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DMS-40LCD Series

4½ Digit, LCD Display Digital Panel Voltmeters

MPM_DMS40LCD.D01 Page 3 of 6

APPLICATIONS

1. Single-Ended Input Configurations: True single-ended measurements

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-40LCD 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 ac-

curately measure voltages both above and below pin 3 (5V RETURN) in either

single-ended or differential configurations.

8. Soldering Methods: All models in the DMS-40LCD 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 recom-

mend the use of no-clean solders.

9. Suggested Mating Connectors:

Panel mounted:

Connector housing

Murata Power Solutions P/N 4320-01069-0

Terminal type

Murata Power Solutions P/N 4400-01032-0

Crimping tool

Murata Power Solutions 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

Murata Power Solutions P/N 4320-01074-0

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 9. The brightness of the backlight will be reduced proportionately.

5. ANALOG COMMON (Pin 10): This pin is connected to an internal, low-noise,

“relative” ground. It is used in certain “floating” measurements as described in

the Applications section of this data sheet and Ap Note DMS-AN3 at

http://www.murata-ps.com/data/meters/dms-an3.pdf. Pin 10 should not be

connected to pin 3 (5V RETURN/–BATTERY) or to your system’s analog

ground.

6. REFERENCE IN/OUT (Pin 7): This pin accesses the meter’s internal refer-

ence and is used during the factory calibration procedure. Pin 7 should be

left open in most common applications. It can be used in certain “ratiometric”

applications in which it is desireable for the meter’s reference to track an

external reference.

7. Gain Adjust: There is a gain-adjust potentiometer on the back of each

meter. It has approximately ±150 counts 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.

RSeries =

Ohms

+12.6 – 9.2V

0.035

RSeries =

Ohms

+BATTERY – 9.2V

0.035

Example: If +BATTERY (pin 1 with respect to pin 3) is +12.6V,

RSeries = 97 Ohms

Figure 2. Single-Ended Input Configuration

(5V-Powered Models)

3. Low Battery Annunciator: The “BAT” annunciator in the upper left-hand

corner of the display turns on when the supply voltage for 5V-powered

models falls below the approximate range of 2.7V to 3.7V, or when the

supply voltage for 9V-powered models falls below the approximate range of

5.4 to 7.2V. This function can not be disabled.

Please note, the “BAT” annunciator is a convenience feature only. The supply

voltage ranges specified previously in the ‘Performance/Functional Specifica-

tions’ section of this data sheet must be maintained at all times in order to

ensure the DMS-40LCD meets its accuracy and stability specifications.

4. HOLD/BACKLIGHT (Pin 9) Function: For non-backlit models, connecting

pin 9 (HOLD/BACKLIGHT) to pin 3 (5V RETURN/

–BATTERY) will hold (continuously display) the last reading.

If not used, pin 9 should be left open for these models.

For backlit models, grounding pin 9 (i.e. connecting it to pin 3) turns on the

backlighting LED’s. 9V-powered 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 9 in these situations. The value of the series

resistor is determined using the following formula:

1

12

3

+5V SUP

(–) IN LO

5V RET

120 VAC

11

(+) IN HI

6

DP1

+

–

AC to DC Converter

VIN

DMS-40LCD-0/1-5

2

RANGE