AS5040 PB austriamicrosystems, AS5040 PB Datasheet - Page 29

• Manufacturer Part Number: AS5040 PB
• Description: BOARD PROGRAM AS5040
• Manufacturer: austriamicrosystems

Specifications of AS5040 PB

• Module/board Type: ZIF Socket
• For Use With/related Products: AS5000 Programmer, AS5040
• Lead Free Status / RoHS Status: Lead free by exemption / RoHS compliant by exemption
• Other names: AS5045 PB; AS5140H PB; AS5145 PB

AS5040
Data Sheet
Angular Error Caused by Propagation Delay
A rotating magnet will therefore cause an angular error caused by the output delay. This error increases linearly with
speed:
where: e
Note: since the propagation delay is known, it can be automatically compensated by the control unit that is processing
the data from the AS5040, thus reducing the angular error caused by speed.
Internal Timing Tolerance
The AS5040 does not require an external ceramic resonator or quartz. All internal clock timings for the AS5040 are
generated by an on-chip RC oscillator. This oscillator is factory trimmed to ±5% accuracy at room temperature (±10%
over full temperature range). This tolerance influences the ADC sampling rate and the pulse width of the PWM output:
Temperature
Magnetic Temperature Coefficient
One of the major benefits of the AS5040 compared to linear Hall sensors is that it is much less sensitive to
temperature. While linear Hall sensors require a compensation of the magnet’s temperature coefficient, the AS5040
automatically compensates for the varying magnetic field strength over temperature. The magnet’s temperature drift
does not need to be considered, as the AS5040 operates with magnetic field strengths from ±45…±75mT.
Example:
A NdFeB magnet has a field strength of 75mT @ –40°C and a temperature coefficient of -0.12% per Kelvin.
The temperature change is from –40° to +125° = 165K.
The magnetic field change is: 165 x -0.12% = -19.8%, which corresponds to 75mT at –40°C and 60mT at 125°C.
The AS5040 can compensate for this temperature related field strength change automatically, no user adjustment is
required.
Accuracy over Temperature
The influence of temperature in the absolute accuracy is very low. While the accuracy is ≤ ±0.5° at room temperature,
it may increase to ≤±0.9° due to increasing noise at high temperatures.
www.austriamicrosystems.com
e
sampling
rpm
prop.delay
=
sampling
Absolute output; SSI interface:
A new angular value is updated every 100µs (typ.)
Incremental outputs:
the incremental outputs are updated every
100µs (typ.)
PWM output:
A new angular value is updated every 100µs (typ.).
The PWM pulse timings T
If only the PWM pulse width T
tolerance.
However, this tolerance can be cancelled by measuring both T
duty cycle (see section 9):
Position
rpm
∗
6
*
=
prop
(
t
t
on
on
.
⋅
delay
+
1025
= angular error [°]
= rotating speed [rpm]
= propagation delay [seconds]
t
off
)
−
1
on
and T
on
is used to measure the angle, the resulting value also has this timing
off
also have the same tolerance as the internal oscillator.
Revision 2.10
on
and T
off
and calculating the angle from the
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