AS5045-ASST austriamicrosystems, AS5045-ASST Datasheet - Page 29

• 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
17.4 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/f
data from the chip (maximum clock rate = 1MHz, number of bits per reading = 18).
17.4.1 Angular Error Caused by Propagation Delay
A rotating magnet will cause an angular error caused by the output propagation delay.
This error increases linearly with speed:
where
Note: since the propagation delay is known, it can be automatically compensated by the control unit processing the
data from the AS5045.
17.5 Internal Timing Tolerance
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
range). This tolerance influences the ADC sampling rate and the pulse width of the PWM output:
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Absolute output; SSI interface:
A new angular value is updated every 96µs (typ.) in fast mode and every 384µs (typ.) in slow mode.
PWM output:
A new angular value is updated every 400µs (typ.).
The PWM pulse timings T
If only the PWM pulse width T
However, this tolerance can be cancelled by measuring both T
cycle (see section 9):
Position
e
rpm = rotating speed [rpm]
prop.delay = propagation delay [seconds]
e
sampling
sampling
=
,
t
(
= angular error [°]
=
t
on
on
rpm
⋅
+
4097
t
off
∗
6
)
−
*
1
prop
on
and T
sample
.
delay
on
is used to measure the angle, the resulting value also has this timing tolerance.
) and the time it takes the external control unit to read and process the angular
off
also have the same tolerance as the internal oscillator (see above).
Revision 1.7
on
and T
off
and calculating the angle from the duty
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