AS5045TR View Datasheet(PDF) - austriamicrosystems AG
Part Name
Description
MFG CO.
'AS5045TR' PDF : 34 Pages View PDF
AS5045
Data Sheet
17.4 Propagation Delays
The propagation delay is the delay between the time that the sample is taken until it is converted and available as
angular data. This delay is 96µs in fast mode and 384µs in slow mode.
Using the SSI interface for absolute data transmission, an additional delay must be considered, caused by the
asynchronous sampling (0 … 1/fsample) and the time it takes the external control unit to read and process the angular
data from the chip (maximum clock rate = 1MHz, number of bits per reading = 18).
17.4.1 Angular Error Caused by Propagation Delay
lid A rotating magnet will cause an angular error caused by the output propagation delay.
This error increases linearly with speed:
esampling, = rpm ∗ 6* prop.delay
a where
v esampling = angular error [°]
rpm = rotating speed [rpm]
ill prop.delay = propagation delay [seconds]
t Note: since the propagation delay is known, it can be automatically compensated by the control unit processing the
data from the AS5045.
AG t s 17.5 Internal Timing Tolerance
s n The AS5045 does not require an external ceramic resonator or quartz. All internal clock timings for the AS5045 are generated by
an on-chip RC oscillator. This oscillator is factory trimmed to ±5% accuracy at room temperature (±10% over full temperature
e range). This tolerance influences the ADC sampling rate and the pulse width of the PWM output:
am nt Absolute output; SSI interface:
A new angular value is updated every 96µs (typ.) in fast mode and every 384µs (typ.) in slow mode.
o PWM output:
c A new angular value is updated every 400µs (typ.).
The PWM pulse timings Ton and Toff also have the same tolerance as the internal oscillator (see above).
l If only the PWM pulse width Ton is used to measure the angle, the resulting value also has this timing tolerance.
However, this tolerance can be cancelled by measuring both Ton and Toff and calculating the angle from the duty
a cycle (see section 9):
ic Position = ton ⋅4097 −1
Te(ch) n ton +toff
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