AS5043

Data Sheet – Angular Output Tolerances

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Revision 1.80

25 – 36

Figure 23: Example of Linearity Error over 360°

18.3 Transition Noise

Transition noise is defined as the jitter in the transition between two steps.

Due to the nature of the measurement principle (Hall sensors + Preamplifier + ADC), there is always a certain degree of

noise involved.

This transition noise voltage results in an angular transition noise at the outputs. It is specified as 0.06 degrees rms

(1 sigma)

These values are the repeatability of an indicated angle at a given mechanical position.

The transition noise has different implications on the type of output that is used:

absolute output; SSI interface:

The transition noise of the absolute output can be reduced by the user by applying an averaging of readings. An

averaging of 4 readings will reduce the transition noise by 6dB or 50%, e.g. from 0.03°rms to 0.015°rms (1

sigma) in slow mode

analog output:

Ideally, the analog output should have a jitter that is less than one digit. In 360° mode, both fast or slow mode

may be selected for adequate low jitter.

In 180°, 90° or 45° mode, where the step sizes are smaller, slow mode should be selected to reduce the output

jitter.

3 sigma represents 99.73% of readings.

18.4 High Speed Operation

18.4.1 Sampling Rate

The AS5043 samples the angular value at a rate of 10.42k samples per second (ksps) in fast mode and 2.61ksps in slow

mode.

Consequently, a new reading is performed each 96µs. (fast mode) or 384µs (slow mode).

At a stationary position of the magnet, this sampling rate creates no additional error.

Absolute Mode:

With the given sampling rates, the number of samples (n) per turn for a magnet rotating at high speed can be calculated

by

s

rpm

n

μ

96

60

⋅

=

for fast mode

Linearity Error with Centered Magnet [degrees]

-0.5

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5

1

55

109 163 217 271 325 379 433 487 541 595 649 703 757 811 865 919 973

transition noise

Err max

Err min