Martel Electronics OEM1B-LED User Manual

OEM 1B-LED

3½ Digit LED Voltmeter Module

PRODUCT DESCRIPTION

This low cost sub-miniature LED voltmeter module is ideally suited for high volume applications. It features an exceptionally
large display in a miniature package and includes auto-zero and user-selectable decimal points. The use of low current
display technology means this LED product can be considered for battery powered applications. The OEM 1B-LED is
dimensionally compatiblewith its LCD counterpart, the OEM 1B. Connection to the module is via two rows of pins.

FEATURES

•8

mm (0.31") Digit Height

• 200mV d.c. Full Scale Reading

• 50mA (typ) @ +5V d.c. Power Supply

•

Auto-zero and Auto-polarity

• User Selectable

• DIL Pin Connection

• Size compatible with OEM 1B (LCD module)

Decimal Points

Module shown actual size

TYPICAL APPLICATIONS

• High Volume, Low Cost Systems

• Power Supply Monitoring

ORDERING INFORMATION

Stock Number

Standard Meter OEM1B - LED

• Handheld Indication

• Panel-Mount Indication

ELECTRICAL SPECIFICATIONS

Specification Min. Typ. Max. Unit

Accuracy (overall error) * 0.05 0.1 % (±1 count)
Linearity ±1 count
Sample rate 2.5 samples/sec
Operating temperature range 0 50 °C
Temperature stability 150 ppm/°C
Warm-up time 10 minutes
Supply voltage 4.75 5 5.25 V d.c.
Supply current ** 50 100 mA
Input leakage current 1 10 pA

* To ensure maximum accuracy, re-calibrate periodically.
** Depends on reading and temperature.

Unless otherwise noted, specifications apply at T =25°C, V =5Vd.c. (f =40kHz) and are tested with the module configured for floating input
mode.

A supply clock

SAFETY

To comply with the Low Voltage Directive (LVD 93/68/EEC), input voltages to the module’s pins must not exceed
60Vdc. The usermustensurethat the incorporation of the panel meter into the user’s equipment 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.martelcorp.com

www.lascarelectronics.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]

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OEM 1B-LED

DIMENSIONS

All dimensions in mm (inches)

3½ Digit LED Voltmeter Module

8.0

Viewing Area

(0.31)

23.4 (0.92)

19.5 (0.77)

Viewing Area

16.4 (0.65)

5.4 (0.21)

5.5 (0.22)

6.35

(0.25)

5.5
(0.22)

1.27 (0.05)

CAL

12.7 (0.50)

2.54 (0.10)5.0 (0.20)

FUNCTIONAL BLOCK DIAGRAM

V+

RHI

Vref

COM

RLO

IHI

ILO

+

CAL

0V

A/D

1

DP321

_

TEST

8

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

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PIN CONFIGURATION

CAL

7

6

RHI

RLO

NC

COM

DP1

ILO

DP2

IHI

DP3

V+

(rear view)

12

TEST

0V

1

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Pin 1
identifier

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OEM 1B-LED

OEM 1B-LED

CIRCUIT DIAGRAM

V+

2

IHI

3

ILO

4
5

COM

RHI

7
6

RLO

1

0V

3½ Digit LED Voltmeter Module

3½ Digit LED Voltmeter Module

DP1

9

DISPLAY

(199.9)

DP2

(19.99)

DP3

(1.999)

NC

TEST

10

11

8

NC

12

CERMET

0

PIN FUNCTIONS

1. 0V Negative power supply to the meter.

2. V+ Positive power supply to the meter.

3. IHI Positivemeasuring input.
IHI must be no closer than 1.5V to either the positive or negative supply (see Note).

4. ILO Negative measuring input.
ILO must be no closer than 1.5V to the positive supply (see Note).

5. COM

6. RLO Negative input for the reference voltage.

7. RHI Positive input for the reference voltage.

8. NC Not connected.

9. DP1 Connect to 0V to display DP1 (199.9).

10. DP2 Connect to 0V to display DP2 (19.99).

11. DP3 Connect to 0V to display DP3 (1.999).

12. TEST Connect to V+ to display all segments, except the decimal points.

Ground for the analogue section of the A/D converter. It is actively held at 3.05V (nom.) below
V+ and must not be allowed to sink excessivecurrent (>100 A) by,for instance, connecting

µ

to a higher voltage.

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, then the limitations on the input range are (V- + 1.5V) to (V+ - 1.5V).

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

www.lascarelectronics.com

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OEM 1B-LED

3½ Digit LED Voltmeter Module

EXTERNAL SCALING

Two external 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 re-calibrated
by adjusting the calibration
potentiometer on the rear of
the module.

Voltage

Vin 200V 1M 1k

Current

Iin 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

IHI

OEM 1B-LED

ILO

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.

+4.75 to +5.25V +4.75 to +5.25V

2

V+

3

+

±200mV

-

IHI

49

DP1

ILO

5

COM

0V

1

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.
Circuit shows DP1 enabled.

7805

V

supply

220nF 470nF

+5V

10uF

5

COM

V+

0V

2

IHI

ILO

1

Measuring supply voltage and current to a load.

S selectsbetween voltage and current measurement.

1

2

V+

3

+

±200mV

-

IHI

4

ILO

0V

1

0V

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.

I

Ra=1M

V

3

S

1

A

4

Rb=1k

Rs

Shunt

Load

R

L

Set Zero

220k

4

5k

4-20mA

current loop

I

+

R

I-

5

3

Measuring a 4-20mA loop current.

R= Reading at 20mA

160

The meter's power supply must be
isolated from the 4-20mA current
loop.

V+

3

4

5

IHI

ILO

COM

0V

R = 0.2

R

I

FSR

Measuring current.
The meter's supply is isolated
from the current being measured.

2

V+

ILO
COM

IHI

0V

1

+4.75 to +5.25V

2

1

0V

+4.75 to +5.25V

0V

Ra and Rb shown scaled for 200V

FSR

Rs = 200mV

I

(e.g. 0.1 / 400mW for 2A full scale)Ω

FSR

Display DP1, DP2 or DP3, by connecting to 0V,as required.

Specifications liable to change without prior warning OEM 1B-LED Issue 2 September/2002 M.C. Applies to OEM 1B-LED/1

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

www.lascarelectronics.com

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www.martelcorp.com