DATEL DMS-30PC Service Manual

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Actual Size

®®

DMS-30PC Series

3½ Digit, LED Display

Low-P o wer, Miniature

Digital Panel Voltmeters

Features

••

• Large (0.56"/14.2mm) LED display

••

••

• 7 LED colors

••

••

• Low-power LED’s optional

••

••

• Epoxy-encapsulated, 12-pin DIP with

••

built-in color filter and bezel

••

• Miniature size:

••

2.17" x 0.92" x 0.56"
55mm x 23mm x 14mm

••

• Panel or pc-board mountable

••

••

• 4 differential input voltage ranges

••

••

• Auto-calibration, ±1 count accuracy

••

••

• User-selectable decimal point placement

••

••

• Single +5V supply (60mW for low-power

••

models)

••

• 0 to +60°C temperature range

••

••

• Numerous "plug-on" application

••

boards

••

• Low cost

••

DP 3

DP 2

DP 1

1

2

CONVERTER

3

4

5

6

+5V SUPPLY

DISPLAY TEST

5V RETURN

The DMS-30PC Series is a broad line of self-contained, fully operational, 3½
digit voltmeters with large, easy-to-read LED displays. The 0.56"(14.2mm) high
LED's are available in a wide variety of colors including red, orange, amber, yellow,
green, aqua and blue. A high-intensity version of the red display is optional as are
low-power versions of the red, orange and green displays.

The small size (2.17" x 0.92" x 0.56") of DMS-30PC meters is achieved by
integrating their display, display drivers, reference circuit, and A/D converter into in a
single, epoxy-encapsulated assembly. The device's 12-pin, component-like, DIP
package is both vibration and moisture proof. Each package incorporates a built-in
color filter and bezel and is easily mounted in either panels or pc cards.

These meters are available in four differential input voltage ranges (±200mV,
±2V, ±20V and ±200V). Input impedance is 1,000 megohms f or the ±200mV and
±2V inputs and 1 megohm for the ±20V and ±200V inputs. CMRR for all devices is
86dB, and inputs are overvoltage protected to ±250V.

Each meter incorporates an extremely stable, double-regulated reference and is
fully calibrated prior to potting. We guarantee outstanding initial accuracy (±1 count)
and excellent stability (±0.15 counts/°C). All models operate from a single +5V
supply, and the low-power models draw as little as 10mA (50mW total power). A
DISPLAY TEST function is standard on each device.

For popular applications (4-to-20mA, rms-to-dc conversion, ac line power, J and
K thermocouples, etc.), the DMS-30PC Series includes a complete line of optional
"plug-on" application boards that conveniently convert your meter into an applica­tion-specific instrument.

DC/DC

0 Vdc

+5V

–5V

CONVERTER

DATA

A/D

V+

0.01µF

V–

+2.0V

≈

1.23V
REF.

+5V

1

R2 is not used on ±200mV (-0) models or ±2V (-1) models.
R2 = 100k on ±20V

R2

12

(–) INPUT LO

1

R1

11

(+) INPUT HI

909k

10

ANALOG
COMMON

9

+1.23V REFERENCE OUT

1.82k

8

REFERENCE OUT

7

REFERENCE IN

models and 9.1k on ±200V (-3) models.

Figure 1. DMS-30PC Series Simplified Schematic

DATEL, Inc., Mansfield, MA 02048 (USA) • Tel: [phone] Fax: [phone] • Email: [e-mail] • Internet: www.datel.com

DMS-30PC

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.

Analog Inputs Min. Typ. Max. Units

Full Scale Input Range:

DMS-30PC-0 -- ±200 -- mV
DMS-30PC-1 -- ±2 -- Volts
DMS-30PC-2 -- ±20 -- Volts
DMS-30PC-3 -- ±200 -- Volts

Input Impedance:

DMS-30PC-0, -1 100 1000 -- MΩ
DMS-30PC-2, -3 0.8 1 -- MΩ

Overvoltage Protection ➀ -- -- ±250 Volts
Common Mode Voltage Range -- -- ±2 Volts
CMRR (dc to 60Hz) -- 86 -- dB

Control Inputs ➁

Decimal Point Placement (Pins 4-6) Tie to pin 3 to activate
Display Test (Pin 2) Tie to +5V to activate all segments

Performance

Sampling Rate 2.5 samples per second
Accuracy (3 minute warm-up):

DMS-30PC-0 (VIN = +0.19V) -- ±1 ±2 Counts
DMS-30PC-1 (VIN = +1.9V) -- ± 1 ±2 Counts
DMS-30PC-2 (VIN = +19V) -- ±2 ±3 Counts
DMS-30PC-3 (VIN = +190V) -- ±2 ±3 Counts

Zero Reading (VIN = 0 Volts) "– 001" "000" "001"
Temperature Drift (0 to +60°C) -- ±0.15 ±0.3 Cnts/°C
+1.23V Reference Output (Pin 9) ➁ +1.20 +1.23 +1.25 Volts

Power Supply Requirements

Supply Voltage +4.75 +5.00 +5.25 Volts
Supply Current:

Standard Models:

Blue display -- +400 +550 m A
All others -- +150 +225 m A

Low-Power Models:

Red display -- +12 +17 mA
Green or orange display -- +6 0 +100 mA

Display

Display Type and Size 3½ Digit LED, 0.56"/14.2mm high
Polarity Indication Autopolarity ("–" for negative VIN )
Overrange Indication "–1___" for negative VIN

"1___" for positive VIN

Physical/Environmental

Operating Temperature:

Blue display models 0 -- +50 °C
All other models 0 -- +60 °C

Storage Temperature –40 -- +75 °C
Humidity (Non-condensing) 0 -- 95 %
Case Material Polycarbonate
Weight 0.75 ounces (21 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.

Ordering Information

DMS-30PC -1 - RS

LED Color:

Input Range:

0 = ±200mV
1 = ±2V
2 = ±20V

3 = ±200V Available on the

following models only:

-GS (Standard Green)

-RS (Standard Red)

-RL (Low-Power Red)

Accessories:

DMS-30-CP Panel cutout punch
DMS-BZL1 DMS-30 bezel assembly
DMS-BZL2 DMS-30 bezel assembly with sealing gasket
RN-DMS Gain/offset potentiometer kit for DMS-EB,

DMS-EB-AC/DC and DMS-EB-DC/DC

Add-On Application Boards:

DMS-EB Multi-purpose (gain/offset, 4-20mA, etc.)
DMS-EB-HTB High-accuracy temperature probe sensing for

±200mV models

DMS-EB-DC/DC Provides isolated +5V power
DMS-EB-TCJ J-type thermocouple inputs for ±2V models
DMS-EB-TCK K-type thermocouple inputs for ±2V models
DMS-EB-RMS For true rms measurements of ac voltages
DMS-EB-AC/DC For ac line-powered applications
DMS-EB-LP For 4-to-20mA loop-powered applications

A panel-mount retaining clip is supplied with each model.

Te chnical Notes

1. +1.23V REFERENCE OUTPUT (Pin 9): This pin is the output of the
meter’s precision +1.23V internal reference, and it is referenced to
ANALOG COMMON (pin 10) which sits at a potential of approxi­mately +2V. This output should be buffered if used to drive external
loads since sourcing more than 15µA from pin 9 can affect both the
initial accuracy and temperature drift of the meter.

2. ANALOG COMMON (Pin 10): This pin is connected to an internal,
low-noise, "relative" ground. It is used in cer tain 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. 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.

AS = Standard Amber
BS = Standard Blue
GS = Standard Green
OS = Standard Orange
QS = Standard Aqua
RS = Standard Red
YS = Standard Yellow
RH = High-Intensity Red
GL = Low-Power Green
OL = Low-Power Orange
RL = Low-Power Red

2

3½ DIGIT, LED DISPLAY DIGITAL PANEL VOLTMETERS

4. DISPLA Y TEST (Pin 2): Connecting pin 2 to +5V SUPPLY (pin

1) will activate all LED segments, except the decimal points, and
the display will read "1888" regardless of the actual applied input.
If a negative input is applied, DISPLAY TEST will also activate
the minus sign. To protect the LED's, the display should not

be left in the "test" mode for more than 10 seconds.

5. 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 desired 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-30PC-X-RL +0.05V max. 0.7mA max.
DMS-30PC-X-BS +0.3V max. 18mA max.
All Others +0.4V max. 6mA max.

* The driving gates must be able to sink this much current

OL) with a logic "0" output.

(I

6. Gain Adjust: There is a gain-adjust potentiometer on the back
of each meter. It has approximately ±50 counts (±2.5%) of
adjustment range. 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-30PC Series easily
withstand most common wave soldering operations. We
recommend, however, that you evaluate the effects y our
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 DATEL P/N 39-2079400
Terminal type DATEL P/N 39-2099090
Crimping tool DATEL 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 DATEL P/N 39-2359625

DMS-30PC

Applications

DMS-30PC meters are highly versatile devices that can be used in
hundreds of applications. The application circuits chosen for this
section have historically received many inquiries. Every attempt has
been made to ensure technical accuracy, and all of the following
circuits have been prototyped and tested to ensure functionality.
Please keep in mind, however, that real-world applications are
seldom as straightforward as the approaches presented here. Most
applications have many more components — and many more
connections — than the illustrations show.

The simplified schematic shown in Figure 1 can be very useful when
debugging a malfunctioning panel meter circuit, particularly if the
user has some knowledge of operational amplifiers (op amps). The
meter's high-impedance input consists of an op amp powered from a
±5Vdc power supply (the –5V is internally generated). Knowing this,
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).

One of the simplified schematic's noteworthy features is that it
shows internal voltage values. It 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-30PC 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). This will ensure
that large LED currents will not flow in the wiring that connects

IN to (–) INPUT LO (pin 12). Ground-loop currents can cause

V
unstable readings.

1

DMS-30PC-1

6

DP1

3

5V RET

8

REF OUT

7

REF IN

+

V

IN

–

120 VAC

(+) IN HI

(–) IN LO

DATEL

UPA-5/500

11

12

+5V SUP

AC to DC Converter

Figure 2. Single-Ended Input Configuration

3

DMS-30PC

3½ DIGIT, LED DISPLAY DIGITAL PANEL VOLTMETERS

Applications

2. Differential Input Configurations: Differential measurements
can be made with all DMS-30PC 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.

REF OUT

REF IN

120 VAC

8

7

DP1

6

DATEL

UPA-5/500

AC to DC Converter

DMS-30PC-1

1

+5V SUP

Figure 3. Differential Input Configuration

3

5V RET

11

(+) IN HI

12

(–) IN LO

R1
1k

R2
1k

R3
1k

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.

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.

DMS-30PC-1

DP1

6

1

13

3

5V RET

DMS-30PC-1

5V RET

DP1

8

REF OUT

7

REF IN

8

REF OUT

7

REF IN

6

1.5V

CELL

1.5V

CELL

120 VAC

11

(+) IN HI

+

12

(–) IN LO

DATEL

UPA-5/500

12

+5V SUP

–

AC to DC Converter

Figure 5. Floating Input Measurements

11

(+) IN HI

ANA COMM

(–) IN LO

10

12

+5V SUP

+

–

50kΩ < R1 + R2 < 10MΩ

R2

x VIN = Reading

R1 + R2

+

V

–

IN

120 VAC

R1

(+) IN HI

R2

(–) IN LO

DATEL

UPA-5/500

AC to DC Converter

11

12

DMS-30PC-1

1

+5V SUP 5V RET

3

8

REF OUT

7

REF IN

Figure 4. Input Attenuation Circuit

4. Floating Signal Source Measurements: Floating signals can

be measured using the circuits shown in Figures 5 and 6.

120 VAC

DATEL

UPA-5/500

AC to DC Converter

Figure 6. Floating Input Measurements

(Alternate Configuration)

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-30PC 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:

Shunt = R1 = VFsr/IFsr

R

Where: VFsr = Full scale reading (in Volts)

I

Fsr = Relative full scale current (in Amps)

4

3½ DIGIT, LED DISPLAY DIGITAL PANEL VOLTMETERS

Applications

DMS-30PC

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

R

Shunt = 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 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 RShunt accordingly.

9

1.23V
REF

DMS-30PC-1

1

5V SUP

3

5V RET

+

4-20mA

–

120 VAC

11

(+) IN HI

10

ANA COMM

R1

DATEL

UPA-5/500

AC to DC Converter

12

(–) IN LO

R2

50k

Figure 7. 4-to-20mA Current Loop Operation

8

REF OUT

7

REF IN

protection features: reverse polarity, short circuit and thermal run­away. When using other, higher-power, DMS-30PC 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 0.1Ω 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.

1

+5V SUP

+

5Vdc

–

3

5V RET

6

DP1

1.5 Amp (Load Current)

Figure 9. Basic DC Ammeter Circuit

DMS-30PC-0-YS

12

(–) IN LO

0.150V

0.1

R

Shunt

8

REF OUT

7

11

(+) IN HI

Load

Ω

(3.3 )

REF IN

Ω

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-30PC-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. The
LM-2931 was chosen because it has the following on-chip

+

4.5 - 18Vdc

–

LM2931Z-5

IN

OUT

GND

22µF

10V

(+) IN HI

1

+5V SUP

5V RET

DP2

3

5

+

11

7

REF

IN

DMS-30PC-2-RL

8

REF
OUT

12

(–) IN LO

8. External Gain Adjustment: Connect REFERENCE OUT
(pin 8) to REFERENCE IN (pin 7) for normal, factory calibrated,
operation. Use the +1.23V REFERENCE OUT (pin 9) f or
applications needing external gain adjustment. Figure 10 shows
the wiring configuration for each model. Calibration is performed
with a precise, near-full-scale, input voltage.

VOLTAGE

12

CALIBRATOR

OUT

COM

Figure 10. External Gain AdjustmentFigure 8. 4.5- 18V Power Supply Monitor

(+) IN HI

5V RET

(–) IN LO

ANA COMM

11

3

12

10

DMS-30PC

8

NC

8.45k, 1%

1k

10 to 20 Turns

7

REF IN

1k

10 to 20 Turns

8.45k, 1%

9

1.23V REF

for ±2V, ±20V

and ±200V models

Connections

for ±200mV

Connections

models

5

DMS-30PC

3½ DIGIT, LED DISPLAY DIGITAL PANEL VOLTMETERS

Mechanical Specifications

MECHANICAL DIMENSIONS: Inches (mm)
TOLERANCES: 2 PL DEC ±0.02 (±0.51)

LEAD DIMENSIONS: 0.025 (0.635) x 0.025 (0.635) NOMINAL
RECOMMENDED PC BOARD FINISHED HOLE DIAMETER:

3 PL DEC ±0.010 (±0.254)

0.042 ±0.003 (1.067 ±0.076)

PIN 1

CALIBRATION POTENTIO M ETER HOLE LOCATION

0.125 (3.175) D IA M ETE R

(U SE ON LY W HEN PC BOARD M OU NTIN G)

0.250
(6.35)

0.260
(6.60)

0.92

(23.4)

0.84

(21.3)

PIN #1

ID EN TIFIER

+5V SUPPLY

DISPLAY TEST

5V RETURN

DP3
DP2
DP1

DM S-30PC-X-XX

MADE IN USA

FRO NT V IEW

1
2
3
4
5
6

DP1

DP2

2.17

(55.1)

2.09

(53.1)

®®

12

( ) IN P U T L O

11

(+ ) IN P U T H I

10

ANALOG COM MO N

9

+1.23V REFERENCE OUT

8

REFERENCE OUT

7

REFERENCE IN

DP3

0.040
(1.02)

OPTIONAL BEZEL (DMS-BZL1 and DMS-BZL2)

0.187
(4.75)

FRONT VIEW

#2-56 INSERT

0.156 (3.96) DEEP

2.55 (64.77)

RECOMMENDED DRILL AND PANEL CUTOUT DIMENSIONS

INTERNAL CORNER RADII:

0.032 (0.81) MAX.

1.270

(32.26)

0.116
(2.95)

0.17
(4 .3 )
TYP.

0.50

(12.7)

0.10
(2 .5 )
TYP.

0.040
(1.02)

1.80

0.040

(1.02)

(45.7)

BEZEL INSTALLATION

MADE IN USA

BEZEL

RETAINING CLIP INSTALLATION

0.560

(14.22)

0.25 (6.4) TY P.

0.15
(3 .7 )
TYP.

PANEL

®®

1.07

(27.18)

0.093 (2.362) DIAMETER (4 REQUIRED)
ONLY WHEN USING OPTIONAL BEZEL ASSEMBLY

PANEL CUTOUT

2.118 (53.80)

2.35 (59.69)

0.878

(22.30)

0.096
(2.44)

PANEL

® ®

®®

ISO 9001

ISO 9001

REGISTERED

DATEL, Inc. 11 Cabot Boulevard, Mansfield, MA 02048-1151
Tel: [phone] [phone] Fax: [phone]
Internet: www.datel.com Email: [e-mail]
Data sheet fax back: [phone]

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.

DATEL (UK) LTD. Tadley, England Tel: [phone]
DATEL S.A.R.L. Montigny Le Bretonneux, France Tel: [phone]
DATEL GmbH München, Germany Tel: [phone]
DATEL KK Tokyo, Japan Tel: [phone], Osaka Tel: [phone]

DS-0258D 1/98