DMS-30LCD Series

3½ Digit, LCD Display Digital Panel Voltmeters

www.murata-ps.com

MPM_DMS30LCD.D01 Page 3 of 6

APPLICATIONS

Figure 2. Single-Ended Input Configuration

(5V-Powered Models)

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

Ohms

+12.6 – 9.2V

0.035

Ohms

+BATTERY – 9.2V

0.035

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.

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).

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

DATEL P/N 39-2079400

Terminal type

DATEL P/N 39-2099090

Crimping tool

DATEL 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 DATEL P/N 39-2359625

1

12

3

+5V SUP

(–) IN LO

5V RET

DATEL

UPA-5/500

120 VAC

11

(+) IN HI

6

DP1

+

–

AC to DC Converter

DMS-30LCD-1-5

8

7

REF OUT

REF IN

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: