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www.datel.com
DMS-20PC Series
Actual Size
31/2 Digit, LED Display Low-Cost, Subminiature Digital Panel Voltmeters
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 5 LED colors * High-intensity or low-power (7mA) red LED's optional * Epoxy-encapsulated, 12-pin DIP package with built-in color filter 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
DMS-20PC Series, 31/2 Digit, LED Display, Digital Panel Voltmeters combine a precision 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 or green colors. High-intensity and low-power (35mW total) red LED's 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 filters and bezels; are moisture and vibration proof; and function well in the harshest environments. Their 12-pin, dual-in-line configuration 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 "powerdown" 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 31/2 digit, LED, DPM applications.
1 +5V SUPPLY
+5V V+ 0.01 F V- +2.0V
2
12 (-) INPUT LO R2
1
-5V DISPLAY 2 ENABLE DC/DC CONVERTER
R1 909k
11 (+) INPUT HI
3 5V RETURN 0 Vdc
A/D CONVERTER DATA
10 ANALOG COMMON
4 DP 3
9 DISPLAY 3 TEST/HOLD
5 DP 2 +5V
8 REFERENCE OUT
6 DP 1
7 REFERENCE IN
1
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.
2 3
Only used on 200mV (-0) and 2V (-1) models. Pin 9 is DISPLAY TEST on all but eight models. On those models (-H option), it is DISPLAY HOLD.
Figure 1. DMS-20PC Series Simplified Schematic
DATEL, Inc., Mansfield, MA 02048 (USA) * Tel: (508)339-3000, (800)233-2765 Fax: (508)339-6356 * E-mail: sales@datel.com * Internet: www.datel.com
DMS-20PC
31/2 D I G I T, L E D D I S P L AY D I G I TA L PA N E L V O LT M E T E R S
Performance/Functional Specifications
Typical at TA = +25C and supply voltage = +5V using the single-ended input circuit, unless otherwise noted. Analog Inputs Full Scale Input Range: DMS-20PC-0 DMS-20PC-1 DMS-20PC-2 DMS-20PC-3 Input Impedance: DMS-20PC-0, -1 DMS-20PC-2, -3 Overvoltage Protection Common Mode Voltage Range CMRR (dc to 60Hz) Control Inputs Decimal Point Placement (Pins 4-6) Display Test (Pin 9) Display Hold (Pin 9) Performance Sampling Rate Accuracy (3 minute warm-up): DMS-20PC-0 (VIN = +0.19V) DMS-20PC-1 (VIN = +1.9V) DMS-20PC-2 (VIN = +19V) DMS-20PC-3 (VIN = +190V) Zero Reading (VIN = 0 Volts) Temperature Drift (0 to +60C) Power Supply Requirements Supply Voltage Supply Current: DMS-20PC-X-RS DMS-20PC-X-RL DMS-20PC-X-AS DMS-20PC-X-GS DMS-20PC-X-OS DMS-20PC-X-YS DMS-20PC-X-RS-H DMS-20PC-X-GS-H DMS-20PC-X-RH Display Display Type and Size Polarity Indication Overrange Indication Physical/Environmental Operating Temperature Storage Temperature Humidity (Non-condensing) Case Material Weight 0 -40 0 ---+60 +75 95 C C % 31/2 Digit LED, 0.37"/9.4mm high Autopolarity ("-" for negative VIN) "-1_ _ _" for negative VIN "1_ _ _" for positive VIN +4.75 ---------+5.00 +60 +7 +90 +90 +90 +90 +60 +90 +60 +5.25 +90 +12 +120 +120 +120 +120 +90 +120 +90 Volts mA mA mA mA mA mA mA mA mA ----"-001" -2.5 samples per second 1 1 2 2 "000" 0.2 3 3 3 3 "001" 0.4 Cnts/C Counts Counts Counts Counts Tie to pin 3 to activate Tie to pin 1 to activate all segments Tie to pin 1 to hold last reading Min. ----100 0.8 ---Typ. 200 2 20 200 1000 1 --86 Max. ------250 2 -Units mV Volts Volts Volts M M Volts Volts dB LED Color: AS = Standard Amber GS = Standard Green OS = Standard Orange RS = Standard Red Accessories: DMS-20-CP DMS-BZL3 DMS-BZL4 DMS-EB2
Ordering Information
DMS-20PC - 1 - RS
Input Range: 0 = 200mV 1 = 2V 2 = 20V 3 = 200V Leave blank for standard models. Add -H for DISPLAY HOLD option (available on standard red and green LED models only). YS = Standard Yellow RH = High-Intensity Red RL = Low-Power Red
Panel cutout punch DMS-20 bezel assembly DMS-20 bezel assembly with sealing gasket Application/evaluation board with standard MOLEX connector, decimal point solder pads and attenuation resistor pads.
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. 2. 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) or to your system's 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 DMS-20PC-X-RL All Others Applied "0" Voltage +0.05V max. +0.4V max. Load Current* 0.7mA max. 6mA max.
Polycarbonate 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. See Technical Notes. The DISPLAY HOLD function is optional on standard red and green LED models only. See Ordering Information. 2
* The driving gates must be able to sink this much current (IOL) with a logic "0" output.
31/2 D I G I T, L E D D I S P L AY D I G I TA L PA N E L V O LT M E T E R S
DMS-20PC
4. DISPLAY TEST/HOLD (Pin 9) Function: Pin 9 is a dual-function pin. On all standard models (without "-H" suffix), 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" ("-1888" 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" suffix (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 reading indefinitely. 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 connected, via a selector switch, to pin 1 (+5V SUPPLY). If automatic, logic-controlled operation is desired, only PNP or MOSFET transistors should be used. The base or gate of these transistors should be driven sufficiently 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 (DMS20PC-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 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 10 provides 10% range of adjustment. 7. Soldering Methods: All models in the DMS-20PC 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 Terminal type Crimping tool Wire size Insulation diameter Stripping length Board mounted: Socket DATEL P/N 39-2079400 DATEL P/N 39-2099090 DATEL P/N 39-2099000 22 to 26 AWG 0.062" (1.57mm) maximum 0.100 to 0.125" (2.54 to 3.17mm) DATEL P/N 39-2359625
Applications
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 -5V is internally generated). One can easily see why input signals applied to (-) 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 Configurations: True single-ended measurements 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 (-) INPUT LO (pin 12).
11 (+) IN HI
DMS-20PC-1
8 REF OUT
+
VIN
-
12 (-) IN LO 1 +5V SUP 2 DISPLAY ENABLE 6 DP1 3
7 REF IN
5V RET
120 VAC
DATEL UPA-5/500
AC to DC Converter
Figure 2. Single-Ended Input Configuration
3
DMS-20PC
31/2 D I G I T , L E D D I S P L AY D I G I TA L PA N E L V O LT M E T E R S
Applications
2. Differential Input Configurations: 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 careful not to exceed the 2V common mode voltage limitation for 5Vpowered meters.
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.
DMS-20PC-1
REF OUT 8
1.5V CELL
REF IN
7
DP1 6 2 DISPLAY ENABLE
12 (-) IN LO
R2 1k
1 +5V SUP
3 5V RET
R3 1k
120 VAC
120 VAC
DATEL UPA-5/500
AC to DC Converter
Figure 3. Differential Input Configuration
1.5V CELL
50k < R1 + R2 < 10M R2 R1 + R2
AC to DC Converter
x VIN = Reading
120 VAC
R1 VIN R2
11 (+) IN HI
DMS-20PC-1
8 REF OUT
-
12 (-) IN LO 7 REF IN 1 +5V SUP 2 DISPLAY ENABLE 3 5V RET
120 VAC
DATEL UPA-5/500
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 requirements of the particular application and can be calculated using the following equation: RShunt = R1 = VFsr / IFsr Where: VFsr = Full scale reading (in Volts) IFsr = Relative full scale current (in Amps)
AC to DC Converter
Figure 4. Input Attenuation Circuit
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)
4
+
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.
- 12 (-) IN LO 1 +5V SUP 2 DISPLAY ENABLE 3 5V RET 6 DP1 7 REF IN
+
11 (+) IN HI
R1 1k
11 (+) IN HI
DMS-20PC-1
8 REF OUT
-
12 (-) IN LO 7 REF IN 1 +5V SUP 2 DISPLAY ENABLE 3 5V RET 6 DP1
DATEL UPA-5/500
AC to DC Converter
Figure 5. Floating Input Measurements
11 (+) IN HI 10 ANA COMM
DMS-20PC-1
8 REF OUT
DATEL UPA-5/500
+
Figure 6. Floating Input Measurements (Alternate Configuration)
31/2 D I G I T, L E D D I S P L AY D I G I TA L PA N E L V O LT M E T E R S
DMS-20PC
Applications
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), VFsr = 1.000 Volts RShunt = 1.000V/(0.020 - 0.004)A RShunt = 1.000V/0.016A = 62.5 Ohms 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 RShunt accordingly.
DMS-20PC-1
8 REF OUT
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 regulator manufacturer's data sheet to ensure the regulator is being utilized safely and correctly. 7. Digital Ammeter: Digital ammeters are finding ever-increasing usage because analog-style ammeters (moving-vane types) now cost roughly the same as their digital counterparts. Additionally, 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. A detailed application note describing digital dc ammeters is included in DATEL's new Digital Panel Meter Databook.
1 +5V SUP
11 (+) IN HI 10 ANA COMM
4-20mA
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 configured to allow power supply monitoring over the range of 4.5-18Vdc. The circuit in Figure 8 uses a low-drop-out, threeterminal regulator (LM-2931Z-5, available from National Semiconductor) to provide regulated 5V-power to the meter.
+
R1
DMS-20PC-0
8 REF OUT
12 (-) IN LO 1 R2 +5V SUP 2 DISPLAY ENABLE 3 5V RET 7 REF IN
+
5Vdc
2 DISP EN 3 5V RET 6 DP1
-
-
50k
7 REF IN 12 (-) IN LO 0.150V 11 (+) IN HI
120 VAC
DATEL UPA-5/500
1.5 Amp (Load Current)
AC to DC Converter
0.1W RShunt
Load (3.3 W )
Figure 7. 4-to-20mA Current Loop Operation Figure 9. DC Ammeter Circuit
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.
11 (+) IN HI 3 5V RET 12 COM (-) IN LO 10 ANA COMM 8 NC 8.06k, 1% 7 REF IN 2k
1
DMS-20PC-1
1 +5V IN
OUT
12
VOLTAGE CALIBRATOR
DMS-20PC-2-RL
LM2931Z-5 IN 1 +5V SUP 11 (+) IN HI
Connections for 2V, 20V and 200V models
OUT GND
+
4.5 - 18Vdc
-
22F 10V
+
2 DISP EN 3 5V RET 5 DP2 7 REF IN 8 REF OUT 12 (-) IN LO
17.4k, 1%
732, 1%
1
200
1
24.3k, 1%
Connections for 200mV models
= 10 to 20 Turns
Figure 8. 4.5V-18V Power Supply Monitor Figure 10. External Gain Adjustment
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DMS-20PC
31/2 D I G I T , L E D D I S P L AY D I G I TA L PA N E L V O LT M E T E R S
Mechanical Specifications
DMS-20PC-X-XX FRONT VIEW +5V SUPPLY DISPLAY ENABLE 5V RETURN DP3 DP2 DP1 1 2 3 4 5 6 12 11 10 9 8 7 (-) INPUT LO (+) INPUT HI ANALOG COMMON DISPLAY TEST/HOLD REFERENCE OUT REFERENCE IN DP1 DP2 DP3 1.38 (35.1) 1.30 (33.0) 0.040 (1.02) 0.25 (6.4) TYP. 0.040 (1.02) 0.15 (3.8) TYP. 1.10 (27.9) 0.040 (1.02) 0.50 (12.7)
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)
PIN #1 IDENTIFIER
(R)
CALIBRATION POTENTIOMETER HOLE LOCATION
PIN 1 0.170 (4.32)
0.150 (3.81)
0.125 (3.175) DIAMETER (USE ONLY WHEN PC BOARD MOUNTING)
0.88 (22.4) 0.80 (20.3)
0.10 (2.5) TYP.
OPTIONAL BEZEL (DMS-BZL3 and DMS-BZL4)
#2-56 INSERT 0.156 (3.96) DEEP FRONT VIEW 0.187 (4.75)
BEZEL INSTALLATION
1.280 (32.51)
LEZ B
1.826 (46.38)
RECOMMENDED DRILL AND PANEL CUTOUT DIMENSIONS
INTERNAL CORNER RADII: 0.032 (0.81) MAX.
RETAINING CLIP INSTALLATION
1.07 (27.18) 0.838 (21.29)
1.336 (33.93) 1.626 (41.30) 0.093 (2.362) DIAMETER (4 REQUIRED) ONLY WHEN USING OPTIONAL BEZEL ASSEMBLY
0.116 (2.95)
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ISO 9001
REGISTERED
DATEL, Inc. 11 Cabot Boulevard, Mansfield, MA 02048-1151 Tel: (508) 339-3000 (800) 233-2765 Fax: (508) 339-6356 Internet: www.datel.com Email: sales@datel.com Data sheet fax back: (508) 261-2857
DATEL DATEL DATEL DATEL
(UK) LTD. Tadley, England Tel: (01256)-880444 S.A.R.L. Montigny Le Bretonneux, France Tel: 01-34-60-01-01 GmbH Munchen, Germany Tel: 89-544334-0 KK Tokyo, Japan Tel: 3-3779-1031, Osaka Tel: 6-354-2025
DATEL 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 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.
(R)
(R)
0.145 (3.68)
(R)
(R)
MADE IN USA
(R)
0.475 (12.07)
0.10 (2.5) TYP.
LENAP
LENAP
DS-0271B 1/98

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