ATS674 Allegro MicroSystems, ATS674 Datasheet - Page 12

• Manufacturer Part Number: ATS674
• Description: (ATS673 / ATS674) Self-Calibrating TPOS Gear Tooth Sensor Optimized
• Manufacturer: Allegro MicroSystems

ATS673 and
ATS674
Switchpoints
Switchpoints in the ATS673 and ATS674 are established dynami-
cally as a percentage of the amplitude of the signal, V
normalization with AGC. Two DACs track the peaks of V
(see the Update subsection).
The switching thresholds are established at fixed percentages
of the values held in the two DACs. The value of the thresholds
has been carefully selected, where the signal is steepest and least
affected by air gap variation, thus providing the most accurate
and consistent switching.
The low hysteresis, 10%, provides high performance over vari-
ous air gaps while maintaining immunity to false switching on
noise, vibration, backlash, or other transient events.
Figure 8 graphically demonstrates the establishment of the
switching threshold levels. Because the thresholds are estab-
lished dynamically as a percentage of the peak-to-peak signal,
the effect of a baseline shift is minimized.
Self-Calibrating TPOS Gear Tooth Sensor Optimized
PROC
for Automotive Cam Sensing Applications
PROC
, after
Figure 8. Switchpoint Relationship to Thresholds.The device switches
when V
corresponding direction: increasing for a B
for a B
Target
Mechanical
Profile
Device
State
RP
-LT option
-HT option
PROC
switchpoint.
100
passes a threshold level, B
V+
0
On
Off
115 Northeast Cutoff, Box 15036
Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 [phone]
www.allegromicro.com
B
Off
On
OP
%
On
Off
OP
OP
or B
switchpoint, and decreasing
RP
B
Off
On
RP
, while changing in the
%
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