A17501POKATN-PDTRYJGA
更新时间:2024-09-18 22:44:44
品牌:ALLEGRO
描述:Dual Output Differential Speed and Direction Sensor IC
A17501POKATN-PDTRYJGA 概述
Dual Output Differential Speed and Direction Sensor IC
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Dual Output Differential Speed and Direction Sensor IC
FEATURES AND BENEFITS
DESCRIPTION
• High-speed switching bandwidth up to 40 kHz
• Two independent output channels with options for high
resolution XOR speed, pulse, and direction protocol
• ASIL B(D) compliant (ISO 26262), assessment pending
• Optional fault detection output protocol
• Immune to common external magnetic disturbance
• EEPROM enables factory traceability throughout product
life cycle
The A17501 is a single IC solution designed for rotational
position sensing of a ring magnet target found in automotive
and industrial electric motor applications (often with specific
application and safety requirements).
ThreeHallelementsareincorporatedtocreatetwoindependent
differential channels. These inputs are processed by digital
circuits and robust algorithms designed to eliminate the
detrimental effects of magnetic and system offsets, and to
address false output transitions caused by target vibrations
in electric motors at startup and low speed operation. The
differential signals are used to produce a highly accurate
speed output and, if desired, provide information on the
direction of rotation.
• Ideally suited for asynchronous electric motor applications
• Also available with integrated magnet (see ATS17501
datasheet)
2
-
Advanced calibration techniques are used to optimize signal
offset and amplitude. This calibration, combined with the
digital tracking of the signal, results in accurate switch points
over air gap, speed, and temperature.
PACKAGE:
The IC can be programmed for a variety of applications
requiring dual-phase target speed and position signal
information or simultaneous high-resolution target speed
and direction information. It can be configured to enable
Fault Detection mode for ASIL B(D) utilization (assessment
pending).
4-Pin SIP
(suffix K)
The A17501 K package is a lead (Pb) free 4-pin SIP package
with a 100% matte-tin-plated lead frame.
Not to scale
Functional Block Diagram
Analog
Regulator
EEPROM
VCC
Diagnostics
Digital
Regulator
Temperature
Sensor
OUTA
Digital
Controller
Oscillator
Hall
Elements
Analog
Gain
OUTB
GND
ADC
Filter
Analog
Filter
Gain
ADC
A17501-DS
MCO-0000793
March 19, 2020
Advance Information Datasheet • Subject to Change Without Notice
A17501
Dual Output Differential Speed and Direction Sensor IC
SELECTION GUIDE [1]
Part Number
Packing
A17501POKATN-SDFUYJE
4000 pieces per 13-inch reel
[1] Not all selectable combinations are available, contact Allegro for additional
selections and packing options.
2
Allegro MicroSystems
Advance Information Datasheet
Subject to Change Without Notice
March 19, 2020
955 Perimeter Road
Manchester, NH 03103-3353 U.S.A.
www.allegromicro.com
A17501
Dual Output Differential Speed and Direction Sensor IC
ABSOLUTE MAXIMUM RATINGS
Characteristic
Symbol
VCC
Notes
Refer to Power Derating section
Rating
28
Unit
V
Supply Voltage
Reverse Supply Voltage
Output Voltage
VRCC
–18
28
V
VOUT
Each output pin
V
Reverse Output Voltage
VROUT
Each output pin; RPULLUP ≥ 1 kΩ
–0.5
V
Short-term output current for OUTA and OUTB independently,
not intended for continuous operation
Output Sink Current
IOUT
50
mA
Operating Ambient Temperature Range
Junction Temperature
TA
TJ
–40 to 160
175
°C
°C
°C
Storage Temperature Range
Tstg
–65 to 170
PINOUT DIAGRAM
Branded
Face
1
2
3
4
K Package, 4-Pin SIP
PINOUT TABLE
Name
Pin
Function
VCC
1
2
3
4
Supply Voltage
OUTA
OUTB
GND
Configurable Output A
Configurable Output B
Ground
3
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Advance Information Datasheet
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A17501
Dual Output Differential Speed and Direction Sensor IC
TYPICAL APPLICATION CIRCUIT
[2]
VPULLUP
VSUPPLY
RSERIES
RPULLUP(A)
VCC
OUTA
VOUT(A)
CLOAD(A)
VPULLUP
[2]
CBYPASS
A17501
RPULLUP(B)
GND
OUTB
VOUT(B)
CLOAD(B)
COMPONENTS [3]
Characteristic
Symbol
Notes
Value (Typ.)
Unit
Series Resistance
RSERIES
Recommended for typical EMC requirements
100
1
Ω
Required for functional operation; recommended value
dependent on programming options
OUTA Pullup Resistance
RPULLUP(A)
kΩ
Required for functional operation; recommended value
dependent on programming options
OUTB Pullup Resistance
Bypass Capacitance
RPULLUP(B)
CBYPASS
CLOAD(A)
1
kΩ
nF
nF
Recommended for typical EMC requirements
100
2.2
Recommended for typical EMC requirements; required for
certain programming options
OUTA Load Capacitance
Recommended for typical EMC requirements; required for
certain programming options
OUTB Load Capacitance
CLOAD(B)
2.2
nF
[2]
V
may be connected to VCC if VCC meets VPULLUP requirements. See Operating Characteristics section.
PULLUP
[3] Components listed are typical recommended values and are not suited for all applications and/or programmable options. See Operating Characteristics and Selection Guide for more information.
4
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Advance Information Datasheet
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Subject to Change Without Notice
March 19, 2020
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A17501
Dual Output Differential Speed and Direction Sensor IC
OPERATING CHARACTERISTICS: Valid throughout operating ranges, unless otherwise specified
Characteristic
Symbol
Test Conditions
Min.
Typ. [4]
Max.
Unit
ELECTRICAL SUPPLY CHARACTERISTICS
Supply Voltage [5]
VCC
VCC(UV)
ICC
Voltage across VCC and GND
4
–
–
–
24
3.99
15
V
Undervoltage Lockout
Supply Current
V
–
10
–
mA
mA
Reverse Supply Current
IRCC
VCC = –18 V
–10
–
ELECTRICAL PROTECTION CHARACTERISTICS
Supply Clamp Voltage
VCSUPPLY TA = 25°C; ICC = 18 mA
VRCSUPPLY TA = 25°C; ICC = –3 mA
28
–
–
–
–
–
–18
–
V
V
V
Reverse Supply Clamp Voltage
Output Clamp Voltage
VCOUT
TA = 25°C; IOUT = 3 mA
28
Current limited by design for short circuit event
on OUTA and OUTB independently;
low impedance output state
Output Current Internal Limiter
IOUT(LIM)
30
55
85
mA
POWER-ON CHARACTERISTICS
Power-On State
POS
tPO
For OUTA and OUTB
VOUT(HIGH)
–
V
Time from VCC > VCC(min) to when sensor IC
output is valid
Power-On Time
–
1
ms
CALIBRATION CHARACTERISTICS
Amount of target rotation with constant direction
following power-on until first electrical output
transition; Dynamic Threshold option; see Figure 1
First Output Edge
–
–
–
–
1
2
TCYCLE
–
Amount of target rotation with constant direction
following power-on until calibration is complete;
Dynamic Threshold option; see Figure 1
Initial Calibration
–
TCYCLE
OUTPUT CHARACTERISTICS [6]
Fault Detection Mode disabled; IOUT = 10 mA
–
0.165
–
0.35
1.25
V
V
5 V, 1 kΩ or 5 V, 3 kΩ
option
Output Low Voltage
VOUT(LOW)
0.5
Fault Detection Mode
enabled
12 V, 1 kΩ option
1.2
–
–
3.6
–
V
V
Fault Detection Mode disabled
5 V, 1 kΩ or 5 V, 3 kΩ
VPULLUP
Output High Voltage
VOUT(HIGH)
3.75
8.4
–
–
4.5
V
V
Fault Detection Mode
enabled
option
12 V, 1 kΩ option
10.8
Continued on next page...
[4] Typical values are at TA = 25°C and VCC = 5 V. Performance may vary for individual units, within the specified maximum and minimum limits.
[5] Maximum voltage must be adjusted for power dissipation and junction temperature; see representative for Power Derating discussions.
[6] Output characteristics are valid for each output independently, unless otherwise specified.
5
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A17501
Dual Output Differential Speed and Direction Sensor IC
OPERATING CHARACTERISTICS (continued): Valid throughout operating ranges, unless otherwise specified
Characteristic
Symbol
Test Conditions
Min.
Typ. [7]
Max.
Unit
OUTPUT CHARACTERISTICS (continued) [8]
Fault Detection
Mode enabled;
5 V, 1 kΩ or
High fault (VFAULT(HIGH)
)
4.5
1.25
–
–
–
–
–
–
–
–
–
–
1
–
–
–
–
–
–
3.75
0.5
–
V
V
Mid fault (VFAULT(MID)
Low fault (VFAULT(LOW)
High fault (VFAULT(HIGH)
Mid fault (VFAULT(MID)
Low fault (VFAULT(LOW)
)
)
V
5 V, 3 kΩ option
Fault Voltage [9]
VFAULT
)
10.8
3.6
–
V
Fault Detection
Mode enabled;
12 V, 1 kΩ option
)
8.4
1.2
24
V
)
V
Fault Detection Mode disabled
4
V
Allowable Pullup Voltage
VPULLUP
5 V, 1 kΩ or 5 V, 3 kΩ option
12 V, 1 kΩ option
4.75
11.4
–
5.25
12.6
–
V
Fault Detection
Mode enabled
V
Fault Detection Mode disabled
5 V, 1 kΩ option
Fault Detection
Mode enabled
kΩ
kΩ
kΩ
kΩ
nF
µA
0.8
1.46
0.9
1
1.46
3.4
1.1
–
Allowable Pullup Resistor [10]
RPULLUP
5 V, 3 kΩ option
12 V, 1 kΩ option
Allowable Load Capacitor [11]
Output Leakage Current
CLOAD
Fault Detection Mode enabled
IOUT(OFF) Fault Detection Mode disabled; VOUT = VOUT(HIGH)
–
10
Speed output protocol; Dynamic Threshold
option; sinusoidal input signal; fOP < 1 kHz
Duty Cycle
D
45
–
50
5
55
–
%
µs
µs
µs
µs
10%→90%; VPULLUP = 5 V; RPULLUP = 1 kΩ;
CLOAD = 2.2 nF
Output Rise Time
tr
Fault Detection Mode disabled;
–
0.5
3.5
6
–
Fast fall time option
90%→10%;
VPULLUP = 5 V;
Fault Detection Mode disabled;
Output Fall Time
tf
–
–
RPULLUP = 1 kΩ; Slow fall time option
CLOAD = 2.2 nF
Fault Detection Mode
–
–
enabled
Forward Pulse Width [12]
Reverse Pulse Width [12]
tw(FWD)
tw(REV)
38
76
45
90
52
µs
µs
104
Delay from the magnetic signal crossing a switch
point threshold to the start of the output transition
Propagation Delay
td
–
8
–
µs
target degrees
target degrees
target degrees
BDIFF(pk-pk) = 100 G
–
–
–
–
–
–
0.13
0.086
0.064
σ×6; sinusoidal
input signal;
fOP = 1 kHz
Jitter [13]
BDIFF(pk-pk) = 150 G
BDIFF(pk-pk) = 200 G
–
Continued on next page...
[7] Typical values are for VCC = 5 V and TA = 25°C, unless otherwise specified.
[8] Output characteristics are valid for each output independently, unless otherwise specified.
[9] Valid with Fault Detection Mode enabled and correct programming of the Fault Detection Load Circuit option; see Selection Guide.
[10] See Application Circuit section.
[11] Minimum capacitor required when Fault Detection Mode is enabled to ensure correct output levels over operating conditions. Increased load capacitance will directly impact maximum operating
frequency due to the increased rise and fall times; see Application Circuit section.
[12] Time from start of output transition from VOUT(HIGH) to VOUT(LOW) to start of output transition from VOUT(LOW) to VOUT(HIGH). Measured pulse width will vary with load circuit configurations and measure-
ment thresholds. Valid with Pulse or Pulse Inverted output protocol; see Programming Options section.
[13] Guaranteed by design and characterization only. Characterization performed by measuring greater than 1,000 falling output edges of the same target feature at constant temperature using Reference
Target 60-0, see Reference Target Characteristics section. Value representative of a 6-σ distribution, such that 99.76% of the measured values are within the specified target degree.
6
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A17501
Dual Output Differential Speed and Direction Sensor IC
OPERATING CHARACTERISTICS (continued): Valid over operating ranges, unless otherwise specified
Characteristic
Symbol
Test Conditions
Min.
Typ. [14]
Max.
Unit
SWITCH POINT CHARACTERISTICS
% of BDIFF(PKPK); VOUT = VOUT(LOW) → VOUT
VOUT(HIGH); Dynamic Threshold option
=
Operate Point
BOP
BRP
–
–
70
30
–
–
%
%
% of BDIFF(PKPK); VOUT = VOUT(HIGH) → VOUT
VOUT(LOW); Dynamic Threshold option
=
Release Point
Hysteresis
ΔBDIFF after
switch point
% of BDIFF(PKPK);
Dynamic Threshold option
–
–
40
10
–
–
%
G
BHYS
to allow next
output transition
Fixed Threshold option
INPUT CHARACTERISTICS
Sinusoidal input signal; forward and reverse
target rotation; not valid for Pulse or Inverse
Pulse output protocol
Operating Frequency
fOP
0
–
40
kHz
Forward Pulse Operating Frequency
Reverse Pulse Operating Frequency
fOP(FWD)
fOP(REV)
Pulse or Inverse Pulse output protocol
Pulse or Inverse Pulse output protocol
0
0
–
–
9
6
kHz
kHz
Dynamic Threshold option;
fOP ≤ 20 kHz
30
40
–
–
–
–
G
G
Operating Magnetic Input [15]
BDIFF(pk-pk) See Figure 2
Dynamic Threshold option;
fOP > 20 kHz
Fixed Threshold option
100
–
–
–
G
G
Operating Magnetic Input Peak [15]
BDIFF
See Figure 2
–1150
1150
Bounded amplitude ratio within TWINDOW; no
missed output transitions; possible incorrect
direction information and/or reduction in switch
point accuracy; see Figure 3 and Figure 4
Operating Magnetic Input Signal
Variation [16]
ΔBDIFF(pk-pk)
0.6
8
–
–
2
–
–
Operating Magnetic Input Signal
Variation Window
Rolling window in which ΔBDIFF(pk-pk) cannot
exceed bounded ratio; see Figure 3 and Figure 4
TWINDOW
TCYCLE
THERMAL CHARACTERISTICS
Single-sided PCB, with copper limited to solder
pads
Package Thermal Resistance
RθJA
–
177
–
°C/W
[14] Typical values are for VCC = 5 V and TA = 25°C, unless otherwise specified.
[15] Differential magnetic field is measured for Left Channel (E1-E2) and Right Channel (E2-E3) independently; see Package Diagram. Magnetic field is measured orthogonally to the branded package
face.
[16] Operating magnetic input variation is valid for symmetrical peak variation about the signal offset. BDIFF(pk-pk) must always be greater than BDIFF(pk-pk,min)
.
7
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955 Perimeter Road
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A17501
Dual Output Differential Speed and Direction Sensor IC
REFERENCE
Typical Application Circuit
TCYCLE
Target
S
N
S
N
S
TCYCLE
BDIFF
Figure 1: Definition of TCYCLE
TCYCLE = Target Cycle; the amount of rotation that moves one tooth and valley across the sensor.
BDIFF = The differential magnetic flux density sensed by the IC.
Differential Magnetic Input
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ꢀꢁꢂꢃꢃ
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ꢀꢁꢂꢃꢃꢄꢅinꢇ
ꢀiꢁe
Figure 2: Differential Magnetic Input
BDIFF = The differential magnetic flux density sensed by the IC.
BDIFF(pk-pk) = The peak-to-peak magnetic flux density sensed by the IC.
8
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A17501
Dual Output Differential Speed and Direction Sensor IC
Operating Magnetic Signal Variation and Window
Figure 3: Repeated Period Variation
Figure 4: Single Period Variation
9
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A17501
Dual Output Differential Speed and Direction Sensor IC
CHARACTERIZATION PLOTS [17]
[17] Characterization data representative of distribution averages. Characterization tested with Dynamic Threshold algorithm at fOP = 1 kHz, VCC = 5 V, VPULLUP = 5 V,
RPULLUP = 1 kΩ, and CLOAD = 2.2 nF unless otherwise specified.
10
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March 19, 2020
955 Perimeter Road
Manchester, NH 03103-3353 U.S.A.
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A17501
Dual Output Differential Speed and Direction Sensor IC
11
Allegro MicroSystems
Advance Information Datasheet
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March 19, 2020
955 Perimeter Road
Manchester, NH 03103-3353 U.S.A.
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A17501
Dual Output Differential Speed and Direction Sensor IC
FUNCTIONAL DESCRIPTION
General
As shown in Figure 5, the A17501 supports three Hall elements
that sense the magnetic profile of the ring magnet target simulta-
neously but at different points (each channel spaced at 1.75 mm
pitch), generating two differential internal signals processed
for precise switching of the digital output signals. Direction of
rotation can be determined based on the phase relationship of the
two differential internal signals. The A17501 is intended for use
with ring magnet targets, or ferromagnetic targets when properly
back-biased.
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ꢊ1
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The Hall-effect sensor IC is self-calibrating and possesses a tem-
perature compensated amplifier as well as a full-range analog-to-
digital converter (ADC). This allows for accurate processing of
a wide range of target magnetic profile amplitudes and offsets.
The on-chip voltage regulator provides supply noise rejection
throughout the operating voltage range. Changes in tempera-
ture do not greatly affect the A17501 due to the stable amplifier
design and full-range ADC. The Hall elements and signal pro-
cessing electronics are integrated on the same silicon substrate.
ꢓarget
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ꢀ
S
ꢀ
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ꢑꢀ
ꢒꢀ
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ꢀꢁꢂ
ꢀꢁꢂ
ꢃight Channeꢉ
The A17501 is capable of providing digital information that is
representative of the mechanical features of a rotating target. Fig-
ure 5 shows the automatic translation of the mechanical profile
to the digital output signal. No additional optimization is needed,
and minimum processing circuitry is required. This ease of use
reduces design time and incremental assembly costs for most
applications.
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ꢀꢃꢂ
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ꢃight Channeꢉ
Sꢔeeꢇ
ꢌeꢍt Channeꢉ
Sꢔeeꢇ
Figure 5: Magnetic Profile and Switch Points
(BOP = 70%, BRP = 30%)
12
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955 Perimeter Road
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A17501
Dual Output Differential Speed and Direction Sensor IC
Threshold Algorithms
The A17501 contains selectable algorithms for determining when
to produce an output transition from the magnetic input signal. For
all options, a threshold is set within the sensor IC that triggers the
output transition when crossed by the digitized magnetic signals
(switch point).
Ring Magnet
S N S N S N S N S
BDIFF
Dynamic Threshold
With the A17501 programmed for the Dynamic Threshold option,
each switch point is calculated from information learned from the
previous target feature. This algorithm allows for robust tracking to
produce accurate output transitions for inconsistent magnetic input
signals (offset drift, amplitude changes, etc.).
Speed Output Protocol
After power-on, the magnetic input signal is tracked to find the
peaks of the signal. After each new peak is found, the switch points
are updated based on a percentage of the previous two peaks.
Figure 6: Dynamic Threshold Option
Switch Point Algorithm (BOP = 70%, BRP = 30%)
Fixed Threshold
With the A17501 programmed for the Fixed Threshold option, an
absolute threshold stored in memory is used to set the switch point
for both the operate point and release point. This algorithm allows
for accurate output transitions immediately after power-on for
consistent magnetic input signals without the need to “learn” the
signal. The threshold stored in memory and loaded during power-
on contains threshold levels over temperature to allow for offset
drift adjustment of the magnetic input signal over temperature. The
A17501 sensor IC contains a temperature sensor used continu-
ously to adjust the switch point over temperature as needed by the
application.
Ring Magnet
S N S N S N S N S
BDIFF
The fixed thresholds stored in memory can be pre-programmed
for unique switch points over temperature for each application.
Additionally, the A17501 can find and set the threshold for each
installation over temperature during end-of-line calibration.
Speed Output Protocol
If during the application the magnetic input signal offset does not
match the programmed threshold stored in memory (due to inac-
curate programming, mechanical shift, etc.), the A17501 identifies
the threshold as “out of range”, calculates the threshold for the
current temperature, and updates the threshold to produce correct
output transitions. After the update, algorithms use the current
temperature to recharacterize the threshold over the operational
temperature range. This prevents the update from overcompensat-
ing the threshold at a distant temperature relative to the update
temperature. After the updated threshold is confirmed to be within
the magnetic input signal’s switch point range over several target
features, the updated threshold is stored into memory such that it
can be used for subsequent power-on cycles.
Figure 7: Fixed Threshold Option
Switch Point Algorithm
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A17501
Dual Output Differential Speed and Direction Sensor IC
from the magnetic input signal, the algorithm will transition from
using the fixed threshold switch point to using the dynamic thresh-
old switch points. This transition occurs only when the magnetic
input signal is near a maximum or minimum value, such that
“double-switching” on the transition can be avoided.
Hybrid Threshold
With the A17501 programmed for the Hybrid Threshold option,
the threshold is determined from the Fixed Threshold option at
startup, then transitions to the Dynamic Threshold option after
tracking signals have correctly acquired the magnetic input
signals. This algorithm allows for both accurate output transi-
tions immediately following power-on for consistent magnetic
input signals as well as robust tracking to produce accurate output
transitions of inconsistent magnetic input signals (offset drift,
amplitude changes, etc.).
While the majority of the power-on will use the Dynamic Thresh-
old option for robust signal tracking, the A17501 will continue to
monitor the fixed threshold for comparison to the fixed threshold
stored in memory. Should the fixed threshold require an update, the
A17501 will update and write the new threshold to memory for use
in subsequent power-on cycles.
Once the tracking signals have identified consistent peak values
14
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A17501
Dual Output Differential Speed and Direction Sensor IC
put transitions. These channels are determined by the Hall elements
used to produce the differential signal, where the left channel
Output
The A17501 contains a number of selectable options to change the
output protocol or adjust the output behavior. These options allow for
the A17501 to be programmed to application-level needs.
differential signal is determined by the left and center element (E1-
E2), and the right channel is referenced from the center and right
element (E2-E3); see Package Diagram. XOR Speed and Direction
output protocols are channel-independent, as both channels are
used to determine the output transitions.
Output Protocol
The A17501 contains several programmable output protocols; see
Figure 8. These protocols can be programmed for either output
pin (OUTA or OUTB) independently. For example, Left Chan-
nel Speed can be programmed as the output protocol for OUTA,
OUTB, or both output pins.
For Speed, XOR Speed and Direction output protocols, the polarity
of the signal can be inverted by selecting the “Inverse” option of
the corresponding protocol. Selecting one of these options will
invert the polarity of the output (VOUT(HIGH) and VOUT(LOW)) rela-
tive to the BDIFF signal(s). For the Pulse output protocols, selecting
the “Inverse” option will invert the pulse width for forward and
reverse rotation (tw(FWD) and tw(REV)).
The A17501 contains two independent signal paths. Most out-
put protocols reference a specific magnetic input signal channel
(BDIFF(LEFT) or BDIFF(RIGHT)), which is used to determine the out-
ꢀDIꢁꢁꢂꢃꢄꢁꢅꢆ
Cꢊanꢋe in Direction
ꢀDIꢁꢁꢂꢇIꢈꢉꢅꢆ
ꢃeft Cꢊannel
Speed
ꢇiꢋꢊt Cꢊannel
Speed
ꢃeft Cꢊannel
Speed Inꢌerted
ꢇiꢋꢊt Cꢊannel
Speed Inꢌerted
ꢍOꢇ
ꢍOꢇ Inꢌerted
Direction
ꢏOꢐꢅꢂꢃOꢑꢆ
ꢏOꢐꢅꢂꢉIꢈꢉꢆ
ꢁirst Sꢒitcꢊ ꢎoint After Direction Cꢊanꢋe
ꢏOꢐꢅꢂꢃOꢑꢆ
Direction Inꢌerted
ꢏOꢐꢅꢂꢉIꢈꢉꢆ
ꢃeft Cꢊannel
ꢎulse
ꢅꢒꢂꢇꢄꢏꢆ
ꢅꢒꢂꢁꢑDꢆ
ꢇiꢋꢊt Cꢊannel
ꢎulse
ꢃeft Cꢊannel
ꢎulse Inꢌerted
ꢇiꢋꢊt Cꢊannel
ꢎulse Inꢌerted
Figure 8: Output Protocol Options
15
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A17501
Dual Output Differential Speed and Direction Sensor IC
Fault Detection Mode
tPO
The A17501 allows for the output to transition between one
of two sets of values. With Fault Detection mode disabled, the
output will transition between approximately 0% and 100% of
VPULLUP. With Fault Detection mode disabled, the output transi-
VHIGH = VPULLUP
tions between approximately 20% and 80% of VPULLUP
.
At the beginning of power-on, the A17501 outputs initialize to
the VPULLUP level. With Fault Detection mode enabled, the output
levels transition from VPULLUP to VHIGH before the end of power-
on. After power-on, the output transitions as determined by the
programmed algorithm and output protocol between VOUT(HIGH)
VLOW
and VOUT(LOW)
.
Figure 9: Fault Detection Mode Disabled Output
Enabling Fault Detection mode allows for additional communica-
tion for cases of open wire or short circuit, as well as allowing
for the A17501 to communicate a fault detected from the internal
diagnostics. For a typical application load circuit, these cases can
be detected by observing either OUTA or OUTB transition to
tPO
VPULLUP
VHIGH
approximately 0 V or VPULLUP after tPO
.
VLOW
0 V
Figure 10: Fault Detection Mode Enabled Output
16
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A17501
Dual Output Differential Speed and Direction Sensor IC
Fault Voltage
>1 ms
The A17501 communicates a fault condition by configuring
either output to hold within one of three VFAULT ranges (high,
mid, and low) for greater than 1 millisecond. Normal operation
allows for output transitions to occur over the VFAULT(MID) range;
as such, it is necessary to ignore fast transients for less than
1 millisecond through this range.
VFAULT (HIGH,min)
VFAULT (MID,max)
For internal diagnostics that trigger fault conditions (force the
output to go to VFAULT), both outputs will go to the VFAULT(HIGH)
range. As there may exist internal or external faults that cause
either or both output pins to hold a VFAULT(MID) or VFAULT(LOW)
level, these fault ranges should also be monitored. Examples of
these fault conditions could be a short circuit of the output to
ground, forcing the output to VFAULT(LOW), or a fault in the IC
VFAULT (MID,min)
VFAULT (MID,min)
output controller that forces the output to VFAULT(MID)
.
See Figure 11, Figure 12, and Figure 13 for examples of the out-
put communicating a fault condition.
Normal Opera�on
Assumed Fault
Figure 11: Assumed Fault Example: High Fault
>1 ms
>1 ms
VFAULT (HIGH,min)
VFAULT (HIGH,min)
VFAULT (MID,max)
VFAULT (MID,max)
VFAULT (MID,min)
VFAULT (MID,min)
VFAULT (MID,min)
VFAULT (MID,min)
Normal Opera�on
Normal Opera�on
Assumed Fault
Assumed Fault
Figure 12: Assumed Fault Example: Mid Fault
Figure 13: Assumed Fault Example: Low Fault
17
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955 Perimeter Road
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A17501
Dual Output Differential Speed and Direction Sensor IC
DEVICE FEATURES
Undervoltage Lockout
Vibration Robust Signal Tracking
When supply voltage falls below the Undervoltage Lockout volt-
age (VCC(UV)), the A17501 enters Reset, where the output state
returns to the Power-On State (POS) until sufficient VCC is sup-
plied. This feature prevents false signals, caused by undervoltage
conditions, from propagating to the output of the sensor IC.
During vibration events, the magnetic input signals can produce
oscillations with a sufficient amplitude for the peak tracking
algorithms to bound in and produce a non-ideal peak-to-peak.
When the A17501 detects a direction change, inward bounding
of the peak tracking signals is prevented. This prevents cases of
erroneous output transitions from switch points being incorrectly
set from vibration signals. Additionally, this allows for immediate
acquisition of the magnetic input signals once real target rotation
resumes following a vibration event.
Power Supply Protection
The A17501 contains an on-chip regulator and can operate over
a wide VCC range. For applications that need to operate from an
unregulated power supply, transient protection must be added
externally. For applications using a regulated line, EMI/RFI pro-
tection is recommended. Contact Allegro for more information
Signature Region Robust Signal Tracking
Signature teeth (characterized by an extra target tooth and/or
about circuitry to address EMC requirement compliance. Refer to valley) can produce significant variations of the magnetic input
the Typical Application Circuit section.
signals. The bounded updating of the tracking signals prevent
overcompensation for these signature variations to provide robust
and accurate switch points for the signature region, as well as the
features about the signature region.
Startup Hysteresis
With a Power-On and a target held at zero-speed (fOP ≈ 0 Hz),
noise and/or vibration can produce magnetic input signals.
Startup hysteresis prevents peak tracking and switch point setting
at startup immediately following power-on. This occurs until
the sensed differential magnetic signal has moved sufficiently
to satisfy the hysteresis band for signal tracking. This feature
helps to ensure optimal self-calibration of the magnetic signals
by rejecting electrical noise and low-amplitude target vibrations
during startup and ensures that calibration occurs on actual target
features.
Temperature Drift Robust Signal Tracking
As temperature changes can impact both the amplitude and offset
of the magnetic signal, a full-range ADC, advanced algorithms,
temperature compensation, watchdog timers, and an internal tem-
perature sensor ensure robust signal tracking over temperature.
To compensate for amplitude changes over temperature, tempera-
ture compensated gain is first applied to normalize the amplitude
over temperature. The full-range ADC and peak tracking algo-
rithms track and acquire the signal to accurately set the switch
points.
Small Signal Lockout
When BDIFF(pk-pk) falls below specification, the internal logic of
the sensor IC will indicate a reduced signal, as measured in an
excessive air gap or a vibration condition. Small Signal Lockout
will hold the output state at the level when BDIFF(pk-pk) was last
in-specification. Once BDIFF(pk-pk) returns to an in-specification
value, the output state is released to transition as expected during
normal operation. When direction information is not explicitly
defined by the selected output protocol, Small Signal Lockout
is controlled independently for each channel. For example, Left
Channel Speed + Right Channel Speed output protocol will allow
for one channel to continue switching while the other is in lock-
out. When direction information is explicitly communicated, for
example XOR + Direction output protocol, Small Signal Lockout
will occur when either channel’s BDIFF(pk-pk) falls below specifi-
cation.
To compensate for offset changes over temperature, two algo-
rithms are implemented to ensure the signal tracking accurately
follows and updates the switch points to follow the offset. With
nominal target rotation, peak-tracking algorithms automatically
follow and update the switch points over offset drift. With no
target rotation (stopped condition), a watchdog timer is imple-
mented which adjust the algorithms to track together, allowing
for preservation of the correct signal peak-to-peak and switch
points once rotation resumes.
With the Fixed Threshold algorithm option selected, algorithms
are implemented for continuous monitoring and updating of the
fixed threshold over temperature to follow the offset drift of the
system. This compensation is implemented for each channel
independently to provide robust tracking of both signal channels
over temperature.
18
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A17501
Dual Output Differential Speed and Direction Sensor IC
to-peak and phase relationship of the magnetic input signals can
meet the conditions to calibrate. Once normal rotation resumes,
Diagnostics and Fault Reporting
The A17501 contains diagnostics monitors of analog and digital
circuits of the IC. These continuously monitor and report if any
defect, calculation error, or invalid input stimulus is found. If a
diagnostic monitor fires, the outputs of the A17501 will transi-
tion to a VFAULT level. For all faults, the outputs will remain at
the VFAULT level for enough time to allow the system controller
to monitor that a fault has occurred. For some diagnostics, it is
possible to clear the fault with a reset of the internal controller
of the sensor IC. If any of those diagnostic monitors triggers the
fault event, the A17501 will automatically perform a reset of the
internal controller after the output is held VFAULT for enough time
to allow the system controller to monitor the fault event.
the actual signal amplitudes can be much larger than the peak
signals acquired during calibration. Rather than wait several
TCYCLE events for the peak signal to be tracked to actual levels,
the A17501 will detect the difference and recalibrate on the new
signal. Recalibration allows for fast and robust correction from
cases of calibration on vibration events.
Pulse Collision Prevention
In cases of “high-speed” vibration, output transitions can occur at
very high frequencies, to prevent pulse collision (truncation of the
pulse width), the A17501 will prevent output transitions until the
current output pulse transition is complete to ensure the system
controller can accurately interpret the output signal. This feature
is only implemented when a pulse protocol option is selected.
For diagnostics and fault reporting to perform correctly, proper
programming and adherence to the specifications and assump-
tions stated in this datasheet, the A17501 Safety Manual, and any
other addendum, corrigendum, and application note that applies
to the A17501. For more information on diagnostics and fault
reporting, see the A17501 Safety Manual.
High Configurability
The A17501 contains programmable parameters, as shown in the
Selection Guide, that can be configured to provide application-
level optimization.
Recalibration
Under large amplitude vibration conditions at startup, the peak-
19
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A17501
Dual Output Differential Speed and Direction Sensor IC
POWER DERATING
The device must be operated below the maximum junction tem-
perature 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 MicroSystems website.)
A worst-case estimate, PD(max), represents the maximum allow-
able power level (VCC(max), ICC(max)), without exceeding TJ(max)
at a selected RθJA and TA.
,
For example, calculating reliability of VCC given observed worst-
case ratings, specifically:
TA = 160°C, RθJA=177°C/W, TJ(max) =175°C, VCC(max)= 24 V,
and ICC(max) = 15 mA.
The Package Thermal Resistance (RθJA) 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 (RθJC ) is a rela-
tively small component of RθJA. Ambient air temperature (TA) and
air motion are significant external factors, damped by overmolding.
Calculation of the maximum allowable power, PD(max), can be
done by first inverting equation 3 and calculating the maximum
allowable increase to TJ:
ΔTmax = TJ(max) – TA = 175°C–160°C = 15°C
Then, maximum allowable power can be calculated by:
PD(max) = ΔTmax ÷RθJA =15°C÷177°C/W=84.7mW
The effect of varying power levels (Power Dissipation or PD), can
be estimated. The following formulas represent the fundamental
relationships used to estimate TJ, at PD.
Finally, invert equation 1 with respect to voltage:
VCC(est) = PD(max) ÷ ICC(max) = 84.7mW÷15mA=5.65 V
The results indicate that, at TA, the application and A17501 can
dissipate adequate amounts of heat at voltages less than or equal
PD = VIN
I
(1)
(2)
(3)
×
IN
ꢀ
ꢀ
ΔT = PD
R
×
θJA
to VCC(est)
.
TJ = TA + ΔT
Compare VCC(est) to VCC(max). If VCC(est) ≤ VCC(max), then reli-
able 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(avg) = 8.5 mA, and RθJA = 177°C/W, then:
PD = VCC
I
= 12 V 8.5 mA = 102 mW
CC(avg)
×
×
ΔT = PD
R
= 102 mW 177°C/W = 18.1°C
×
×
θJA
TJ = TA + ΔT = 25°C + 18.1°C = 43.1°C
20
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A17501
Dual Output Differential Speed and Direction Sensor IC
PACKAGE OUTLINE DRAWING
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ꢢꢇeꢦereꢝꢔe ꢓꢲꢜꢳꢄꢄꢄꢄꢂꢴꢑꢤ
ꢓꢕꢚeꢝsꢕꢠꢝs ꢕꢝ ꢚꢕꢡꢡꢕꢚeters ꢮ ꢋꢌꢵ ꢵꢌ ꢥꢬꢏꢶꢈ
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Exact case and lead configuration at supplier discretion within limits shown
ꢭꢄꢅꢄꢆ
ꢮꢄꢅꢄꢑ
ꢑꢅꢀꢃ
ꢁꢑꢒ
ꢛ
ꢈ
ꢈ
ꢃꢅꢑꢑ ꢯꢄꢅꢄꢑ
ꢃꢅꢊꢑ
ꢃꢅꢊꢑ
ꢓ
ꢐꢐꢐꢐ
ꢃꢅꢂꢀ
ꢍꢠꢡd ꢈꢩeꢔtꢠr
ꢪꢕꢝ ꢫꢝdeꢝt
ꢈ
ꢓate ꢬꢠde
ꢭꢄꢅꢄꢆ
ꢂꢅꢁꢂ
ꢮꢄꢅꢄꢑ
ꢈꢂ
ꢈꢀ
ꢈꢃ
ꢃ
ꢁꢑꢒ
ꢄꢅꢆꢁ ꢇꢈꢉ
ꢛraꢝded
ꢉaꢔe
ꢥtaꢝdard ꢛraꢝdꢕꢝg ꢇeꢦereꢝꢔe ꢧꢕeꢨ
ꢓ
ꢀꢅꢃꢎ
ꢍꢏꢐ
ꢂine 1, 2 ꢃ ꢄ characterꢅ
ꢂine 1ꢆ ꢇart Nuꢈber
ꢏ
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ꢃ
ꢀ
ꢂ
ꢁ
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ꢀ
ꢁ
C
ꢃꢁꢅꢊꢂ ꢯꢄꢅꢑꢃ
ꢜate aꢝd tꢕe ꢞar ꢞꢟrr area
ꢛraꢝdꢕꢝg sꢔaꢡe aꢝd aꢗꢗearaꢝꢔe at sꢟꢗꢗꢡꢕer dꢕsꢔretꢕꢠꢝ
ꢭꢄꢅꢄꢎ
ꢮꢄꢅꢄꢂ
ꢭꢄꢅꢄꢊ
ꢮꢄꢅꢄꢑ
ꢄꢅꢂꢆ
ꢄꢅꢁꢃ
ꢏꢔtꢕꢖe ꢏrea ꢓeꢗtꢘꢙ ꢄꢅꢁꢀ ꢚꢚ
ꢓ
ꢈ
ꢰaꢡꢡ eꢡeꢚeꢝts ꢢꢈꢃꢙ ꢈꢀꢙ aꢝd ꢈꢂꢤꢱ ꢝꢠt tꢠ sꢔaꢡe
ꢃꢅꢀꢊ ꢋꢌꢍ
Figure 14: Package K, 4-Pin SIP
21
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955 Perimeter Road
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www.allegromicro.com
A17501
Dual Output Differential Speed and Direction Sensor IC
Revision History
Number
Date
March 19, 2020
Description
–
Initial release
Copyright 2020, Allegro MicroSystems.
Allegro MicroSystems 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 assumes no responsibility for its use; nor
for any infringement of patents or other rights of third parties which may result from its use.
Copies of this document are considered uncontrolled documents.
For the latest version of this document, visit our website:
www.allegromicro.com
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