AS5045-ASST austriamicrosystems, AS5045-ASST Datasheet - Page 28

• Manufacturer Part Number: AS5045-ASST
• Description: IC ENCODER PROG 12-BIT 16-SSOP
• Manufacturer: austriamicrosystems
• Type: Linear, Rotary Encoder - Programmabler

Specifications of AS5045-ASST

• Sensing Range: 45mT ~ 75mT
• Voltage - Supply: 3 V ~ 3.6 V, 4.5 V ~ 5.5 V
• Current - Supply: 21mA
• Current - Output (max): 4mA
• Output Type: Digital, PWM, 12-Bit Serial
• Features: Programmable
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 16-SSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: AS5045-ASSTTR

AS5045
Data Sheet
17.2 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)
open).
This is 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:
*1
17.3 High Speed Operation
17.3.1 Sampling Rate
The AS5045 samples the angular value at a rate of 2.61k (slow mode) or 10.42k (fast mode, selectable by pin
MODE) samples per second. Consequently, the absolute outputs are updated each 384µs (96µs in fast mode).
At a stationary position of the magnet, the sampling rate creates no additional error.
Absolute Mode
At a sampling rate of 2.6kHz/10.4kHz, the number of samples (n) per turn for a magnet rotating at high speed can be
calculated by
The upper speed limit in slow mode is ~6.000rpm and ~30.000rpm in fast mode. The only restriction at high speed is
that there will be fewer samples per revolution as the speed increases (see Table 2).
Regardless of the rotational speed, the absolute angular value is always sampled at the highest resolution of 12 bit.
www.austriamicrosystems.com
: statistically, 1 sigma represents 68.27% of readings, 3 sigma represents 99.73% of readings.
Absolute output; SSI interface:
The transition noise of the absolute output can be reduced by the user by implementing 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.
PWM interface:
If the PWM interface is used as an analog output by adding a low pass filter, the transition noise can be reduced
by lowering the cutoff frequency of the filter.
If the PWM interface is used as a digital interface with a counter at the receiving side, the transition noise may
again be reduced by averaging of readings.
n
n
*1
slow
fast
in fast mode (pin MODE = high) and 0.03 degrees rms (1 sigma)
mod
mod
e
e
=
=
rpm
rpm
60
⋅
60
⋅
384
96
μ
μ
s
s
Revision 1.7
*1
in slow mode (pin MODE = low or
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