AS5045

Data Sheet

www.austriamicrosystems.com

Revision 1.7

30 – 33

17.6 Temperature

17.6.1 Magnetic Temperature Coefficient

One of the major benefits of the AS5045 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 coefficients, the AS5045

automatically compensates for the varying magnetic field strength over temperature. The magnet’s temperature drift

does not need to be considered, as the AS5045 operates with magnetic field strengths from

±45…±75mT.

Example:

An 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 AS5045 can compensate for this temperature related field strength change automatically, no user adjustment is

required.

17.7 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.

17.7.1 Timing Tolerance over Temperature

The internal RC oscillator is factory trimmed to

±5%. Over temperature, this tolerance may increase to ±10%.

Generally, the timing tolerance has no influence in the accuracy or resolution of the system, as it is used mainly for

internal clock generation.

The only concern to the user is the width of the PWM output pulse, which relates directly to the timing tolerance of

the internal oscillator. This influence however can be cancelled by measuring the complete PWM duty cycle instead

of just the PWM pulse (see 17.5).