3507
3508
AND
RATIOMETRIC, LINEAR HALL-EFFECT SENSORS
FOR HIGH-TEMPERATURE OPERATION
The A3507– and A3508– are sensitive, temperature-stable linear
Hall-effect sensors. Ratiometric, linear Hall-effect sensors provide a
voltage output that is proportional to the applied magnetic field and have
a quiescent output voltage that is approximately 50% of the supply
voltage. These magnetic sensors are ideal for use in linear and rotary
position sensing systems in the harsh environments of automotive and
industrial applications over extended temperatures to -40°C and +150°C.
The two devices are similar except for temperature stability over the
operating temperature range. See the Magnetic Characteristics table for
complete, individual device parametrics.
Each monolithic circuit integrates a quadratic Hall element, im-
proved temperature compensating circuitry to reduce the intrinsic
sensitivity drift of the Hall element, a small-signal high-gain amplifier,
and a rail-to-rail low-impedance output stage. Many problems normally
associated with low-level analog signals are minimized by having the
Hall element and amplifier in a single chip. Output precision is obtained
by internal gain and offset trim adjustments during the manufacturing
process.
The first character of the part number suffix determines the device
operating temperature range: suffix ‘S–’ is for -20
°
C to +85
°
C, suffix
‘E–’ is for -40
°
C to +85
°
C, and suffix ‘L–’ is for -40
°
C to +150
°
C.
These devices are supplied in a 3-pin ultra-mini-SIP ‘–UA’ package.
Data Sheet
27501.1C
X
V
CC
1
2
3
GROUND
OUTPUT
SUPPLY
Dwg. PH-006
Pinning is shown viewed from branded side.
ABSOLUTE MAXIMUM RATINGS
Supply Voltage, V
CC
. . . . . . . . . . . .
6.0 V
Output Voltage, V
O
. . . . . . . . . . . . .
6.0 V
Output Sink Current, I
O
. . . . . . . .
5.0 mA
Magnetic Flux Density, B . . . .
Unlimited
Package Power Dissipation,
P
D
. . . . . . . . . . . . . . . . . . . .
See Graph
Operating Temperature Range, T
A
Suffix ‘S–’ . . . . . . . . . . . .
-20
°
C to +85
°
C
Suffix ‘E–’ . . . . . . . . . . . .
-40
°
C to +85
°
C
Suffix ‘L–’ . . . . . . . . . . .
-40
°
C to +150
°
C
Storage Temperature Range,
T
S
. . . . . . . . . . . . . . .
-65
°
C to +170
°
C
-
u
T
d
S
te
A
ep
L
FEATURES
IM
T
E
B
ti
n
t
c
O
l
Y
U
3
.
,
1
0
2
1
0
s
Output Voltage Proportional to Applied Magnetic Field
s
Ratiometric Rail-to-Rail Output
s
Improved Sensitivity
s
Superior Temperature Stability
s
4.5 V to 5.5 V Operation
s
Small Package Size
s
Solid-State Reliability
r
O
e
d
rs
c
c
a
Always order by complete part number, e.g.,
A3507EUA
.
3507
AND
3508
RATIOMETRIC,
LINEAR HALL-EFFECT SENSORS
FOR HIGH-TEMP. OPERATION
FUNCTIONAL BLOCK DIAGRAM
ALLOWABLE PACKAGE POWER DISSIPATION in MILLIWATTS
700
600
1
V
CC
"U" PACKAGE
R
θJA
= 183°C/W
500
400
300
"UA" PACKAGE
R
θJA
= 206°C/W
200
X
3
OUTPUT
GROUND
2
100
Dwg. FH-011
0
20
40
60
100
80
AMBIENT TEMPERATURE in
°C
120
140
160
Dwg. GH-046A
noted).
ELECTRICAL CHARACTERISTICS
over operating temperature range, at V
CC
= 5 V (unless otherwise
Limits
Characteristic
Supply Voltage
Supply Current
Quiescent
Voltage Output
Output Voltage
Symbol
V
CC
I
CC
V
OQ
V
OH
V
OL
Bandwidth (-3 dB)
Output Resistance
Wide-Band
Output Noise
BW
r
O
e
o
B = 0, BW = 10 Hz to 10 kHz,
T
A
= 25°C
Test Conditions
Operating
B = 0, V
CC
= 5.5 V, I
O
= 0
B = 0, I
O
= 1 mA, T
A
= 25°C
B = 0, I
O
= 1 mA
B = +X
*
, I
O
= 1 mA
B = -X
*
, I
O
= -1 mA
Min.
4.5
—
2.0
1.8
4.5
—
20
—
—
Typ.
5.0
—
2.5
2.5
4.8
0.2
—
2.5
125
Max.
5.5
10
3.0
3.2
—
0.5
—
10
—
Units
V
mA
V
V
V
V
kHz
Ω
µV
Negative current is defined as coming out of (sourcing) the output.
* This test requires positive and negative fields sufficient to swing the output driver between fully OFF and saturated (ON), respec-
tively. It is NOT intended to indicate a range of linear operation.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
Copyright © 1994, 2000, Allegro MicroSystems, Inc.
3507
AND
3508
RATIOMETRIC,
LINEAR HALL-EFFECT SENSORS
FOR HIGH-TEMP. OPERATION
MAGNETIC CHARACTERISTICS
over operating temperature range, at V
CC
= 5 V, I
O
= 1 mA
(unless otherwise noted).
Part Numbers
A3507LUA
Characteristic
*
˚Operating Temp. Range, T
A
˚Sensitivity at T
A
= 25°C
over Oper. Temp. Range
˚∆Sens
(∆T)
at T
A
= Max.
at T
A
= Min.
˚∆V
OQ(∆T)
˚Ratiometry,
∆V
OQ(∆V)
˚Ratiometry,
∆Sens
(∆V)
˚Positive Linearity, Lin+
˚Negative Linearity, Lin—
˚Symmetry
Min.
-40
2.0
1.7
-5.0
-8.8
—
—
—
—
—
—
Typ.
—
2.5
2.5
2.5
-1.3
—
100
100
100
100
100
Max.
+150
3.0
3.3
10
6.2
±35
—
—
—
—
—
Min.
-40
2.0
1.7
-6.3
-8.8
—
—
—
—
—
—
A3507EUA
Typ.
—
2.5
2.5
1.2
-1.3
—
100
100
100
100
100
Max.
+85
3.0
3.3
8.7
6.2
±35
—
—
—
—
—
Min.
-20
2.0
1.7
-10
-10
—
—
—
—
—
—
A3508SUA
Typ.
—
2.5
2.5
—
—
—
100
100
100
100
100
Max.
+85
3.0
3.3
10
10
±50
—
—
—
—
—
Units
°C
mV/G
mV/G
%
%
G
%
%
%
%
%
Magnetic flux density is measured at most sensitive area of device located 0.018" (0.46 mm) below the branded face of the “UA”
package.
* See Characteristics Definitions for test conditions.
† The nominal sensitivity temperature stability is designed to compensate for the temperature coefficient of samarium-cobalt
magnets (-0.02%/°C).
‡ This calculation (formula 1, next page) yields the device’s equivalent accuracy, over the operating temperature range, in gauss.
www.allegromicro.com
3507
AND
3508
RATIOMETRIC,
LINEAR HALL-EFFECT SENSORS
FOR HIGH-TEMP. OPERATION
CHARACTERISTICS DEFINITIONS
Quiescent Voltage Output.
In the quiescent state (no mag-
netic field), the output is ideally equal to one-half of the supply
voltage over the operating voltage and temperature range (V
OQ
∪
V
CC
/2). Due to internal component tolerances and thermal
considerations, there is a tolerance on the quiescent voltage
output and on the quiescent voltage output as a function of
supply voltage and ambient temperature. For purposes of
specification, the quiescent voltage output as a function of
temperature is defined as
∆V
OQ(∆T)
=
V
OQ(TA)
– V
OQ(25°C)
Sens
(25°C)
Ratiometry.
The A3507– and A3508– feature a ratiometric
output. The quiescent voltage output and sensitivity are
proportional to the supply voltage (ratiometric).
The per cent ratiometric change in the quiescent voltage
output is defined as
∆V
OQ(∆V)
=
V
OQ(VCC)
/ V
OQ(5V)
V
CC
/ 5 V
x 100%
(4)
(1)
and the per cent ratiometric change in sensitivity is defined as
∆Sens
(∆V)
=
Sens
(VCC)
/ Sens
(5V)
V
CC
/ 5 V
This calculation yields the device’s equivalent accuracy,
over the operating temperature range, in gauss.
Sensitivity.
The presence of a south-pole magnetic field
perpendicular to the package face (the branded surface) will
increase 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
V
O(500G)
– V
O(-500G)
1000 G
x 100%
(5)
Linearity and Symmetry.
The on-chip output stage is de-
signed to provide a linear output to within 500 mV of either rail
with a supply voltage of 5 V. This is equivalent to approxi-
mately
±800
gauss of ambient field. Although application of
stronger magnetic fields will not damage these devices, it will
force the output into a non-linear region. Linearity in per cent
is measured and defined as
V
O(500G)
– V
OQ
2 (V
O(250G)
– V
OQ
)
V
O(-500G)
– V
OQ
2 (V
O(-250G)
– V
OQ
)
Lin+ =
(2)
x 100%
(6)
Sens =
The stability of sensitivity as a function of temperature is
defined as
∆Sens
(∆T)
=
Sens
(TA)
– Sens
(25°C)
Sens
(25°C)
Lin– =
x 100%
(7)
and output symmetry as
x 100%
(3)
Sym =
V
O(500G)
– V
OQ
V
OQ
– V
O(-500G)
x 100%
(8)
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
3507
AND
3508
RATIOMETRIC,
LINEAR HALL-EFFECT SENSORS
FOR HIGH-TEMP. OPERATION
APPLICATIONS INFORMATION
Calibrated linear Hall devices, which can be used to
determine the actual flux density presented to the sensor in a
particular application, are available.
For safe, reliable operation, the output should not be
pulled above the supply voltage or pulled below the device
ground.
For optimum performance, a 100 pF capacitor between
the output and ground should be added.
The nominal sensitivity is factory set to compensate for
the temperature coefficient of samarium-cobalt magnets
(-0.02%/°C).
The ratiometric feature is especially valuable when these
devices are used with an analog-to-digital converter. A/D
converters typically derive their LSB step size by ratioing off a
reference voltage line. If the reference voltage varies, the LSB
will vary proportionally. This is a major error source in many
sensing systems. The A3507/08– can eliminate this source of
error by their ratiometric operation. Because their gain and
offsets are proportional to the supply voltage, if they are
powered from the A/D reference voltage, the sensor output
voltage will track changes in the LSB value.
Hall-effect applications information is available in the
application note “Linear Hall-Effect Sensors” (AN 27702),
which can be found in the latest issue of
Allegro Electronic
Data Book,
AMS-702, or at
BRANDED
SURFACE
SENSOR LOCATION
ACTIVE AREA DEPTH
0.0195"
0.50 mm
NOM
0.082"
2.07 mm
0.055"
1.40 mm
A
1
2
3
Dwg. MH-011-6B
TYPICAL CURRENT-SENSING APPLICATION
B
≈
N x 6.9 G/A
www.allegromicro.com
Dwg. AH-005A
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