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:
±(0.1% 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): 90dB min
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
Input Maximum 
Range Resolution Impedance Input (unfused)
200
mV 100V >100M
⍀
50V
2V
1mV 10M
⍀
250V
20V
10mV  10M
⍀
250V
200V 100mV 10M
⍀
250V
Specifications
Connections
Safety Symbols
INPUTS: DC Voltage
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 is 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 M135 has a limited range adjustment for calibration. Apply the appropriate current input for a 
near full scale reading, typically 1900 counts on the 
display. The adjustment is accessed through the 
exposed hole in the upper left corner of the rear 
panel. For this adjustment to function, REFOUT must 
be connected to REFIN.
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 M135
Rear Connections
In Hi Analog Supply Negative REFIN DP2
Ground Ground Supply
Positive
In Low REFOUT Supply Hold DP1 DP3
5
VDC
Input Signal
+
-
In Hi Analog Supply Negative REFIN DP2
Ground Ground Supply
Positive
In Low REFOUT Supply Hold DP1 DP3
-5
VDC
Input Signal
+5
VDC
In Hi Analog Supply Negative REFIN DP2
Ground Ground Supply
Positive
In Low REFOUT Supply Hold DP1 DP3
Decimal Point 
DP3
DP2
DP1
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 Supply Negative REFIN DP2
Ground 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
M135
0 
1 
2
0 
1
0 
1 
2 
3 
4 
5
11 
12 
13 
14
3-1/2 Digit Indicator
+5VDC 
±5VDC 
+9VDC
200 mV
2 V
20 V
200 V
None
5VDC 
10VDC 
12VDC 
24VDC 
48VDC
Mini Voltage Indicators can be configured by making an entry for each box
SIMPSON ELECTRIC COMPANY 520 Simpson Avenue, Lac du Flambeau, WI 54538 • (715) 588-3311 • FAX (715) 588-3326
www.simpsonelectric.com                        Printed in U.S.A. Part No. 06-115972, Edition 11, 05/07