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DMS-20LCD Series
3½ Digit, LCD Display Digital Panel Voltmeters
MPM_DMS20LCD.C01 Page 1 of 6
DMS-20LCD Series, 3½ 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 incorporate a built-in
bezel and are easily mounted in either panels or pc boards. Both backlit 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 800k. 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 400µA) or a single
+9V supply/battery (drawing 230µA). All models have a low-battery ("B") annunciator and
feature autopolarity changeover and overrange indication.
Also available is an application/evaluation board (DMS-EB2) 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.
FEATURES
Lowest cost
Lowest power, 2mW
Subminiature size:
1.38" x 0.88" x 0.43"
35mm x 22mm x 11mm
Large (0.37"/9.4mm), enhanced-contrast LCD display
Epoxy-encapsulated, 12-pin DIP
Panel or pc-board mountable
4 differential input voltage ranges
High accuracy, ±1 count (±0.05%)
Single +5V supply or 9V battery
Low-battery annunciator
User-selectable decimal point placement
0 to +60°C temperature range
SIMPLIFIED SCHEMATIC DIAGRAM
(+) INPUT HI
ANALOG
(–) INPUT LO
COMMON
REFERENCE OUT
REFERENCE IN
R1
DP 1
DP 2
DP 3
6
5
+5V SUPPLY/
+BATTERY
49
11
12
10
8
7
1
3
DC/DC
CONVERTER
2
5V RETURN/
+5V
–BATTERY
–5V
R2
DATA
≈+2.0V
V+
909k
V–
A/D
CONVERTER
0 Vdc
0.01μF
N.C.
J1
N.C./BACKLIGHT
+5V
DC/DC converter is not used on 9V-powered models,
J1 is connected.
Used on backlit models only.
N.C. for non-backlit models.
1
2
3
1
2
4
3
4
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.
www.murata-ps.com/support
DMS-20LCD Series
3½ Digit, LCD Display Digital Panel Voltmeters
MPM_DMS20LCD.C01 Page 2 of 6
TECHNICAL NOTES
Performance/Functional Specifi cations
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.
➀ 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.
➁ 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).
➂See Technical Notes.
Leave blank for standard
models.
Add B for backlit models.
DMS-20LCD - 1 - 5 - C
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 Power Source:
5 = +5V
9 = +9V
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 specifi 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 “fl oat-
ing” measurements as described in the Applications section of this data
sheet and Ap Note DMS-AN3 at
http://www.murata-ps.com/data/meters/dms-an3.pdf. Pin 10 should
not be connected to pin 3 (5V RETURN/–BATTERY) 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
A panel-mount retaining clip is supplied with each model.
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 Impedence: –
DMS-20LCD-0, -1 100 1000 – M
DMS-20LCD-2, -3 0.8 1 – M
Overvoltage Protection ➀
DMS-20LCD-0, -1, -2 – – ±100 Volts
DMS-20LCD-3 – – ±250 Volts
Common Mode Voltage Range – – ±2 Volts
CMRR (dc to 60Hz) – 86 – dB
Control Inputs ➁
Decimal Pt. Placement (Pins 4-6) Tie to pin 3 to activate
Functionality Tie to pin 3 to activate
Logic Compatibility TTL (on 5V-powered models)
Backlight (Pin 9) Tie to pin 3 to turn on backlight
Performance
Sampling Rate 2.5 reading per second
Accuracy (1 minute warm-up):
DMS-20PC-0 (Vin = +0.19V) – ±1 ±2 Counts
DMS-20PC-1 (Vin = +1.9V) – ±1 ±2 Counts
DMS-20PC-2 (Vin = +19V) – ±2 ±3 Counts
DMS-20PC-3 (Vin = +190V) – ±2 ±3 Counts
Zero Reading (Vin = 0 Volts) “–001” “000” “001”
Temperature Drift (0 = +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 +650 µA
Backlit Models – +35 +50 mA
Power Supply Requirements (9V Models)
Supply Voltage +7.5 +9.0 +14.0 Volts
Supply Current:
Standard Models – +230 +350 µA
Backlit Models – +35 +50 mA
Display
Display Type and Size 3½ digit, 0.37"/9.4mm high LCD
Polarity Indication Autopolarity ("–" for negative Vin)
Overrange Indication "–1_ _ _" for negative Vin
"1_ _ _" for positive Vin
Ordering Information
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)
Add -C for RoHS
See www.murata-ps.com/dpm-availability for model-specifi c availability.
www.murata-ps.com/support
DMS-20LCD Series
3½ Digit, LCD Display Digital Panel Voltmeters
MPM_DMS20LCD.C01 Page 3 of 6
APPLICATIONS
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 location pins are TTL compatible and may be hard wired as
described above or driven with 5V TTL logic gates.
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 measure 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 confi gurations.
1. Single-Ended Input Confi gurations: True single-ended measure-
ments 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).
8. Suggested Mating Connectors:
Panel mounted:
Connector housing Murata Power Solutions P/N 4320-01069-0
Terminal type Murata Power Solutions P/N 4400-01032-0
Crimping tool Murata Power Solutions 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 Murata Power Solutions P/N 4320-01074-0
Figure 2. Single-Ended Input Confi guration
(5V-Powered Models)
RSeries = Ohms
+12.6 – 9.2V
0.035
Example: If +BATTERY (pin 1 with respect to pin 3) is +12.6V,
+BATTERY – 9.2V
0.035
RSeries = Ohms
RSeries = 97 Ohms
5. 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 +3.7V, or when the supply voltage for
9V-powered models falls below approximately 7.2V. However, the low-
battery annunciator’s turn-on threshold can vary signifi cantly from unit-
to-unit: as low as 2.7V for 5V-powered meters, and as low as 5.4V for
9V-powered models. Applications that use the LOW BAT annunciator
must be fully tested by the user, using a combination of low supply volt-
ages and the input signal’s minimum and maximum levels, to ensure
that all display readings are valid as long as the LOW BAT annunciator
remains off.
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 9 provides ±10% range of adjustment.
7. Soldering Methods: All models in the DMS-20LCD Series easily
withstand most common wave soldering operations. We recom-
mend, 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 no-clean solders.
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 back-
light (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:
1
12
3
+5V SUP
(–) IN LO
5V RET
120 VAC
11
(+) IN HI
6
DP1
+
–
AC to DC Converter
V
IN
DMS-20LCD-1-5
7
REF OUT
REF IN
8
www.murata-ps.com/support
DMS-20LCD Series
3½ Digit, LCD Display Digital Panel Voltmeters
MPM_DMS20LCD.C01 Page 4 of 6
APPLICATIONS
R2
R1 + R2
x VIN = Reading
50k < R1 + R2 < 10M
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 “fl oating” input is a signal that has no galvanic connection to the
meter’s power supply. In the fi gures below, the 1.5V battery illustrates a
true fl oating input.
Figure 3. Differential Input Confi guration
(5V-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 function of the scaling requirements of
the particular application and can be calculated using the following
equation:
Figure 6. Floating Input Measurements
(9V-Powered Models)
Figure 5. Floating Input Measurements
(5V-Powered Models)
Figure 4. Input Attenuation Circuit
2. Differential Input Confi gurations: 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 demon-
strate the concept of a differential input signal. Be careful 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-fi lm resistors with absolute TCR’s less than
50ppm/°C. See Ap Note 4 for more information on engineering scaling.
13
+ BAT –BAT
9V
BATTERY
6
DP1
12
(–) IN LO
10
ANA COMM
11
(+) IN HI
1.5V
CELL
+
–
+
–
8
7
REF OUT
REF IN
DMS-20LCD-1-9
1
12
3
+5V SUP
(–) IN LO
5V RET
120 VAC
11
(+) IN HI
6
AC to DC Converter
R2
R1
R3
1k
1k
1k
8
7
REF IN
DP1
REF OUT
DMS-20LCD-1-5
R2
11
12
(+) IN HI
(–) IN LO
V
IN
R1
+
–
13
+5V SUP 5V RET
120 VAC
AC to DC Converter
8
7
REF OUT
REF IN
DMS-20LCD-1-5
13
+5V SUP 5V RET
120 VAC
6
DP1
AC to DC Converter
12
(–) IN LO
11
(+) IN HI
1.5V
CELL
+
–
8
7
REF OUT
REF IN
DMS-20LCD-1-5
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DMS-20LCD Series
3½ Digit, LCD Display Digital Panel Voltmeters
MPM_DMS20LCD.C01 Page 5 of 6
APPLICATIONS
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 "1999". For different full
scale readings, alter the value of RShunt accordingly.
R
Shunt = R1 = VFsr /IFsr
Where: VFsr = Full scale reading (in Volts)
I Fsr = 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), VFsr = 1.000 Volts
RShunt = 1.000V/(0.020 – 0.004)A
R
Shunt = 1.000V/0.016A = 62.5 Ohms
Figure 7. 4-to-20mA Current Loop Operation
(5V-Powered Models)
R2
(R1 + R2 + R3) = 0.1
6. Power Supply Monitoring: A popular application for Murata Power
Solutions’ 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 require-
ment 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 (+BAT-
TERY) and 3 (–BATTERY). The divider should be designed so that
1/10th the battery voltage falls across the inputs to the meter:
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 fi rst measuring the actual battery volt-
age with another meter and then adjusting the gain-adjust potentiom-
eter on the back of the DMS-20LCD until a similar reading is obtained.
If possible, the resistors in the divider should be ±1% metal-fi lm types
with TCR’s less than 50ppm/°C.
7. 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.
Figure 9. External Gain Adjustment
Figure 8. Power Supply Monitor
(9V-Powered Models)
12
VOLTAGE
OUT
CALIBRATOR
10
(+) IN HI
(–) IN LO
ANA
COMM
7
REF
IN
11
= 10 to 20 Turns
732, 1%
8.06k, 1%
5V RET/
–BAT IN
Connections
and ±200V models
for ±2V, ±20V
Connections
for ±200mV
models
COM
1
+5V IN/
+BAT IN
2k 17.4k, 1%
3
12
24.3k, 1%
DMS-20LCD
8
NC
200
For +5V models, tie (–) IN LO to pin 3.
For +9V models, tie (–) IN LO to pin 10
13
+5V SUP 5V RET
120 VAC
AC to DC Converter
12
(–) IN LO
10
ANA COMM
11
(+) IN HI
R1
+
–
4-20mA
50k
R2
8
7
REF OUT
REF IN
DMS-20LCD-1-5
1
12
3
+BAT
11
(–) IN LO
–BAT
5
DP2
(+) IN HI
R2
R1
DMS-20LCD-1-9
R3
45.3k
10.1k
9V
45.3k
BATTERY
+
–
8
7
REF OUT
REF IN
MECHANICAL SPECIFICATIONS
BEZEL INSTALLATION AND RECOMMENDED DRILL AND PANEL CUTOUT
www.murata-ps.com/support
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 herein do not imply
the granting of licenses to make, use, or sell equipment constructed in accordance therewith. Specifi cations are subject to change without
notice. © 2015 Murata Power Solutions, Inc.
Murata Power Solutions, Inc.
11 Cabot Boulevard, Mansfi eld, MA 02048-1151 U.S.A.
ISO 9001 and 14001 REGISTERED
This product is subject to the following operating requirements
and the Life and Safety Critical Application Sales Policy:
Refer to: http://www.murata-ps.com/requirements/
DMS-20LCD Series
3½ Digit, LCD Display Digital Panel Voltmeters
MPM_DMS20LCD.C01 Page 6 of 6
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)
DMS-20LCD-X-XX
FRONT VIEW
DP1 DP2 DP3
PIN #1
IDENTIFIER
+5V SUPPLY/ +BATTERY
N.C.
5V RETURN/ –BATTERY
DP3
DP2
DP1
1
2
3
4
5
6
(–) INPUT LO
(+) INPUT HI
ANALOG COMMON
N.C./BACKLIGHT
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.
0.425
(10.80)
0.040
(1.02)
1.30
(33.0)
1.38
(35.1)
0.88
(22.3)
0.160
(4.06)
0.160
(4.06)
PIN 1
CALIBRATION POTENTIOMETER HOLE LOCATION
0.125 (3.175) DIAMETER
(USE ONLY WHEN PC
BOARD MOUNTING)
#2-56 INSERT
0.156 (3.96) DEEP
FRONT VIEW
1.280
(32.51)
0.187
(4.75)
OPTIONAL BEZEL (DMS BZL3 and DMS BZL4)
RECOMMENDED DRILL AND PANEL CUTOUT DIMENSIONS
1.826 (46.38)
0.838
(21.29)
1.336 (33.93)
1.626 (41.30)
1.07
(27.18)
INTERNAL CORNER RADII:
0.032 (0.81) MAX.
0.145
(3.68)
0.093 (2.362) DIAMETER (4 REQUIRED)
ONLY WHEN USING OPTIONAL BEZEL ASSEMBLY
0.116
(2.95)
BEZEL INSTALLATION
BEZEL
PANEL
RETAINING CLIP INSTALLATION
PANE
L
