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PDF A1642LK Data sheet ( Hoja de datos )
| Número de pieza | A1642LK | |
| Descripción | Two-Wire True Zero-Speed Miniature Differential Peak-Detecting Sensor | |
| Fabricantes | Allegro MicroSystems | |
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Hay una vista previa y un enlace de descarga de A1642LK (archivo pdf) en la parte inferior de esta página. Total 13 Páginas | ||
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A1642LK
Two-Wire True Zero-Speed Miniature Differential
Peak-Detecting Sensor with Continuous Calibration
Package K, 4-pin SIP
1234
1. VCC
2. No connection
3. Test pin (float or tie to GND)
4. GND
The A1642 is an optimized Hall effect sensing integrated circuit that provides a
user-friendly solution for true zero-speed digital ring-magnet sensing in two-wire
applications. This small package can be easily assembled and used in conjunction
with a wide variety of target shapes and sizes.
The integrated circuit incorporates a dual-element Hall effect sensor 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 operat-
ing time with the use of a running-mode calibration. The running-mode calibration
allows immunity to environmental effects such as micro-oscillations of the target
or sudden air gap changes.
The regulated current output is configured for two-wire applications and the
sensor is ideally suited for obtaining speed and duty cycle information in ABS
(antilock braking systems). The 1.5 mm spacing between the dual Hall elements is
optimized for fine pitch ring-magnet-based configurations. For applications requir-
ing sensing of rotating ferrous gears and targets, refer to the ATS642LSH series of
productsw.wTw.hDaetaSphaeect4kU.acogme is lead (Pb) free, with 100% matte tin leadframe plating.
ABSOLUTE MAXIMUM RATINGS
Supply Voltage, VCC .......................................... 28 V
Reverse-Supply Voltage, VRCC ........................ –18 V
Operating Temperature
Ambient, TA,............................... –40ºC to 150ºC
Maximum Junction, TJ(max)........................165ºC
Storage Temperature, TS .................. –65ºC to 170ºC
Features and Benefits
• Running mode calibration for continu-
ous optimization
• Single chip IC for high reliability
• Internal current regulator for 2-wire
operation
• Precise duty cycle signal over
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
• Wide operating voltage range
A1642LK-DS
Use the following complete part numbers when ordering:
Part Number
Packing*
A1642LK-I1-T
Bulk, 500 pieces/bag
A1642LKTN-I1-T
Tape and reel, 13-inch reel
4000 pieces/reel
A1642LK-I2-T
Bulk, 500 pieces/bag
A1642LKTN-I2-T
Tape and reel, 13-inch reel
4000 pieces/reel
*Contact Allegro for additional packing options.
ICC Typical
6.0 Low to 14.0 High mA
7.0 Low to 14.0 High mA
Allegro MicroSystems, Inc.
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
1 page  
A1642LK
Two-Wire True Zero-Speed Miniature Differential Peak-Detecting Sensor with Continuous Calibration
Characteristic Data
Supply Current (High) versus Ambient Temperature
(I1 Trim)
16
15
Vcc (V)
14 24
12
4
13
12
-50
0 50 100 150
TA (°C)
Supply Current (Low) versus Ambient Temperature
(I1 Trim)
8
7
Vcc (V)
6 24
12
4
5
4
-50 0
50 100 150
TA (°C)
Supply Current (High) versus Supply Voltage
(I1 Trim)
16
15
14
13
12
0
TA (°C)
-40
25
85
150
5 10 15 20 25
VCC (V)
Supply Current (Low) versus Supply Voltage
(I1 Trim)
8
7
TA (°C)
6 -40
25
150
5
4
05
10 15 20 25
VCC (V)
A1642LK-DS
Allegro MicroSystems, Inc.
5
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
5 Page 
A1642LK
Two-Wire True Zero-Speed Miniature Differential Peak-Detecting Sensor with Continuous Calibration
SENSOR OPERATION
Each operating mode is described in detail below.
Power-On
When power (VCC > VCC(Min)) is applied to the device, a short
period of time is required to power the various portions of the
IC. During this period, the A1642 powers-on in the high current
state, ICC(High). After power-on, there are conditions that could
induce a change in the output state. Such an event could be
caused by thermal transients, but would require a static applied
magnetic field, proper signal polarity, and particular direction
and magnitude of internal signal drift.
Initial Offset Adjust
The sensor initially cancels the effects of chip, magnet, and
installation offsets. Once offsets have been cancelled, the digital
tracking DAC is ready to track the signal and provide output
switching. The period of time required for both Power-On and
Initial Offset Adjust is defined as the Power-On Time.
Calibration Mode
The calibration mode allows the sensor to automatically select
the proper signal gain and continue to adjust for offsets. The
AGC is active, and selects the optimal signal gain based on the
amplitude of the VPROC signal. Following each adjustment to
the AGC DAC, the Offset DAC is also adjusted to ensure the
internal analog signal is properly centered.
During this mode, the tracking DAC is active and output switch-
ing occurs, but the duty cycle is not guaranteed to be within
specification.
Running Mode
After the Initial Calibration period, CI, establishes a signal gain,
the device moves to Running mode. During Running mode, the
sensor tracks the input signal and gives an output edge for every
peak of the signal. AOA remains active to compensate for any
offset drift over time.
The A1642 incorporates a novel algorithm for adjusting the
signal gain during Running mode. This algorithm is designed
to optimize the VPROC signal amplitude in instances where the
magnetic signal “seen” during the calibration period is not repre-
sentative of the amplitude of the magnetic signal for the installed
sensor air gap (see figure 9).
1
Internal Differential
Signal, VPROC
2 34
BOP
BRP
5
BOP
BRP
Sensor Electrical
Output, IOUT
Figure 9: Operation of Running Mode Gain Adjust.
Position 1. The device is initially powered-on. Self-calibration occurs.
Position 2. Small amplitude oscillation of the target sends an erroneously small differential signal to the sensor. The ampli-
tude of VPROC is greater than the switching hysteresis (BOP and BRP), and the device output switches.
Position 3. The calibration period completes on the third rising output edge, and the device enters Running mode.
Position 4. True target rotation occurs and the correct magnetic signal is generated for the installation air gap. The estab-
lished signal gain is too large for the target’s rotational magnetic signal at the given air gap.
Position 5. Running Mode Calibration corrects the signal gain to an optimal level for the installation air gap.
A1642LK-DS
Allegro MicroSystems, Inc.
11
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
11 Page | ||
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