as5304 austriamicrosystems, as5304 Datasheet - Page 8

• Manufacturer Part Number: as5304
• Description: Integrated Hall Ics For Linear And Off-axis Rotary Motion Detection
• Manufacturer: austriamicrosystems

AS5304/AS5306 Integrated Hall IC for linear and off-axis rotary motion detection
8.1.2
The length of a pole pair across the median of the multi-pole ring must remain fixed at either 4mm (AS5304) or 2.4mm
(AS5306). Hence, with increasing pole pair count, the diameter increases linearly with the number of pole pairs on the magnetic
ring.
Magnetic ring diameter = [pole length] * [number of pole pairs] / π
8.1.3
The AS5304 / 06 uses a fast interpolation technique allowing an input frequency of 5kHz. This means, it can process magnetic
field changes in the order of 5000 pole pairs per second or 300.000 revolutions per second. However, since a magnetic ring
consists of more than one pole pair, the above figure must be divided by the number of pole pairs to get the maximum rotation
speed:
Maximum rotation speed = 300.000 rpm / [number of pole pairs]
Example: same as above: multi-pole ring with 22 pole pairs:
8.1.4
For linear motion sensing, a multi-pole strip using equally spaced north and south poles is used. The pole length is again fixed
at 2.0mm for the AS5304 and 1.2mm for the AS5306. As shown in 8.1.3 above, the sensors can process up to 5000 pole pairs
per second, so the maximum travelling speed is:
Maximum linear travelling speed = 5000 * [pole pair length]
Revision 1.0
Example: same as above: multi-pole ring with 22 pole pairs for AS5304
Ring diameter =
For the AS5306, the same ring would have a diameter of: 2.4 * 22 / 3.14 = 16.8mm
Max.speed = 300.000 / 22 = 13636 rpm (this is independent of the pole length)
Example : linear multipole strip:
Max. linear travelling speed = 4mm * 5000 1/sec = 20.000mm/sec = 20m/sec
Max. linear travelling speed = 2.4mm * 5000 1/sec = 12.000mm/sec = 12m/sec
Multi-pole ring diameter
Maximum rotation speed
Maximum linear travelling speed
4 * 22 / 3.14 = 28.01mm (this number represents the median diameter of the ring)
for AS5304: d = 4.0mm * number of pole pairs / π
for AS5306: d = 2.4mm * number of pole pairs / π
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for AS5304
for AS5306
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