DMS-20PC Просмотр технического описания (PDF) - Murata Power Solutions

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производитель

DMS-20PC

3½ Digit, LED Display, Low-Cost, Subminiature Digital Panel Voltmeters

Murata Power Solutions 

APPLICATIONS

Example: For a meter with a 2V full scale input (1.999 full scale

reading) and a desired display reading of "1000" (with an

input of 20mA), VFsr = 1.000 Volts

RShunt = 1.000V/(0.020 – 0.004)A

RShunt= 1.000V/0.016A = 62.5 Ohms

To calibrate the circuit of Figure 7, perform the following:

1. With 4mA applied, adjust the 50kΩ potentiometer (R2) to

display a reading of "000" (assuming that is the desired

reading).

2. With 20mA applied, adjust the gain-adjust potentiometer

on the back of the meter to display a reading of "1000".

For different full scale readings, alter the value of RShunt

accordingly.

11

(+) IN HI

10

ANA COMM

DMS-20PC-1

8

REF OUT

4-20mA R1

–

12

(–) IN LO

1

R2

+5V SUP

50k

7

REF IN

2

DISPLAY

ENABLE

3

5V RET

DATEL

85-264Vac DMS-PS1-CM

AC to DC Converter

Figure 7. 4-to-20mA Current Loop Operation

6. Power Supply Monitoring: One of the most common digital

panel meter applications involves monitoring the output voltage

of the system power supply — often this supply also powers the

meter itself. The low-power, red LED DMS-20PC-2-RL can be

configured to allow power supply monitoring over the range of

4.5-18Vdc. The circuit in Figure 8 uses a low-drop-out, three-ter-

minal regulator (LM-2931Z-5, available from National Semicon-

ductor) to provide regulated 5V-power to the meter.

LM2931Z-5

IN OUT

+

GND

+

4.5 - 18Vdc

22μF

–

10V

DMS-20PC-2-RL

1

+5V SUP

2

DISP EN

3

5V RET

11 (+) IN HI

5

DP2

7

REF

IN

8

REF

OUT

12

(–) IN LO

Figure 8. 4.5-18V Power Supply Monitor

DMS-20PC Series

3½ Digit, LED Display, Low-Cost, Subminiature

Digital Panel Voltmeters

The LM-2931 was chosen because it has the following on-chip

protection features: reverse polarity, short circuit and thermal

runaway. When using other, higher-power, DMS-20PC models

with three-terminal regulators, be sure to consult the regula-

tor manufacturer's data sheet to ensure the regulator is being

utilized safely and correctly.

7. Digital Ammeter: Digital ammeters are finding ever-increasing

usage because analog-style ammeters (moving-vane types)

now cost roughly the same as their digital counterparts. Addi-

tionally, analog ammeters are not nearly as rugged as modern

digital panel voltmeters. Figure 9 illustrates a typical ammeter

application. The circuit uses a ±200mV input meter — the

preferred range for most ammeters — to measure the voltage

developed across a 0.1Ω current shunt. The circuit shown

represents a basic ammeter connection diagram. A detailed

application note describing digital dc ammeters is included in

DATEL's new Digital Panel Meter Databook.

+

5Vdc

–

1

+5V SUP

2

DISP EN

DMS-20PC-0

8

REF OUT

3

5V RET

6

DP1

12

(–) IN LO

7

REF IN

11

(+) IN HI

1.5 Amp (Load Current)

0.150V

0.1W

RShunt

Load

(3.3 W)

Figure 9. Basic DC Ammeter Circuit

8. External Gain Adjustment: Connect REFERENCE OUT

(pin 8) to REFERENCE IN (pin 7) for normal, factory calibrated,

operation. Use the circuit shown in Figure 10 for applications

needing external gain adjustment. Calibration is performed

with a precise, near-full-scale, input voltage.

OUT

12

VOLTAGE

CALIBRATOR

COM

11

(+) IN HI

3

5V RET

DMS-20PC-1

1

+5V IN

12

(–) IN LO

10

ANA

COMM

8

7

NC REF

IN

8.06k, 1%

Connections

for ±2V, ±20V

and ±200V models

2k 1 17.4k, 1%

732, 1%

200 1

24.3k, 1%

Connections

for ±200mV

models

1 = 10 to 20 Turns

Figure 10. External Gain Adjustment

www.murata-ps.com

Technical enquiries email: sales@murata-ps.com, tel: +1 508 339 3000

MPM_DMS_20PC.D02 Page 5 of 6

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