DMS-40LCD-4/20S Series
Ultra-Low 2.9V Loop-Drop 4�½ Digit
LCD Display Process Monitor
FEATURES
Loop-powered, no power supply required!
2.9V typical loop-drop; 190-Ohm (max.) loop
impedance
Dip-switch-selectable range, offset, and
decimal points
Hundreds of different input/readout combinations
Non-interacting gain (span) and offset (zero)
20-turn potentiometers
Large, 0.40" (10.0mm) high, sunlight-viewable
LCD digits
Miniature size: 2.17" x 0.92" x 0.90" (55mm x
23mm x 23mm)
Vibration-resistant package; reliable screw-
terminal connections
100% soldered connections
The DMS-40LCD-4/20S’s ultra-low 2.9V typical loop-drop (190-Ohm burden) makes it
ideal for use in 4-20mA process monitoring applications which have two or more series-
connected loop-monitoring devices. The low loop-burden means it can be used in current
loops that are powered from supply voltages as low as +8Vdc! The DMS-40LCD-4/20S is
self-powered; all required operating power is derived directly from the current loop itself.
It requires no separate dc power supply or special grounding considerations and can be
connected ANYWHERE in the loop!
The DMS-40LCD-4/20S's input, span, and offset circuits all employ super-stable,
±0.5% thin-film chip resistors. Long-term stability and accuracy are assured by driving
these tight-tolerance resistors with an ultra-stable, ±0.2% band-gap voltage reference.
Unlike many competitor’s designs, the two precision 20-turn span and zero adjust poten-
tiometers do not interact with one another. Its full-size, 0.40" (10.0mm) high-contrast 4�½
digit LCD display offers 19,999 counts of resolution and can be read in virtually any lighting
condition—including full sunlight!
All range-change and decimal point selections are made by configuring two gold-plat-
ed, vibration-resistant, six-position DIP switches. The two connections to the current loop
are made via a reliable, screw-type terminal block. To further enhance reliability, the design
features 100% soldered connections—no troublesome zebra/elastomercic connectors are
used. All these outstanding features make the DMS-40LCD-4/20S the highest quality, most
rugged, 4�½ digit, LCD-display process monitor available.
4�½ DIGIT A/D
CONVERTER
Range
Offset
Gain
DATA
R3
ZERO
ADJUST
R7
GAIN
ADJUST
BAND-GAP
REFERENCE
CIRCUIT
ON
ON
DP1
DP2
DP3
DP4
S1
1
2
3
4
5
6
S2
1
2
3
4
5
6
+5V
–5V
TB1
CURRENT TO
VOLTAGE
CONVERTER
+
–
DC/DC
CONVERTER
1
2
+
–
For full details go to
www.murata-ps.com/rohs
Figure 1. DMS-40LCD-4/20S Simplified Schematic
4-20mA
Current Loop Input
www.murata-ps.com
Technical enquiries
email: sales@murata-ps.com, tel:
+1 508 339 3000
MPM_DMS401LCD-420S.D02
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MURATA-PS [ MURATA POWER SOLUTIONS INC. ]
