AS5311

Data Sheet

www.austriamicrosystems.com

Revision 1.01

16 - 23

Figure 11: Connections for 5V and 3.3V Supply Voltages

LDO

I

N

T

E

R

F

A

C

E

2.2...10µF

100n

4.5 - 5.5V

VDD3V3

VSS

VDD5V

5V Operation

Internal

VDD

LDO

100n

3.0 - 3.6V

VDD3V3

VSS

VDD5V

3.3V Operation

Internal

VDD

I

N

T

E

R

F

A

C

E

Prog

Prog

AS5311

AS5311

PWM

Index

B

A

CSn

CLK

DO

PWM

Index

B

A

CSn

CLK

DO

10 Magnet Specifications

10.1 Magnetization

The AS5311 accepts magnetic multi-pole strip or ring magnets with a pole length of 1.0mm. Recommended

magnet materials include plastic or rubber bonded ferrite or Neodymium magnets.

It is not recommended to use the AS5311 with other pole lengths as this will create additional nonlinearities.

Figure 12: Additional Error from Pole Length Mismatch

Figure 12 shows the error caused by a mismatch of pole length. Note that this error is an additional error on top

of the chip-internal INL and DNL errors (see 6.5). For example, when using a multi-pole magnet with 1.2mm pole

length instead of 1.0mm, the AS5311 will provide 1024 incremental steps or 4096 absolute positions over

2.4mm, but with an additional linearity error of up to 50µm.

The curvature of ring magnets may cause linearity errors as well due to the fact that the Hall array on the chip is

a straight line while the poles on the multi-pole ring are curved. These errors decrease with increasing ring

diameter. It is therefore recommended to keep the ring diameter measured at the location of the Hall array at

20mm or higher.

AS5311 Systematic Linearity Error Caused by Pole

Length Deviation

0.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

750 800 850 900 950 1000 1050 1100 1150 1200 1250

Pole Length [µm]

Error

[µm]

Error [µm]