US Digital

MA3 Miniature Absolute Magnetic Shaft Encoder

Overview

  • Patent pending
  • Miniature size (0.48" diameter)
  • Non-contacting magnetic single chip sensing technology
  • -40C to 125C. operating temperature range
  • 10-bit Analog output - 2.6 kHz sampling rate
  • 10-bit PWM output - 1024 positions per revolution, 1 kHz
  • 12-bit PWM output - 4096 positions per revolution, 250 Hz

The MA3 is a miniature rotary absolute shaft encoder that reports the shaft position over 360° with no stops or gaps. The MA3 is available with an analog or a pulse width modulated (PWM)...

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Product Specifications

SpecificationSleeve BushingBall Bearing
Moment of Inertia 4.1 x 10^-6 oz-in-s² 4.1 x 10^-6 oz-in-s²
Angular Accuracy <0.5 deg. @ 25C <0.5 deg. @ 25C
Angular Accuracy Over Temperature <0.9 deg. @ -40 to 125C <0.9 deg. @ -40 to 125C
Shaft Speed 100 RPM max. continuous 15,000 RPM max. continuous
Acceleration 10,000 rad/sec² 250,000 rad/sec²
Vibration 20G. 5Hz to 2kHz 20G. 5Hz to 2kHz
Shaft Torque 0.5 ± 0.2 in. oz. (D - torque option)
0.3 in. oz. max. (N - torque option)		 0.05 in. oz. max.
Shaft Loading 2 lbs. max. dynamic*
20 lbs. max. static		 1 lb. max.
Bearing Life - (40/P)³ = life in millions of revs.
where P = radial load in pounds
Weight 0.46 oz. 0.37 oz.
Shaft Runout 0.0015 T.I.R. max. 0.0015 T.I.R. max.

* When a pulley, gear, or friction wheel drives the shaft, the Ball Bearing option is recommended instead of the Sleeve Bushing.

ParameterDimension
Operating Temperature -40C to +125C
Storage Temperature -55C to +125C
ESD 2 kV minimum
Humidity Non-condensing 5% to 85%
ParameterDimension
Hole Diameter 0.375" +0.005 / -0.0
Panel Thickness 0.125" max.
Panel Nut Max. Torque 20 in.-lbs.
ParameterDimension
Shaft Stainless
Bushing Brass

The MA3 absolute encoder contains a small internal magnet, mounted on the end of the shaft that generates a weak magnetic field extending outside the housing of each encoder. If two MA3 units are to be installed closer than 1 inch apart (measured between the center of both shafts), a magnetic shield, such as a small steel plate should be installed in between to prevent one encoder from causing small changes in reported position through magnetic field cross-talk.

ParameterMin.Typ.Max.Units
Power Supply 4.5 5.0 5.5 Volts
Supply Current - 16 20 mA
Power-up Time - - 50 mS

10bit-analog.gifAnalog output is only available in 10-bit resolution. The analog output voltage is ratiometric to the power supply voltage and will typically swing within 15 millivolts of the power supply rails with no output load. This non-linearity near the rails increases with increasing output loads. For this reason, the output load impedance should be ≥ 4.7kΩ and less than 100pF. The graphs below show the typical output levels for various output loads when powered by a 5V supply.

ParameterMin.Typ.Max.Units
Position Sampling Rate 2.35 2.61 2.87 kHz
Propagation Delay - - 384 μS
Analog Output Voltage Maximum - 4.987 - Volts*
Analog Output Voltage Minimum - 0.015 - Volts*
Output Short Circuit Sink Current - 32 50 mA**
Output Short Circuit Source Current - 36 66 mA**
Output Noise 160 220 490 Vrms**
Output Transition Noise - 0.06 - Degrees RMS***

* With no output load. See graphs below.
** Continuous short to +5V or ground will not damage the MA3.
*** Transition noise is defined as the jitter in the transition between two adjacent position steps.

pullup.gif

pulldown.gif

The magnetic sensor chip in the MA3 has an on-chip RC oscillator which is factory trimmed to 5% accuracy at room temperature (10% over full temperature range). This tolerance influences the sampling rate and the pulse width of the PWM output. If only the PWM pulse width t on is used to measure the angle, the resulting value also has this timing tolerance. However, this tolerance can be cancelled by measuring both ton and toff and calculating the angle from the duty cycle. Angular accuracy including non-linearity is within 0.5 deg. at 25C, but may increase to 0.9 deg. at high temperatures.

ParameterMin.Typ.Max.Units
PWM Frequency (-40C to 125C)
  10-bit
  12-bit		 0.878
220		 0.976
244		 1.074
268		 kHz
Hz
Minimum Pulse Width
  10-bit
  12-bit		 0.95
0.95		 1.00
1.00		 1.05
1.05		 μS
μS
Maximum Pulse Width
  10-bit
  12-bit		 973
3891		 1024
4096		 1075
4301		 μS
μS
Internal Sampling Rate
  10-bit
  12-bit		 9.38
2.35		 10.42
2.61		 11.46
2.87		 kHz
kHz
Propagation
  10-bit
  12-bit		 -
-		 -
-		 48
384		 μS
μS
High Level Output Voltage (V OH: @4mA Source) Vcc -0.5 - - V*
Low Level Output Voltage (V OL: @4mA Sink) - - 0.4 V*

* Continuous short to +5V or ground will not damage the MA3.

10-bit PWM:
Position = ((t on * 1025) / (t on+ t off)) -1
10bit-pwm.gif

12-bit PWM:
Position = ((t on * 4097) / (t on+ t off)) -1
12bit-pwm.gif

Analog Output (MA3-A):

PinNameDescription
1 5 +5VDC power
2 A Analog output
3 G Ground

PWM Output (MA3-P10, MA3-P12):

PinNameDescription
1 5 +5VDC power
2 A PWM output
3 G Ground

3-pin Micro:

Part #Description
CON-MIC3 Connector
CA-MIC3-W3-NC Connector on one end with 3 wires
CA-MIC3-SH-NC Connector on one end with shielded cable
  • Connector built into encoder: Molex# 53398-0371.
  • Mating connector housing: Molex# 51021-0300.
  • Mating connector individual crimp-on pins: Molex# 50079-8100.
  • To install connector pins, a special crimp tool is needed: Molex# 50079.

Product Description

RoHS Compliant

The MA3 is a miniature rotary absolute shaft encoder that reports the shaft position over 360° with no stops or gaps. The MA3 is available with an analog or a pulse width modulated (PWM) digital output.

Analog output provides an analog voltage that is proportional to the absolute shaft position. Analog output is only available in 10-bit resolution.

PWM output provides a pulse width duty cycle that is proportional to the absolute shaft position. PWM output is available in 10-bit and 12-bit resolutions. While the accuracy is the same for both encoders, the 12-bit version provides higher resolution.

Three shaft torque versions are available. The standard torque version has a sleeve bushing lubricated with a viscous motion control gel to provide torque and feel that is ideal for front panel human interface applications.

The no torque added option has a sleeve bushing and a low viscosity lubricant (that does not intentionally add torque) for low RPM applications where a small amount of torque is acceptable.

The ball bearing version uses miniature precision ball bearings that are suitable for high speed and ultra low torque applications. The shaft diameter for ball bearing version option is 1/8" rather than 1/4".

Connecting to the MA3 is simple. The 3-pin high retention snap-in 1.25mm pitch polarized connector provides for +5V, output, and ground.

Product Notes
  • Cables and connectors are not included and must be ordered separately.
  • US Digital warrants its products against defects in materials and workmanship for two years. See complete warranty for details.
Related Documentation

Purchasing

Configure and Purchase

1. Interface



2. Shaft



3. Torque



Product Part Number
Quantity Price
1 $36.00
10 $31.54
50 $27.78
100 $23.89
Quantity
Unit Price

$36.00

Subtotal

$36.00

For your convenience, use the above part number to order via phone 800.736.0194

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