Simpson Electric M145 Instruction Manual

Minimum Depth Indicator - Less than 1.25" (31.75mm)
of Space Required Behind the Panel

Fits 3/64 DIN Cutout, 22mm x 68mm

4-1/2 Digit, 0.5" (12.7mm) High LCD

User-Selectable Decimal Point

Optional Negative Image, Bright Red Backlighting

12 Pin Mating Connector With 6" Lead Wires Included
for Easy Installation

Display Hold Standard on All Units

Four Current Ranges: 200␮A, 2mA, 20mA, 200mA

Three Power Supply Alternatives: 5VDC, ±5VDC or
9VDC (With Low Battery Indication)

Mini M145 Series Digital Panel Meter

Installation and Panel Cutout

No mounting hardware required, snaps right into panel!

Mounting Requirements

The Mini indicators require a panel cutout of 2.68" (68mm) wide by 0.88"
(22mm) high, and a panel area of 0.945" (24mm) high by 2.84" (72mm)
wide. The depth behind the panel, including terminals, is 0.7" (17.8mm).
The front bezel protrudes 0.158" (4mm) from the front of the mounting
surface. The unit will snap-mount into panels from 0.050" to 0.125" thick.
A 12-pin connector with 6" wire leads is included with each unit for quick
installation.

Simpson’s Mini DC Current Indicators provide high quality,
accuracy and reliability in a compact 12mm deep case.
M145 has a 4-1/2 digit, 0.5” LCD display and is available
with a negative image, bright red backlight option. Mini
M145s feature user-selectable decimal point and display
hold.

Three power supply choices are available, and a low battery
indication is provided for 9VDC battery applications. Mini
units feature a standard 3/64 DIN, high-impact plastic case.
The standard LCD units have a clear viewing window. The
units with optional negative image, bright red backlighting,
have a red window.

DC Current

DISPLAY
Type: 7-segment LCD
Height: 0.5” (12.7mm)
Decimal point: 3-position programmable
Overrange indication: Most significant = “1”
Backlighting: Optional negative image, red

backlighting at 5, 10, 12, 24, or 48VDC
Polarity: Auto with “-” indication, “+” indication
implied

POWER REQUIREMENTS
DC Power: ±5V, +5V, and +9V

(Low battery indication provided with 9V units)

Power supply current: 2mA max
Backlight supply current: 50mA typical

For 24 and 48VDC, 10mA typical

ACCURACY @ 25°C:

±(0.04% of reading + 1 count)

ENVIRONMENTAL
Operating Temperature: 0 to 55°C
Storage Temperature: -10 to 60°C
Relative Humidity: 0 to 85% non-condensing
Warmup time: Less than 20 minutes
Temperature Coefficient: (All inputs)

⫾ (0.2% of input ⫾ 0.2 digit) /⬚C

NOISE REJECTION
NMRR: 60dB, 50/60Hz
CMRR: (with 1KV unbalanced @ 60 Hz): 90dBmin

ANALOG TO DIGITAL CONVERSION
Technique: Integrating
Rate: 3 samples/second-typical

MECHANICAL
Bezel: 0.945” x 2.835”

(24mm x 72mm)

Depth: 0.473” (12mm)
Panel cutout: 0.874” x 2.677”

(22.2mm x 68mm)

Weight: 10oz (28.3g)
Case Material: 94-VO, UL-rated ABS

Specifications

Connections

Safety Symbols

These instruments are designed for maximum safety
to the operator when mounted in a panel according
to instructions. They are not to be used unmounted
or for exploratory measurements in unknown circuits.

A reversed polarity power supply will permanently
damage this instrument.

IN HIGH and IN LOW must remain within the limits of
the power supply breakdown voltage.

No internal isolation provided. Each meter requires
an isolated power supply. Supply voltage must also
be isolated from the circuit being measured.

A positive reading will be displayed when IN Hi is
more positive than IN Low.

Internal Reference: REFOUT must always be con­nected to REFIN unless an external reference is
being used.

External Reference: Connect between REFIN and
ANALOG GROUND; REFOUT should then be uncon­nected (open). For best results, external reference
voltage should be in the range of 50mV to 150mV.
System stability is then only as good as the external
reference.

Calibration

Model M145 has two internal adjustments on the
rear panel, one that is covered by a label, and one
that is always exposed. The exposed adjustment is
a

“

fine” calibration point, and the covered adjustment
is for “coarse” calibration. Apply an appropriate cur­rent input for a near full scale reading, typically 19000
counts on the display. For these adjustments to
function, REFOUT must be connected to REFIN.
Once a unit has been calibrated with the “coarse”
adjustment, future calibrations should be performed
with the "fine" adjustment only.

Backlight Power Supply

A 2-pin connector is included with the unit if back­lighting is specified. The right pin is the Positive, and
the left pin is for the Negative power supply. See the
Rear Connections

diagram for location.

Mini M145

Rear Connections

In Hi Analog DP4 Negative REFIN DP2

Ground Supply

Positive

In Low REFOUT Supply Hold DP1 DP3

5

VDC

Input Signal

+

-

In Hi Analog DP4 Negative REFIN DP2

Ground Supply

Positive

In Low REFOUT Supply Hold DP1 DP3

-5

VDC

Input Signal

+5

VDC

Decimal Point

Decimal Point: DP 1 is the first decimal

point to the left of the least significant digit.
Connect DP# to Positive Supply to activate.
Unneeded features should remain uncon­nected.

Display Hold: The display can be held
indefinitely by connecting Hold to Positive
Supply. The display will function normally
when this connection is removed.

In Hi Analog DP4 Negative REFIN DP2

Ground Supply

Positive

In Low REFOUT Supply Hold DP1 DP3

9

VDC

Input Signal

+

-

±5 VDC Power Supply

+5 VDC Power Supply

9 VDC Power Supply

Optional Connections

The WARNING sign denotes a hazard. It
calls attention to a procedure, practice, or
the like, which, if not correctly performed
or adhered to, could result in personal
injury.

The CAUTION sign denotes a hazard. It
calls attention to an operating procedure,
practice, or the like, which, if not correctly
adhered to, could result in damage to or
destruction of part or all of the instrument.

Ordering Information

Non Backlight
Negative Image Red

Basic Unit Display DPM Power Supply Range Backlight Power

M145

0
1
2

0
1

0
1
2
3
4
5

21
22
23
24

4-1/2 Digit Indicator

+5VDC
±5VDC
+9VDC

200␮A

2mA

20mA

200mA

None

5VDC
10VDC
12VDC
24VDC
48VDC

Mini Current Indicators can be configured by making an entry for each box

INPUTS: DC Current

Voltage Maximum

Range Resolution Drop Input (unfused)

200␮A

10␮A 200mV 10mA

2mA

100␮A 200mV 40mA

20mA

1␮A 200mV 100mA

200mA

10␮A 200mV 400mA

DP3

DP2

DP1

DP4

In Hi Analog DP4 Negative REFIN DP2

Ground Supply

Positive

In Low REFOUT Supply Hold DP1 DP3

SIMPSON ELECTRIC COMPANY 520 Simpson Avenue, Lac du Flambeau, WI 54538 • [phone] • FAX [phone]

www.simpsonelectric.com Printed in U.S.A. Part No. 6-115973, Edition 11, 05/07