Description
The ATS667 is a true zero-speed gear tooth sensor IC consisting
of an optimized Hall IC-rare earth pellet configuration in a
single overmolded package. The unique IC and package design
provides a user-friendly solution for digital gear tooth sensing
applications. This small package can be easily assembled and
used in conjunction with gears of various shapes and sizes.
The device incorporates a dual element Hall IC that switches
in response to differential magnetic signals created by a ferro-
magnetic target. The IC contains a sophisticated compensating
circuit designed to eliminate the detrimental effects of magnet
and system offsets. Digital processing of the analog signal
provides zero-speed performance independent of air gap and
also dynamic adaptation of device performance to the typical
operating conditions found in automotive applications (reduced
vibration sensitivity). High-resolution peak detecting DACs
are used to set the adaptive switching thresholds of the device.
Hysteresis in the thresholds reduces the negative effects of any
anomalies in the magnetic signal associated with the targets
used in many automotive applications.
The ATS667 is optimized for transmission applications. It is
available in a lead (Pb) free 4-pin SIP package with a 100%
matte tin plated leadframe.
ATS667-DS, Rev. 5
Features and Benefits
▪ Optimized robustness against magnetic offset variation
▪ Small signal lockout for immunity against vibration
▪ Tight duty cycle and timing accuracy over full operating
temperature range
▪ True zero-speed operation
▪ Air gap independent switchpoints
▪ Large operating air gaps achieved through use of gain
adjust and offset adjust circuitry
▪ Defined power-on state (POS)
▪ Wide operating voltage range
▪ Digital output representing target profile
▪ Single chip sensing IC for high reliability
▪ Small mechanical size
▪ Optimized Hall IC magnetic system
▪ Fast start-up
▪ Undervoltage lockout (UVLO)
T rue Zero-Speed, High Accuracy Gear Tooth Sensor IC
Functional Block Diagram
ATS667LSG
Not to scale
Package: 4-pin SIP (suffix SG)
GND
VOUT
VCC
TEST
Output
Transistor
Current
Limit
Voltage
Regulator
Hall
Amp
Automatic
Gain
Control VPROC
PThresh
NThresh
Threshold
Logic
Threshold
Comparator
Offset
Adjust
Reference
Generator
PDAC
NDAC
T rue Zero-Speed, High Accuracy Gear Tooth Sensor IC
ATS667LSG
2
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
Pin-out Diagram
Absolute Maximum Ratings
Characteristic Symbol Notes Rating Unit
Supply Voltage VCC See Power Derating section 26.5 V
Reverse Supply Voltage VRCC –18 V
Reverse Supply Current IRCC –50 mA
Reverse Output Voltage VROUT –0.5 V
Output Sink Current IOUT 25 mA
Operating Ambient Temperature TARange L –40 to 150 ºC
Maximum Junction Temperature TJ(max) 165 ºC
Storage Temperature Tstg –65 to 170 ºC
Selection Guide
Part Number Packing*
ATS667LSGTN-T 13-in. reel, 800 pieces/reel
*Contact Allegro™ for additional packing options
2431
Terminal List
Number Name Function
1 VCC Supply voltage
2 VOUT Device output
3 TEST Tie to GND or float
4 GND Ground
T rue Zero-Speed, High Accuracy Gear Tooth Sensor IC
ATS667LSG
3
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
OPERATING CHARACTERISTICS Valid over operating voltage and temperature ranges; unless otherwise noted
Characteristics Symbol Test Conditions Min. Typ.1Max. Unit
Electrical Characteristics
Supply Voltage2VCC Operating, TJ < TJ(max) 4.0 – 24 V
Undervoltage Lockout (UVLO) VCC(UV) – 3.5 3.95 V
Reverse Supply Current IRCC VCC = –18 V – – – 10 mA
Supply Zener Clamp Voltage VZICC = 15 mA, TA = 25 °C 26.5 – – V
Supply Zener Current IZTA = 25°C, TJ < TJ(max), continuous, VZ = 26.5 V – – 15 mA
Supply Current ICC
Output off 4 7 12 mA
Output on 4 7 12 mA
Power-On State Characteristics
Power-On State POS Connected as in figure 6 – High – –
Power-On Time3tPO SROT < 200 rpm; VCC > VCC(min) – – 2 ms
OUTPUT STAGE
Low Output Voltage VOUT(SAT) IOUT = 10 mA, Output = on – 100 250 mV
Output Zener Clamp Voltage VZOUT IOUT = 3 mA, TA = 25°C 26.5 – – V
Output Current Limit IOUT(LIM) VOUT = 12 V, TJ < TJ(max) 25 45 70 mA
Output Leakage Current IOUT(OFF) Output = off, VOUT = 24 V – – 10 μA
Output Rise Time tr
RPULLUP = 1 kΩ, CL = 4.7 nF, VPULLUP = 12 V,
10% to 90%, connected as in figure 6 – 10 – μs
Output Fall Time tf
RPULLUP = 1 kΩ, CL = 4.7 nF, VPULLUP = 12 V,
90% to 10%, connected as in figure 6 – 0.6 2 μs
D-to- A Converter (DAC) Characteristics
Allowable User Induced Differential
Offset4,5 BDIFFEXT User induced differential offset – ±60 – G
Calibration
Initial Calibration6CALI
Possible reduced edge detection accuracy, duty
cycle not guaranteed – 1 6 edge
Update Method Running mode operation, bounded for
increasing AG, unlimited for decreasing AG –Continuous ––
Operating Characteristics (with Allegro 60-0 Reference Target)
Operational Air Gap Range7AGOP Repeatability and duty cycle within specification 0.5 – 2.5 mm
Maximum Operational Air Gap Range AGOPMAX Output switching only (no missing edges) – – 3.1 mm
Relative Repeatability8TθE
100 Gpk-pk ideal sinusoidal signal, TA = 150°C,
SROT = 1000 rpm (f = 1000 Hz) – 0.06 – deg.
Maximum Single Outward Sudden Air
Gap Change9ΔAGMAX
Percentage of most recent AGpk-pk
, single
instantaneous air gap increase, f < 500 Hz,
VPROC(pk-pk) > VLOE after sudden AG change
– 40 – %
Duty Cycle D
Measured as VOUT
, connected as in figure 6;
Wobble < 0.5 mm, AGOP < AGOP(max) , direction
of target rotation pin 4 to pin 1
42 47 52 %
Continued on the next page…
T rue Zero-Speed, High Accuracy Gear Tooth Sensor IC
ATS667LSG
4
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
OPERATING CHARACTERISTICS (continued) Valid over operating voltage and temperature ranges; unless otherwise noted
Characteristics Symbol Test Conditions Min. Typ.1Max. Unit
Switchpoint Characteristics
Operational Speed SROT Allegro 60–0 Reference Target 0 – 12000 rpm
Bandwidth f-3dB Cutoff frequency for low-pass filter 15 20 – kHz
Operate Point BOP
% of peak-to-peak VPROC referenced from
PDAC to NDAC, AG < AGmax, VOUT high to low – 70 – %
Release Point BRP
% of peak-to-peak VPROC referenced from
PDAC to NDAC, AG < AGmax , VOUT low to high – 30 – %
Running Mode Lockout Enable (LOE) VLOE(RM)
VPROC(PK-PK) < VLOE(RM) = output switching
disabled – 100 – mV
Running Mode Lockout Release (LOR) VLOR(RM)
VPROC(PK-PK) < VLOR(RM) = output switching
enabled – 220 – mV
1Typical data is at VCC = 12 V and TA = 25°C, unless otherwise noted. Performance may vary for individual units, within the specified maximum and
minimum limits.
2 Maximum voltage must be adjusted for power dissipation and junction temperature; see Power Derating section.
3 Power-On Time is the time required to complete the internal Automatic Offset Adjust; the DACs are then ready for peak acquisition.
41 G (gauss) = 0.1 mT (millitesla).
5The device compensates for magnetic and installation offsets. Offsets greater than specification in gauss may cause inaccuracies in the output.
6For power-on SROT ≤ 200 rpm, edges are sensed target mechanical edges (see figure Definitions of Terms for Switchpoints).
7Operational Air Gap Range is dependent on the available magnetic field. The available field is target geometry and material dependent and should be
independently characterized. The field available from the Allegro 60-0 reference target is given in the reference target parameter section.
8The repeatability specification is based on statistical evaluation of a sample population, evaluated at 1000 Hz. Repeatability is measured at 150°C
because the lowest signal-to-noise ratio for the VPROC signal occurs at elevated temperatures. Therefore, the worst-case repeatability for the device
will also occur at elevated temperatures.
9Single maximum allowable air gap change in outward direction (increase in air gap).
Differential Magnetic
Flux Density, B
DIFF
(G)
ValleyTooth
Forward
Reverse
+B
–B
Differential Processed
Signal, V
Proc
(V)
+V
–V
t
B
OP(FWD)
b
V
PROC(BOP)
V
PROC(BRP)
B
RP(FWD)
B
OP
%B
RP
%
100 %
B
OP(REV)
b
B
RP(REV)
Sensed Edgea
aSensed Edge: leading (rising) mechanical edge in forward rotation, trailing (falling) mechanical edge in reverse rotation
b
B
OP(FWD)
triggers the output transition during forward rotation, and B
OP(REV)
triggers the output transition during reverse rotation
Definitions of Terms for Switchpoints
T rue Zero-Speed, High Accuracy Gear Tooth Sensor IC
ATS667LSG
5
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
Reference Gear Magnetic Profile
Reference Target 60-0, Hall element spacing 2.20 mm
Gear Rotation (°)
Air Gap (mm)
Differential B (G)
0 2 4 6 8 101214161820
600
400
200
0
200
400
600
0.50 mm AG
3.00 mm AG
0.50
0.75
1.00
1.25
1.50
1.75
2.00
2.25
2.50
2.75
3.00
1.0 2.00 3.0
1200
1000
800
600
400
200
0
Reference Gear Magnetic Gradient Amplitude versus Air Gap
Reference Target 60-0, Hall element spacing 2.20 mm
Air Gap (mm)
Peak-to-Peak Differential B (G)
Reference Target 60-0 (60 Tooth Target)
Characteristics Symbol Test Conditions Typ. Units Symbol Key
Outside Diameter DoOutside diameter of target 120 mm
Face Width F Breadth of tooth, with respect
to branded face 6mm
Angular Tooth Thickness t Length of tooth, with respect
to branded face 3 deg.
Angular Valley Thickness tv
Length of valley, with respect
to branded face 3 deg.
Tooth Whole Depth ht3mm
Material Low Carbon Steel – –
t
tV
ØDOhtF
Branded Face
of Package
Air Gap
Reference Target
60-0
of Package
Branded Face
T rue Zero-Speed, High Accuracy Gear Tooth Sensor IC
ATS667LSG
6
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
Characteristic Performance
T
A
(°C)
Supply Current (Off) versus Ambient Temperature
ICCOFF (mA)
14
12
10
8
6
4
2
0
0 10050-50 150
V
CC
(V)
V
CC
(V)
Supply Current (Off) versus Supply Voltage
ICCOFF (mA)
14
12
10
8
6
4
2
0
10 20030
10 20030
T
A
(°C)
Supply Current (On) versus Ambient Temperature
ICCON (mA)
14
12
10
8
6
4
2
0
0 10050-50 150
Supply Current (On) versus Supply Voltage
ICCON (mA)
14
12
10
8
6
4
2
0
T
A
(°C)
Output Voltage versus Ambient Temperature
VCC = 12 V, ILOAD = 10 mA
VOUT(SAT) (mV)
180
160
140
120
100
80
60
40
20
0
0 10050-50 150
AG (mm)
Duty Cycle versus Air Gap
Allegro 60-0 Reference Target
D (%)
52
51
50
49
48
47
46
45
44
43
42
1.00.5 1.5 2.52.003.0
TA (°C)
25
150
–40
TA (°C)
25
150
–40
TA (°C)
25
150
–40
VCC (V)
12
24
4
VCC (V)
12
24
4
T rue Zero-Speed, High Accuracy Gear Tooth Sensor IC
ATS667LSG
7
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
THERMAL CHARACTERISTICS may require derating at maximum conditions, see application information
Characteristic Symbol Test Conditions* Value Units
Package Thermal Resistance RθJA
Single-sided PCB with copper limited to solder pads 126 ºC/W
Two-sided PCB with copper limited to solder pads and 3.57 in.2
(23.03 cm2) of copper area each side, connected to GND pin 84 ºC/W
*Additional information is available on the Allegro website.
6
7
8
9
2
3
4
5
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
20 40 60 80 100 120 140 160 180
Temperature (ºC)
Maximum Allowable V
CC
(V)
Power Derating Curve
(R
QJA
= 126 ºC/W)
(R
QJA
= 84 ºC/W)
VCC(min)
VCC(max)
0
100
200
300
400
500
600
700
800
900
1000
1100
1200
1300
1400
1500
1600
1700
1800
1900
20 40 60 80 100 120 140 160 180
Temperature (°C)
Power Dissipation, P
D
(mW)
Power Dissipation versus Ambient Temperature
(R
QJA
= 126 ºC/W)
(R
QJA
= 84 ºC/W)
T rue Zero-Speed, High Accuracy Gear Tooth Sensor IC
ATS667LSG
8
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
Functional Description
Hall Technology
The ATS667 contains a single-chip differential Hall-effect sensor
IC, a samarium cobalt pellet, and a flat ferrous pole piece (con-
centrator). As shown in figure 1, the Hall IC supports two Hall
elements, which sense the magnetic profile of the ferrous gear
target simultaneously, but at different points (spaced at a 2.2 mm
pitch), generating a differential internal analog voltage, VPROC,
that is processed for precise switching of the digital output signal.
The Hall IC is self-calibrating and also possesses a tempera-
ture compensated amplifier and offset cancellation circuitry. Its
voltage regulator provides supply noise rejection throughout the
operating voltage range. Changes in temperature do not greatly
affect this device due to the stable amplifier design and the offset
compensation circuitry. The Hall transducers and signal process-
ing electronics are integrated on the same silicon substrate, using
a proprietary BiCMOS process.
Target Profiling During Operation
An operating device is capable of providing digital information
that is representative of the mechanical features of a rotating gear.
The waveform diagram in figure 3 presents the automatic transla-
tion of the mechanical profile, through the magnetic profile that
it induces, to the digital output signal of the ATS667. No addi-
tional optimization is needed and minimal processing circuitry is
required. This ease of use reduces design time and incremental
assembly costs for most applications.
Determining Output Signal Polarity
In figure 3, the top panel, labeled Mechanical Position, represents
the mechanical features of the target gear and orientation to the
device. The bottom panel, labeled IC Output Signal, displays the
square waveform corresponding to the digital output signal that
results from a rotating gear configured as shown in figure 2, and
electrically connected as in figure 6. That direction of rotation (of
the gear side adjacent to the package face) is: perpendicular to
the leads, across the face of the device, from the pin 1 side to the
pin 4 side. This results in the IC output switching from low state
to high state as the leading edge of a tooth (a rising mechanical
edge, as detected by the IC) passes the package face. In this con-
figuration, the device output switches to its high polarity when a
tooth is the target feature nearest to the package. If the direction
of rotation is reversed, so that the gear rotates from the pin 4 side
to the pin 1 side, then the output polarity inverts. That is, the out-
put signal goes high when a falling edge is detected, and a valley
is nearest to the package.
Target (Gear)
Back-biasing
Rare-earth Pellet
South Pole
North Pole Case
(Pin 1 Side)(Pin 4 Side)
Hall IC
Pole Piece
Element Pitch
(Concentrator)
Dual-Element
Hall Effect Device
Hall Element 1
Hall Element 2
of Package
Rotating Target Branded Face
14
B
OP(#1)
B
RP(#1)
B
RP(#2)
B
OP(#2)
On OffOff On
IC Internal Switch State
Package Orientation to Target
IC Internal Differential Analog Signal, V
PROC
Mechanical Position (Target movement pin 1 to pin 4)
IC Output Signal, V
OUT
Target
(Gear)
(Package Top View)
Sensor Branded Face
Pin 1
Side
Pin 4
Side
Branded Face Hall Element Pitch
Target Magnetic Profile
+B
This tooth
sensed earlier
This tooth
sensed later
Back-Biasing
Pellet
IC
Figure 1. Relative motion of the target is detected by the dual Hall
elements mounted on the Hall IC.
Figure 2. This left-to-right (pin 1 to pin 4) direction of target rotation results
in a high output state when a tooth of the target gear is nearest the
package face (see figure 3). A right-to-left (pin 4 to pin 1) rotation inverts
the output signal polarity.
Figure 3. The magnetic profile reflects the geometry of the target, allowing
the ATS667 to present an accurate digital output response.
T rue Zero-Speed, High Accuracy Gear Tooth Sensor IC
ATS667LSG
9
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
Continuous Update of Switchpoints
Switchpoints are the threshold levels of the differential internal
analog signal, VPROC
, at which the device changes output signal
state. The value of VPROC is directly proportional to the magnetic flux
density, B, induced by the target and sensed by the Hall elements.
As VPROC rises through a certain limit, referred to as the operate
point, BOP
, the output state changes from high to low. As VPROC
falls below BOP to a certain limit, the release point, BRP
, the output
state changes from low to high.
As shown in panel C of figure 4, threshold levels for the ATS667
switchpoints are established as a function of the peak input signal
levels. The ATS667 incorporates an algorithm that continuously
monitors the input signal and updates the switching thresholds
accordingly with limited inward movement of VPROC. The
switchpoint for each edge is determined by the detection of the
previous two signal edges. In this manner, variations are tracked
in real time.
(A) TEAG varying; cases such as
eccentric mount, out-of-round region,
normal operation position shift
(B) Internal analog signal, V
PROC
,
typically resulting in the IC
0360
Target Rotation (°)
Hysteresis Band
(Delimited by switchpoints)
V
PROC
(V)
V+
Larger
TEAG
Smaller
TEAG
IC
Target
Larger
TEAG
Target
IC
Smaller
TEAG
Smaller
TEAG
Pk
(#4)
Pk
(#5)
Pk
(#7)
Pk
(#9)
Pk
(#2)
Pk
(#3)
Pk
(#1)
Pk
(#6)
Pk
(#8)
V
PROC
(V)
B
HYS(#4)
B
HYS(#3)
V+
B
RP(#1)
B
OP(#1)
B
RP(#2)
B
RP(#3)
B
OP(#3)
B
RP(#4)
B
OP(#4)
B
OP(#2)
V
PROC(BOP)
(#1)
V
PROC(BOP)
(#2)
V
PROC(BOP)
(#3)
V
PROC(BOP)
(#4)
V
PROC(BRP)
(#1)
V
PROC(BRP)
(#2)
V
PROC(BRP)
(#3)
V
PROC(BRP)
(#4)
B
HYS(#1)
B
HYS(#2)
BHYS Switchpoint Determinant
Peak Values
1BOP(#1) Pk(#1), Pk(#2)
BRP(#1) Pk(#2), Pk(#3)
2BOP(#2) Pk(#3), Pk(#4)
BRP(#2) Pk(#4), Pk(#5)
3BOP(#3) Pk(#5), Pk(#6)
BRP(#3) Pk(#6), Pk(#7)
4
BOP(#4) Pk(#7), Pk(#8)
BRP(#4) Pk(#8), Pk(#9)
(C) Referencing the internal analog signal, VPROC, to continuously update device response
Figure 4. The Continuous Update algorithm allows the Allegro IC to interpret and adapt to variances in the magnetic field generated by the
target as a result of eccentric mounting of the target, out-of-round target shape, and similar dynamic application problems that affect the TEAG
(Total Effective Air Gap). Not detailed in the figure are the boundaries for peak capture DAC movement which intentionally limit the amount of
inward signal variation the IC is able to react to over a single transition. The algorithm is used to establish and subsequently update the device
switchpoints (BOP and BRP). The hysteresis, BHYS(#x)
, at each target feature configuration results from this recalibration, ensuring that it remains
properly proportioned and centered within the peak-to-peak range of the internal analog signal, VPROC.
As shown in panel A, the variance in the target position results in a change in the TEAG. This affects the IC as a varying magnetic field, which
results in proportional changes in the internal analog signal, VPROC, shown in panel B. The Continuous Update algorithm is used to establish
switchpoints based on the fluctuation of VPROC, as shown in panel C.
T rue Zero-Speed, High Accuracy Gear Tooth Sensor IC
ATS667LSG
10
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
BRP
BOP
BOP
BOP(initial)
BRP(initial)
1 4
23
Start Mode
Hysteresis, POHYS
Output Signal, VOUT
If exceed POHYS
on high side
If exceed POHYS
on low side
IC Position
Relative to Target
Target Magnetic Profile
Differential Signal, VPROC
Target, Gear
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 IC on such
spurious signals. Calibration can be performed using the actual
target features.
A typical scenario is shown in figure 5. The Start Mode Hysteresis,
POHYS , is a minimum level of the peak-to-peak amplitude of the
internal analog electrical signal, VPROC, that must be exceeded
before the ATS667 starts to compute switchpoints.
Figure 5. Operation of Start Mode Hysteresis
• At power-on (position 1), the ATS667 begins sampling VPROC.
• At the point where the Start Mode Hysteresis, POHYS , is exceeded, the device establishes an initial switching threshold, by using the Continuous
Update algorithm. If VPROC is falling through the limit on the low side (position 2), the switchpoint is BRP , and if VPROC is rising through the limit on the
high side (position 4), it is BOP . After this point, Start Mode Hysteresis is no longer a consideration. Note that a valid VPROC value exceeding the Start
Mode Hysteresis can be generated either by a legitimate target feature or by excessive vibration.
• In either case, because the switchpoint is immediately passed as soon as it is established, the ATS667 enables switching:
--If on the low side, at BRP (position 2) the output would switch from low to high. However, because output is already high, no output switching occurs.
At the next switchpoint, where BOP is passed (position 3), the output switches from high to low.
--If on the high side, at BOP (position 4) the output switches from high to low.
As this example demonstrates, initial output switching occurs with the same polarity, regardless of whether the Start Mode Hysteresis is exceeded on the
high side or on the low side.
T rue Zero-Speed, High Accuracy Gear Tooth Sensor IC
ATS667LSG
11
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
Undervoltage Lockout
When the supply voltage falls below the undervoltage lockout
voltage, VCC(UV) , the device enters Reset, where the output
state returns to the Power-On State (POS) until sufficient VCC
is supplied. ICC levels may not meet datasheet limits when VCC
< VCC(min). This lockout feature prevents false signals, caused
by undervoltage conditions, from propagating to the output of the
IC.
Power Supply Protection
The device contains an on-chip regulator and can operate over a
wide VCC range. For devices that must operate from an unregu-
lated power supply, transient protection must be added externally.
For applications using a regulated line, EMI/RFI protection may
still be required. Contact Allegro for information on the circuitry
needed for compliance with various EMC specifications. Refer
to figure 6 for an example of a basic application circuit.
Automatic Gain Control (AGC)
This feature allows the device to operate with an optimal internal
electrical signal, regardless of the air gap (within the AG speci-
fication). At power-on, the device determines the peak-to-peak
amplitude of the signal generated by the target. The gain of the IC
is then automatically adjusted. Figure 7 illustrates the effect of
this feature.
Automatic Offset Adjust (AOA)
The AOA circuitry automatically compensates for the effects of
chip, magnet, and installation offsets. This circuitry is continu-
ously active, including during both power-on mode and running
mode, compensating for any offset drift (within the Allowable
User Induced Differential Offset). Continuous operation also
allows it to compensate for offsets induced by temperature varia-
tions over time.
Running Mode Lockout
The ATS667 has a running mode lockout feature to prevent
switching in response to small signals that are characteristic of
vibration signals. The internal logic of the chip considers small
signal amplitudes below a certain level to be vibration. The out-
put is held to the state prior to lockout until the amplitude of the
signal returns to normal operational levels.
Assembly Description
The ATS667 is integrally molded into a plastic body that has
been optimized for size, ease of assembly, and manufacturability.
High operating temperature materials are used in all aspects of
construction.
Figure 6. Typical circuit for proper device operation. Figure 7. Automatic Gain Control (AGC). The AGC function corrects for
variances in the air gap. Differences in the air gap cause differences in
the magnetic field at the device, but AGC prevents that from affecting
device performance, as shown in the lowest panel.
Mechanical Profile
AGSmall
AGLarge
AGSmall
AGLarge
Internal Differential
Analog Signal
Response, with AGC
Internal Differential
Analog Signal
Response, without AGC
Ferrous Target
V+
V+
43
VCC
VCC VPULLUP
RPULLUP
GND TEST
VOUT
CBYPASS
0.1 μF
(Required)
CL
ATS667
12
T rue Zero-Speed, High Accuracy Gear Tooth Sensor IC
ATS667LSG
12
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
Power Derating
The device must be operated below the maximum junction
temperature of the device, TJ(max). Under certain combinations of
peak conditions, reliable operation may require derating supplied
power or improving the heat dissipation properties of the appli-
cation. This section presents a procedure for correlating factors
affecting operating TJ. (Thermal data is also available on the
Allegro website.)
The Package Thermal Resistance, RJA, is a figure of merit sum-
marizing the ability of the application and the device to dissipate
heat from the junction (die), through all paths to the ambient air.
Its primary component is the Effective Thermal Conductivity, K,
of the printed circuit board, including adjacent devices and traces.
Radiation from the die through the device case, RJC, is relatively
small component of RJA. Ambient air temperature, TA, and air
motion are significant external factors, damped by overmolding.
The effect of varying power levels (Power Dissipation, PD), can
be estimated. The following formulas represent the fundamental
relationships used to estimate TJ, at PD.
P
D = VIN × IIN (1)
T = PD × RJA (2)
TJ = TA + ΔT (3)
For example, given common conditions such as: TA= 25°C,
VCC = 12 V, ICC = 7.5 mA, and RJA = 126 °C/W, then:
P
D = VCC × ICC = 12 V × 7.5 mA = 90 mW
T = PD × RJA = 90 mW × 126 °C/W = 11.3°C
T
J = TA + T = 25°C + 11.3°C = 36.3°C
A worst-case estimate, PD(max), represents the maximum allow-
able power level (VCC(max), ICC(max)), without exceeding
TJ(max), at a selected RJA and TA.
Example: Reliability for VCC at TA =
150°C, package SG, using a
single-layer PCB.
Observe the worst-case ratings for the device, specifically:
RJA
=
126 °C/W, TJ(max) =
165°C, VCC(max)
=
24 V, and
ICC(max) = 12
mA.
Calculate the maximum allowable power level, PD(max). First,
invert equation 3:
Tmax = TJ(max) – TA = 165
°C
–
150
°C = 15
°C
This provides the allowable increase to TJ resulting from internal
power dissipation. Then, invert equation 2:
PD(max) = Tmax ÷ RJA = 15°C ÷ 126 °C/W = 119 mW
Finally, invert equation 1 with respect to voltage:
VCC(est) = PD(max) ÷ ICC(max) = 119 mW ÷ 12 mA = 9.9 V
The result indicates that, at TA, the application and device can
dissipate adequate amounts of heat at voltages ≤ VCC(est).
Compare VCC(est) to VCC(max). If VCC(est) ≤ VCC(max), then
reliable operation between VCC(est) and VCC(max) requires
enhanced RJA. If VCC(est) ≥ VCC(max), then operation between
VCC(est) and VCC(max) is reliable under these conditions.
T rue Zero-Speed, High Accuracy Gear Tooth Sensor IC
ATS667LSG
13
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
0.71±0.05
5.50±0.05
4.70±0.10
0.60±0.10
0.40±0.10
24.65±0.10
15.30±0.10
1.0 REF
0.71±0.10 0.71±0.10
1.60±0.10
1.27±0.10
5.50±0.10
8.00±0.05
5.80±0.05
1.70±0.10
243
1A
A
D
B
For Reference Only, not for tooling use (reference DWG-9002)
Dimensions in millimeters
A
B
C
C
D
E
F
F
Dambar removal protrusion (16X)
Metallic protrusion, electrically connected to pin 4 and substrate (both sides)
Thermoplastic Molded Lead Bar for alignment during shipment
E
E2E1
Hall elements (E1, E2), not to scale
Active Area Depth, 0.43 mm
Branded
Face
Standard Branding Reference View
= Supplier emblem
L = Lot identifier
N = Last three numbers of device part number
Y = Last two digits of year of manufacture
W = Week of manufacture
LLLLLLL
YYWW
NNN
Branding scale and appearance at supplier discretion
0.38 +0.06
–0.04
2.20
Package SG, 4-Pin SIP
T rue Zero-Speed, High Accuracy Gear Tooth Sensor IC
ATS667LSG
14
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
Copyright ©2009-2013, Allegro MicroSystems, LLC
Allegro MicroSystems, LLC reserves the right to make, from time to time, such de par tures from the detail spec i fi ca tions as may be required to
permit improvements in the per for mance, reliability, or manufacturability of its products. Before placing an order, the user is cautioned to verify that
the information being relied upon is current.
Allegro’s products are not to be used in life support devices or systems, if a failure of an Allegro product can reasonably be expected to cause the
failure of that life support device or system, or to affect the safety or effectiveness of that device or system.
The in for ma tion in clud ed herein is believed to be ac cu rate and reliable. How ev er, Allegro MicroSystems, LLC assumes no re spon si bil i ty for its
use; nor for any in fringe ment of patents or other rights of third parties which may result from its use.
For the latest version of this document, visit our website:
www.allegromicro.com
Revision History
Revision Current
Revision Date Description of Revision
Rev. 5 April 14, 2011 Update TθE
