Self-Calibrating TPOS Gear Tooth Sensor ICs
Optimized for Automotive Cam Sensing Applications
ATS673 and
ATS674
4
Allegro MicroSystems, LLC
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com
SWITCHPOINT CHARACTERISTICS
Tooth Speed
S   Tooth frequency, target generating sinusoidal signal
0
8
kHz
Bandwidth
BW   Corresponds to output switching frequency 3 dB
40
kHz
Operate
B
OP
ATS673
% of peak-to-peak, referenced to tooth signal,
AG < AG
(Max)
40
%
ATS674
30
%
Release
B
RP
ATS673
% of peak-to-peak, referenced to tooth signal,
AG < AG
(Max)
50
%
ATS674
40
%
CALIBRATION CHARACTERISTICS
4
Initial Calibration
Cal
IC
Quantity of rising edges required to complete edge detec-
tion calibration
3    edges
AGC Disable
Cal
AGC
Quantity of rising edges required to complete Automatic
Gain Control calibration
3    edges
Calibration Update
Cal
UPD
Quantity of rising edges required to update edge detection
calibration while running after initial calibration
Contin-
uous
    edges
PERFORMANCE CHARACTERISTICS
3
TPOS Air Gap Range
5
AG
TPOS
TPOS functionality guaranteed
0.5
2.5    mm
Operational Air Gap Range
AG   TPOS guaranteed, output switching, running mode
0.5
2.5    mm
Extended Minimum Air Gap
6
AG
EXTMIN
Output switching, running mode; valleys may be detected
as teeth in this range
0.5    mm
Extended Maximum Air Gap
7
AG
EXTMAX
Output switching, running mode; teeth may be detected as
valleys in this range
2.5
5
mm
Relative Timing Accuracy
4,8
Err
ICREL
ATS673
During initial calibration; rising or falling edges,
gear speed = 1000 rpm, target eccentricity
< 0.1 mm
3
6
deg
ATS674
3
6
deg
Err
RELR
ATS673
Rising edges; after initial calibration, gear speed
= 1000 rpm, target eccentricity < 0.1 mm
0.5    0.8    deg
ATS674
0.4    0.8    deg
Err
RELF
ATS673
Falling edges; after initial calibration, gear speed
= 1000 rpm, target eccentricity < 0.1 mm
0.8    1.2    deg
ATS674
0.6    1.2    deg
Phase Delay
9
DErr
SREL
After initial calibration, AG = 1.5 mm, T
A
= 25癈
   1.6 x 10
4
   deg/rpm
1
Typical values are taken at V
CC
= 12 V and T
A
= 25癈.
2
I
ZSupply(Max)
is equivalent to I
CCON(Max)
+ 3 mA.
3
Using reference target 8X.
4
The term edge refers to a mechanical edge, such as the side of a gear tooth, passing under the device. Rising edge: from valley to approaching tooth.
Falling edge: from tooth to approaching valley.
5
The TPOS Air Gap Range is the range of installation air gaps within which the TPOS (True Power-On State) function is guaranteed to correctly detect
a tooth when powered-on over a tooth and correctly detecting a valley when powered-on over a valley, using reference target 8X or equivalent, as
specified in the Target/Gear Parameters for Correct TPOS Operation section in this document.
6
The Extended Minimum Air Gap is a range of installation air gaps, smaller than AG
(Min)
, within which the the device will accurately detect target fea-
tures but TPOS is NOT guaranteed to be fully accurate, possibly evaluating the initial valley as a tooth.
7
The Extended Maximum Air Gap is an extended range of installation air gaps, greater than AG
(Max)
, within which the the device will accurately detect
target features but TPOS is not guaranteed to be fully accurate, possibly evaluating the intiial tooth as a valley.
8
Relative Timing Accuracy is the change in edge position before the resulting change in device output; for a single device, over the full Operational Air
Gap Range, AG, and Operating Ambient Temperature, T
A
, range.
9
Phase Delay is the change in edge position at detection, through the full operational Tooth Speed, S, range for a single device, and at a single ambi-
ent temperature, T
A
, and installation air gap, AG.
OPERATING CHARACTERISTICS, continued Valid at T
A
= 40癈 to 150癈, T
J
d T
J(max)
, over full range of AG, unless otherwise noted
Characteristic
Symbol
Test Conditions
Min.   Typ.
1
Max.   Units