High Precision, Output Pin Programmable
Linear Hall Effect Sensor ICs
A1373 and
A1374
14
Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
Characteristic Definitions
Quiescent Output Voltage. In the quiescent state (no signifi-
cant magnetic field: B = 0), the output, V
OUTQ
, equals a ratio of
the supply voltage, V
CC
, throughout the entire operating ranges
of V
CC
and ambient temperature, T
A
. Due to internal component
tolerances and thermal considerations, there is a tolerance on the
quiescent output voltage, ∆V
OUTQ
, which is a function of both
∆V
CC
and ∆T
A
. For purposes of specification, the quiescent out-
put voltage as a function of temperature, ∆V
OUTQ(∆T
A
)
, is defined
as:
where Sens is in mV/G, and the result is the device equivalent
accuracy, in gauss (G), applicable over the entire operating tem-
perature range.
Sensitivity. The presence of a south-polarity (+B) magnetic
field, perpendicular to the branded face of the device package,
increases the output voltage, V
OUT
, in proportion to the magnetic
field applied, from V
OUTQ
toward the V
CC
rail. Conversely, the
application of a north polarity (–B) magnetic field, in the same
orientation, proportionally decreases the output voltage from its
quiescent value. This proportionality is specified as the magnetic
sensitivity of the device and is defined as:
The stability of the device magnetic sensitivity as a function of
ambient temperature, ∆ Sens
(∆T
A
)
(%) is defined as:
Ratiometric. The A1373 and A1374 feature ratiometric
output. This means that the quiescent voltage output, V
OUTQ
,
magnetic sensitivity, Sens, and clamp voltage, V
OUTCLP
, are
proportional to the supply voltage, V
CC
.
The ratiometric change in the quiescent output voltage,
RAT
VOUT(Q)
(%), is defined as:
the ratiometric change in sensitivity is defined as:
and the ratiometric change in clamp voltage is defined as:
Note that clamping effect is applicable only when clamping is
enabled by programming of the device.
Linearity and Symmetry. The on-chip output stage is
designed to provide linear output at a supply voltage of 5 V.
Although the application of very high magnetic fields does not
damage these devices, it does force their output into a nonlinear
region. Linearity in percent is measured and defined as:
and output symmetry as:
ΔV
OUTQ(ΔΤ
Α
)
Sens
(25ºC)
V
OUTQ(Τ
Α
)
V
OUTQ(25ºC)
–
=
(1)
2B
V
OUT(–B)
V
OUT(+B)
Sens
–
=
ΔSens
(ΔΤ
Α
)
Sens
(Τ
Α
)
Sens
(25ºC)
Sens
(25ºC)
–
=
× 100%
(2)
(3)
V
CC
5 V
V
OUTQ(V
CC
)
V
OUTQ(5V)
RAT
VOUT(Q)
=
× 100%
(4)
V
CC
5 V
=
× 100%
RAT
Sens
Sens
(V
CC
)
Sens
(5V)
(5)
=
¾%
Lin+
V
OUT(+B½)
– V
OUTQ
–
V
OUT(+B)
V
OUTQ
(7)
=
× 100%
Lin–
2(V
OUT(–B½)
– V
OUTQ
)
–
V
OUT(–B)
V
OUTQ
(8)
–
=
× 100%
Sym
V
OUT(+B)
V
OUTQ
– V
OUT(–B)
V
OUTQ
(9)
=
RAT
VCLP
V
CC
5 V
V
CLP(V
CC
)
V
CLP(5V)
× 100%
(6)
