www.murata-ps.com
DMS-40PC Series
4½ Digit, LED Display Digital Panel Voltmeters
FEATURES
Precision, autozeroing, factory-calibrated A/D converter
Scientific-grade accuracy, ±2 counts
Miniature size: 2.17" x 0.92" x 0.56"
55mm x 23mm x 14mm
Large (0.52"/13.2mm) LED display
Choice of red, green or yellow colors
High-intensity or low-power red LED's optional
Single +5V supply (175mW for low-power models)
Epoxy-encapsulated, 12-pin DIP with built-in color filter
and bezel
differential input voltage ranges
3
DISPLAY HOLD and TEST functions
Optional BCD data outputs for CPU interface
to +50°C temperature range
0
DMS-40PC Series, 4½ Digit, LED Display, Miniature DPM’s are fully self-contained,
component-like, plug-in meters that provide scientific-grade accuracy (typically ±2 counts
or ±0.005% of full scale) and outstanding reliability at a very affordable price.
Within its miniature (2.17” x 0.92” x 0.56”), epoxy-encapsulated package, each meter
contains a precision reference circuit; a high-resolution, autozeroing, factory-calibrated
A/D converter; and a large (0.52”/13.2mm), easy-to-read, LED display. LED’s are available
in red, yellow and green colors. Red LED’s are also offered in high-intensity or low-power
versions.
The versatile design of the DMS-40PC Series assures trouble-free installation and
long-term operation. Differential input voltage ranges include ±2V, ±20V and ±200V. Input
impedance is a minimum 800kΩ. Non-inverting inputs are overvoltage protected to ±250V,
and CMRR is typically 86dB (dc to 60Hz).
The DMS-40PC's epoxy-encapsulated package has an integral bezel and color filter.
The moisture and vibration-proof package is extremely rugged and well suited for harsh
environments and extended temperatures. Devices are fully specified for
0 to +50°C operation.
All models operate from a single +5V supply and typically consume 500mW. Low-
power models, whose display is just as bright as standard models, typically consume
175mW. DISPLAY TEST and HOLD functions are standard on each meter, and a complete set
of BCD outputs are optional for sending data to CPU's or remote displays.
+5V
1
+5V SUPPLY
–5V
2
DISPLAY TEST
DC/DC
CONVERTER
V–
V+
R2
1
12
(–) INPUT LO
0.01µF
R1
909k
11
(+) INPUT HI
10 ANALOG
COMMON
3
5V RETURN
0 Vdc
A/D
CONVERTER
2.5V
REF.
4
DP 3
DATA
9
5
DP 2
8
DP4
6
DP 1
+5V
7
REFERENCE IN/OUT
1
DISPLAY HOLD
R2 is not used on ±2V (-1) models.
R2 = 101k on ±20V (-2) models and 9.2k on ±200V (-3) models.
For full details go to
www.murata-ps.com/rohs
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MPM_DMS-40PC.D02
Page 1 of 6
DMS-40PC Series
4½ Digit, LED Display Digital Panel Voltmeters
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-40PC-1
DMS-40PC-2
DMS-40PC-3
Input Impedence:
DMS-40PC-1
DMS-40PC-2, -3
Overvoltage Protection
➀
Common Mode Voltage Range
CMRR
(dc to 60Hz)
Control Inputs
➁
Decimal Pt. Placement
(Pins 4-6, 8)
Display Test
(Pin 2)
Display Hold
(Pin 9)
BCD Outputs
➂
Logic Levels
(1 LSTTL load max.):
Logic “1”
Logic “2”
Performance
Sampling Rate
Accuracy
(3 minute warm-up):
DMS-40PC-1 (Vin = +1.9V)
DMS-40PC-2 (Vin = +19V)
DMS-40PC-3 (Vin = +190V)
Zero Reading
(Vin = 0 Volts)
Temperature Drift
(0 = +50°C)
DMS-40PC-1
DMS-40PC-2, -3
Power Supply Requirements
Supply Voltage
Supply Current:
Standard Models
➃
Low-Power Models
Display
Display Type and Size
Polarity Indication
Overrange Indication
Physical/Environmental
Operating Temperature
Storage Temperature
0
–20
–
–
+50
+75
°C
°C
4½ digit, 0.52"/13.2mm high LED
Autopolarity ("–" for negative Vin)
"–0000" (flashing) for negative Vin
"0000" (flashing) for positive Vin
–
–
+100
+35
+140
+50
mA
mA
+4.75
+5.00
+5.25
Volts
–
–
±0.4
±0.4
±1
±1.5
Cnts/°C
Cnts/°C
–
–
–
“–001”
±2
±3
±3
“000”
±3
±4
±4
“001”
Counts
Counts
Counts
2.5 reading per second
+2.4
–
–
+0.4
–
+0.8
Volts
Volts
Tie to pin 3 to activate
Tie to pin 3 to activate all segments
Tie to pin 3 to hold last reading
–
–
–
–
100
0.8
–
–
–
1000
1
–
–
86
–
–
±250
±2
–
MΩ
MΩ
Volts
Volts
dB
±2
±20
±200
–
–
–
Volts
Volts
Volts
Min.
Typ.
Max.
Units
Humidity (non-condensing)
Case Material
Weight
0
–
95
%
Polycarbonate
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.
➂
BCD outputs are optional and must be specified in the part number.
See Ordering Information.
➃
Includes high-intensity and BCD-output models.
Ordering Information
DMS-40PC - 1 - R S - C
Add -C for RoHS
LED Color:
GS
= Standard Green
RH
= High-Intensity Red
RL
= Low-Power Red
RS
= Standard Red
YS
= Standard Yellow
See
www.murata-ps.com/dpm-availability
for model-specific availability.
Input Range:
1
= ±2V
2
= ±20V
3
= ±200V
BCD Output Models:
BCD outputs are only available on the following red meters.
DMS-40PC-1-RS-BCD-C
for ±2V input range
DMS-40PC-2-RS-BCD-C
for ±20V input range
DMS-40PC-3-RS-BCD-C
for ±200V input range
DMS-40PC-1-RL-BCD-C
for ±2V input range
DMS-40PC-2-RL-BCD-C
for ±20V input range
DMS-40PC-3-RL-BCD-C
for ±200V input range
Accessories:
DMS-30-CP
Panel cutout punch
DMS-BZL1-C
DMS-40 bezel assembly
DMS-BZL2-C
DMS-40 bezel assembly with sealing gasket
DMS-EB-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
1. ANALOG COMMON (Pin 10):
This pin is an internal, low-noise
ground for the DMS-40PC. It is internally connected to pin 3
(5V RETURN). Do not connect pin 10 to either pin 3 or your system
ground as this will create a ground loop and possibly result in errone-
ous readings.
2. REFERENCE INPUT/OUTPUT (Pin 7):
This pin accesses the meter’s
internal reference and is used during the factory calibration proce-
dure. Pin 7 should be left open in most common applications. It can
be used in certain “ratiometric” applications in which it is desirable
for the meter’s reference to track an external reference. See Ap Note
DMS-AN3 at http://www.murata-ps.com/data/meters/dms-an3.pdf.
3. DISPLAY TEST (Pin 2):
Connecting pin 2 to ground (pin 3, 5V
RETURN) will activate all LED segments, and the display will read
“–18888” regardless of the actual applied input. To reduce self-
heating, the display should not be left in the “test” mode for more
than 10 seconds. This pin should be left open if unused.
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MPM_DMS-40PC.D02
Page 2 of 6
DMS-40PC Series
4½ Digit, LED Display Digital Panel Voltmeters
4. DISPLAY HOLD (Pin 9):
For normal operation, this pin should be left
open. To hold the meter’s last reading and display it continuously, tie
pin 9 to ground (pin 3, 5V RETURN).
5. Decimal Point Placement:
The location of the decimal point is user-
selectable, and the decimal point control pins (DP1-DP4) are active
low functions. Select the appropriate decimal point by tying pin 4,
5, 6 or 8 to pin 3 (5V RETURN). Unused decimal point location pins
should be left open.
Hard wiring is preferable, however, you can exercise dynamic control
over the location of the decimal point by employing drive circuits that
are capable of sinking a minimum of 20mA at voltages less than +0.4
Volts.
6. Gain Adjust:
There is a gain-adjust potentiometer on the back of
each meter. It has approximately ±150 counts of adjustment range.
Since these meters 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 adjust-
ments are most effective when performed with higher level input
signals.
7. Soldering Methods:
All models in the DMS-40PC 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.
8. Suggested Mating Connectors:
Panel mounted:
Connector housing
Terminal type
Crimping tool
Wire size
Insulation diameter
Stripping length
Board mounted:
Socket
1. Single-Ended Input Configurations:
The DMS-40PC can measure
single-ended signals with either positive or negative polarities. True
single-ended inputs always have one of their two terminals at the
same potential as the DMS-40PC’s 5V RETURN (pin 3). Single-ended
inputs are usually derived from power supplies that have a common
ground with the meter’s +5V supply. Figure 2 shows the recom-
mended connections to be used with this type of input. Pin 12, (–)
INPUT LO, is shown directly tied to ground. This connection to ground
must be a separate wire or pc-board trace originating at V
IN
’s negative
terminal. This hook-up will normally eliminate display instabilities and
errors caused by ground-loop currents which can occur if
(–) INPUT LO is tied to ground at, or near, pin 3.
DMS-40PC-1-GS
show up as unstable display readings. When an input signal, assumed to
be exactly zero volts, has a 1mV (0.001V) ground-loop induced offset, it
is displayed as “0010” on a ±2V input-range meter! See
Ap Note DMS-
AN2 at http://www.murata-ps.com/data/meters/dms-an2.pdf
describing
power supply wiring and ground loop avoidance techniques.
The DMS-40PC’s simplified schematic, shown in Figure 1, can be very
useful when debugging a malfunctioning circuit, especially 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). Figure 1 shows that input
signals applied to (–) INPUT LO and (+) INPUT HI must to be kept within
the ±5V power-supply rails. Also note that only pin 11 has a current-
limiting 909kΩ series resistor. High input voltages that have a common
ground connection 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 more noteworthy features is that it
shows some DMS-40PC internal voltage values and also 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
using digital multimeters to perform system-level measurements. The
multimeter’s negative lead (usually the black one) must always be con-
nected to pin 3 (5V RETURN). This is the only way accurate readings can
be made, particularly if the meter is configured for a differential input and
concerns arise regarding common-mode voltages.
Murata Power Solutions P/N 4320-01069-0
Murata Power Solutions P/N 4400-01032-0
Murata Power Solutions P/N 39-2099000
22 to 26 AWG
0.062" (1.57mm) maximum
0.100 to 0.125” (2.54 to 3.17mm)
Murata Power Solutions P/N 4320-01074-0
APPLICATIONS
DMS-40PC Series meters are high-precision versatile devices that
can be used in many applications requiring a 0 to 19,999 count digital
display. The application circuits chosen for this section are ones that
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.
All inputs applied to DMS-40PC meters must be steady, dc values,
otherwise the input itself may cause display instabilities. Due to their 4½
digit resolution, DMS-40PC meters must be wired with greater care than
their 3½ digit counterparts. Correct power-supply and input-signal wiring
— an absolute must! — helps eliminate ground-loop induced errors that
11
(+) IN HI
+
V
IN
–
12
(–) IN LO
1
+5V SUP
6
DP1
3
5V RET
120 VAC
AC to DC Converter
Figure 2.
Single-Ended Input Configuration
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MPM_DMS-40PC.D02
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DMS-40PC Series
4½ Digit, LED Display Digital Panel Voltmeters
APPLICATIONS
2. Differential Input Configurations:
Differential inputs can also be
measured with DMS-40PC meters as shown in the circuit of Figure
3. Differential inputs must also originate from power supplies that
have a common ground with the meter’s 5V RETURN (pin 3). However,
differential inputs usually have both terminals above and/or below
5V RETURN. Figure 3, though not necessarily a typical real-world
application, does serve the purpose of illustrating the concept of a
differential signal.
The voltages developed across R1, R2 and R3 are equal to each other
and measure approximately +1.6666Vdc or 1/3 of the +5V power
source. More importantly, while the signal across R3 is single-ended,
both ends of R1 and R2 are well above ground and are described
here as being differential. Please note that while the DMS-40PC can
measure the voltages across either R2 or R3, it cannot measure
the +1.6666 volts across R1! The voltage at the lower end of R1 is
approximately 3.333V and this exceeds the common mode voltage
limit of ±2V.
When using other, higher-power, DMS-40PC models in combina-
tion with three-terminal regulators, be sure to consult the regulator
manufacturer’s data sheet to ensure the device is being utilized safely
and correctly.
LM2931T-5
IN
OUT
GND
4.5 - 18Vdc
22µF
10V
(+) IN HI
11
1
+5V SUP
DMS-40PC-2-RL
+
–
+
3
5V RET
5
DP2
12
(–) IN LO
Figure 4. 4.5-18V Power Supply Monitor
DMS-40PC-1-GS
11
(+) IN HI
R1
1k
DP1
12
(–) IN LO
R2
1k
1
+5V SUP
3
5V RET
R3
1k
4. Floating Signal Source Measurements:
A floating input is a signal
that, before it is applied to the DMS-40PC’s inputs, has no galvanic
connection (direct current path) to the meter or the meter’s power
supply. The circuit shown in Figure 5 illustrates the necessary con-
nections for measuring floating inputs. The 1.5V battery represents a
true floating input signal since it initially has no connection whatso-
ever in common with the meter. Real-world floating inputs typically
originate from power supplies which are transformer isolated from
the DMS-40PC’s +5V supply.
The connection of pin 12 ((–) INPUT LO) to pin 10 (ANALOG COMMON)
is required in order to provide a bias return for the meter’s input
amplifier. This is because neither pin 11 nor pin 12 are tied to any
reference voltage inside the DMS-40PC (see Figure 1). These connec-
tions are not made internally in order to give the meter the ability
to
make differential measurements as described in a previous section.
11
(+) IN HI
10
ANA COMM
12
(–) IN LO
3
5V RET
6
DP1
120 VAC
AC to DC Converter
Figure 3.
Differential Input Configuration
3. Power Supply Monitoring:
One of the most widely used digital panel
voltmeter applications is monitoring the output voltage of a system
power supply — often the same supply that also powers the meter.
The low-power, red LED DMS-40PC-2-RL, with its excellent 0.001Vdc
resolution, can be configured to monitor power supplies with outputs
in the range of 4.5-18Vdc. The circuit in Figure 4 uses a low-drop-
out, three-terminal regulator (LM-2931T-5, in a T0-220 package,
available from National Semiconductor) to provide regulated 5V
power to the meter.
The LM-2931 was chosen because it has the following on-chip pro-
tection features: reverse polarity, short circuit and thermal runaway.
The DMS-40PC-3-RL can monitor voltages up to ±200Vdc, provided
a separate +5V power source is used since many three-terminal
regulators cannot operate with supply voltages greater than 24V. Red,
low-power LED models, with their very low self-heating, are recom-
mended for applications in which low calibration drift is desirable.
DMS-40PC-1-GS
1.5V
CELL
+
–
1
+5V SUP
120 VAC
AC to DC Converter
Figure 5.
Floating Input Measurements
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DMS-40PC Series
4½ Digit, LED Display Digital Panel Voltmeters
APPLICATIONS
5. Engineering Scaling and Input Attenuation:
In many applications,
the input signal must be scaled, or divided down, before being applied
to the DMS-40PC. In some situations, the input signal exceeds the
full-scale range of the meter, and in other applications, a direct
one-to-one relation does not exist between the input voltage and
the desired display reading. For an example of the second situation,
assume an input voltage of 1.0Vdc is required to display a reading of
“7500” when applied to a ±2V input meter. An input divider circuit,
constructed with two series resistors with an output-to-input ratio of
0.75, will scale the 1.0V signal down to 0.75V.
Engineering scaling and input attenuation are discussed in Ap Note
DMS-AN4 at http://www.murata-ps.com/data/meters/dms-an4.pdf.
Compensating for inputs which have a zero offset is also discussed.
6. BCD Outputs (DMS-40PC-X-RS and -RL-BCD Models Only):
Models with a “-BCD” suffix have 12 extra output pins, labeled
A through L (6 per side), that provide the following information: mul-
tiplexed serial BCD data, digit drive, and polarity indication. The data
present on pins A - L simultaneously drives the meter’s internal LED
display. All functions on pins A - L are 5V CMOS compatible, however,
they are only rated to drive one, 74LS series, TTL load. CMOS logic
IC’s, for example 74HC or 74HCT series devices, should be used when
more fan-out capability is required.
As the timing diagram in Figure 5 indicates, 100Hz is the optimum
display scan rate when the BCD outputs are used to drive external
LED displays. Faster scan rates, while permissible, are not necessary.
Slower scanning, however, may result in noticeable “flickering” of
the display. Common anode LED’s, combined with a 74LS247 BCD
to seven-segment decoder, is the simplest way of implementing an
external display. A seventy-five to one-hundred Ohm resistor on each
LS247 segment-drive output provides adequate display brightness.
The functions of pins A - L are listed below:
BCD DATA (pins I - L):
Four lines are used for BCD (Binary Coded
Decimal) data outputs, representing the numbers 0 - 9. Positive-logic
convention (a high represents a “1”) is used.
DIGIT DRIVE ( pins A - E):
These five outputs, when gated with STROBE,
can be used to direct the BCD DATA into external latches. DIGIT DRIVE
outputs may also be connected directly to the bases of NPN transistors
in remote-display configurations. The digits are scanned right-to-left, i.e.,
MSD (DIGIT 1 DRIVE) to LSD (DIGIT 5 DRIVE).
BUSY (pin G):
This is a status pin that goes high at the start of an ana-
log-to-digital (A/D) conversion cycle and remains high until the conver-
sion ends.
STROBE (pin H):
A string of five sequential, active-low, STROBE pulses
are output (after BUSY goes low) indicating the end of a conversion and
the availability of new data. The 5 STROBE pulses occur only once per
conversion, or 2.5 times each second. STROBE can be used to latch the
BCD data (on pins I - L) into external latches. Either edge can be used
since STROBE (~ 5μsec wide) is active only in the center of the cor-
responding DIGIT DRIVE and BCD DATA outputs.
POLARITY (pin F):
This pin, which is also used inside the DMS-40PC to
drive the negative-sign segment, indicates whether the last input signal
conversion was positive (POLARITY set high) or negative (POLARITY set
low). POLARITY, unlike BCD DATA, is not multiplexed. For data latching
purposes, POLARITY should be sampled during the STROBE pulse for
digit 1 (most significant digit).
Approx. 8msec
Approx. 2msec
Approx. 2msec
DIGIT DRIVE 1
(MSD)
DIGIT DRIVE 2
DIGIT DRIVE 3
DIGIT DRIVE 4
DIGIT DRIVE 5
(LSD)
BUSY
Approx. 5µsec
STROBE OUT
Data from
Previous Conversion
BCD DATA
(4 LINES)
1
MSD
2
3
4
5
LSD
1
2
3
4
5
5 Strobes Only Per Conversion
Figure 6.
BCD Data Timing Diagram
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