ats643 Allegro MicroSystems, Inc., ats643 Datasheet - Page 13

• Manufacturer Part Number: ats643
• Description: Ats643lsh Self-calibrating Zero-speed Differential Gear Tooth Sensors With Continuous Update
• Manufacturer: Allegro MicroSystems, Inc.

ATS643LSH
Undervoltage Lockout. When the supply voltage falls
below the minimum operating voltage, V
and remains high regardless of the state of the magnetic gradi-
ent from the target. This lockout feature prevents false signals,
caused by undervoltage conditions, from propagating to the
output of the sensor.
Power Supply Protection. The device contains an on-chip
regulator and can operate over a wide V
that need to operate from an unregulated power supply, transient
protection must be added externally. For applications using a
regulated line, EMI/RFI protection may still be required. Contact
Allegro Microsystems for information on the circuitry needed
for compliance with various EMC specifications. Refer to fig-
ure 7 for an example of a basic application circuit.
Automatic Gain Control (AGC). This feature allows the
device to operate with an optimal internal electrical signal,
regardless of the air gap (within the AG specification). At
Figure 7. Typical basic circuit for proper device operation.
(Optional)
2
ATS643
1
4
100 Ω
3
(Optional)
CC
CC(UV)
range. For devices
0.01 μF
Gear Tooth Sensor with Continuous Update
, I
CC
Self-Calibrating, Zero-Speed Differential
goes high
VCC
power-on, the device determines the peak-to-peak amplitude
of the signal generated by the target. The gain of the sensor is
then automatically adjusted. Figure 8 illustrates the effect of this
feature.
Automatic Offset Adjust (AOA). The AOA is patented cir-
cuitry that automatically cancels the effects of chip, magnet, and
installation offsets. (For capability, see Dynamic Offset Cancel-
lation, in the Operating Characteristics table.) This circuitry is
continuously active, including both during power-on mode and
running mode, compensating for any offset drift. Continuous
operation also allows it to compensate for offsets induced by
temperature variations over time.
Assembly Description. The ATS643 is integrally molded
into a plastic body that has been optimized for size, ease of
assembly, and manufacturability. High operating temperature
materials are used in all aspects of construction.
Figure 8. Automatic Gain Control (AGC). The AGC function corrects for
variances in the air gap. Differences in the air gap cause differences in
the magnetic field at the device, but AGC prevents that from affecting
device performance, a shown in the lowest panel.
Response, without AGC
Response, with AGC
Internal Differential
Internal Differential
Mechanical Profile
Ferrous Target
Analog Signal
Analog Signal
V+
V+
115 Northeast Cutoff, Box 15036
Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 [phone]
www.allegromicro.com
AG
AG
AG
AG
Large
Small
Small
Large
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