DMS-20LCD Series
www.murata-ps.com
3½ Digit, LCD Display Digital Panel Voltmeters
FEATURES
■
Lowest cost
■
Lowest power, 2mW
■
Subminiature size:
1.38" x 0.88" x 0.43"
35mm x 22mm x 11mm
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.
■
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
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.
SIMPLIFIED SCHEMATIC DIAGRAM
+5V
+5V SUPPLY/ 1
+BATTERY
12
V+
(–) INPUT LO
2
0.01μF
–5V
N.C.
2
R2
1
3
R1
DC/DC
CONVERTER
V–
11
(+) INPUT HI
909k
≈+2.0V
5V RETURN/ 3
–BATTERY
J1
10 ANALOG
COMMON
A/D
CONVERTER
0 Vdc
DATA
DP 3
9
4
N.C./BACKLIGHT
4
8
5
DP 2
REFERENCE OUT
+5V
7
6
DP 1
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.
3
DC/DC converter is not used on 9V-powered models,
J1 is connected.
2
Only used on ±200mV (-0) and ±2V (-1) models.
4
Used on backlit models only.
N.C. for non-backlit models.
For full details go to
www.murata-ps.com/rohs
www.murata-ps.com/dpm
email: [email protected]
05 Apr 2011
MPM_DMS20LCD.B08 Page 1 of 6
DMS-20LCD Series
3½ 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.
Analog Inputs
Min.
Typ.
Max.
Units
Operating Temperature
Full Scale Input Range:
DMS-20LCD-0
Physical/Environmental
–
±200
–
mV
Storage Temperature
DMS-20LCD-1
–
±2
–
Volts
Humidity (non-condensing)
DMS-20LCD-2
–
±20
–
Volts
Case Material
Weight
DMS-20LCD-3
–
Input Impedence:
–
±200
–
Volts
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
Tie to pin 3 to activate
Functionality
+60
°C
–20
–
+75
°C
0
–
95
%
Polycarbonate
0.4 ounces (11 grams)
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.
DMS-20LCD - 1 - 5
Tie to pin 3 to activate
Logic Compatibility
-C
Add -C for RoHS
TTL (on 5V-powered models)
Input Range:
0 = ±200mV
1 = ±2V
2 = ±20V
3 = ±200V
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”
–
±0.2
±0.4
Temperature Drift (0 = +60°C)
–
Ordering Information
Decimal Pt. Placement (Pins 4-6)
Backlight (Pin 9)
0
Cnts/°C
Accessories:
DMS-20-CP
DMS-BZL3-C
DMS-BZL4-C
DMS-EB2-C
Leave blank for standard
models.
Add B for backlit models.
Power Source:
5 = +5V
9 = +9V
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.
Power Supply Requirements (5V Models)
Supply Voltage
+4.75
+5.00
+5.25
Volts
TECHNICAL NOTES
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
Standard Models
–
+230
+350
μA
Backlit Models
–
+35
+50
mA
Supply Current:
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
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/–BATTERY) or to
your system’s analog ground.
3. Decimal Point Placement: The location of the decimal point is userselectable, 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
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05 Apr 2011
MPM_DMS20LCD.B08 Page 2 of 6
DMS-20LCD Series
3½ Digit, LCD Display Digital Panel Voltmeters
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.
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 currentlimiting 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:
RSeries =
+BATTERY – 9.2V
0.035
Ohms
Example: If +BATTERY (pin 1 with respect to pin 3) is +12.6V,
RSeries =
+12.6 – 9.2V
0.035
8. Suggested Mating Connectors:
Panel mounted:
Connector housing
Terminal type
Crimping tool
Wire size
Insulation diameter
Stripping length
DATEL P/N 4320-01069-0
DATEL P/N 4400-01032-0
DATEL P/N 39-2099000
22 to 26 AWG
0.062” (1.57mm) maximum
0.100 to 0.125” (2.54 to 3.17mm)
Board mounted:
Socket
DATEL P/N 4320-01074-0
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 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 configurations.
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 lowbattery annunciator’s turn-on threshold can vary significantly from unitto-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 voltages 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.
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).
DMS-20LCD-1-5
11
(+) IN HI
+
8
REF OUT
VIN
–
12
(–) IN LO
7
REF IN
1
+5V SUP
6
3
DP1
5V RET
120 VAC
AC to DC Converter
Figure 2. Single-Ended Input Configuration
(5V-Powered Models)
7. 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 no-clean solders.
www.murata-ps.com/dpm
email: [email protected]
05 Apr 2011
MPM_DMS20LCD.B08 Page 3 of 6
DMS-20LCD Series
3½ 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.
8
REF IN
7
11
(+) IN HI
R2
1k
12
(–) IN LO
DP1 6
R3
1k
3
1
+5V SUP
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.
5V RET
DMS-20LCD-1-5
11
(+) IN HI
8
REF OUT
+
DMS-20LCD-1-5
REF OUT
R1
1k
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.
1.5V
CELL
–
12
7
REF IN
(–) IN LO
120 VAC
1
+5V SUP
3
6
5V RET
DP1
AC to DC Converter
Figure 3. Differential Input Configuration
(5V-Powered Models)
120 VAC
AC to DC Converter
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.
DMS-20LCD-1-9
11
(+) IN HI
+
50k: < R1 + R2 < 10M:
R2
Figure 5. Floating Input Measurements
(5V-Powered Models)
1.5V
CELL
8
REF OUT
10
ANA COMM
–
x VIN = Reading
12
7
REF IN
(–) IN LO
R1 + R2
1
3
6
–BAT
DP1
+
+ BAT
+
9V
BATTERY
R1
8
REF OUT
VIN
R2
–
–
DMS-20LCD-1-5
11
(+) IN HI
Figure 6. Floating Input Measurements
(9V-Powered Models)
12
(–) IN LO
7
REF IN
1
+5V SUP
3
5V RET
120 VAC
AC to DC Converter
Figure 4. Input Attenuation Circuit
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:
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05 Apr 2011
MPM_DMS20LCD.B08 Page 4 of 6
DMS-20LCD Series
3½ Digit, LCD Display Digital Panel Voltmeters
APPLICATIONS
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.
RShunt = R1 = VFsr / I Fsr
Where:
VFsr = Full scale reading (in 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 possible, the resistors in the divider should be ±1% metal-film types
with TCR’s less than 50ppm/°C.
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
RShunt = 1.000V/0.016A = 62.5 Ohms
DMS-20LCD-1-9
R1
45.3k
11
(+) IN HI
REF OUT 8
To calibrate the circuit of Figure 7, perform the following:
R2
10.1k
12
(–) IN LO
1. With 4mA applied, adjust the 50k: potentiometer (R2) to
display a reading of "000" (assuming that is the desired
reading).
REF IN 7
1
+BAT
+
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.
R3
45.3k
5
DP2
3
–BAT
9V
BATTERY
–
Figure 8. Power Supply Monitor
(9V-Powered Models)
11
(+) IN HI
DMS-20LCD-1-5
8
REF OUT
+
10
ANA COMM
4-20mA
R1
12
7
REF IN
(–) IN LO
1
R2
+5V SUP
3
5V RET
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.
–
50k
11
(+) IN HI
DMS-20LCD
OUT
120 VAC
12
AC to DC Converter
Figure 7. 4-to-20mA Current Loop Operation
(5V-Powered Models)
VOLTAGE
CALIBRATOR
COM
3
5V RET/
–BAT IN
1
+5V IN/
+BAT IN
12
Connections
for ±2V, ±20V
and ±200V models
(–) IN LO
10
ANA
COMM
6. Power Supply Monitoring: A popular application for DATEL’s lowpower 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:
7
REF
IN
8
NC
8.06k, 1%
2k
732, 1%
c
c
17.4k, 1%
For +5V models, tie (–) IN LO to pin 3.
For +9V models, tie (–) IN LO to pin 10
c
200
24.3k, 1%
Connections
for ±200mV
models
= 10 to 20 Turns
Figure 9. External Gain Adjustment
R2
= 0.1
(R1 + R2 + R3)
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05 Apr 2011
MPM_DMS20LCD.B08 Page 5 of 6
DMS-20LCD Series
3½ Digit, LCD Display Digital Panel Voltmeters
MECHANICAL SPECIFICATIONS
MECHANICAL DIMENSIONS: Inches (mm)
TOLERANCES: 2 PL DEC ±0.02 (±0.51)
3 PL DEC ±0.010 (±0.254)
PIN #1
IDENTIFIER
DMS-20LCD-X-XX
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)
CALIBRATION POTENTIOMETER HOLE LOCATION
PIN 1
0.160
(4.06)
FRONT VIEW
+5V SUPPLY/ +BATTERY
N.C.
5V RETURN/ –BATTERY
DP3
DP2
DP1
12
11
10
9
8
7
1
2
3
4
5
6
0.160
(4.06)
DP1
0.125 (3.175) DIAMETER
(USE ONLY WHEN PC
BOARD MOUNTING)
DP2
(–) INPUT LO
(+) INPUT HI
ANALOG COMMON
N.C./BACKLIGHT
REFERENCE OUT
REFERENCE IN
DP3
0.88
(22.3)
1.38
(35.1)
0.80
(20.3)
1.30
(33.0)
0.425
(10.80)
0.040
(1.02)
0.040
(1.02)
0.10
(2.5)
TYP.
0.15
(3.8)
TYP.
BEZEL INSTALLATION AND RECOMMENDED DRILL AND PANEL CUTOUT
0.10
(2.5)
TYP.
1.10
(27.9)
0.040
(1.02)
0.50
(12.7)
OPTIONAL BEZEL (DMS-BZL3 and DMS-BZL4)
#2-56 INSERT
0.156 (3.96) DEEP
0.25
(6.4) TYP.
BEZEL INSTALLATION
0.187
(4.75)
FRONT VIEW
PANEL
1.280
(32.51)
1.826 (46.38)
BEZEL
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
0.145
(3.68)
PANEL
0.116
(2.95)
Murata Power Solutions, Inc.
11 Cabot Boulevard, Mansfield, MA 02048-1151 U.S.A.
ISO 9001 and 14001 REGISTERED
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. Specifications are subject to change without
notice.
© 2011 Murata Power Solutions, Inc.
www.murata-ps.com/locations
email: [email protected]
05 Apr 2011
MPM_DMS20LCD.B08 Page 6 of 6