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A1468
Three-Wire True Zero-Speed Differential Peak-Detecting
Sensor IC with Continuous Calibration
FEATURES AND BENEFITS
• 4.0 to 26.5 V supply operating range
• Minimum differential field 20 Gpk-pk
• Running mode calibration for continuous optimization
• Single chip IC for high reliability
• Precise duty cycle signal throughout operating
temperature range
• Large operating air gaps
• Automatic Gain Control (AGC) for air-gap–independent
switchpoints
• Automatic Offset Adjustment (AOA) for signal
processing optimization
• True zero-speed operation
• Undervoltage lockout
• Reverse battery protection
• Scan and IDDQ for increased test coverage
PACKAGE: 4-PIN SIP (SUFFIX K)
Not to scale
DESCRIPTION
TheA1468 is an optimized Hall effect sensing IC that provides
a user-friendly solution for digital ring-magnet sensing, or
when coupled with a magnet, ferromagnetic target sensing,
in three-wire applications. The small device package can be
easily assembled into applications for use in conjunction with
a wide variety of target shapes and sizes.
The integrated circuit incorporates dual Hall effect elements
with a 2.2 mm spacing and signal processing that switches
in response to differential magnetic signals created by ring-
magnet poles. The circuitry contains a sophisticated digital
circuit to reduce system offsets, to calibrate the gain for air-
gap–independent switchpoints, and to achieve true zero-speed
operation. Signal optimization occurs at power-on through
the combination of offset and gain adjust, and is maintained
throughout the operating time with the use of a running-mode
calibration. The running-mode calibration provides immunity
to environmental effects such as micro-oscillations of the target
or sudden air gap changes.
The device is ideally suited to obtaining speed and duty cycle
information in ring-magnet–based speed, position, and timing
applications, such as in speedometers.
The A1468 is available in a 4-pin SIP (suffix K). The package
is lead (Pb) free, with 100% matte tin leadframe plating.
VCC
E1
Hall
Amplifier
E2
Automatic Offset
Adjustment (AOA)
Control
AOA DAC
Gain
Internal
Regulator
A1468-DS, Rev. 3
Automatic Gain
Control (AGC)
AGC DAC
Test Signals
TEST
Tracking DAC
Peak Hold
+
Functional Block Diagram
Current
Limit
OUT
GND

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A1468
Three-Wire True Zero-Speed Differential Peak-Detecting
Sensor IC with Continuous Calibration
Selection Guide
Part Number
Package
A1468LK-T
4-pin through hole SIP
*Contact Allegrofor additional packing options.
Packing*
Bulk, 500 pieces per bag
Operating Ambient
Temperature Range, TA
(°C)
-40 to 150
Absolute Maximum Ratings
Characteristic
Forward Supply Voltage
Reverse Supply Voltage
Output Current
Reverse Output Current
Reverse Output Voltage
Output Off Voltage
Operating Ambient Temperature
Maximum Junction Temperature
Storage Temperature
SPECIFICATIONS
Symbol
VCC
VRCC
IOUT
IROUT
VROUT
VOUT
TA
TJ(max)
Tstg
Notes
Refer to Power Derating Curves chart
L temperature range
Rating
38
–18
30
–50
–0.5
28
–40 to 150
165
–65 to 170
Unit
V
V
mA
mA
V
V
ºC
ºC
ºC
1 23 4
Package K, 4-Pin SIP Pin-out Diagram
Terminal List Table
Number
Name
1 VCC
2 VOUT
3 TEST
4 GND
Function
Supply voltage
Output
Test pin, float
Ground
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
2

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A1468
Three-Wire True Zero-Speed Differential Peak-Detecting
Sensor IC with Continuous Calibration
OPERATING CHARACTERISTICS: valid throughout operating voltage and ambient temperature ranges, typical data ap-
plies at VCC = 12 V and TA = 25°C; unless otherwise specified
Characteristics
Symbol
Test Conditions
Min.
Typ.
Max.
Unit1
Electrical Characteristics
Supply Voltage2
Undervoltage Lockout
Supply Current
Power-On Characteristics
VCC
VCC(uv)
ICC
Operating, TJ ≤ 165°C
VCC = 0 → VCC(min) + 1 V and
VCC(min) + 1 V → 0 V
VCC > VCC(min)
4 – 26.5 V
– – VCC(min) V
3.0 5.0 7.5 mA
Power-On State
Power-On Time3
Transient Protection Characteristics
POS
tPO
VOUT, connected as in figure 6
VCC > VCC(min)
– High –
V
– – 2.3 ms
Supply Zener Clamp Voltage
Supply Zener Current
VZ(supply) ICC = ICC(max) + 3 mA, TA = 25 °C
IZ(supply) Vsupply = 38 V
38 – – V
ICC(max)
+3
mA
Reverse Supply Current
Output Zener Clamp Voltage
Output Zener Current
Output Current Limit
Output Stage Characteristics
IRCC
VZ(output)
IZ(output)
IOUT(lim)
VRCC = –18 V, TJ < TJ(max)
IOUT = 3 mA, TA = 25°C
VOUT = 28 V
– – –1 mA
28 – – V
– – 3 mA
30 – 85 mA
Output Saturation Voltage
Output Leakage Current
Output Fall Time
Performance Characteristics
VOUT(sat)
IOFF
tf
IOUT(sink) = 20 mA
VOUT = 24 V, output off
RPU = 1 kΩ, VPU = 20 V, COUT = 10 pF
– 220 400 mV
– – 10 µA
– 2 – µs
Operating Magnetic Signal Range
BDIFF
Peak-to-peak of differential signal; operation
within specification
20
– 1200 G
Operate Point4
BOP See figure 5
– 120 – mV
3 – 10 G
Release Point4
BRP See figure 5
– 120 – mV
3 – 10 G
Operating Frequency
Analog Signal Bandwidth
fOP
BW Equivalent to f = –3 dB
0 – 10 kHz
20 –
– kHz
Initial Calibration Cycle5
Output Duty Cycle Precision
Output Period Precision
Allowable User Induced Differential
Offset
ncal
DOUT
TOUT
Output rising edges before calibration is
completed, 0 offset, fOP ≤ 200 Hz
Using a pure sine magnetic signal, with fOP and
BDIFF within specification
Using pure sine magnetic signal with
BDIFF = 50 Gpk-pk and fOP = 1 kHz
BDIFFEXT Output switching only
– 3 edge
– ±15 %
0.3 –
%
– ±100 G
11 G (gauss) = 0.1 mT (millitesla).
2Maximum voltage operation must not exceed maximum junction temperature. Refer to Power Derating Curves chart.
3Time required to initialize device. Power-On Time includes the time required to complete the internal automatic offset adjust. The DAC is then ready for peak acquisition.
4Values in G are based on device in maximum gain setting.
5Non-uniform magnetic profiles may require additional output pulses before calibration is complete.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
3