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Электронный компонент: A1423

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A1421, A1422, A1423
A1421-DS Rev. 0
Worcester, Massachusetts 01615-0036 (508) 853-5000
115 Northeast Cutoff, Box 15036
www.allegromicro.com
Allegro MicroSystems, Inc.
AB SO LUTE MAX I MUM RAT INGS
Supply Voltage, V
CC
..........................................28 V
Reverse-Supply Voltage, V
RCC
........................ 18 V
Output Current, I
OUT
.......................................25 mA
Reverse-Output Current, I
ROUT
.....................50 mA
Reverse-Output Voltage, V
ROUT
...................50 mA
Operating Temperature
Ambient
(L) , T
A
......................... 40C to 150C
Maximum
Junction,
T
J(max)
........................165C
Storage Temperature, T
S
.................. 65C to 170C
High Accuracy Analog Speed Sensor
with Integrated Filter Capacitor
Package K, 4-pin SIP
Features and Benefi ts
Integrated tracking capacitor
Senses motion of ring magnet or ferrous targets
Wide operating temperature range
Operation with frequency of sensed transitions from 20 Hz to 30 kHz
EMI/ESD-resistant
Large effective air gaps
4.0 to 26.5 V operating range
Output compatible with both TTL and CMOS logic families
Reverse battery protection
Resistant to mechanical and thermal stress
1. VCC
2. VOUT
3. Test pin, tie to GND
4. GND
1
2
3
4
The A1421, A1422, and A1423 are ac-coupled Hall-effect sensors which include
monolithic integrated circuits that switch in response to changing differential
magnetic fi elds created by rotating ring magnets, or when coupled with a magnet,
by ferrous targets. This family of devices also includes an integrated capacitor,
providing the high accuracy of analog sensing without an external fi lter capaci-
tor. This reduces cost and components, while improving the reliability of the fi nal
sensor solution.
The magnetic fi eld changes are sensed by two integrated Hall transducers and then
are differentially amplifi ed on the chip. Differential sensing provides immunity to
radial vibration, within the device operating air gap range, by rejection of
common-mode signal changes. Steady-state system offsets are eliminated using an
on-chip differential bandpass fi lter with integrated capacitor. This fi lter also pro-
vides relative immunity to interference from electromagnetic sources. The device
utilizes advanced temperature compensation for the high-pass fi lter, sensitivity,
and Schmitt trigger switchpoints to guarantee optimal operation to low frequen-
cies over a wide range of air gaps and temperatures.
Each device includes a voltage regulator, two Hall transducers, temperature com-
pensating circuitry, a low-level amplifi er, bandpass fi lter, Schmitt trigger, and an
output driver. The on-board regulator permits operation with supply voltages from
4.0 to 26.5 V. The output stage can switch 20 mA over the full frequency response
range of the sensor, and is compatible with TTL and CMOS logic circuits.
Continued on next page.
Preliminary Data Sheet
Subject to Change Without Notice
June 16, 2004
Engineering samples available on a limited basis. Contact your local sales
or applications support offi ce for additional information.
2
A1421-DS Rev. 0
Worcester, Massachusetts 01615-0036 (508) 853-5000
115 Northeast Cutoff, Box 15036
www.allegromicro.com
Allegro MicroSystems, Inc.
High Accuracy Speed Sensor with Integrated Filter Capacitor
A1421, A1422, A1423
Product Selection Guide
Part Number
Output Switching
at B
DIFF
= 0
Switchpoints
Hysteresis
Symmetry
B
Diff
Increasing
B
Diff
Decreasing
B
OP(typ)
(G)
B
RP
(G)
B
Hys (typ)
(G)
B
OP(max)
+
B
RP(min)
(G)
B
OP(typ)
+
B
RP(typ)
(G)
B
OP(min)
+
B
RP(max)
(G)
A1421LK
Low (On) to
High (Off)
High (Off) to
Low (On)
15
0
15
15
15
7.5
A1422LK
High (Off) to
Low (On)
Low (On) to
High (Off)
15
15
30
0
0
0
A1423LK
High (Off) to
Low (On)
Low (On) to
High (Off)
65
65
130
0
0
0
The devices in this family differ from each other in their switch-
point specifi cations and their switching polarity. The A1421
has a small hysteresis and asymmetrical switchpoints, with one
switchpoint at the zero-crossing. The A1422 has a small hys-
teresis and symmetrical switchpoints, both near the zero-cross-
ing. The A1423 offers high vibration immunity, by means of its
larger hysteresis, establishing symmetrical switchpoints further
from the zero-crossing. The output polarity is shown in the Prod-
uct Selection Guide table.
This variety of options provides fl exibility for achieving solu-
tions for a wide range of applications, including automotive
transmission and crankshaft speed sensing.
The device package has an operating ambient temperature range
40 C to 150C (suffi x L), and is provided in a 4-pin plastic SIP
(part number suffi x K).
Use the following complete part numbers when ordering:
Preliminary - Subject to Change
Without Notice June 16, 2004
3
A1421-DS Rev. 0
Worcester, Massachusetts 01615-0036 (508) 853-5000
115 Northeast Cutoff, Box 15036
www.allegromicro.com
Allegro MicroSystems, Inc.
High Accuracy Speed Sensor with Integrated Filter Capacitor
A1421, A1422, A1423
Functional Block Diagram
Hall
Amp
Regulator
Bandpass Filter Integrated
Tracking Capacitor
VOUT
(Pin 2)
VCC
(Pin 1)
GND
(Pin 4)
0.1 uF
V+
Diagnostic
Circuitry
Gain
Stage
Dual Hall
Transducers
Dual
Comparators
Pulse
Generation
Logic
Test Pin
(Pin 3)
Preliminary - Subject to Change
Without Notice June 16, 2004
4
A1421-DS Rev. 0
Worcester, Massachusetts 01615-0036 (508) 853-5000
115 Northeast Cutoff, Box 15036
www.allegromicro.com
Allegro MicroSystems, Inc.
High Accuracy Speed Sensor with Integrated Filter Capacitor
A1421, A1422, A1423
OPERATING CHARACTERISTICS
Valid at T
A
= 40
C to 150
C, T
J
165C; over operational air gap range and V
CC
within
operating range, unless otherwise noted. Typical operating parameters: V
CC
= 12 V and T
A
= 25C.
Characteristic
Symbol
Test Conditions
Min.
Typ.
Max.
Units
ELECTRICAL CHARACTERISTICS
Supply Voltage
V
CC
Operating; T
J
< T
J(max)
4.0
12.0
26.5
V
Supply Current
I
CC
4.2
7.0
mA
Output Saturation Voltage
V
OUT(SAT)
I
SINK
= 20 mA
140
400
mV
Output Leakage Current
I
OFF
V
OUT
= 24 V, B
diff
= 0
5
A
PROTECTION COMPONENT CHARACTERISTICS
Reverse Supply Current
I
RCC
V
CC
= 18 V
1
mA
Supply Zener Current
I
ZCC
V
CC
= 28 V
10
mA
Supply Zener Clamp Voltage
V
ZCC
I
CC
= 10 mA
1
, T
A
= 25C
28
33
37
V
Output Zener Current
I
ZOUT
V
OUT
= 28 V
3
mA
Output Zener Clamp Voltage
V
ZOUT
I
OUT
= 3 mA, T
A
= 25C
28
V
Output Short Circuit Current Limit
I
OUT(lim)
50
mA
RESPONSE CHARACTERISTICS
Power-On State
POS
t < t
R
High
V
Power-On Time
2,6
t
PO
V
CC
> V
CC(min)
4.5
9
ms
Settling Time
3,6
t
S
f
Bdiff
100 Hz
0
50
ms
Response Time
6
t
R
Equal to t
PO
+ t
S
;
f
Bdiff
100 Hz
4.5
59
ms
Upper Corner Frequency
f
cu
3 dB, single pole
30
kHz
Lower Corner Frequency
f
cl
3 dB, single pole
20
Hz
OUTPUT CHARACTERISTICS
Output Rise Time
4
t
rise
R
PU
= 1 k, C = 10 pF
200
ns
Output Fall Time
t
fall
R
PU
= 1 k, I
SINK
= 20 mA, C = 10 pF
200
ns
Continued on next page.
Preliminary - Subject to Change
Without Notice June 16, 2004
5
A1421-DS Rev. 0
Worcester, Massachusetts 01615-0036 (508) 853-5000
115 Northeast Cutoff, Box 15036
www.allegromicro.com
Allegro MicroSystems, Inc.
High Accuracy Speed Sensor with Integrated Filter Capacitor
A1421, A1422, A1423
OPERATING CHARACTERISTICS, continued
Valid at T
A
= 40
C to 150
C, T
J
165C; over operational air gap range and V
CC
within operating range, unless otherwise noted. Typical operating parameters: V
CC
= 12 V and T
A
= 25C.
Characteristic
Symbol
Test Conditions
Min.
Typ.
Max.
Units
MAGNETIC CHARACTERISTICS
5
Operate point
B
OP
6
1421, B
diff
increasing, f
Bdiff
= 200 Hz, B
diff
= 50 Gp-p
0.0
15.0
27.5
G
1422, B
diff
increasing, f
Bdiff
= 200 Hz, B
diff
= 50 Gp-p
5.0
15.0
35.0
G
1423, B
diff
increasing, f
Bdiff
= 200 Hz, B
diff
= 200 Gp-p
10.0
65.0
100.0
G
Release Point
B
RP
6
1421, B
diff
decreasing, f
Bdiff
= 200 Hz, B
diff
= 50 Gp-p
-12.5
0.0
7.5
G
1422, B
diff
decreasing, f
Bdiff
= 200 Hz, B
diff
= 50 Gp-p
-35.0
-15.0
-5.0
G
1423, B
diff
decreasing, f
Bdiff
= 200 Hz, B
diff
= 200 Gp-p
-100.0
-65.0
-10.0
G
Hysteresis
B
HYS
6
1421, f
Bdiff
= 200 Hz, B
diff
= 50 Gp-p
5
15
35
G
1422, f
Bdiff
= 200 Hz, B
diff
= 50 Gp-p
30
G
1423, f
Bdiff
= 200 Hz, B
diff
= 200 Gp-p
130
G
Applied Magnetic Field
7
B
diff
Differential p-p magnetic fi eld
1250
G
1
Equivalent to I
CC(max)
+ 3 mA.
2
Time required to initialize device.
3
Time required for the output switchpoints to be within specifi cation.
4
Output Rise Time will be dominated by the RC time constant.
5
For lower frequencies, the absolute values of B
OP
, B
RP
, and B
HYS
may decrease due to delay induced by the high-pass fi lter.
6
See Defi nitions of Terms section.
7
Exceeding the maximum magnetic fi eld may result in compromised absolute accuracy.
Preliminary - Subject to Change
Without Notice June 16, 2004