DMS-30LCD Series
3�½ Digit, LCD Display Digital Panel Voltmeters
should not be connected to pin 3 (5V RETURN/–BATTERY) 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/
–BATTERY). Unused decimal point location pins should be left open.
For 5V-powered models, the decimal location pins are TTL compatible
and may be hard wired as described above or driven with 5V TTL logic
gates.
4. REFERENCE OUTPUT (Pin 8) and INPUT (Pin 7):
Pin 8 is a preci-
sion reference actively trimmed at the factory. In normal operation, pin
8 must be tied to pin 7 to achieve all listed accuracy and drift specifica-
tions.
5. DISPLAY TEST (Pin 2):
(Not available on backlit models)
Connect DISPLAY TEST (pin 2) to +5V SUPPLY/+BATTERY
(pin 1) to activate. All LCD segments, exclusive of the decimal points,
will be momentarily enabled.
Do not leave the unit in the TEST
mode for more than 10 seconds as this will damage the LCD seg-
ments.
6. BACKLIGHT (Pin 2) Function:
For backlit models, grounding pin 2
(i.e. connecting it to pin 3) turns on the backlighting LED’s. 9V-pow-
ered backlit models function with supply voltages up to +14V, however,
activating the backlight with voltages greater than 9.2V can damage
the meter. Therefore, a 1/4 Watt series resistor must be installed
between pins 3 and 2 in these situations. The value of the series resis-
tor is determined using the following formula:
R
Series
=
+BATTERY – 9.2V
0.035
Example: If +BATTERY (pin 1 with respect to pin 3) is +12.6V,
R
Series
=
+12.6 – 9.2V
0.035
R
Series
= 97 Ohms
In any backlit application, including those with supply voltages
< 9.2V, the current drawn by the backlight (and therefore the current
drawn by the meter) can be reduced by installing a 1/4 Watt resistor
between pins 3 and 2. The brightness of the backlight will be reduced
proportionately.
7. 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.
Refer to Figure 9 for applications requiring greater ( ±10%) gain adjust-
ments.
Ohms
Ohms
8. Soldering Methods:
All models in the DMS-30LCD Series easily
withstand most common wave soldering operations. We recommend,
however, 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.
9. Suggested Mating Connectors:
Panel mounted:
Connector housing
Terminal type
Crimping tool
Wire size
Insulation diameter
Stripping length
DATEL P/N 39-2079400
DATEL P/N 39-2099090
DATEL P/N 39-2099000
22 to 26 AWG
0.062” (1.57mm) maximum
0.100 to 0.125” (2.54 to 3.17mm)
Board mounted:
Socket DATEL P/N 39-2359625
APPLICATIONS
DMS-30LCD meters are available in either 5V-powered or 9V-powered
models. 9V devices operate directly from 7.5V to 14V supplies (usually
batteries) without the need for external voltage regulators. 9V devices,
however, can not be used to measure voltages referenced to the negative
battery terminal (pin 3) because the minus input to the meter (pin 12, (–)
INPUT LO) must always be at least 1.5V above pin 3. 9V-powered meters
can only be used to make differential and not single-ended measurements.
5V-powered devices operate from any well-regulated +5V supply and will
accurately measure voltages both above and below pin 3 (5V RETURN) in
either single-ended or differential configurations.
1. Single-Ended Input Configurations:
True single-ended measure-
ments can only be made with 5V-powered meters. 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).
DMS-30LCD-1-5
+
V
IN
–
12
(–) IN LO
1
+5V SUP
6
DP1
3
5V RET
7
REF IN
11
(+) IN HI
8
REF OUT
120 VAC
DATEL
UPA-5/500
AC to DC Converter
Figure 2. Single-Ended Input Configuration
(5V-Powered Models)
www.murata-ps.com
Technical enquiries
email: sales@murata-ps.com, tel:
+1 508 339 3000
MPM_DMS30LCD.D01
Page 3 of 6
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