The MA3 IS NOT RECOMMENDED FOR NEW PROJECTS
Please discover our New Redesigned MA4
MA3 Product Description 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
± 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)
100 RPM
15000 RPM
Max. Acceleration
10000 rad/sec²
250000 rad/sec²
Max. Shaft Torque
0.5 in-oz (D-option)
0.05 in-oz (B-option)
Max. Shaft Loading
2 lb. dynamic
1 lb.
Bearing Life (2)
> 1,000,000 revolutions
L10 = (18.3/Fr )³L10 = bearing life in millions of revs, andFr = 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)
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.
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)
Minimum Pulse Width
Maximum Pulse Width
Internal Sampling Rate
Propagation
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.
10-bit PWM:
on * 1026) / (t on + t off )) -1
If x <= 1022, then Position = x
If x = 1024, then Position = 1023
12-bit PWM:
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:
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.
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Datasheet
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