AS5046ASST datasheet(30/33 Pages) AMSCO

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AS5046 Programmable 360° Magnetic Angle Encoder – Preliminary Data Sheet

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The maximum non-linearity error on this example is

better than

±1 degree (inner circle) over a misalignment

radius of ~0.7mm. For volume production, the placement

tolerance of the IC within the package (

±0.235mm) must

also be taken into account.

The total nonlinearity error over process tolerances,

temperature and a misalignment circle radius of 0.25mm

is specified better than

±1.4 degrees.

The magnet used for this measurement was a cylindrical

NdFeB (Bomatec® BMN-35H) magnet with 6mm diameter and

2.5mm in height.

Figure 26: 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)*1 in fast mode (pin MODE = high)

and 0.03 degrees rms (1 sigma)*1 in slow mode (pin

MODE = low or open).

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; serial 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.

: statistically, 1 sigma represents 68.27% of readings,

3 sigma represents 99.73% of readings.

18.4 High Speed Operation

18.4.1 Sampling Rate

The AS5046 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

rpm

⋅

for fast mode

rpm

384

⋅

for slow mode

linearity error with centered magnet

-0.5

-0.4

-0.3

-0.2

-0.1

0.1

0.2

0.3

0.4

0.5

55 109 163 217 271 325 379 433 487 541 595 649 703 757 811 865 919 973

transition noise

Err max

Errmin

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