Datasheet

Linear Hall Effect Sensor ICs with Analog Output
A1324, A1325,
and A1326
6
Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
T
A
= 25°C, and Sens
(25°C)1
is the value of sensitivity at T
A
= 25°C
after temperature cycling T
A
up to 150°C, down to –40°C, and
back to up 25°C.
Linearity Sensitivity Error The 132x is designed to provide
linear output in response to a ramping applied magnetic field.
Consider two magnetic fields, B1 and B2. Ideally the sensitivity
of a device is the same for both fields for a given supply voltage
and temperature. Linearity sensitivity error is present when there
is a difference between the sensitivities measured at B1 and B2.
Linearity Sensitivity Error is calculated separately for the positive
(LIN
ERR+
) and negative (LIN
ERR–
) applied magnetic fields. Lin-
earity Sensitivity Error (%) is measured and defined as:
Sens
B(++)
Sens
B(+)
1–
Lin
ERR+
=
×
100%








Sens
B(– –)
Sens
B(–)
1–
Lin
ERR–
=
×
100%








(7)
and
Lin
ERR
= max(| Lin
ERR+
| , |Lin
ERR–
| ) (8)
where:
|V
OUT(Bx)
– V
OUT(Q)
|
B
X
Sens
Bx
=








(9)
and B(++), B(+), B(– –), and B(–) are positive and negative mag-
netic fields with respect to the quiescent voltage output such that
|B(++)| > |B(+)| and |B(– –)| > |B(– )| .
Symmetry Sensitivity Error The magnetic sensitivity of a
device is constant for any two applied magnetic fields of equal
magnitude and opposite polarities.
Symmetry Error (%), is measured and defined as:
Sens
B(+)
Sens
B(–)
1–
Sym
ERR
=
×
100%








(11)
where Sens
Bx
is defined as in equation 9, and B(+), B(–) are posi-
tive and negative magnetic fields such that |B(+)| = |B(–)|.
Ratiometry Error The A132x features a ratiometric output.
This means that the quiescent voltage output, V
OUT(Q)
, magnetic
sensitivity, Sens, and clamp voltages, V
CLPHIGH
and V
CLPLOW
,
are proportional to the supply voltage, V
CC
. In other words, when
the supply voltage increases or decreases by a certain percent-
age, each characteristic also increases or decreases by the same
percentage. Error is the difference between the measured change
in the supply voltage, relative to 5 V, and the measured change in
each characteristic.
The ratiometric error in quiescent voltage output, Rat
VOUT(Q)
(%), for a given supply voltage, V
CC
, is defined as:
V
OUT(Q)VCC
cV
OUT(Q)5V
V
CC
c V
1–
Rat
VOUT(Q)
=
×
100%








(12)
The ratiometric error in magnetic sensitivity, Rat
SENS
(%), for a
given supply voltage, V
CC
, is defined as:
Sens
VCC
cSens
5V
V
CC
cV
1–
Rat
VOUT(Q)
=
×
100%








(13)