A1667 Datasheet

A1667
True Zero-Speed, High Accuracy, Ring Magnet Sensor IC
FEATURES AND BENEFITS
DESCRIPTION
▪Optimized robustness to 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 switch points
▪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
▪Fast startup
▪Undervoltage lockout (UVLO)
The A1667 is a true zero-speed ring magnet sensor integrated
circuit (IC) consisting of an optimized Hall IC available in
two package options that provides a user-friendly solution for
digital ring magnet sensing applications.
The sensor incorporates a dual element Hall IC that switches
in response to differential magnetic signals created by a
ring magnet. 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.
Packages:
8-Pin SOIC (suffix L)
4-Pin SIP (suffix K)
The open-drain output is configured for three-wire applications.
This sensor is ideal for obtaining speed and duty cycle
Continued on the next page…
KEY APPLICATIONS
• Automotive – Transmissions Applications
• 2- and 3-Wheeler Speed Applications
• White Goods – Drum Speed Applications
Not to scale
Functional Block Diagram
VCC
Voltage
Regulator
Automatic
Gain
Control
Hall
Amp
Offset
Adjust
Threshold
Comparator
PDAC
PThresh
VPROC
Reference
Generator
NDAC
Threshold
Logic
NThresh
TEST
Current
Limit
GND
A1667-DS, Rev. 1
Output
Transistor
VOUT
A1667
True Zero-Speed, High Accuracy, Ring Magnet Sensor IC
DESCRIPTION (continued)
information using ring magnet based systems in applications such
as automotive transmissions and industrial equipment.
The A1667 is available in a 4-pin SIP through-hole package (suffix K) and an 8-pin SOIC surface-mount package (suffix L). Both
packages are lead (Pb) free with 100% matte-tin-plated leadframes.
SELECTION GUIDE
Part Number
Packaging
Packing*
A1667LK-T
4-pin SIP through hole
Bulk, 500 pieces per bag
A1667LLTR-T
8-pin SOIC surface mount
3000 pieces per 13-in. reel
*Contact Allegro™ for additional packing options
ABSOLUTE MAXIMUM RATINGS
Characteristic
Symbol
Supply Voltage
VCC
Reverse Supply Voltage
VRCC
Notes
Rating
Unit
26.5
V
–18
V
See Power Derating section
Reverse Supply Current
IRCC
–50
mA
Reverse Output Voltage
VROUT
–0.5
V
Output Sink Current
IOUT
25
mA
–40 to 150
ºC
TJ(max)
165
ºC
Tstg
–65 to 170
ºC
Operating Ambient Temperature
TA
Maximum Junction Temperature
Storage Temperature
Range L
PINOUT DIAGRAMS AND TERMINAL LIST TABLE
Terminal List
Number
1
2
3
1
8
2
7
3
6
4
5
4
Package K, 4-Pin SIP
Package L, 8-Pin SOIC
Name
Function
K
L
1
1
VCC
Supply voltage
2
2
VOUT
Device output
3
3
TEST
Test pin (float or tie to GND)
4
4
GND
Ground
–
5,6,7,8
NC
No connect*
* Pins 5, 6, 7, and 8 should be externally connected to Ground.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
2
A1667
True Zero-Speed, High Accuracy, Ring Magnet Sensor IC
OPERATING CHARACTERISTICS: Valid over operating voltage and temperature ranges, unless otherwise noted
Characteristics
Symbol
Test Conditions
Min.
Typ.1
Max.
Unit
4
–
24
V
2.7
3.5
3.95
V
–
–
–10
mA
26.5
–
–
V
ELECTRICAL CHARACTERISTICS
Supply Voltage
Undervoltage Lockout (UVLO)
Reverse Supply Current
VCC
Operating, TJ < TJ(max)
VCC(UV)
IRCC
VCC = –18 V
Supply Zener Clamp Voltage
VZ
ICC = 15 mA, TA = 25 °C
Supply Zener Current
IZ
TA = 25°C, TJ < TJ(max), continuous, VZ = 26.5 V
–
–
15
mA
Output off
4
7
12
mA
Output on
4
7
12
mA
–
6
–
V
Connected as in figure 6
–
High
–
–
fOP < 200 Hz; VCC > VCC(min)
–
–
2
ms
mV
Supply Current
Test Pin Zener Clamp Voltage 2
ICC
VTESTZ
POWER-ON STATE CHARACTERISTICS
Power-On State
Power-On
Time 3
POS
tPO
OUTPUT STAGE
Low Output Voltage
Output Zener Clamp Voltage
VOUT(SAT)
ISINK = 10 mA, Output = on
VZOUT
–
100
250
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
–
10
–
µs
–
0.6
2
µs
–150
–
150
G
Output Rise Time
tr
RL = 1 kΩ, CL = 4.7 nF, VPULLUP = 12 V,
10% to 90%, connected as in figure 6
Output Fall Time
tf
RL = 1 kΩ, CL = 4.7 nF, VPULLUP = 12 V,
10% to 90%, connected as in figure 6
DIGITAL-TO-ANALOG CONVERTER (DAC) CHARACTERISTICS
Allowable User-Induced Differential
Offset 4,5
BDIFFEXT
User induced differential offset
SWITCHPOINT CHARACTERISTICS
Operational Switching Frequency
fOP
0
–
12
kHz
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, BSIG > BSIG(MIN),
VOUT high to low
65
70
75
%
Release Point
BRP
% of peak-to-peak VPROC referenced from
PDAC to NDAC, BSIG > BSIG(MIN),
VOUT low to high
25
30
35
%
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
Continued on the next page…
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
3
A1667
True Zero-Speed, High Accuracy, Ring Magnet Sensor IC
OPERATING CHARACTERISTICS (continued): Valid over operating voltage and temperature ranges, unless otherwise noted
Characteristics
Symbol
Test Conditions
Min.
Typ.1
Max.
Unit
CALI
Possible reduced edge detection accuracy, duty
cycle not guaranteed
–
1
6
electrical
edge
Running mode operation, bounded for
decreasing BSIG, unlimited for increasing BSIG
–
Continuous
–
–
CALIBRATION
Initial Calibration 6
Update Method
OPERATING CHARACTERISTICS
Operating Signal Range
BSIG
Differential magnetic signal
operation within specification
30
–
1400
G
Relative Repeatability 7
TθE
60 pole-pair target, using 100 GPK-PK ideal
sinusoidal signal, TA = 150°C, and fOP = 1000 Hz
–
0.12
–
degrees
Single instantaneous air gap peak-to-peak
amplitude change, fOP < 500 Hz, VPROC(pk-pk) >
VLOE after sudden AG change
–
40
–
%PK-PK
Maximum Single Outward Sudden Air
Gap Change 8
∆AGMAX
1 Typical
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 Sustained voltages beyond the clamp voltage may cause permanent damage to the IC.
3 Power-On Time is the time required to complete the internal Automatic Offset Adjust; the DACs are then ready for peak acquisition.
4 The device compensates for magnetic and installation offsets. Offsets greater than specification in gauss may cause inaccuracies in the output.
5 1 G (gauss) = 0.1 mT (millitesla).
6 For power-on frequency, f
OP < 200 Hz. Higher power-on frequencies may result in more input magnetic cycles until full output edge accuracy is
achieved, including the possibility of missed output edges.
7 The repeatability specification is based on statistical evaluation of a sample population, evaluated at 1000 Hz.
8 Single maximum allowable air gap change in outward direction (increase in air gap).
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
4
A1667
True Zero-Speed, High Accuracy, Ring Magnet Sensor IC
Characteristic Performance
Supply Current (Off) versus Supply Voltage
14
14
12
12
10
VCC (V)
8
4
12
24
6
ICCOFF (mA)
ICCOFF (mA)
Supply Current (Off) versus Ambient Temperature
TA (°C)
–40
25
150
8
6
4
4
2
2
0
0
-50
0
50
100
150
0
10
30
VCC (V)
Supply Current (On) versus Ambient Temperature
Supply Current (On) versus Supply Voltage
14
14
12
12
8
4
12
24
6
ICCON (mA)
10
VCC (V)
TA (°C)
–40
25
150
8
6
4
4
2
2
0
0
-50
0
50
100
0
150
10
TA (°C)
160
140
BOP, BRP (%)
120
100
80
60
40
20
0
-50
0
50
TA (°C)
30
Switchpoints versus Ambient Temperature
VCC = 12 V
180
20
VCC (V)
Output Saturation Voltage versus Ambient Temperature
VOUT(SAT) (mV)
20
TA (°C)
10
ICCON (mA)
10
100
150
100
90
80
70
60
50
40
30
20
10
0
BOP
BRP
-50
0
50
100
150
T A (°C)
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
5
A1667
True Zero-Speed, High Accuracy, Ring Magnet Sensor IC
THERMAL CHARACTERISTICS: May require derating at maximum conditions; see application information
Characteristic
Symbol
Test Conditions*
RθJA
Package Thermal Resistance
Value
Units
Package K, 1-layer PCB with copper limited to solder pads
177
ºC/W
Package L, 1-layer PCB with copper limited to solder pads
140
ºC/W
Package L, 4-layer PCB based on JEDEC standard
80
ºC/W
*Additional thermal data available on the Allegro Website.
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
VCC(max)
Package L, 4-layer PCB
(RθJA = 80ºC/W)
Package L, 1-layer PCB
(RθJA = 140ºC/W)
Package K, 1-layer PCB
(RθJA = 177ºC/W)
VCC(min)
20
40
60
80
100
120
140
160
180
Temperature (ºC)
Power Dissipation versus Ambient Temperature
Power Dissipation, PD (mW)
Maximum Allowable VCC (V)
Power Derating Curve
1900
1800
1700
1600
1500
1400
1300
1200
1100
1000
900
800
700
600
500
400
300
200
100
0
Package L, 4-layer PCB
(RθJA = 80 °C/W)
Package L, 1-layer PCB
(RθJA = 140 °C/W)
Package K, 1-layer PCB
(RθJA = 177 °C/W)
20
40
60
80
100
120
140
160
180
Temperature (°C)
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
6
A1667
True Zero-Speed, High Accuracy, Ring Magnet Sensor IC
Functional Description
HALL TECHNOLOGY
The single-chip differential Hall-effect sensor IC contains two
Hall elements as shown in figure 1, which simultaneously sense
the magnetic profile of the ring magnet. The magnetic fields are
sensed 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 temperaturecompensated 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
rejection circuitry. The Hall transducers and signal processing
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 translation of the mechanical profile, through the magnetic profile that
it induces, to the digital output signal of the A1667. No additional optimization is needed and minimal processing circuitry is
required. This ease of use reduces design time and incremental
assembly costs for most applications.
Target
(Ring Magnet)
S
N
N
S
Mechanical Position (Target moves past device pin 1 to pin 4)
(Pin 1 Side)
Figure 1. Relative motion of the target is detected by the dual Hall
elements mounted on the Hall IC.
Branded Face
of L Package
Rotating Target
S
N
S N
S NS
N
Pin 1
+B
Device Orientation to Target
Pin 4
N
S N
S NS
Pin 1
Hall Element 2
Hall Element 1
IC
(Pin 4 Side)
(Pin 1 Side)
(View of Sensor
Opposite Pins)
Device Internal Differential Analog Signal, VPROC
BOP(#1)
BRP(#2)
Device Internal Switch State
On
Off
Branded Face
of K Package
Element Pitch
Sensor Branded Face
BRP(#1)
Rotating Target
S
S
N
S
This pole
sensed later
Target Magnetic Profile
Hall Element 1
Hall IC
(Pin 4 Side)
Target
(Radial Ring Magnet)
This pole
sensed earlier
–B
Element Pitch
Hall Element 2
DETERMINING OUTPUT SIGNAL POLARITY
In figure 3, the top panel, labeled Mechanical Position, represents
the mechanical features of the target ring magnet and orientation to the device. The bottom panel, labeled Device Output
Signal, displays the square waveform corresponding to the digital
output signal that results from a rotating ring magnet configured
as shown in figure 2. That direction of rotation (of the target
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 device output switching from low to high
output state as the leading edge of a north magnetic pole passes
the device face. In this configuration, the device output voltage
switches to its high polarity when a north pole is the target feature
nearest to the device. If the direction of rotation is reversed, then
the output polarity inverts.
On
Off
Device Output Signal, VOUT
+t
N
Pin 4
Figure 2. This left-to-right (pin 1 to pin 4) direction of target rotation results
in a high output state when a north magnetic pole of the target is nearest
the face of the device (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 A1667 to present an accurate digital output response.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
7
A1667
True Zero-Speed, High Accuracy, Ring Magnet Sensor IC
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
(A) TEAG varying; cases such as
eccentric mount, out-of-round region,
normal operation position shift
state changes from low to high.
As shown in figure 5, threshold levels for the A1667 switchpoints
are established as a function of the peak input signal levels. The
A1667 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.
(B) Internal analog signal, VPROC,
typically resulting in the IC
V+
Smaller
TEAG
IC
Target
Smaller
TEAG
Hysteresis Band
(Delimited by switchpoints)
Larger
TEAG
IC
Larger
TEAG
VPROC (V)
Target
Smaller
TEAG
0
Target Rotation (°)
360
(C) Internal analog signal, VPROC, representing
magnetic field for digital output
V+
BOP
VPROC (V)
BOP
BRP
BOP
BRP
BOP
BOP
BRP
BRP
VOUT (V)
BRP
BOP
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). 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.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
8
A1667
+B
True Zero-Speed, High Accuracy, Ring Magnet Sensor IC
V+
PK(1)
PK(9)
PK(3)
PK(7)
VPROC (V)
BSIG (G)
PK(5)
BOP(A)
BOP(B)
BHYS(A)
BHYS(B)
BRP(A)
BOP(C)
BOP(D)
BHYS(D)
BRP(C)
BRP(B)
PK(4)
BHYS(C)
BRP(D)
PK(6)
PK(2)
PK(8)
–B
t+
Figure 5. The Continuous Update algorithm operation. 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.
Magnetic Field
Chart
Index
PK(1)
Peak VPROC
Amplitude
Target Behavior
(Example only)
Peak Magnetic
Signal, BPK
TEAG small
+BPK
(South Polarity)
VPROCPK(1)
PK(2)
TEAG small
–BPK
(North Polarity)
VPROCPK(2)
PK(3)
TEAG mid
+BPK
(South Polarity)
VPROCPK(3)
PK(4)
TEAG mid
–BPK
(North Polarity)
VPROCPK(4)
PK(5)
TEAG large
+BPK
(South Polarity)
VPROCPK(5)
PK(6)
TEAG large
–BPK
(North Polarity)
VPROCPK(6)
PK(7)
TEAG mid
+BPK
(South Polarity)
VPROCPK(7)
PK(8)
TEAG mid
–BPK
(North Polarity)
VPROCPK(8)
PK(9)
TEAG small
+BPK
(South Polarity)
VPROCPK(9)
Centered Calculated Range, BHYS
Operate Point. BOP Release Point. BRP
(70% B(PKPK) ∝
(30% B(PKPK) ∝
70% VPROC(PKPK))
30% VPROC(PKPK))
BHYS
(Previous state)
BOP(A)
A
BRP(A)
BOP(B)
BRP(B)
BOP(C)
BRP(C)
BOP(D)
BRP(D)
B
C
D
(Next state)
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
9
A1667
True Zero-Speed, High Accuracy, Ring Magnet Sensor IC
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.
Target, Ring Magnet
A typical scenario is shown in figure 6. 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 A1667 starts to compute switchpoints.
S
N
S
Target Magnetic Profile
BOP(initial)
Differential Signal, VPROC
BRP
Start Mode
Hysteresis, POHYS
BOP
BRP(initial)
IC Position
Relative to Target
Output Signal, VOUT
1
2
3
BOP
4
If exceed POHYS
on high side
If exceed POHYS
on low side
Figure 6. Operation of Start Mode Hysteresis
• At power-on (position 1), the A1667 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 A1667 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.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
10
A1667
True Zero-Speed, High Accuracy, Ring Magnet Sensor IC
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 unregulated 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 7 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 specification). 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 8 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 continuously 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 variations over time.
RUNNING MODE LOCKOUT
The A1667 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 output is
held to the state prior to lockout until the amplitude of the signal
returns to normal operational levels.
Target
Ring Magnet
VPULLUP
VCC
A1667
1
CBYPASS
0.1 µF
(Optional)
VCC
VOUT
RL
2
N
S
N
S
V+
Internal Differential
Analog Signal
Response, without AGC
AGLarge
AGSmall
GND
4
TEST
3
CL
V+
Internal Differential
Analog Signal
Response, with AGC
Figure 7. Typical circuit for proper device operation.
AGSmall
AGLarge
Figure 8. 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.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
11
A1667
True Zero-Speed, High Accuracy, Ring Magnet Sensor IC
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 application. This section presents a procedure for correlating factors
affecting operating TJ. (Thermal data is also available on the
Allegro website.)
The Package Thermal Resistance, RθJA, is a figure of merit summarizing 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, RθJC, is relatively
small component of RθJA. 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. PD = VIN × IIN ΔT = PD × RθJA TJ = TA + ΔT
(1)
(2)
(3)
Example: Reliability for VCC at TA = 150°C, package K, using a
single-layer PCB.
Observe the worst-case ratings for the device, specifically: RθJA = 177 °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:
ΔTmax = 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) = ΔTmax ÷ RθJA = 15°C ÷ 177 °C/W = 84.7 mW
Finally, invert equation 1 with respect to voltage:
VCC(est) = PD(max) ÷ ICC(max) = 119 mW ÷ 12 mA = 7.1 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 RθJA. If VCC(est) ≥ VCC(max), then operation between
VCC(est) and VCC(max) is reliable under these conditions.
For example, given common conditions such as: TA= 25°C,
VCC = 12 V, ICC = 7.5 mA, and RθJA = 177 °C/W, then:
PD = VCC × ICC = 12 V × 7.5 mA = 90 mW
ΔT = PD × RθJA = 90 mW × 177 °C/W = 11.3°C
TJ = TA + ΔT = 25°C + 11.3°C = 36.3°C
A worst-case estimate, PD(max), represents the maximum allowable power level (VCC(max), ICC(max)), without exceeding
TJ(max), at a selected RθJA and TA.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
12
A1667
True Zero-Speed, High Accuracy, Ring Magnet Sensor IC
Package K, 4-Pin SIP
+0.08
5.21 –0.05
B
45°
E
2.20
E
1.55 ±0.05
1.50
D
1.32 E
+0.08
3.43 –0.05
E2
E1
Branded
Face
2.16
MAX
2
3
1
C Standard Branding Reference View
0.84 REF
N = Device part number
Y = Last two digits of year of manufacture
W = Week of manufacture
For Reference Only; not for tooling use (reference DWG-9010)
Dimensions in millimeters
Dimensions exclusive of mold flash, gate burrs, and dambar protrusions
Exact case and lead configuration at supplier discretion within limits shown
4
14.73 ±0.51
+0.06
0.38 –0.03
+0.07
0.41 –0.05
YYWW
45°
A
1
NNNN
Mold Ejector
Pin Indent
A
Dambar removal protrusion (8X)
B
Gate and tie bar burr area
C
Branding scale and appearance at supplier discretion
D Active Area Depth, 0.42 mm
E Hall elements (E1 and E2); not to scale
1.27 NOM
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
13
A1667
True Zero-Speed, High Accuracy, Ring Magnet Sensor IC
Package L, 8-Pin SOIC
For Reference Only – Not for Tooling Use
(Reference DWG-9204)
Dimensions in millimeters – NOT TO SCALE
Dimensions exclusive of mold flash, gate burrs, and dambar protrusions
Exact case and lead configuration at supplier discretion within limits shown
4.90 ±0.10
8°
0°
E
1.95
E
1.00
0.65
1.27
8
A
8
1.75
0.21 ±0.04
1.95 E
3.90 ±0.10
E1
5.60
6.00 ±0.20
+0.43
0.84
–0.44
E2
D
1.04 REF
1
2
1
2
0.25 BSC
B
SEATING PLANE
8X
+0.13
1.62
–0.27
B
0.10
0.41 ±0.10
1.27 BSC
0.15
SEATING
PLANE
Active Area Depth, 0.40 mm REF
B
Reference land pattern layout (reference IPC7351 SOIC127P600X175-8M);
all pads a minimum of 0.20 mm from all adjacent pads; adjust as necessary
to meet application process requirements and PCB layout tolerances
Branding scale and appearance at supplier discretion
D
Terminal #1 mark area
E
Hall elements (E1 and E2); not to scale
PCB Layout Reference View
+0.10
–0.05
A
C
B
GAUGE PLANE
NNNNNNN
YYWW
LLLL
1
C
Standard Branding Reference View
N
Y
W
L
= Device part number
= Supplier emblem
= Last two digits of year of manufacture
= Week of manufacture
= Lot number
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
14
A1667
True Zero-Speed, High Accuracy, Ring Magnet Sensor IC
Revision History
Revision
Date
1
May 13, 2016
Change
Added L package option
Copyright ©2016, Allegro MicroSystems, LLC
Allegro MicroSystems, LLC reserves the right to make, from time to time, such departures from the detail specifications as may be required to
permit improvements in the performance, 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 any devices or systems, including but not limited to life support devices or systems, in which a failure of
Allegro’s product can reasonably be expected to cause bodily harm.
The information included herein is believed to be accurate and reliable. However, Allegro MicroSystems, LLC assumes no responsibility for its
use; nor for any infringement 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
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
15
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