DATEL, Inc., 11 Cabot Boulevard, Mansfield, MA 02048-1151 (U.S.A.) • Tel: (508) 339-3000 Fax: (508) 339-6356 • For immediate assistance: (800) 233-2765
Features DMS-20PC Series, 3½ Digit, LED Display, Digital Panel V oltmeters 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 submin-
iature (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. 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.
Figure 1. DMS-20PC Series Simplified Schematic
••
••
•
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 +60°C temperature range
3½ Digit, LED Display
Low-Cost, Subminiature
Digital Panel Voltmeters
DMS-20PC Series
Actual Size
®®
(+) INPUT HI
(–) INPUT LO
ANALOG
COMMON
REFERENCE OUT
REFERENCE IN
+5V SUPPLY
R1
DP 1
DP 2
DP 3
6
5
4
11
12
10
8
7
1
3
DC/DC
CONVERTER
2
5V RETURN
+5V
–5V R2
»
+2.0V
DATA
909k
V+
V–
A/D
CONVERTER
0 Vdc
0.01
µF
9
DISPLAY
ENABLE
+5V
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.
DISPLAY
TEST/HOLD
11
Pin 9 is DISPLAY TEST on all but four models. On those models
(-H option), it is DISPLAY HOLD.
1
2
3
2
1
3
DMS-20PC 3½ DIGIT, LED DISPLAY DIGITAL PANEL VOLTMETERS
Performance/Functional Specifications
Typical at TA = +25°C and supply voltage = +5V using the single-ended input circuit,
unless otherwise noted.
➀
Applies for transient or continuous overvoltages applied to (+) INPUT HI (pin 11) with
(–) INPUT LO (pin 12) at 0 Volts. Pin 12 is not overvoltage protected. 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 LED models only.
See Ordering Information.
Leave blank for standard
models.
Add -H for DISPLAY
HOLD option (available
on standard red LED
models only).
DMS-20PC-1- RS
LED Color:
AS = Standard Amber
GS = Standard Green
OS = Standard Orange
RS = Standard Red
YS = Standard Yellow
RH = High-Intensity Red
RL = Low-Power Red
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.
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 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 Applied "0" Voltage Load Current*
DMS-20PC-X-RL +0.05V max. 0.7mA max.
All Others +0.4V max. 6mA max.
* The driving gates must be able to sink this much current
(IOL) with a logic "0" output.
Ordering Information
Input Range:
0 = ±200mV
1 = ±2V
2 = ±20V
3 = ±200V
Analog Inputs Min. Typ. Max. Units
Full Scale Input Range:
DMS-20PC-0 -- ±200 -- mV
DMS-20PC-1 -- ±2 -- Volts
DMS-20PC-2 -- ±20 -- Volts
DMS-20PC-3 -- ±200 -- Volts
Input Impedance:
DMS-20PC-0, -1 100 1000 -- M
Ω
DMS-20PC-2, -3 0.8 1 -- M
Ω
Overvoltage Protection
➀
-- -- ±250 Volts
Common Mode Voltage Range -- -- ±2 Volts
CMRR (dc to 60Hz) -- 86 -- dB
Control Inputs ➁ ➂
Decimal Point Placement (Pins 4-6) Tie to pin 3 to activate
Display Test (Pin 9) Tie to pin 3 to activate all segments
Display Hold (Pin 9)
➂
Tie to pin 3 to hold last reading
Performance
Sampling Rate 2.5 samples per second
Accuracy (3 minute warm-up):
DMS-20PC-0 (VIN = +0.19V) -- ±1 ±3 Counts
DMS-20PC-1 (VIN = +1.9V) -- ±1 ±3 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 to +60°C) -- ±0.2 ±0.4 Cnts/°C
Power Supply Requirements
Supply Voltage +4.75 +5.00 +5.25 Volts
Supply Current:
DMS-20PC-X-RS -- +60 +90 mA
DMS-20PC-X-RL -- +7 +12 mA
DMS-20PC-X-AS -- +90 +120 mA
DMS-20PC-X-GS -- +90 +120 mA
DMS-20PC-X-OS -- +90 +120 mA
DMS-20PC-X-YS -- +90 +120 mA
DMS-20PC-X-RS-H -- +60 +90 mA
DMS-20PC-X-RH -- +60 +90 mA
Display
Display Type and Size 3½ Digit LED, 0.37"/9.4mm high
Polarity Indication Autopolarity ("–" for negative VIN)
Overrange Indication "–1___" for negative VIN
"1___" for positive VIN
Physical/Environmental
Operating Temperature 0 -- +60 °C
Storage Temperature –40 -- +75 °C
Humidity (Non-condensing) 0 -- 95 %
Case Material Polycarbonate
Weight 0.4 ounces (11 grams)
2
3½ DIGIT, LED DISPLAY DIGITAL PANEL VOLTMETERS DMS-20PC
Applications
Figure 2. Single-Ended Input Configuration
1
12
3
+5V SUP
(–) IN LO
5V RET
DATEL
UPA-5/500
120 VAC
11
(+) IN HI
6
DP1
+
–
AC to DC Converter
V
IN
DMS-20PC-1
7
REF OUT
REF IN
8
2
DISPLAY
ENABLE
8. Suggested Mating Connectors:
Panel mounted:
Connector housing MOLEX P/N 22-01-2061
Terminal type MOLEX P/N 08-65-0805
Crimping tool MOLEX P/N 11-01-0037
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 SAMTEC P/N SSW-106-02-T- S
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
Ω
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).
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 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
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-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.
3
DMS-20PC 3½ DIGIT, LED DISPLAY DIGITAL PANEL VOLTMETERS
Figure 3. Differential Input Configuration
Figure 6. Floating Input Measurements
(Alternate Configuration)
RShunt = R1 = VFsr /IFsr
Where: VFsr = Full scale reading (in Volts)
IFsr = Relative full scale current (in Amps)
R2
R1 + R2 x VIN = Reading
50k
Ω
< R1 + R2 < 10M
Ω
Figure 4. Input Attenuation Circuit
1
12
3
+5V SUP
(–) IN LO
5V RET
DATEL
UPA-5/500
120 VAC
11
(+) IN HI
6
AC to DC Converter
DMS-20PC-1
R2
R1
R3
1k
1k
1k
8
7
REF IN
DP1
REF OUT
2
DISPLAY
ENABLE
DMS-20PC-1
R2
11
12
(+) IN HI
(–) IN LO
V
IN
R1
+
–
13
+5V SUP 5V RET
DATEL
UPA-5/500
120 VAC
AC to DC Converter
8
7
REF OUT
REF IN
2
DISPLAY
ENABLE
DMS-20PC-1
12
(–) IN LO
10
ANA COMM
11
(+) IN HI
1.5V
CELL
+
–
8
7
REF OUT
REF IN
13
+5V SUP
DATEL
UPA-5/500
120 VAC
6
DP1
AC to DC Converter
2
DISPLAY
ENABLE 5V
RET
Figure 5. Floating Input Measurements
13
+5V SUP
DATEL
UPA-5/500
120 VAC
6
DP1
AC to DC Converter
DMS-20PC-1
12
(–) IN LO
11
(+) IN HI
1.5V
CELL
+
–
8
7
REF OUT
REF IN
2
DISPLAY
ENABLE 5V
RET
Applications
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.
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:
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)
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.
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.
4
Applications
3½ DIGIT, LED DISPLAY DIGITAL PANEL VOLTMETERS DMS-20PC
Figure 8. 4.5V-18V Power Supply Monitor Figure 10. External Gain Adjustment
Figure 7. 4-to-20mA Current Loop Operation
To calibrate the circuit of Figure 7, perform the following:
1. With 4mA applied, adjust the 50k
Ω
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
di fferent full scale readings, alter the value of RShunt accordingly.
13
+5V SUP 5V RET
DATEL
UPA-5/500
120 VAC
AC to DC Converter
DMS-20PC-1
12
(–) IN LO
10
ANA COMM
11
(+) IN HI
R1
+
–
4-20mA
50k
R2
8
7
REF OUT
REF IN
2
DISPLAY
ENABLE
12
VOLTAGE
CALIBRATOR
OUT
10
(+) IN HI
(–) IN LO
ANA
COMM
= 10 to 20 Turns
7
REF
IN
11
732, 1%
8.06k, 1%
5V RET
Connections
for ±2V, ±20V
and ±200V models
Connections
for ±200mV
models
COM
17.4k, 1%
2k
24.3k, 1%
3
12
DMS-20PC-1
8
NC
200
+5V IN
1
1
1
1
Figure 9. DC Ammeter Circuit
5
78
+
–
DMS-20PC-2-RL
12
11
1
4.5 - 18Vdc
LM2931Z-5
GND
IN OUT +5V SUP
3
DP2
REF
IN REF
OUT (–) IN LO
5V RET
2
DISP_EN
(+) IN HI
22µF
10V
+
6
3
+
–
DMS-20PC-0
11
0.150V
1
1.5 Amp (Load Current)
5VDC
7
8
+5V SUP
5V RET
DP1 (+) IN HI
REF OUT
REF IN
2
DISP EN
0.1
W
R
Shunt
Load
(3.3 )
12
(–) IN LO
W
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
Ω
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.
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.
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-
terminal regulator (LM-2931Z-5, available from National
Semiconductor) to provide regulated 5V-power to the meter.
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
5
MADE IN USA
DMS-20PC-X-XX
TOP VIEW
DP1 DP2 DP3
PIN #1
IDENTIFIER
+5V SUPPLY
DISPLAY ENABLE
5V RETURN
DP3
DP2
DP1
1
2
3
4
5
6
(–) INPUT LO
(+) INPUT HI
ANALOG COMMON
DISPLAY TEST/HOLD
REFERENCE OUT
REFERENCE IN
12
11
10
9
8
7
0.80
(20.3)
0.15
(3.81)
TYP. 0.50
(12.70)
0.10
(2.54)
TYP.
0.040
(1.02)
0.040
(1.02)
1.10
(27.9) 0.10
(2.54)
TYP.
0.250 (6.35) TYP.
0.475 (12.0)
0.040
(1.02)
1.30
(33.0)
1.38
(35.0)
0.88
(22.4)
®®
0.170
(4.32)
0.150
(3.81)
PIN 1
CALIBRATION POTENTIOMETER HOLE LOCATION
0.125 (3.175) DIAMETER
(USE ONLY WHEN PC BOARD MOUNTING)
DAT E L 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.
DMS-20PC 3½ DIGIT, LED DISPLAY DIGITAL PANEL VOLTMETERS
®®
DATEL,
INC.
1.21
(30.73)
RETAINING CLIP INSTALLATION
PANEL RETAINING CLIP (Supplied)
PANEL
1.71
(43.43)
Mechanical Specifications
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)
RECOMMENDED DRILL AND PANEL CUTOUT DIMENSIONS
1.21 (30.734)
1.826 (46.38)
1.626 (41.3)
0.838
(21.28)
1.336 (33.96)
1.626 (41.3)
1.07
(27.18)
#2-56 INSERT
0.156 (3.96) DEEP
1.07
(27.18) 0.60
(15.24) 1.280
(32.51)
0.10
(2.54)
0.10
(2.54)
0.187
(4.75)
INTERNAL CORNER RADII:
0.062 (1.57) MAX.
0.145
(3.68)
0.093 (2.362) DIAMETER (4REQUIRED)
ONLY WHEN USING OPTIONAL BEZEL ASSEMBLY
BOTTOM VIEW
0.116
(2.94)
OPTIONAL BEZEL
(DMS-BZL3 and DMS-BZL4)
DATEL (UK) LTD. Tadley, England Tel: (01256)-880444
DATEL S.A.R.L. Montigny Le Bretonneux, France Tel: 1-34-60-01-01
DATEL GmbH Munchen, Germany Tel: 89-544334-0
DATEL KK Tokyo, Japan Tel: 3-3779-1031, Osaka Tel: 6-354-2025
DATEL, Inc. 11 Cabot Boulevard, Mansfield, MA 02048-1151
Tel: (508) 339-3000 / Fax: (508) 339-6356
For immediate assistance: (800) 233-2765
DS-0271A 10/96
®®
ISO 9001
ISO 9001
REGISTERED
