MA3 Miniature Absolute Magnetic Shaft Encoder

Ma3 Webproduct 01 Product Photo

MA3 Features

  • Miniature size (0.48 in. 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 - 1,024 positions per revolution, 1 kHz
  • 12-bit PWM output - 4,096 positions per revolution, 250 Hz

See more info below

Configure the MA3

The MA3 IS NOT RECOMMENDED FOR NEW PROJECTS

Please discover our New Redesigned MA4

MA3 Product Description

Restriction of Hazardous Substances

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 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 a higher resolution.

Three shaft torque options are available:

  • Default (-D): sleeve bushing with higher damping for human interface applications.
  • Ball bearing (-B): miniature precision ball bearings suitable for high-speed applications (1/8" diameter shaft only).
  • Light static drag (-N): sleeve bushing with lower damping for low-speed applications.

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 Specifications

ENVIRONMENTAL

PARAMETER VALUE UNITS
Operating Temperature -40 to +125 C
Vibration (5Hz to 2kHz) 20 G
Electrostatic Discharge, Human Body Model
MIL-STD-883E, Method 3015.7 		 ± 2 kV

MECHANICAL

SPECIFICATION SLEEVE BUSHING BALL BEARING
Moment of Inertia 4.1 x 10^-6 oz-in-s² 4.1 x 10^-6 oz-in-s²
Max. Shaft Speed (1)
(mechanical)		 100 RPM 15000 RPM
Max. Acceleration 10000 rad/sec² 250000 rad/sec²
Max. Shaft Torque 0.5 in-oz (D-option)
0.3 in-oz (N-option)		 0.05 in-oz (B-option)
Max. Shaft Loading 2 lb. dynamic
20 lb. static		 1 lb.
Bearing Life (2) > 1,000,000 revolutions L10 = (18.3/Fr)³
Where L10 = bearing life in millions of revs, and
Fr = radial shaft loading in pounds
Weight 0.46 oz. 0.37 oz.
Max. Shaft Runout 0.0015 in. T.I.R. 0.0015 in. T.I.R.
Technical Bulletin TB1001 - Shaft and Bore Tolerances Download

(1) The chip that decodes position uses sampled data. There will be fewer readings per revolution as the speed increases.  The formula for number of readings per revolution is given by:

10-bit PWM:

n = 625200 / rpm

12-bit PWM / Analog:

n = 156600 / rpm 

(2) only valid with negligible axial shaft loading

MOUNTING

PARAMETER VALUE UNITS
Hole Diameter 0.375 +0.005 / -0.0 in.
Panel Thickness 0.125 max. in.
Panel Nut Max. Torque 20.0 in-lbs

MATERIALS

COMPONENT MATERIAL TORQUE OPTION(S)
Shaft Stainless Sleeve Bushing (-D and -N options)
Brass Ball Bearing (-B option only)
Bushing Brass -

MAGNETIC FIELD CROSSTALK

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 the reported position through magnetic field cross-talk.

ELECTRICAL

PARAMETER MIN. TYP. MAX. UNITS
Power Supply 4.5 5.0 5.5 Volts
Supply Current   16 20 mA
Power-up Time     50 mS

ANALOG OUTPUT OPERATION

Analog 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.

PARAMETER MIN. TYP. MAX. UNITS
Position Sampling Rate 2.35 2.61 2.87 kHz
Propagation Delay     384 μS
Analog Output Voltage Maximum (1)   4.987   Volts
Analog Output Voltage Minimum (1)   0.015   Volts
Output Short Circuit Sink Current (2)   32 50 mA
Output Short Circuit Source Current (2)   36 66 mA
Output Noise   0.046   Deg. RMS

(1) With no output load. See graphs below.
(2) Continuous short to +5V or ground will not damage the MA3.

 

PWM OUTPUT OPERATION

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 pulse period of the PWM output. If only the PWM pulse width ton and the nominal pulse period 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.

PARAMETER MIN. TYP. MAX. UNITS
PWM Frequency (-40C to 125C)
  10-bit
  12-bit
0.877
220
0.975
244
1.072
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
974
3892
1025
4097
1076
4302
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
Output Transition Noise, 12-bit version (1)   0.03   Deg. RMS 
Output Transition Noise, 10-bit version (1)   0.12   Deg. RMS
Output High Voltage (V OH: @4mA Source) (2) Vcc -0.5     V
Output Low Voltage (V OL: @4mA Sink) (2)     0.4 V

(1) Transition noise is the jitter in the transition between two adjacent position steps.
(2) Continuous short to +5V or ground will not damage the MA3.

10-bit PWM:


x = ((t on * 1026) / (t on+ t off)) -1

If x <= 1022, then Position = x

If x = 1024, then Position = 1023

 

12-bit PWM:

 


x = ((t on * 4098) / (t on+ t off)) -1

If x <= 4094, then Position = x

If x = 4096, then Position = 4095

 

PIN-OUTS

ANALOG OUTPUT (MA3-A):

PIN NAME DESCRIPTION
1 5 +5VDC power
2 A Analog output
3 G Ground

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

PIN NAME DESCRIPTION
1 5 +5VDC power
2 P PWM output
3 G Ground

CABLES / CONNECTORS

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.

Additional Information

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.

Datasheets

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