| 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 ± 0.2 in-oz (D - torque option)
0.3 in-oz (N- torque option) |
0.05 in-oz |
| 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 Total Indicated Runout |
0.0015 in. |
0.0015 in. |
| Technical Bulletin TB1001 - Shaft and Bore Tolerances |
Download |
(1) When a pulley, gear, or friction wheel drives the shaft, the Ball Bearing option is recommended instead of the Sleeve Bushing. 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
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.
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 (2) |
160 |
220 |
490 |
µVrms |
| Output Transition Noise (3) |
- |
0.03 |
- |
Deg. RMS |
(1) With no output load. See graphs below.
(2) Continuous short to +5V or ground will not damage the MA3.
(3) Transition noise is the jitter in the transition between two adjacent position steps.
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
