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Part: A1422LK
Category:
Description: High Accuracy Analog Speed Sensor With Integrated Filter Capacitor
Company: Allegro Micro Systems, Inc.
Datasheet: Download A1422LK datasheet File size : 89 kB
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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 fields 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 filter capacitor. This reduces cost and components, while improving the reliability of the final sensor solution. The magnetic field 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 filter with integrated capacitor. This filter also provides relative immunity to interference from electromagnetic sources. The device utilizes advanced temperature compensation for the high-pass filter, sensitivity, and Schmitt trigger switchpoints to guarantee optimal operation to low frequencies over a wide range of air gaps and temperatures. Each device includes a voltage regulator, two Hall transducers, temperature compensating circuitry, a low-level amplifier, bandpass filter, 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, VCC ......... 28 V Reverse-Supply Voltage, VRCC ...... 18 V Output Current, IOUT ...... 25 mA Reverse-Output Current, IROUT............ 50 mA Reverse-Output Voltage, VROUT ..........50 mA Operating Temperature Ambient (L) , TA....... 40ºC to 150ºC Maximum Junction, TJ(max)......165ºC Storage Temperature, TS ......... 65ºC to 170ºC
· · · · · · · · · ·
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
Preliminary - Subject to Change Without Notice June 16, 2004
A1421, A1422, A1423
High Accuracy Speed Sensor with Integrated Filter Capacitor
The devices in this family differ from each other in their switchpoint specifications 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 hysteresis and symmetrical switchpoints, both near the zero-crossing. 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 Product Selection Guide table.
This variety of options provides flexibility for achieving solutions 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 150°C (suffix L), and is provided in a 4-pin plastic SIP (part number suffix K).
Product Selection Guide
Use the following complete part numbers when ordering:
Output Switching at BDIFF = 0 Part Number BDiff Increasing Low (On) to High (Off) High (Off) to Low (On) High (Off) to Low (On) BDiff Decreasing High (Off) to Low (On) Low (On) to High (Off) Low (On) to High (Off) Switchpoints BOP(typ) (G) 15 15 65 BRP (G) 0 15 65 Hysteresis BHys (typ) (G) 15 30 130 BOP(max)+ BRP(min) (G) 15 0 0 Symmetry BOP(typ)+ BRP(typ) (G) 15 0 0 BOP(min)+ BRP(max) (G) 7.5 0 0
A1421LK A1422LK A1423LK
A1421-DS Rev. 0
Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com
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Preliminary - Subject to Change Without Notice June 16, 2004
A1421, A1422, A1423
High Accuracy Speed Sensor with Integrated Filter Capacitor
Functional Block Diagram
V+ VCC (Pin 1) Test Pin (Pin 3)
Regulator Dual Hall Transducers Dual Comparators
Diagnostic Circuitry
Bandpass Filter Integrated Tracking Capacitor Hall Amp Gain Stage
VOUT (Pin 2) Pulse Generation Logic
0.1 uF
GND (Pin 4)
A1421-DS Rev. 0
Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com
3
Preliminary - Subject to Change Without Notice June 16, 2004
A1421, A1422, A1423
High Accuracy Speed Sensor with Integrated Filter Capacitor
OPERATING CHARACTERISTICS Valid at TA = 40ºC to 150ºC, TJ 165°C; over operational air gap range and VCC within operating range, unless otherwise noted. Typical operating parameters: VCC = 12 V and TA = 25°C.
Characteristic ELECTRICAL CHARACTERISTICS Supply Voltage Supply Current Output Saturation Voltage Output Leakage Current VCC ICC VOUT(SAT) ISINK = 20 mA IOFF VOUT = 24 V, Bdiff = 0 Operating; TJ < TJ(max) 4.0 12.0 4.2 140 26.5 7.0 400 5 V mA mV µA Symbol Test Conditions Min. Typ. Max. Units
PROTECTION COMPONENT CHARACTERISTICS Reverse Supply Current Supply Zener Current Supply Zener Clamp Voltage Output Zener Current Output Zener Clamp Voltage Output Short Circuit Current Limit RESPONSE CHARACTERISTICS Power-On State Power-On Time2,6 Settling Time3,6 Response Time6 Upper Corner Frequency Lower Corner Frequency OUTPUT CHARACTERISTICS Output Rise Time4 Output Fall Time
Continued on next page.
IRCC IZCC VZCC IZOUT VZOUT IOUT(lim)
VCC = 18 V VCC = 28 V ICC = 10 mA1, TA = 25°C VOUT = 28 V IOUT = 3 mA, TA = 25°C
28 28
33
1 10 37 3 50
mA mA V mA V mA
POS tPO tS tR fcu fcl trise tfall
t VCC(min) fBdiff 100 Hz Equal to tPO + tS; fBdiff 100 Hz 3 dB, single pole 3 dB, single pole RPU = 1 k, C = 10 pF RPU = 1 k, ISINK = 20 mA, C = 10 pF
0 4.5 30
High 4.5
9 50 59 20 200 200
V ms ms ms kHz Hz ns ns
A1421-DS Rev. 0
Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com
4
Preliminary - Subject to Change Without Notice June 16, 2004
A1421, A1422, A1423
High Accuracy Speed Sensor with Integrated Filter Capacitor
OPERATING CHARACTERISTICS, continued Valid at TA = 40ºC to 150ºC, TJ 165°C; over operational air gap range and VCC
within operating range, unless otherwise noted. Typical operating parameters: VCC = 12 V and TA = 25°C. Characteristic Symbol Test Conditions 1421, Bdiff increasing, fBdiff = 200 Hz, Bdiff = 50 Gp-p Operate point BOP6 1422, Bdiff increasing, fBdiff = 200 Hz, Bdiff = 50 Gp-p 1423, Bdiff increasing, fBdiff = 200 Hz, Bdiff = 200 Gp-p 1421, Bdiff decreasing, fBdiff = 200 Hz, Bdiff = 50 Gp-p Release Point BRP
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Min. 0.0 5.0 10.0 -12.5 -35.0 -100.0 5
Typ. 15.0 15.0 65.0 0.0 -15.0 -65.0 15 30 130
Max. 27.5 35.0 100.0 7.5 -5.0 -10.0 35 1250
Units G G G G G G G G G G
MAGNETIC CHARACTERISTICS5
1422, Bdiff decreasing, fBdiff = 200 Hz, Bdiff = 50 Gp-p 1423, Bdiff decreasing, fBdiff = 200 Hz, Bdiff = 200 Gp-p 1421, fBdiff = 200 Hz, Bdiff = 50 Gp-p
Hysteresis Applied Magnetic Field7
1Equivalent to I
2Time
BHYS6 Bdiff
1422, fBdiff = 200 Hz, Bdiff = 50 Gp-p 1423, fBdiff = 200 Hz, Bdiff = 200 Gp-p Differential p-p magnetic field
CC(max) + 3 mA. required to initialize device. 3Time required for the output switchpoints to be within specification. 4Output Rise Time will be dominated by the RC time constant. 5For lower frequencies, the absolute values of B , B , and B OP RP HYS may decrease due to delay induced by the high-pass filter. 6 See Definitions of Terms section. 7 Exceeding the maximum magnetic field may result in compromised absolute accuracy.
A1421-DS Rev. 0
Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com
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Others parts begin by a1
A1-1 A1-2 A1-3 A1-4 A1-5 A1-6 A1-7 A1-8 A1-9
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