Martel Electronics DPM750S-BL User Manual

Page 2 of 4

DPM 750S-BL

3½ Digit Backlit LCD Voltmeter Module

The DPM 750S-BL features a 200mV d.c. measurement range with auto-zero and auto-polarity. Decimal points are
user selectable.

The meter features a negative rail generator which enables the meter to measure a signal referenced to
its own power supply GND. A low drift bandgap reference circuit ensures accurate readings over a wide temperature
range. low cost means it will

LED backlighting ensures excellent readability under low light conditions. The module's
suit high and low volume applications. This module is supplied with a plastic mounting bezel. A waterproof seal to
IP67 / NEMA 4X is achievable, using the optional BEZ 700-IP bezel.

FEATURES

• 12.7

mm (0.5") Digit Height

• 200mV d.c. Full Scale Reading

• 3.0 to 7.5V or 6.0 to 15V d.c. Operation

•

Auto-zero and Auto-polarity

•

Programmable Decimal Points

•

LED Backlighting (30mA @ 5V typ.)

• Low Battery Warning

• Bandgap Reference

°°

CF

µA

mV

kΩ

MH

z

TYPICAL APPLICATIONS

• Precision Instrumentation Systems

• Power Supply Monitoring

• Test Boxes

ORDERING INFORMATION

Stock Number
Standard Meter DPM 750S-BL
IP67 / NEMA 4X Bezel BEZ 700-IP

• Panel-Mount Indication

• Low Power Voltage Measurement

ELECTRICAL SPECIFICATIONS

Specification Min. Typ. Max. Unit

Accuracy (overall error) * 0.1 % (±1 count)
Linearity ±1 count
Sample rate 2.5 samples/sec
Operating temperature range 0 50 °C
Temperature stability 50 ppm/°C
Supply voltage V+ to GND configuration 3 5 7.5 V d.c.

Supply current V+ to GND configuration 500 A

Backlight supply voltage 4.75 5.0 ** V d.c.
Backlight supply current @ 5V d.c. 30 mA
Input leakage current (Vin = 0V) 1 10 pA

* To ensure maximum accuracy, re-calibrate periodically.

** An external series resistor is required above 5V, see Applications.

*** This specification linearly derates to 30mA @ 50°C.

V+ to V- configuration 6 9 15 V d.c.

µ

V+ to V- configuration

350 A

50 ***

µ

SAFETY

To comply with the Low Voltage Directive (LVD93/68/EEC), input voltages to the module’s pins must not exceed
60Vdc. The user must ensure that the incorporation of the panel meter into the user’sequipment conforms to the
relevant sections of BS EN 61010 (Safety Requirements for Electrical Equipment for Measuring, Control and
Laboratory Use).

LASCAR ELECTRONICS LTD.
MODULE HOUSE
WHITEPARISH
WILTSHIRE SP5 2SJ
UK
TEL: [phone]
FAX: [phone]
E-mail: [e-mail]

LASCAR ELECTRONICS INC.
3750 West 26th Street
Erie
PA 16506
USA
TEL: [phone]
FAX: [phone]
E-mail: [e-mail]

PO Box 770, Londonderry, NH 03053 1-800-821-0023

www.lascarelectronics.com

www.martelcorp.com

LASCAR ELECTRONICS (HK) LIMITED
FLAT C, 5/FL., LUCKY FTY. BLDG.
63-65 HUNG TO ROAD
KWUN TONG KOWLOON
HONG KONG
TEL: [phone]
FAX: [phone]
E-mail: [e-mail]

Page2of4

Page1of4

page 1 of 4

Page 2 of 4

DPM 750S-BL

DIMENSIONS

All dimensions in mm (inches)

3½ Digit Backlit LCD Voltmeter Module

34.5 (1.36)

64.5 (2.54)

Panel cut-out: 62.0 - 32.0

(2.44 - 1.26)

PANEL FITTING

Panel thickness: 1.0 - 3.0

(0.04 - 0.12)

25.0 (0.98)

53.0 (2.17)

46.7 (1.84)

60 (2.36)

2.8 (0.11) dia

6.1 (0.24)

30 (1.18)

17.7 (0.7)

6.1

(0.24)

1.6 (0.06)

(0.26)

1.6

(0.06)

6.5

9.5

(0.37)

Insulating
Washer

FUNCTIONAL BLOCK DIAGRAM

V+

Vref

COM

INHI

INLO

CAL

BL-

+

_

A/D

8

1

Shake-proof
Washer

21

3

PIN CONFIGURATION (rear view)

Vm°CA°FµMkOhmHz:

CAL

V+

GND

(0.1)

LCOM

BL-

INHI

INLO

DP1

Rb
Ra

DP2

DP3V-COM

~

La

101

18.6 (0.73)2.54

6.3

(0.25)

V-

DP321GND

Page2of4

PO Box 770, Londonderry, NH 03053 1-800-821-0023

www.lascarelectronics.com

www.martelcorp.com

Page2of4

page 2 of 4

DPM 750S-BL

CIRCUIT DIAGRAM

1

4

5

10

LCOM

3½ Digit Backlit LCD Voltmeter Module

XDP

2

BC847

BC847

V+

33

3

9

6

7

8

PIN FUNCTIONS

1. V+ Positivepower supply to the meter andLEDbacklighting.

2. GND 0V powersupplyto the meter.

3. BL- Negativepowersupplyconnectionto the LED backlighting.

4. INHI Positivemeasuring input.

5. INLO Negative measuring input.

6. DP1 Connect toV+todisplayDP1 (199.9).

7. DP2 Connect toV+todisplayDP2 (19.99).

8. DP3 Connect toV+todisplayDP3 (1.999).

9. V- Negative power supplytothe meter.

10. COM Ground foranaloguesection of A/D converter.
It isactivelyheldat3.05V (nom.) below V+ and mustnotbeallowed to sink excessive
current (>100 A) by,for instance, connecting to a highervoltage.

µ

LCD 600

XDP

BC847

Note:
A negative supply is generated internally and mirrors the positive supply. For example: if V+ is +5V, then the

internally generated V- is -5V. When measuring with the input referenced to the same supply rail as that of the panel
meter,thenthelimitationson the input range are (V- + 1.5V) to (V+ - 1.5V).

SOLDER LINKS

LCOM Normally Open. When soldered,connectsCOMtoINLO.
La Normally Closed. Short circuitsthescalingresistorRa.

PO Box 770, Londonderry, NH 03053 1-800-821-0023

www.lascarelectronics.com

Page3of4

www.martelcorp.com

page 3 of 4

Page 4 of 4

DPM 750S-BL

3½ Digit Backlit LCD Voltmeter Module

SCALING

Two resistors Ra and Rb
may be used to alter the
full scale reading (FSR) of
the meter - see table. The
meter will have to be re­calibrated by adjusting the
calibration potentiometer
on the rear of the module.

Voltage

Vin 200V 1M 1k

Current

I

in 20mA 0R 10R

*Ensure that Ra is rated for high voltage use.

FSR Ra Rb

2V 910k 100k

20V 1M 10k

2000V* 1M 100R

200 A 0R 1k

µ

2mA 0R 100R

200mA 0R 1R

+

Vin or inI

-

Ra

Rb

4

INHI

5

INLO

APPLICATIONS

Do not connect more than one meter to the same power supply if the meters cannot use the same signal
ground. Taking any input beyond the power supply rails will damage the meter.

3.0 to 7.5V Meter Power Supply

+3.0 to +7.5V

+

4

11 1

V+

INHI

BL-

3

±200mV

-

Measuring a single ended input voltage
referenced to supply, i.e. the input
voltage and the meter's power supply
share the same 0V rail. Ensure solder
link LCOM is open.

5

INLO

GND

22 2

6.0 to 15.0V Meter Power

+3.0 to +7.5V

+

±200mV

-

-3.0 to -7.5V

4

5

INHI

INLO

V+

V-

1

3

BL-

9

+3.0 to +7.5V

V+

44

+

INHI

±200mV

S

BL

R=

BL

V+-5V

30mA

-

5

INLO

GND

0V

Measuring an input voltage referenced to a
floating supply, i.e. the input voltage and the
meter's power supply are isolated from each
other. Ensure solder link LCOM is closed.

+6.0 to +15.0V

1

V+

4

+

INHI

±200mV

S

BL

R=

BL

V+-V--5V

30mA

-

5

INLO

V-

9

+3.0 to +7.5V

V+

5

INHI

INLO

GND

S

BL

V+-5V

BL

30mA

33

I+

BL- BL-

S

BL

R=

V+-5V R=

BL

30mA

Rb

I-

0V 0V

Measuring a current from a circuit which is
floating with respect to the DPM's supply,
i.e. the current and the meter's power
supply are isolated from each other. Ensure
solder link LCOM is closed.

BL-

+6.0 to +15.0V

3

S

BL

R=

V+-5V

BL

30mA

Rb

I-

I+

4

5

0V

INHI

INLO

V+

V-

1

R=

V+-5V

BL

30mA

3

BL-

S

BL

R

BL

9

0V

Measuring a single ended input voltage
referenced to a split supply, i.e. the input
voltage and the meter's power supply
share the same 0V rail. Ensure solder link
LCOM is open.

Specifications liable to change without prior warning DPM 750S-BL Issue 1 August/2002 M.C. Applies to DPM 750S-BL/2

Measuring an input voltage referenced to a
floating supply, i.e. the input voltage and
the meter's power supply are isolated from
each other. Ensure solder link LCOM is
closed.

PO Box 770, Londonderry, NH 03053 1-800-821-0023

www.lascarelectronics.com

www.martelcorp.com

Measuring a current from a circuit which is
floating with respect to the DPM's supply,
i.e. the current and the meter's power
supply are isolated from each other. Ensure
solder link LCOM is closed.

Page4of4

Page4of4

page 4 of 4