AS5040

Data Sheet

www.austriamicrosystems.com

Revision 2.10

9 - 33

6

Functional Description

The AS5040 is manufactured in a CMOS standard process and uses a spinning current Hall technology for sensing

the magnetic field distribution across the surface of the chip.

The integrated Hall elements are placed around the center of the device and deliver a voltage representation of the

magnetic field at the surface of the IC.

Through Sigma-Delta Analog / Digital Conversion and Digital Signal-Processing (DSP) algorithms, the AS5040

provides accurate high-resolution absolute angular

position information. For this purpose a Coordinate Rotation Digital Computer (CORDIC) calculates the angle and the

magnitude of the Hall array signals.

The DSP is also used to provide digital information at the outputs M agI NCn and M agDE Cn that indicate

movements of the used magnet towards or away from the device’s surface.

A small low cost diametrically magnetized (two-pole) standard magnet provides the angular position information (see

Figure 20).

The AS5040 senses the orientation of the magnetic field and calculates a 10-bit binary code. This code can be

accessed via a Synchronous Serial Interface (SSI). In addition, an absolute angular representation is given by a Pulse

Width Modulated signal at pin 12 (PWM).

Besides the absolute angular position information the device simultaneously provides incremental output signals. The

various incremental output modes can be selected by programming the OTP mode register bits (see page 19). As

long as no programming voltage is applied to pin Prog, the new setting may be overwritten at any time and will be

reset to default when power is turned off. To make the setting permanent, the OTP register must be programmed (see

Figure 15). The default setting is a quadrature A/B mode including the Index signal with a pulse width of 1 LSB. The

Index signal is logic high at the user programmable zero position.

The AS5040 is tolerant to magnet misalignment and magnetic stray fields due to differential measurement technique

and Hall sensor conditioning circuitry.

Figure 4: AS5040 Block Diagram