DMS-40LCD-4/20S Series
Ultra-Low 2.9V Loop-Drop 4½ Digit
LCD Display Process Monitor
For full details go to
www.murata-ps.com/rohs
www.murata-ps.com
Technical enquiries
email: [email protected], tel:
+1 508 339 3000
MPM_DMS401LCD-420S.D01
Page 1 of 5
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 4½
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, 4½ digit, LCD-display process monitor available.
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
Figure 1. DMS-40LCD-4/20S Simplified Schematic
DATA
4½ DIGIT A/D
CONVERTER
DP3
DP2
DP1
ZERO
ADJUST
GAIN
ADJUST
CURRENT TO
VOLTAGE
CONVERTER
DP4
R3
R7
Range
Offset
Gain
S1
S2
ON
ON
1
1
1
2
3
4
5
6
2
3
4
5
6
ON
ON
1
1
1
2
3
4
5
6
2
3
4
5
6
+
–
TB1
4-20mA
–
+
DC/DC
CONVERTER
BAND-GAP
REFERENCE
CIRCUIT
+5V
–5V
1
2
Current Loop Input