AS5046-ASST austriamicrosystems, AS5046-ASST Datasheet - Page 38

• Manufacturer Part Number: AS5046-ASST
• Description: IC ENCODER PROG 12-BIT 16-SSOP
• Manufacturer: austriamicrosystems
• Type: Linear, Rotary Encoder - Programmabler

Specifications of AS5046-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: Analog, Ratiometric
• Features: Programmable
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 16-SSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: AS5046-ASSTTR

AS5046
Data Sheet
21.3 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:
21.4 High Speed Operation
21.4.1 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
In practice, there is no upper speed limit. The only restriction is that there will be fewer samples per revolution as the speed
increases.
Regardless of the rotational speed, the absolute angular value is always sampled at the highest resolution.
Table 24 Speed Performance
www.austriamicrosystems.com
Fast Mode (pin Mode = 1)
610rpm = 1024 samples / turn
1220rpm = 512 samples / turn
2441rpm = 256 samples / turn
etc…
*1
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.
*1
3 sigma represents 99.73% of readings.
in fast mode (pin MODE = high) and 0.03 degrees rms (1 sigma)
n
n
: statistically, 1 sigma represents 68.27% of readings,
=
=
rpm
rpm
60
⋅
⋅
60
96
384
μ
s
μ
s
for fast mode
for slow mode
Slow Mode (pin Mode = 0 or open)
610rpm = 256 samples / turn
1220rpm = 128 samples / turn
2441rpm = 64 samples / turn
etc…
Revision 1.12
*1
in slow mode (pin MODE = low or open).
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