ats643 Allegro MicroSystems, Inc., ats643 Datasheet - Page 10

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

ATS643LSH
V
induced by the target and sensed by the Hall elements. When
V
higher or lower level, it triggers sensor switch turn-on and turn-
off. As shown in figure 3, when the switch is in the off state, as
V
point, B
in the on state, as V
Figure 4. The Continuous Update algorithm allows the Allegro sensor to immediately interpret and adapt to significant variances in the magnetic field
generated by the target as a result of eccentric mounting of the target, out-of-round target shape, elevation due to lubricant build-up in journal gears, and
similar dynamic application problems that affect the TEAG (Total Effective Air Gap). The algorithm is used to dynamically establish and subsequently
update the device switchpoints (B
it remains properly proportioned and centered within the peak-to-peak range of the internal analog signal, V
As shown in panel A, the variance in the target position results in a change in the TEAG. This affects the sensor as a varying magnetic field, which
results in proportional changes in the internal analog signal, V
switchpoints based on the fluctuation of V
B
PROC
PROC
PROC
HYS
1
2
3
4
is directly proportional to the magnetic flux density, B,
transitions through a switchpoint from the appropriate
rises through a certain limit, referred to as the operate
OP
Switchpoint
, the switch toggles from off to on. When the switch is
B
B
B
B
B
B
B
B
OP(#1)
OP(#2)
OP(#3)
OP(#4)
RP(#1)
RP(#2)
RP(#3)
RP(#4)
(A) TEAG varying; cases such as
eccentric mount, out-of-round region,
normal operation position shift
Sensor
PROC
Target
Determinant
Peak Values
Pk
Pk
Pk
Pk
Pk
Pk
Pk
Pk
falls below B
Smaller
TEAG
(#1)
(#2)
(#3)
(#4)
(#5)
(#6)
(#7)
(#8)
(C) Referencing the internal analog signal, V
, Pk
, Pk
, Pk
, Pk
, Pk
, Pk
, Pk
, Pk
OP
and B
(#2)
(#3)
(#4)
(#5)
(#6)
(#7)
(#8)
(#9)
PROC
RP
OP
). The hysteresis, B
to a certain limit, the
, as shown in panel C.
Sensor
Gear Tooth Sensor with Continuous Update
Target
V+
Self-Calibrating, Zero-Speed Differential
PROC
Larger
TEAG
HYS(#x)
, shown in panel B. The Continuous Update algorithm is used to establish accurate
Pk
, at each target feature configuration results from this recalibration, ensuring that
(#1)
V+
PROC
Pk
B
OP(#1)
release point, B
As shown in panel C of figure 4, threshold levels for the ATS643
switchpoints are established dynamically as function of the
peak input signal levels. The ATS643 incorporates an algorithm
that continuously monitors the system and updates the switch-
ing thresholds accordingly. The switchpoint for each edge is
determined by the detection of the previous two edges. In this
manner, variations are tracked in real time.
(#2)
0
, to continuously update device response
Smaller
TEAG
Pk
B
(#3)
RP(#1)
B
HYS(#1)
Pk
B
(#4)
OP(#2)
(B) Internal analog signal, V
typically resulting in the sensor
RP
Pk
B
, the switch toggles from on to off.
Target Rotation (°)
(#5)
RP(#2)
B
HYS(#2)
Larger
TEAG
Pk
B
OP(#3)
(Delimited by switchpoints)
(#6)
PROC
115 Northeast Cutoff, Box 15036
Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 [phone]
www.allegromicro.com
Hysteresis Band
Pk
.
B
(#7)
RP(#3)
B
HYS(#3)
Pk
B
OP(#4)
(#8)
PROC
Pk
Smaller
,
B
TEAG
(#9)
RP(#4)
B
HYS(#4)
360
t+
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