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DMS-20PC Series
3½ Digit, LED Display, Low-Cost, Subminiature
Digital Panel Voltmeters
New
blue
-power
Low
s
en LED
and gre
FEATURES
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■
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 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 +60°C temperature range
SIMPLIFIED SCHEMATIC DIAGRAM
1
+5V SUPPLY
+5V
■
■
■
■
■
■
■
■
■
■
■
DMS-20PC Series, 3½ 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 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 +60°C.
The meters come with one of four, differential, input voltage ranges: ±200mV, ±2V
±20V or ±200V. Input impedance is a minimum 800kΩ. 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 3½ digit, LED, DPM applications.
V+
0.01
μF
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.
For full details go to
www.murata-ps.com/rohs
Figure 1. DMS-20PC Series simplified schematic
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DMS-20PC Series
Performance/Functional Specifications
Typical at T
A
= +25°C 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 Impedence:
DMS-20PC-0, -1
DMS-20PC-2, -3
Overvoltage Protection
➀
Common Mode Voltage Range
CMRR (dc to 60Hz)
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 = +60°C)
Power Supply Requirements
Supply Voltage
Supply Current:
DMS-20PC-X-RL
DMS-20PC-X-BL & -PGL
DMS-20PC-X-RS, -RH
DMS-20PC-X-RS-H
DMS-20PC-X-BS
DMS-20PC-X-GS-H
DMS-20PC-X-AS, -GS, -OS, -YS
Display
Display Type and Size
Polarity Indication
Overrange Indication
Physical/Environmental
Operating Temperature
Storage Temperature
Humidity (non-condensing)
Case Material
Weight
0
–20
0
–
–
–
+60
+75
95
°C
°C
%
3½ digit, 0.37"/9.4mm high LED
Autopolarity ("–" for negative Vin)
"–1_ _ _ " for negative inputs
"1_ _ _ " for positive inputs
–
–
–
–
–
–
–
+7
+12
+60
+60
+75
+90
+90
+12
+17
+90
+90
+100
+120
+120
mA
mA
mA
mA
mA
mA
mA
+4.75
+5.00
+5.25
Volts
–
–
–
–
“–001”
–
±1
±1
±2
±2
“000”
±0.2
±3
±3
±3
±3
“001”
±0.4
Cnts/°C
Counts
Counts
Counts
Counts
2.5 reading per second
–
–
–
–
–
1000
1
–
–
86
–
–
±250
±2
–
MΩ
MΩ
Volts
Volts
dB
LED Color:
AS = Standard Amber
BS = Standard Blue
GS = Standard Green
OS = Standard Orange
–
–
–
–
±200
±2
±20
±200
–
–
–
–
mV
Volts
Volts
Volts
Min.
Typ.
Max.
Units
3½ Digit, LED Display, Low-Cost, Subminiature
Digital Panel Voltmeters
Ordering Information
DMS-20PC - 1 - R S
Input Range:
0 = ±200mV
1 = ±2V
2 = ±20V
3 = ±200V
-C
Add -C for RoHS
Leave blank for standard
models.
Add -H for DISPLAY HOLD
option (available on
standard red and green
LED models only).
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.
A panel-mount retaining clip is supplied with each model.
TECHNICAL NOTES
RoHS Compliant Parts:
Add "-C" suffix to part number.
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 specifica-
tions.
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-XL
All Others
Applied "0" Voltage Load Current*
+0.05V max.
+0.4V max.
0.7mA max.
6mA max.
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
See Technical Notes.
➂
The DISPLAY HOLD function is optional on standard red and green LED models only.
* The driving gates must be able to sink this much current
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15 Feb 2010 MPM_DMS_20PC.D06
Page 2 of 6
DMS-20PC Series
3½ Digit, LED Display, Low-Cost, Subminiature
Digital Panel Voltmeters
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 read-
ing 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 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 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 400μA (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 meter’s plastic case and high-precision
electrical performance. We recommend the use of no-clean solders.
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-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 909kΩ 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 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 (–)
INPUT LO (pin 12).
DMS-20PC-1
8
REF OUT
11
(+) IN HI
+
V
IN
–
12
(–) IN LO
1
+5V SUP
2
DISPLAY
ENABLE
6
DP1
3
5V RET
7
REF IN
85-264Vac
AC to DC Converter
Figure 2.
Single-Ended Input Configuration
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DMS-20PC Series
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 care-
ful not to exceed the ±2V common mode voltage limitation for
5V-powered meters.
R1
1k
3½ Digit, LED Display, Low-Cost, Subminiature
Digital Panel Voltmeters
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 (–) 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.
11
(+) IN HI
+
DMS-20PC-1
REF OUT
8
11
(+) IN HI
DMS-20PC-1
8
REF OUT
REF IN
7
DP1
6
2
DISPLAY
ENABLE
12
(–) IN LO
R2
1k
1.5V
CELL
–
12
(–) IN LO
7
REF IN
1
+5V SUP
2
DISPLAY
ENABLE
3
5V
RET
6
DP1
1
+5V SUP
3
5V RET
R3
1k
85-264Vac
85-264Vac
AC to DC Converter
AC to DC Converter
Figure 3.
Differential Input Configuration
Figure 5.
Floating Input Measurements
1.5V
CELL
50kΩ < R1 + R2 < 10MΩ
R2
x V
IN
= Reading
R1 + R2
+
85-264Vac
R1
V
IN
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
85-264Vac
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:
R
Shunt
= R1 = V
Fsr
/ I
Fsr
Where:
V
Fsr
= Full scale reading (in Volts)
I
Fsr
= Relative full scale current (in Amps)
AC to DC Converter
Figure 4.
Input Attenuation Circuit
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+
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.
11
(+) IN HI
10
ANA COMM
12
(–) IN LO
1
+5V SUP
DMS-20PC-1
8
REF OUT
–
7
REF IN
2
DISPLAY
ENABLE
3
5V
RET
6
DP1
AC to DC Converter
Figure 6.
Floating Input Measurements
(Alternate Configuration)
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DMS-20PC Series
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), V
Fsr
= 1.000 Volts
R
Shunt
= 1.000V/(0.020 – 0.004)A
R
Shunt
= 1.000V/0.016A = 62.5 Ohms
To calibrate the circuit of Figure 7, perform the following:
1. With 4mA applied, adjust the 50kΩ 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.
11
(+) IN HI
10
ANA COMM
12
(–) IN LO
1
+5V SUP
2
DISPLAY
ENABLE
7
REF IN
3
5V RET
1
+5V SUP
3½ Digit, LED Display, Low-Cost, Subminiature
Digital Panel Voltmeters
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 finding 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 0.1Ω 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.
DMS-20PC-0
8
REF OUT
DMS-20PC-1
8
REF OUT
4-20mA
85-264Vac
1.5 Amp (Load Current)
AC to DC Converter
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, three-ter-
minal regulator (LM-2931Z-5, available from National Semicon-
ductor) to provide regulated 5V-power to the meter.
DMS-20PC-2-RL
LM2931Z-5
IN
1
+5V SUP
11
(+) IN HI
+
4.5 - 18Vdc
–
+
R1
+
5Vdc
2
DISP EN
3
5V RET
6
DP1
–
R2
–
50k
7
REF IN
12
(–) IN LO
0.150V
11
(+) IN HI
0.1W
R
Shunt
Load
(3.3W)
Figure 7.
4-to-20mA Current Loop Operation
Figure 9.
Basic 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
OUT
GND
22μF
10V
Connections
for ±2V, ±20V
and ±200V models
+
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.
4.5-18V Power Supply Monitor
Figure 10.
External Gain Adjustment
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Page 5 of 6
51mcu
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