Precision Hall-Effect Angle Sensor IC

A1334

9

Allegro MicroSystems, LLC

115 Northeast Cutoff

Worcester, Massachusetts 01615-0036 U.S.A.

1.508.853.5000; www.allegromicro.com

APPLICATION INFORMATION

Figure 2: Orientation of Magnet Relative to Primary Die and Secondary Die

(dual die version used as example)

N

S

Target alignment for default angle setting

•Target rotation axis intersects primary die

• Primary die 40° default point

• Secondary die 220° default point

(Example shows element E1 as primary die

element E2 as secondary die)

Target rotation axis

Target poles aligned with

A1334 elements

E1

Pin 1

E1

E2

E2

S

N

Calculating Target Zero Degree Angle

When shipped from the factory, the default angle value when

orientated as shown in Figure 2, is approximately 40º (220º on

secondary die). In some cases, the end user may want to program

an angle offset in the A1334 to compensate for variation in

magnetic assemblies, or for applications where absolute system-

level readings are required.

The internal algorithm for computing the output angle is as

follows:

(2)

The procedure to zero out the A1334 is quite simple. During final

application calibration and programming, position the magnet

above the A1334 in the required zero-degree position, and read

From this angle, the Reference Angle required to program the

A1334 can be computed as follows:

(3)

Bypass Pin Usage

The Bypass pin is required for proper device operation and is

intended to bypass internal IC nodes of the A1334. A 0.1 µF

capacitor must be placed in very close proximity to the Bypass

pin. It is not intended to be used to source external components.

To assist with PCB layout, please see the Operating Characteris-

tics table for output voltage and current requirements.

Changing Sampling Modes

The A1334 features a High RPM sampling mode, and a Low

RPM sampling mode. The default power-on state of the A1334

is loaded from EEPROM. To configure the A1334 to Low RPM

mode, set the Operating mode to Low RPM mode by writing a

logic 1 to bit 2 (RPM) of the configuration commands (CTRL)

register, via the SPI interface.