Vesr Fsr Where Vrs Full scale reading in Volts IFs Relative full scale current in Amps Example For a meter with a 2V full scale input 1 999 full scale reading and a desired full scale display reading of 1000 with an input of 20mA Ves 1 000 Volts Retunt 1 000V 0 020 0 004 A Rsnunt 1 000V 0 016A 62 5 Ohms To calibrate the circuit of Figure 7 perform the following 1 With 4mA applied adjust the 50kQ potentiometer R2 to display a reading of 000 assuming that is the desired reading 2 With 20mA a2. TOAS EO OOE NOST 01076 CALIBRATION POTENTIOMETER HOLE LOCATION FRONT VIEW V XX X d9102e SWG PIN 4 5V SUPPLY BATTERY 1 INPUT LO N C 2 INPUT HI 5V RETURN BATTERY 3 ANALOG COMMON DP3 4 N C BACKLIGHT DP2 5 REFERENCE OUT DP1 6 REFERENCE IN 0 125 3 175 DIAMETER USE ONLY WHEN PC 0 80 BOARD MOUNTING 0 040 l 1 02 0 15 3 8 TYP 0 50 12 7 2 56 INSERT 0 187 0 156 3 96 DEEP 4 75 BEZEL INSTALLATION OPTIONAL BEZEL DMS BZL3 and DMS BZL4 FRONT VIEW a 1 826 wa a RECOMMENDED DRILL AND PANEL CUTOUT DIMENSIONS INTERNAL CORNER RADII 0 032 0 81 a ray RETAINING CLIP INSTALLATION 27 18 21 29 ee y 1 336 33 93 a 1 626 41 30 gt as 0 093 2 362 DIAMETER 4 REQUIRED ONLY WHEN USING OPTIONAL BEZEL ASSEMBLY i ISO 9001 LD at INNOVATION and EXCELLENCE REGIS TERED DS 0291C 01 02 DATEL Inc 11 Cabot Boulevard Mansfield MA 02048 1151 DATEL UK LTD Tadley England Tel 01256 880444 Tel 508 339 3000 800 233 2765 Fax 508 339 6356 DATEL S A R L Montigny Le Bretonneux France Tel 01 34 60 01 01 Internet www datel com Email sales datel com DATEL GmbH M nchen Germany Tel 89 544334 0 Data sheet fax back 508 261 2857 DATEL KK Tokyo Japan Tel 3 3779 1031 Osaka Tel 6 354 2025 DATEL makes no representation that the use of its product
3. possible the resistors in the divider should be 1 metal film types with TCR s less than 50ppm C DMS 20LCD 1 9 11 Rt REF OUT 8 s INHI 45 3k whet R2 EE ONLO REFIN 7 R3 1 3 5_ 45 3k BAT BAT DP2 4 F OV BATTERY Figure 8 Power Supply Monitor 9V Powered Models External Gain Adjustment Connect REFERENCE OUT pin 8 to REFERENCE IN pin 7 for normal factory calibrated operation Use the circuit shown in Figure 9 for applications needing external gain adjustment Calibration is performed with a precise near full scale input voltage 11 4 INHI DMS 20LCD OUT 3 VOLTAGE 5V RET CALIBRATOR aE BATIN TEV IN H i BAT IN com f 5 i E Connections E CPNL for 2V 20V 1 ae 8 7 and 200V models H NC REF y COMM IN PELAR o 8 06k 1 2k 17 4k 1 E F 1 E ji I For 5V models tie INLO to pin 3 i y Connections For 9V models tie IN LO to pin 10 Le A Anant for 200mV 0 models 732 1 200 24 3k 1 10to 20 Turns Figure 9 External Gain Adjustment DMS 20LCD 3 DIGIT LCD DISPLAY DIGITAL PANEL VOLTMETERS Mechanical Specifications MECHANICAL DIMENSIONS Inches mm TOLERANCES 2 PL DEC 0 02 40 51 PNE 3 PL DEC 0 010 0 254 IDENTIFIER LEAD DIMENSIONS 0 025 0 635 x 0 025 0 635 NOMINAL vsnnzow TEA a RECOMMENDED PC BOARD FINISHED HOLE DIAMETER
4. 0 0 DMS2ZQLCDQ 0 0 Purchase On Line EEE www datel com Actual Size D OATEL INNOVATION and EXCELLENCE DMS 20LCD Series 3 Digit LCD Display Low Cost Subminiature Digital Panel Voltmeters Features e Lowest cost e Lowest power 2mW e Subminiature size 1 38 x 0 88 x 0 43 35mm x 22mm x 11mm e Large 0 37 9 4mm enhanced contrast LCD display e Backlit displays optional e Epoxy encapsulated 12 pin DIP e Panel or pc board mountable e 4 differential input voltage ranges e High accuracy 1 count 40 05 e Single 5V supply or 9V battery e Low battery annunciator e User selectable decimal point placement e 0 to 60 C temperature range DMS 20LCD Series 3 Digit LCD Display Digital Voltmeters represent the ultimate combination of low price low power small size and high performance in digital meters Epoxy encapsulated in a subminiature 1 38 x 0 88 x 0 43 12 pin DIP package these completely self contained fully operational meters offer a combination of ruggedness long term reliability and component like ease of use simply not available in any other meters Incorporating a precision reference and a factory calibrated autozeroing A D converter DMS 20LCD meters are extremely accurate 1 count and are only slightly larger than their 0 37 9 4mm enhanced contrast LCD displays All models incorpo rate a built in bezel and are easily mounted in either panels or pc boards Both bac
5. 1 9V 1 2 Counts DMS 20LCD 2 Vin 19V 2 3 Counts DMS 20LCD 3 Vin 190V 2 3 Counts Zero Reading Vin 0 Volts 001 000 001 Temperature Drift 0 to 60 C 0 2 0 4 Cnts C Power Supply Requirements 5V Models Supply Voltage 4 75 5 00 5 25 Volts Supply Current Standard Models 400 600 pA Backlit Models 35 50 mA Power Supply Requirements 9V Models Supply Voltage 47 5 9 0 14 0 Volts Supply Current Standard Models 230 350 pA Backlit Models 35 50 mA Polarity Indication Autopolarity for negative Vin Overrange Indication 1___ for negative Vin ___ for positive Vin Physical Environmental Operating Temperature 0 60 C Storage Temperature 20 75 C Humidity Non condensing 0 95 Case Material Polycarbonate Weight 0 4 ounces 11 grams Applies for transient or continuous overvoltages applied to INPUT HI pin 11 with 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 Listed spec applies to 5V powered models only For 9V powered models both INPUT LO pin 12 and INPUT HIGH pin 11 must always be at least 1 5V above BATTERY pin 3 and at least 1 5V below BATTERY pin 1 See Technical Notes Ordering Information DMS 20LCD 1 5 Input Range L_ Leave blank f
6. EF OUT 8 IN HI JRE OURS eels Ee R2 REF IN 7 12 1k pa IN LO Pi 6 Paistis e R3 a 3 4k 5V SUP 5V RET DATEL 85 264Vac DMS PS1 CM AC to DC Converter Figure 3 Differential Input Configuration 5V Powered Models 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 film resistors with absolute TCR s less than 50ppm C See Ap Note 4 for more information on engineering scaling 50KQ lt R1 R2 lt 10MQ R2 R1 R2 x Vin Reading 11 DMS 20LCD 1 5 IN HI 1 3 5V SUP 5V RET DATEL 85 264Vac DMS PS1 CM AC to DC Converter 8 REF OUT 7 REF IN Figure 4 Input Attenuation Circuit 4 Floating Signal Source Measurements Floating signals can be measured using the circuits shown in Figures 5 and 6 Figure 5 uses a 5V powered meter Figure 6 uses a 9V powered meter Connecting pin 10 ANALOG COMMON to INPUT LO pin 12 provides the reference point for the meter s input A floating input is a signal that has no galvanic connection to the meter s power supply In the figures below the 1 5V battery illustrates a true floating input i DMS 20LCD 1 5 IN HI 8 REF OUT
7. converter is not used on 9V powered models J1 is connected Used on backlit models only N C for non backlit models Figure 1 DMS 20LCD Series Simplified Schematic DATEL Inc Mansfield MA 02048 USA Tel 508 339 3000 800 233 2765 Fax 508 339 6356 e Email sales datel com e Internet www datel com DMS 20LCD 3 DIGIT LCD DISPLAY DIGITAL PANEL VOLTMETERS Performance Functional Specifications Typical at Ta 25 C and supply voltage 5V using the single ended input circuit or 9V using the differential input circuit unless otherwise noted Control Inputs Functionality Logic Compatibility Decimal Point Placement Pins 4 6 Tie to pin 3 to activate TTL on 5V powered models Analog Inputs Min Typ Max Units Full Scale Input Range DMS 20LCD 0 200 mV DMS 20LCD 1 2 Volts DMS 20LCD 2 20 Volts DMS 20LCD 3 200 Volts Input Impedance DMS 20LCD 0 1 100 1000 MQ DMS 20LCD 2 3 0 8 1 MQ Overvoltage Protection DMS 20LCD 0 1 2 100 Volts DMS 20LCD 3 250 Volts Common Mode Voltage Range 2 Volts CMRR dc to 60Hz 86 dB Backlight Pin 9 Performance Sampling Rate Tie to pin 3 to turn on backlight 2 5 samples per second Display Display Type and Size 3 Digit LCD 0 37 9 4mm high Accuracy 1 minute warm up DMS 20LCD 0 Vin 0 19V 1 2 Counts DMS 20LCD 1 Vin
8. easure voltages referenced to the negative battery terminal pin 3 because the minus input to the meter pin 12 INPUT LO must always be at least 1 5V above pin 3 9V powered meters can only be used to make differential and not single ended measurements 5V powered devices operate from any well regulated 5V supply and will accurately measure voltages both above and below pin 3 5V RETURN in either single ended or differential configurations 1 Single Ended Input Configurations True single ended measurements can only be made with 5V powered meters 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 INPUT LO pin 12 41 DMS 20LCD 1 5 x IN HI REF OUT x ERE t 12 INLO REF IN DATEL 85 264Vac pMs PS1 CM AC to DC Converter Figure 2 Single Ended Input Configuration 5V Powered Models DMS 20LCD DMS 20LCD 3 DIGIT LCD DISPLAY DIGITAL PANEL VOLTMETERS Applications 2 Differential Input Configurations Differential measurements can be made with either 5V powered or 9V powered meters Figure 3 though not a practical real world application uses a voltage divider to demonstrate the concept of a differential input signal Be careful not to exceed the 2V common mode voltage limitation for 5V powered meters R1 DMS 20LCD 1 5 1 a R
9. klit and non backlit versions are available DMS 20LCD meters have 4 differential input voltage ranges 200mV 2V 20V and 200V and a user friendly input structure Input impedance is a minimum 800kQ CMRR is typically 86dB with a CMV of 2V Non inverting inputs are overvoltage protected to 100V 250V for the 200V input model All DMS 20LCD meters operate from a single 5V supply drawing 400A or a single 9V supply battery drawing 230A All models have a low battery B annunciator and feature autopolarity changeover and overrange indication Also available is an application evaluation board DMS EBz2 that plugs directly onto the back of any DMS 20LCD allowing direct inputs for common applications such as 4 20mA inputs zero gain adjust decimal point location and input voltage dividing 5V SUPPLY 1 z 5V BATTERY a INPUT LO R2 0 01pF 2 pec al R 44 NGO CONVERTER NVN INPUT HI 909k 2 0V 5V RETURN 3 Ho AD 19 ANALOG BATIERY 0 Vdc CONVERTER COMMON _ DATA JF 4 5 22 DP3 lt 0 N C BACKLIGHT JOG 5 Lm am qm a a DP 2 j REFERENCE OUT 4 o VAR o Yams Yams 5V i 1 T l REFERENCE IN 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 DC DC
10. ocation pins are TTL compatible and may be hard wired as described above or driven with 5V TTL logic gates 3 DIGIT LCD DISPLAY DIGITAL PANEL VOLTMETERS 4 BACKLIGHT Pin 9 Function Grounding pin 9 i e connecting it to pin 3 turns on the backlighting LED s For non backlit models pin 9 has no internal connection All backlit models include internal current limiting resistors With nominal 5V or 9V supplies backlit devices typically draw 35mA of supply current The current drawn by the backlight and therefore the current drawn by the meter can be reduced by installing a 1 4 Watt resistor between pins 3 and 9 The brightness of the meter will be reduced proportionately 9V powered backlit models function with supply voltages up to 14V however activating the backlight with voltages greater than 9 2V can damage the meter Therefore a 1 4 Watt series resistor must be installed between pins 3 and 9 in these situations The value of the series resistor is determined using the following formula BATTERY 9 2V Ohms 0 035 Rseries Example If BATTERY pin 1 with respect to pin 3 is 12 6V 12 6 9 2V 0 035 Ohms Reeries Reeries 97 Ohms Low Battery Annunciator The B annunciator in the upper left hand corner of the display turns on when the supply voltage for 5V powered models falls below approximately 3 75V or when the supply voltage for 9V powered models falls below approximatel
11. or standard 0 200mV models 4 42V Add B for backlit models 2 20V Power Source 3 200V 5 45V 9 9V Accessories DMS 20 CP Panel cutout punch DMS BZL3 DMS 20 bezel assembly DMS BZL4 DMS 20 bezel assembly with sealing gasket DMS EB2 Application evaluation board with standard MOLEX connector decimal point solder pads and attenuation resistor pads DMS PS1 CM 5V 1 0A AC DC power supply module A panel mount retaining clip is supplied with each model Order on line at www datel com Technical Notes 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 specifications ANALOG COMMON Pin 10 This pin is connected to an internal low noise relative ground It is used in certain differential and floating 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 BATTERY or to your system s analog ground 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 BATTERY Unused decimal point location pins should be left open For 5V powered models the decimal l
12. pplied adjust the gain adjust potentiometer on the back of the meter to display a reading of 1999 For different full scale readings alter the value of Renun accordingly 41 DMS 20LCD 1 5 IN HI 8 REF OUT a 999 12 4 20mA SRI 7 C INLO REF IN DATEL 85 264Vac DMS PS1 CM AC to DC Converter Figure 7 4 to 20mA Current Loop Operation 5V Powered Models 6 Power Supply Monitoring A popular application for DATEL s low power LCD meters is monitoring the supply voltage in battery operated portable equipment Figure 8 demonstrates how a 9V powered DMS 20LCD can be used to monitor its own supply The meter used is the DMS 20LCD 1 9 A three resistor voltage divider is used to attenuate the battery voltage and also to satisfy the requirement that the input voltages applied to pins 12 and 11 be at least 1 5 Volts above and below the battery voltage applied to pins 1 BATTERY and 3 BATTERY The divider should be designed so that 1 10th the battery voltage falls across the inputs to the meter a 0 1 R1 R2 R3 Therefore the 9V battery voltage appears to the meter inputs as 0 9V With the decimal point moved to its DP2 position pin 5 tied to pin 3 the meter reads 9 00 Volts The circuit can be calibrated by first measuring the actual battery voltage with another meter and then adjusting the gain adjust potentiometer on the back of the DMS 20LCD until a similar reading is obtained If
13. s 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 herein do not imply the granting of licenses to make use or sell equipment constructed in accordance therewith Specifications are subject to change without notice The DATEL logo is a registered DATEL Inc trademark
14. y 7 2V This function can not be disabled 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 adjustment 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 9 provides 10 range of adjustment Soldering Methods All models in the DMS 20LCD Series easily withstand most common wave soldering operations We recommend however that you evaluate the effects your particular soldering techniques may have on the meter s plastic case and high precision electrical performance We recommend the use of water soluble solders and thorough cleaning procedures 8 Suggested Mating Connectors Panel mounted Connector housing DATEL P N 39 2079400 Terminal type DATEL P N 39 2099090 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 39 2359625 Applications DMS 20LCD meters are available in either 5V powered or 9V powered models 9V devices operate directly from 7 5V to 14V supplies usually batteries without the need for external voltage regulators 9V devices however can not be used to m
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