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AS5140H

Data Sheet - D e t a i l e d D e s c r i p t i o n

7 Detailed Description

The AS5140H 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 AS5140H 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 MagINCn and MagDECn 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 18).

The AS5140H 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).

Simultaneously, the device also provides incremental output signals. The various incremental output modes can be selected by programming the

OTP mode register bits (see Table 20). 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. 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 AS5140H is tolerant to magnet misalignment and magnetic stray fields due to differential measurement technique and Hall sensor

conditioning circuitry.

Figure 4. Typical Arrangement of AS5140H and Magnet

7.1 10-bit Absolute Angular Position Output

7.1.1 Synchronous Serial Interface (SSI)

If CSn changes to logic low, Data Out (DO) will change from high impedance (tri-state) to logic high and the read-out will be initiated.

Each subsequent rising CLK edge shifts out one bit of data.

The serial word contains 16 bits; the first 10 bits are the angular information D[9:0], the subsequent 6 bits contain system information about

the validity of data such as OCF, COF, LIN, Parity and Magnetic Field status (increase/decrease).