AS5045

Data Sheet

www.austriamicrosystems.com

Revision 1.7

29 – 33

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

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:

delay

prop

rpm

e

sampling

.

*

6

,

∗

=

where

rpm

= rotating speed [rpm]

prop.delay

= propagation delay [seconds]

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:

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.).

cycle (see section 9):

4097 −

+

⋅

=

off

on

on

t

t

t

Position