Ratiometric Linear Hall Effect Sensor

for High-Temperature Operation

A1321, A1322,

and

A1323

5

Allegro MicroSystems, Inc.

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000

www.allegromicro.com

Quiescent Voltage Output.

In the quiescent state (no

magnetic field), the output equals one half of the supply voltage

over the operating voltage range and the operating temperature

range. Due to internal component tolerances and thermal con-

siderations, there is a tolerance on the quiescent voltage output

both as a function of supply voltage and as a function of ambient

temperature. For purposes of specification, the quiescent voltage

output as a function of temperature is defined in terms of mag-

netic flux density, B, as:

This calculation yields the device’s equivalent accuracy,

over the operating temperature range, in gauss (G).

Sensitivity.

The presence of a south-pole magnetic field per-

pendicular to the package face (the branded surface) increases

the output voltage from its quiescent value toward the supply

voltage rail by an amount proportional to the magnetic field

applied. Conversely, the application of a north pole will decrease

the output voltage from its quiescent value. This proportionality

is specified as the sensitivity of the device and is defined as:

The stability of sensitivity as a function of temperature is

defined as:

Characteristic Definitions

Ratiometric.

The A132X family features a ratiometric output.

The quiescent voltage output and sensitivity are proportional to

the supply voltage (ratiometric).

The percent ratiometric change in the quiescent voltage output is

defined as:

and the percent ratiometric change in sensitivity is

defined as:

Linearity and Symmetry.

The on-chip output stage

is designed to provide a linear output with a supply voltage of

5 V. Although application of very high magnetic fields will not

damage these devices, it will force the output into a non-linear

region. Linearity in percent is measured and defined as:

and output symmetry as:

–

=

(1)

2B

Sens

–

=

–

=

× 100%

(2)

(3)

× 100%

(4)

=

× 100%

CC

(5)

–

=

× 100%

Lin+

(6)

–

=

× 100%

Lin–

(7)

–

=

× 100%

Sym

(8)