AS5045

Data Sheet

www.austriamicrosystems.com

Revision 1.7

26 – 33

The chip will continue to operate, but with degraded output linearity, if the signal field strength is outside the

recommended range. Too strong magnetic fields will introduce errors due to saturation effects in the internal

preamplifiers. Too weak magnetic fields will introduce errors due to noise becoming more dominant.

16 Failure Diagnostics

The AS5045 also offers several diagnostic and failure detection features:

16.1 Magnetic Field Strength Diagnosis

By software:

the MagINC and MagDEC status bits will both be high when the magnetic field is out of range.

By hardware:

Pins #1 (MagINCn) and #2 (MagDECn) are open-drain outputs and will both be turned on (= low with

external pull-up resistor) when the magnetic field is out of range. If only one of the outputs are low, the magnet is

either moving towards the chip (MagINCn) or away from the chip (MagDECn).

16.2 Power Supply Failure Detection

By software:

If the power supply to the AS5045 is interrupted, the digital data read by the SSI will be all “0”s. Data is

only valid, when bit OCF is high, hence a data stream with all “0”s is invalid. To ensure adequate low levels in the

failure case, a pull-down resistor (~10k

Ω) should be added between pin DO and VSS at the receiving side

By hardware:

The MagINCn and MagDECn pins are open drain outputs and require external pull-up resistors. In

normal operation, these pins are high ohmic and the outputs are high (see Table 5). In a failure case, either when the

magnetic field is out of range of the power supply is missing, these outputs will become low. To ensure adequate low

levels in case of a broken power supply to the AS5045, the pull-up resistors (~10k

Ω) from each pin must be

connected to the positive supply at pin 16 (VDD5V).

By hardware:

PWM output: The PWM output is a constant stream of pulses with 1kHz repetition frequency. In case

of power loss, these pulses are missing

17 Angular Output Tolerances

17.1

Accuracy

Accuracy is defined as the error between measured angle and actual angle. It is influenced by several factors:

the non-linearity of the analog-digital converters,

internal gain and mismatch errors,

non-linearity due to misalignment of the magnet

degrees @ 25°C (see Figure 22).

Misalignment of the magnet further reduces the accuracy. Figure 21 shows an example of a 3D-graph displaying

non-linearity over XY-misalignment. The center of the square XY-area corresponds to a centered magnet (see dot in

the center of the graph). The X- and Y- axis extends to a misalignment of

±1mm in both directions. The total

misalignment area of the graph covers a square of 2x2 mm (79x79mil) with a step size of 100µm.

(e.g.

0.25° in) is entered as the Z-axis in the 3D-graph.