ats643 Allegro MicroSystems, Inc., ats643 Datasheet - Page 12

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

ATS643LSH
Start Mode Hysteresis. This feature helps to ensure optimal
self-calibration by rejecting electrical noise and low-amplitude
target vibration during initialization. This prevents AGC from
calibrating the sensor on such spurious signals. Calibration can
be performed using the actual target features.
Figure 6. Operation of Start Mode Hysteresis
Position 1. At power-on, the ATS643 begins sampling V
Position 2. At the point where the Start Mode Hysteresis is exceeded, the device begins to establish switching thresholds (B
tinuous Update algorithm. After this point, Start Mode Hysteresis is no longer a consideration. Note that a valid V
Hysteresis can be generated either by a legitimate target feature or by excessive vibration.
Position 3. In this example, the first switchpoint transition is through B
If the first switchpoint transition had been through B
polarity. The first transition would occur at position 5 (B
Target, Gear
Sensor Position Relative to Target
Target Magnetic Profile
Differential Signal, V
Output Signal, I
Start Mode Hysteresis, PO
OUT
PROC
RP
Gear Tooth Sensor with Continuous Update
(such as position 4), no output transition would occur because I
OP
PROC
).
Self-Calibrating, Zero-Speed Differential
HYS
.
1
1
OP
. and the output transitions from high to low.
2
2
is a minimum level of the peak-to-peak amplitude of the internal
analog electrical signal, V
ATS643 starts to compute switchpoints.
A typical scenario is shown in figure 6. The hysteresis, PO
3
B
OP(#1)
4
B
RP(#1)
5
5
PROC
115 Northeast Cutoff, Box 15036
Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 [phone]
www.allegromicro.com
B
PROC
OP(#2)
, that must be exceeded before the
value exceeding the Start Mode
OUT
already would be in the high
OP
and B
RP
) using the Con-
HYS
12
,