A1423LK
| Model | A1423LK |
| Description | High Accuracy Analog Speed Sensor with Integrated Filter Capacitor |
| PDF file | Total 16 pages (File size: 2M) |
| Chip Manufacturer | ALLEGRO |
Preliminary Data Sheet
Subject to Change Without Notice
June 16, 2004
A1421, A1422, A1423
High Accuracy Analog Speed Sensor
with Integrated Filter Capacitor
Package K, 4-pin SIP
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 amplified 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 amplifier, 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.
1
2
3
4
1. VCC
2. VOUT
3. Test pin, tie to GND
4. GND
Features and Benefits
ABSOLUTE MAXIMUM RATINGS
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
.........................
–40ºC to 150ºC
Maximum Junction, T
J(max)
........................165ºC
Storage Temperature, T
S
..................
–65ºC to 170ºC
•
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•
•
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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
Engineering samples available on a limited basis. Contact your local sales
or applications support office for additional information.
A1421-DS Rev. 0
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
