True Zero Speed Miniature Differential Peak-
Detecting Gear Tooth Sensor IC
ATS645LSH
4
Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
OPERATING CHARACTERISTICS (continued) using reference target 60-0, T
A
and V
CC
within speci cation, unless otherwise noted
Characteristic
Symbol
Test Conditions
Min.  Typ.
1
Max.  Units
SWITCHPOINT CHARACTERISTICS
Rotation Speed
S
ROT
Reference Target 60-0
0      8,000  rpm
Analog Signal Bandwidth
BW   Equivalent to f 3dB
20   40      kHz
Operate Point
B
OP
Transitioning from I
CC(High)
to I
CC(Low)
; positive peak
referenced; AG < AG
MAX
   120      mV
Release Point
B
RP
Transitioning from I
CC(Low)
to I
CC(High)
; negative peak
referenced; AG < AG
MAX
   120      mV
CALIBRATION
Initial Calibration
C
I
Quantity of rising output (current) edges required for
accurate edge detection
        3   Edge
DAC CHARACTERISTICS
Allowable User-Induced Differential
Offset
Output switching only; may not meet datasheet speci-
cations
60      60   G
FUNCTIONAL CHARACTERISTICS
5
Operational Air Gap Range
6
AG   DC within speci cation
0.5      2.75  mm
Maximum Operational Air Gap
Range
AG
OP(max)
Output switching (no missed edges); DC not
guaranteed
        3   mm
Duty Cycle Variation
7
DC
Wobble < 0.5mm; Typical value at AG = 1.5 mm, for
max., min., AG within speci cation
43   53   63   %
Operating Magnetic Flux Density
Differential
8
B
AG(p-p)
Operating within speci cation
30      1000   G
Minimum Operating Signal
Sig
OP(min)
Output switching (no missed edges); DC not
guaranteed
20           G
1
Typical values are at T
A
= 25癈 and V
CC
= 12 V. Performance may vary for individual units, within the speci ed maximum and minimum limits.
2
Maximum voltage must be adjusted for power dissipation and junction temperature; see Power Derating section.
3
Power-On Time includes the time required to complete the internal automatic offset adjust. The DACs are then ready for peak acquisition.
4
dI is the difference between 10% of I
CC(Low)
and 90% of I
CC(High)
, and dt is time period between those two points.
Note: di/dt is dependent upon the value of the bypass capacitor, if one is used.
5
Functional characteristics valid only if magnetic offset is within the speci ed range for Allowable User Induced Differential Offset.
6
AG is dependent on the available magnetic eld. The available eld is dependent on target geometry and material, and should be independently
characterized. The eld available from the reference target is given in the reference target parameter section of the datasheet.
7
Duty cycle speci cation may not be met if the magnetic signal during the calibration period is not representative of the installation air gap.
8
In order to remain in speci cation, the magnetic gradient must induce an operating signal greater than the minimum value speci ed. This includes the
effect of target wobble.