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Электронный компонент: 3150

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DISCONTINUED PRODUCT
-- FOR REFERENCE ONL
Y.
Use
A3250 for new design
Data Sheet
27621.40
The A3150JLT and A3150JUA programmable switches provide
tooth/valley recognition in large gear-tooth sensing applications. Each
sensor consists of a single element, chopper-stabilized Hall-effect IC
that can be programmed to the desired magnetic switch point, opti-
mizing sensor airgap and timing accuracy performance after final
packaging. The small package can be easily assembled and used in
conjunction with a wide variety of gear/target shapes and sizes. The
two devices differ only in package style.
The sensing technology used for this sensor is Hall-effect based.
The sensor incorporates a single-element Hall IC that switches in
response to magnetic signals created by a ferrous target. The program-
mability of the circuit eliminates magnet and system offsets such as
those caused by tilt yet provides zero-speed detection capabilities
without the associated running jitter inherent in classical digital solu-
tions.
A proprietary dynamic offset cancelation technique, with an
internal high-frequency clock, reduces the residual offset voltage,
which is normally caused by device overmolding, temperature
dependancies, and thermal stress. This technique produces devices that
have an extremely stable quiescent output voltage, are immune to
mechanical stress, and have precise recoverability after temperature
cycling. 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 adjustments
during the manufacturing process and operate-point programming in the
user's application.
This sensor system is ideal for use in gathering speed, position, and
timing information using gear-tooth-based configurations. The
A3150JLT/JUA are particularly suited to those applications that require
accurate duty cycle control or accurate edge detection. The lower
vibration sensitivity also makes these devices extremely useful for
transmission speed sensing.
3150
Dwg. PH-003-2
1
SUPPLY
V
CC
GROUND
3
2
OUTPUT
X
PTCT
Always order by complete part number: the prefix 'A' + the basic four-digit
part number + a suffix to indicate operating temperature range +
a suffix to indicate package style, e.g.,
A3150JLT .
ABSOLUTE MAXIMUM RATINGS
at T
A
= 25
C
PRELIMINARY INFORMATION
(subject to change without notice)
April 12, 1999
Supply Voltage, V
CC
........................... 26.5 V
Reverse Supply Voltage, V
RCC
............ -30 V
Overvoltage Supply Current, I
CC
..... 100 mA
Magnetic Flux Density, B ............ Unlimited
Output Current, I
OUT
..... Internally Limited
Output OFF Voltage, V
OUT
................. 26.5 V
Reverse Output Current, I
ROUT
......... -50 mA
Operating Temperature Range,
T
A
............................... -40
C to +115
C
Storage Temperature, T
S
................... +170
C
PROGRAMMABLE, CHOPPER-
STABILIZED, HALL-EFFECT SWITCH
Continued next page
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
3150
PROGRAMMABLE, CHOPPER-
STABILIZED, PRECISION,
HALL-EFFECT SWITCH
Copyright 2000, Allegro MicroSystems, Inc.
FUNCTIONAL BLOCK DIAGRAM
Dwg. FH-020-3
GROUND
OUTPUT
<1
SUPPLY
DYNAMIC
OFFSET CANCELLATION
CURRENT
LIMIT
REG.
LOW-PASS
FILTER
SAMPLE
& HOLD
PROGRAM
LOGIC
OFFSET
ADJUST
1
3
2
POWER-UP
CONTROL
X
Two package styles provide a magnetically opti-
mized package for most applications. Suffix `LT' is a
miniature SOT-89/TO-243AA transistor package for
surface-mount applications; while suffix `UA' is a
three-lead ultra-mini-SIP for through-hole mounting.
FEATURES AND BENEFITS
s Chopper Stabilized for
Extremely Low Switch-Point Drift and
Immunity to Mechanical Stress
s Externally Programmed Switch Point
s On-Chip Supply-Transient Protection
s Output Short-Circuit Protection
s Single-Chip Sensing IC for High Reliability
s Small Mechanical Size
s <50
s Power-On Time
s Wide Operating Voltage Range
s Defined Power-On State
3150
PROGRAMMABLE, CHOPPER-
STABILIZED, PRECISION,
HALL-EFFECT SWITCH
www.allegromicro.com
Limits
Characteristic
Symbol
Test Conditions
Min.
Typ.
Max.
Units
Operate Point
B
OP
Programmable offset range
500
670
850
G
Initial (before programming)
0
20
40
G
Resolution
8.0
11
14
G
B
OP
V
CC
= 14 V, after programming, B
OP
500 G
-35
8.0
+35
G
Hysteresis
B
hys
5.0
20
35
G
NOTE: Typical data is at V
CC
= 5 V and T
A
= +25
C and is for design information only.
ELECTRICAL CHARACTERISTICS over operating voltage and temperature range (unless
otherwise noted).
Limits
Characteristic
Symbol
Test Conditions
Min.
Typ.
Max.
Units
Supply Voltage
V
CC
Operating, T
J
< 165
C
4.25
26
V
Power-On State
POS
After programming, V
CC
= 0 5 V
HIGH
HIGH
HIGH
Low Output Voltage
V
OUT(SAT)
I
OUT
= 20 mA
175
400
mV
Output Current Limit
I
OUTM
V
OUT
= 12 V
65
80
95
mA
Output Leakage Current
I
OFF
V
OUT
= 24 V
0.2
10
A
Supply Current
I
CC
Before programming, output OFF
4.0
7.0
mA
Before programming, output ON
5.0
8.0
mA
Reverse Supply Current
I
RCC
V
RCC
= -30 V
-5.0
mA
Power-On Delay
t
on
V
CC
> 5 V
20
50
s
Output Rise Time
t
r
R
L
= 820
, C
L
= 20 pF
200
ns
Output Fall Time
t
f
R
L
= 820
, C
L
= 20 pF
100
ns
Clock Frequency
f
C
340
kHz
Zener Voltage
V
Z
I
ZT
= 100
A, T
A
= 25
C
27
32
V
Zener Impedance
z
z
I
ZT
= 10 mA, T
A
= 25
C
50
100
NOTE: Typical data is at V
CC
= 5 V and T
A
= +25
C and is for design information only.
MAGNETIC CHARACTERISTICS over operating supply voltage and temperature ranges.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
3150
PROGRAMMABLE, CHOPPER-
STABILIZED, PRECISION,
HALL-EFFECT SWITCH
TYPICAL ELECTRICAL CHARACTERISTICS
0
25
50
75
100
AMBIENT TEMPERATURE IN
C
-50
Dwg. GH-053-2
125
-25
SUPPLY CURRENT IN mA
5.0
4.0
3.0
2.0
1.0
150
B < B
RP
B > B
OP
V = 5 V
CC
10
15
20
25
SUPPLY VOLTAGE IN VOLTS
0
Dwg. GH-041-2
5
SUPPLY CURRENT IN mA
0
2.0
4.0
6.0
8.0
10
B > B
OP
B < B
RP
T = +25
C
A
0
25
50
75
100
300
0
AMBIENT TEMPERATURE IN
C
200
100
-50
Dwg. GH-040-4
SATURATION VOLTAGE IN mV
150
-25
125
I = 20 mA
V = 4.524 V
OUT
CC
3150
PROGRAMMABLE, CHOPPER-
STABILIZED, PRECISION,
HALL-EFFECT SWITCH
www.allegromicro.com
FUNCTIONAL DESCRIPTION
Dwg. EH-012
REG
SAMPLE
& HOLD
X
Chopper-Stabilized Technique. These devices use a
proprietary dynamic offset cancellation technique, with an
internal high-frequency clock to reduce the residual offset
voltage of the Hall element that is normally caused by device
overmolding, temperature dependencies, and thermal stress.
This technique produces devices that have an extremely stable
quiescent Hall output voltage, are immune to thermal stress, and
have precise recoverability after temperature cycling. This
technique will also slightly degrade the device output repeatabil-
ity.
The Hall element can be considered as a resistor array
similar to a Wheatstone bridge. A large portion of the offset is a
result of the mismatching of these resistors. The chopper-
stabilizing technique cancels the mismatching of the resistors by
changing the direction of the current flowing through the Hall
plate and Hall voltage measurement taps, while maintaining the
Hall-voltage signal that is induced by the external magnetic flux.
The signal is, then, captured by a sample-and-hold circuit.
Operation. The output of these devices switches low (turns
ON) when a magnetic field (south pole) perpendicular to the
Hall sensor exceeds the operate point threshold (B
OP
). After
turn-ON, the output is capable of sinking 25 mA and the output
voltage is V
OUT(SAT)
. When the magnetic field is reduced below
the release point (B
RP
), the device output goes high (turns OFF).
The difference in the magnetic operate and release points is the
hysteresis (B
hys
) of the device. This built-in hysteresis allows
clean switching of the output even in the presence of external
mechanical vibration and electrical noise.
Applications. It is strongly recommended that an external
bypass capacitor be connected (in close proximity to the Hall
sensor) between the supply and ground of the device to reduce
both external noise and noise generated by the chopper-stabiliza-
tion technique.
The simplest form of magnet that will operate these devices
is a bar magnet with the south-seeking pole towards the branded
surface of the device. Many other methods of operation are
possible. Extensive applications information on magnets and
Hall-effect sensors is also available in the Allegro Electronic
Data Book
AMS-702 or Application Note 27701, or
www.allegromicro.com
SUPPLY
OUTPUT
Dwg. EH-013
0.1
F
SUPPLY
1
V
CC
3
2
X
PTCT
+V
HALL
VOLTAGE
B
+
--
Dwg. AH-011-2
+B
0
OUTPUT VOLTAGE
FLUX DENSITY
Dwg. GH-007-2
0
RP
B
V
OUT(SAT)
CC
V
OP
B
+V