ALS31313 datasheet(17/25 Pages) ALLEGRO

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Automotive Grade, 3-D Linear Hall-Effect Sensor

with I2C Output and Advanced Low Power Management

ALS31313

Allegro MicroSystems, LLC

955 Perimeter Road

Manchester, NH 03103-3353 U.S.A.

www.allegromicro.com

It is not advised to switch a factory-trimmed, single-ended device

(0) into other modes (1, 2, or 3). Doing so may result in sen-

sor performance that is outside of the datasheet specifications.

Conversely, a device that is configured for mode 1 or 2 may be

switched into modes 1, 2, or 3 without issue. Switching a factory-

programmed device from mode 1 or 2 into mode 0 may result in

sensor performance that is outside of the datasheet specifications.

SINGLE-ENDED HALL MODE

Magnetic data in registers 0x28 and 0x29 will be proportional to the

magnetic field seen by the inner sensing elements Xi, Yi, and Zi.

DIFFERENTIAL HALL MODE

Magnetic data in registers 0x28 and 0x29 will be proportional to

the difference in field as seen by the outer sensing elements of the

X and Y axes.

Concatenated X axis data {x_axis_MSB:x_axis_LSB} will be the

result of XO(EAST) – XO(WEST) sensing elements, while concat-

enated Y axis data {y_axis_MSB:y_axis_LSB} will be the result

of YO(NORTH) – YO(SOUTH) sensing elements.

Z axis data will be the same as in single-ended mode.

COMMON HALL MODE

Magnetic data in registers 0x28 and 0x29 will be proportional to

the sum of the fields as seen by the outer sensing elements of the

X and Y axes.

Concatenated X axis data {x_axis_MSB:x_axis_LSB} will be the

result of XO(EAST) + XO(WEST) sensing elements, while concat-

enated Y axis data {y_axis_MSB:y_axis_LSB} will be the result

of YO(NORTH) + YO(SOUTH) sensing elements.

Z axis data will be the same as in single-ended mode.

ALTERNATING HALL MODE

The magnetic data in registers 0x28 and 0x29 will toggle between

Differential Mode data and Common Mode data. The value of Hall

status indicates from which mode the sampled data originated.

Interrupt

The Interrupt feature on the ALS31313 integrates detection and

reporting of large changes in applied magnetic field. An interrupt

event is initiated when the applied magnetic field forces the ADC

output to a value greater than or equal to the user-programmed

threshold. Interrupt detection may be independently enabled or

disabled for each of the three axes.

Interrupt Reporting

The ALS31313 will report the presence of an interrupt event by

asserting the INT pin and the INT bit in register 0x28 will be set.

Interrupt reporting may be latched or unlatched depending on the

value of INT Latch Enable, address 0x02, bit 5.

In a latched state, the INT pin will assert when an event is

detected, and the INT bit will be set. Should the event subside,

the INT pin and INT bit will remain set.

In an unlatched state, the INT pin will assert when an event is

detected, and the INT bit will be set. Should the event subside,

the ALS31313 will reset the INT pin and the INT bit will be

cleared.

The ALS31313 may also report an interrupt event in EEPROM.

This is feature enabled by setting INT EEPROM Enable, address

0x03, bit 21. If an interrupt event is detected, the device will

write to INT EEPROM Status, address 0x03, bit 22.

Interrupt Modes

The ALS31313 includes two different interrupt modes, where

the user may select a threshold value or a maximum change in

field to compare. This setting is controlled via INT Mode, address

0x03, bit 23, explained in Table 15.

Table 15: INT Modes

INT Mode

Value

Mode

Description

Threshold

Mode

An interrupt event occurs when the magnetic

ADC Output data ≥ threshold.

Delta

Mode

Recent magnetic data is compared to stored

value when entering LPDCM. An interrupt event

occurs when the change in magnetic ADC

Output data ≥ user-programmed delta value.

ALS31313 Datasheet(PDF) 17 Page - Allegro MicroSystems

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