A1698 Datasheet

A1698
Two-Wire, True Zero-Speed, High Accuracy
Sensor IC with Speed and Direction Output
FEATURES AND BENEFITS
DESCRIPTION
• Integrated capacitor for EMC suppression in a single
overmolded miniature package
• Wide leads facilitate ease of assembly
• True zero-speed operation
• Pulse-width output protocol
• Automatic Gain Control (AGC) for air gap independent
switchpoints
• Automatic Offset Adjustment (AOA) for signal
processing optimization, providing large operating air
gap range
• Single chip sensing IC for high reliability
• Fully synchronous digital logic with Scan and IDDQ
testing
The A1698 is a Hall-effect-based integrated circuit (IC) that
provides a user-friendly solution for two-wire speed sensing of
ring magnets or ferrous targets (when back-biased by the user)
down to zero-speed in applications where speed and direction
is required. The A1698 is offered in the UB package, which
integrates the IC and a high temperature ceramic capacitor in
a single overmolded SIP package. The integrated capacitor
provides enhanced EMC performance.
The integrated circuit incorporates Hall-effect circuits and signal
processing that switches in response to differential magnetic
signals created by magnetic encoders, or, when properly backbiased with a magnet, from ferromagnetic targets. The circuitry
contains a sophisticated digital circuit that reduces magnet
and system offsets, calibrates the gain for air gap independent
switchpoints, and provides true zero-speed operation.
Package: 2-pin SIP (suffix UB)
The regulated current output is configured for two-wire interface
circuitry and is ideally suited for obtaining speed and direction
information in wheel speed applications. The 2-pin SIP package
is lead (Pb) free, with tin leadframe plating.
Not to scale
1
SUPPLY
Internal Regulator
Offset
Adjust
Gain
Adjust
Amp
Filter
ADC
Digital
Controller
Chopper
Stabilization
Amp
Filter
Output
Control
ADC
GROUND
2
Offset
Adjust
Gain
Adjust
Functional Block Diagram
A1698-DS, Rev. 2
Two-Wire, True Zero-Speed, High Accuracy
Sensor IC with Speed and Direction Output
A1698
SELECTION GUIDE
Part Number
Temperature Coefficient
Air Gap Warning and
Standstill Function
A1698LUBTN-FWPE-T
Ring Magnet
Yes
A1698LUBTN-FWPG-T
Back-Biased
Yes
A1698LUBTN-FWBE-T
Ring Magnet
No
A1698LUBTN-FWBG-T
Back-Biased
No
Configuration Options
A1698 L UB TN-
-T
Leadframe Plating
Temperature Coefficient:
E – Ring magnet (0.2%/ºC typ.) or
G – Back-biased
Standstill Pulses:
B – Blanked, no output during Standstill, or
P – Pulses during Standstill with Warning Pulses
Pulse Widths:
N – Forward = 45 µs (narrow) or
W – Forward = 90 µs (wide)
Rotation Direction:
F – Pin 1 to pin 2 forward or
R – Pin 2 to pin 1 forward
Instructions (Packing)
TN – Tape and reel
Package Designation
UB – 2-pin plastic SIP
Operating Temperature Range:
L
Allegro Identifier and Device Type
A1698
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
2
Two-Wire, True Zero-Speed, High Accuracy
Sensor IC with Speed and Direction Output
A1698
SPECIFICATIONS
ABSOLUTE MAXIMUM RATINGS
Characteristic
Symbol
Notes
Rating
Unit
Supply Voltage
VCC
28
V
Reverse Supply Voltage
VRCC
–18
V
Operating Ambient Temperature
TA
–40 to 150
°C
Maximum Junction Temperature
TJ(max)
165
°C
Tstg
–65 to 170
°C
Storage Temperature
L temperature range
Terminal List Table
1
Name
Number
Function
VCC
1
Supply Voltage
GND
2
Ground
2
UB Package, 2-Pin SIP Pinout Diagram
INTERNAL DISCRETE CAPACITOR RATINGS
Characteristic
Nominal Capacitance
Symbol
CSUPPLY
Test Conditions
Connected between VCC and GND
Value (Typ.)
Unit
2200
pF
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
3
Two-Wire, True Zero-Speed, High Accuracy
Sensor IC with Speed and Direction Output
A1698
OPERATING CHARACTERISTICS: Valid throughout full operating and temperature ranges, unless otherwise specified
Characteristic
Symbol
Test Conditions
Min.
Typ.1
Max.
Unit
ELECTRICAL CHARACTERISTICS
Supply Voltage 2
VCC
Operating, TJ < TJ(max)
4
–
24
V
Reverse Supply Current 3
IRCC
VCC = VRCC(max)
–
–
–10
mA
VZsupply
ICC = ICC(max) + 3 mA, TA = 25°C
28
–
–
V
ICC(LOW)
Low-current state
5.9
7
8.4
mA
ICC(HIGH)
High-current state
12
14
16
mA
ICC(HIGH) /
ICC(LOW)
Measured as ratio of high current to low current
(isothermal)
1.9
–
–
–
Signal stabilization time from
VCC > undervoltage lockout level
–
–
1
ms
tr, tf
Voltage measured at terminal 2 in Figure 1,
RL = 100 Ω, CL = 10 pF, measured between
10% and 90% of signal.
0
–
1.5
μs
Operate Point
BOP
% of peak-to-peak IC-processed magnetic
signal
–
60
–
%
Release Point
BRP
% of peak-to-peak IC-processed magnetic
signal
–
40
–
%
0
–
5
kHz
20
–
1200
G
–
2×
BSIG(MIN)
–
G
–300
–
300
G
–
+0.2
–
%/°C
Supply Zener Clamp Voltage
OUTPUT
Power-On State
Supply Current
Supply Current Ratio
ICC(LOW)
Supply Current Stabilization Time
Output Rise/Fall Time
–
OPERATING CHARACTERISTICS
Operating Frequency
Input Signal
f
BSIG
Differential signal, measured peak to peak
Air Gap Warning
BWARN
-P variant
Allowable User-Induced Differential
Offset
BSIGEXT
External differential signal bias (DC), operating
within specification
Sensitivity Temperature Coefficient 5
TC
Total Pitch Deviation
Valid for full
temperature range
E variant, Ring Magnet
G variant, Back-Biased
For constant BSIG, sine wave
Front-End Chopping Frequency
–
TBD
–
%/°C
–
–
+/-2
%
–
340
–
kHz
OUTPUT PULSE CHARACTERISTICS, PULSE PROTOCOL4
Pulse Width Off Time
tw(Pre)
Pulse Width, Air Gap Warning
tw(Warn)
Pulse Width, Forward Rotation
tw(FWD)
38
45
52
μs
-P variant
38
45
52
μs
-N variant
38
45
52
μs
-W variant
76
90
104
μs
-N variant
76
90
104
μs
Pulse Width, Reverse Rotation
tw(REV)
-W variant
153
180
207
μs
Pulse Width, Standstill
tw(STOP)
-P variant
1232
1440
1656
μs
TSTOP
-P variant
590
737
848
ms
Standstill Period
1 Typical
values are at TA = 25°C and VCC = 12 V. Performance may vary for individual units, within the specified maximum and minimum limits.
voltage must be adjusted for power dissipation and junction temperature; see representative discussions in Power Derating section.
3 Negative current is defined as conventional current coming out of (sourced from) the specified device terminal.
4 Load circuit is R = 100 Ω and C = 10 pF. Pulse duration measured at threshold of ( (I
L
L
CC(HIGH) + ICC(LOW)) /2).
5 Ring magnet decreases strength with rising temperature. Device compensates. Note that B
SIG requirement is not influenced by this.
2 Maximum
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
4
Two-Wire, True Zero-Speed, High Accuracy
Sensor IC with Speed and Direction Output
A1698
VSUPPLY
1
A1698
CSUPPLY
2
RL
100 Ω
CL
Figure 1: Typical Application Circuit
BSEQ(n)
BSEQ(n+1)
Target
S
N
S
N
TTARGET
VPROC
TVPROC
VPROC = the processed analog signal of the sinusoidal
magnetic input (per channel)
TTARGET = the period between successive sensed target
magnetic edges of the same polarity (either
both north-to-south or both south-to-north)
Figure 2: Differential Signal Variation
Figure 3: Definition of TTARGET
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
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Two-Wire, True Zero-Speed, High Accuracy
Sensor IC with Speed and Direction Output
A1698
THERMAL CHARACTERISTICS
Characteristic
Symbol
Package Thermal Resistance
RθJA
Test Conditions*
Single-layer PCB with copper limited to solder pads
Value
Unit
213
°C/W
*Additional thermal information is available on the Allegro website.
Maximum Allowable VCC (V)
Power Derating Curve
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
VCC(max)
VCC(min)
20
40
60
80
100
120
140
160
180
Temperature (ºC)
Power Dissipation PD (mW)
Power Dissipation versus Ambient Temperature
1900
1800
1700
1600
1500
1400
1300
1200
1100
1000
900
800
700
600
500
400
300
200
100
0
20
40
60
80
100
120
140
160
180
Temperature (ºC)
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
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Two-Wire, True Zero-Speed, High Accuracy
Sensor IC with Speed and Direction Output
A1698
CHARACTERISTIC PLOTS
8.4
16.0
VCC: 24 V
VCC: 24 V
15.0
7.4
ICC (mA)
ICC (mA)
7.9
VCC: 24 V
15.5
VCC: 24 V
6.9
14.5
14.0
13.5
13.0
6.4
12.5
5.9
12.0
-50
0
50
100
-50
150
0
TA (ºC)
50
100
150
TA (ºC)
Supply Current versus Ambient Temperature
Supply Current versus Ambient Temperature
104
207
tW(FWD),
-W Variant
100
tW(FWD),
-W Variant
201
Pulse Width (µs)
Pulse Width (µs)
195
96
92
88
84
189
183
177
171
165
80
159
76
153
-50
0
50
100
150
TA (ºC)
Output Pulse Widths versus Ambient Temperature
-50
0
50
100
150
TA (ºC)
Output Pulse Widths versus Ambient Temperature
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
7
Two-Wire, True Zero-Speed, High Accuracy
Sensor IC with Speed and Direction Output
A1698
FUNCTIONAL DESCRIPTION
The sensor IC contains a single-chip Hall-effect circuit that
supports a trio of Hall elements. These elements are used in
differential pairs to provide electrical signals containing information regarding edge position and direction of target rotation. The
A1698 is intended for use with ring magnet targets, or, when
back-biased with an appropriate magnet, with ferromagnetic
targets (gears). The IC detects the peaks of the magnetic signals
and sets dynamic thresholds based on these detected signals.
Data Protocol Description
When a target passes in front of the device (opposite the branded
face of the package case), the A1698 generates an output pulse
for each magnetic pole, or each tooth and valley, of the target.
Speed information is provided by the output pulse rate, while
direction of target rotation is provided by the duration of the
output pulses. The sensor IC can sense target movement in both
the forward and reverse directions. The translation of magnetic
input to the output is shown in Figure 6.
FORWARD ROTATION
For the –F variant, when the target is rotating such that a target
feature passes from pin 1 to pin 2, this is referred to as forward
Rotating Target
(Ring magnet or
ferromagnetic)
rotation. This direction of rotation is indicated on the output by
a tW(FWD) pulse width. For the –R variant, forward direction is
indicated for target rotation from pin 2 to 1 (see Figure 4).
REVERSE ROTATION
For the –F variant, when the target is rotating such that a target
feature passes from pin 2 to pin 1, this is referred to as reverse
rotation. This direction of rotation is indicated on the output by
a tW(REV) pulse width. For the –R variant, reverse direction is
indicated for target rotation from pin 1 to 2.
Output edges are triggered by VPROC transitions through the
switchpoints. On a crossing, the output is first set to ICC(LOW) for
a duration of tw(PRE), after which the output pulse of ICC(HIGH) is
present for tw(FWD) or tw(REV).
The IC is always capable of properly detecting input signals up to
the defined operating frequency. However, the end user will note
that a sequence of tw(PRE) and tw(REV) does meet this frequency.
The tw(PRE) period is dominant, thus always providing rising
output edge, but, at high frequencies, potentially truncating the
ICC(HIGH) duration.
Branded Face
of Package
S
N
S N
S
SN
N
N
Pin 1
S
Pin 2
Rotation from pin 1 to pin 2
Branded Face
of Package
Rotating Target
(Ring magnet or
ferromagnetic)
S
N
S N
S
S N
Pin 1
ICC(HIGH)
tw(FWD)
tw(FWD)
N
tw(Pre)
Pin 2
tw(Pre)
ICC(LOW)
Rotation from pin 2 to pin 1
Figure 4: Target Orientation Relative to Device
(ring magnet shown).
Figure 5: Output Timing Example
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115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
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Two-Wire, True Zero-Speed, High Accuracy
Sensor IC with Speed and Direction Output
A1698
Package Case Branded Face
Device Orientation
to Target
Package Case Branded Face
(Pin 2 Side)
IC
(Pin 1 Side)
Device Orientation to Target
(Top View of
Package Case)
(Pin 2 Side)
Back-Biasing Magnet
IC
(Pin 1 Side)
(Top View of
Package Case)
South Pole
North Pole
Mechanical Position (Target moves past device pin 1 to pin 2)
Target
(Radial Ring Magnet)
This pole
sensed earlier
S
N
This pole
sensed later
S
Target Magnetic Profile
Speed Channel
Element Pitch
+B
Mechanical Position (Target moves past device pin 1 to pin 2)
Target
(Gear)
This tooth
sensed
earlier
This tooth
sensed
later
Target Magnetic Profile
Speed Channel
Element Pitch
+B
–B
IC Internal Differential Analog Signals, VPROC
BRP
Speed Channel
IC Internal Differential Analog Signals, VPROC
BRP
Speed Channel
BOP
BOP
Direction Channel
BRP
Direction Channel
BRP
BOP
Detected Channel Switching
BOP
Detected Channel Switching
Channel A
Channel A
Channel B
Channel B
Output (pulse protocol)
Output (pulse protocol)
Figure 6: Basic Operation
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115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
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Two-Wire, True Zero-Speed, High Accuracy
Sensor IC with Speed and Direction Output
A1698
Calibration and Direction Validation
When power is applied to the A1698, the sensor IC internally
detects the profile of the target. The gain and offset of the
detected signals are adjusted during the calibration period,
normalizing the internal signal amplitude for the installation air
gap of the device.
The Automatic Gain Control (AGC) feature ensures that operational characteristics are isolated from the effects of installation
air gap variation.
Automatic Offset Adjustment (AOA) is circuitry that compensates for the effects of chip, magnet, and installation offsets. This
circuitry works with the AGC during calibration to adjust VPROC
in the internal A-to-D range to allow for acquisition of signal
peaks. AOA and AGC function separately on the two differential
signal channels.
During calibration, output pulses with direction information
are immediately transmitted to the output. Depending on target
design, air gap, and the phase of the target, direction may be
momentarily incorrect.
Following a direction change in running mode, direction changes
are immediately transmitted to the output. Depending on target
design and the phase of the target, direction may be fleetingly
incorrect.
Target Rotation
N
S
N
S
N
S
N
S
N
Target
Differential
Magnetic
Profile
tW(FWD) or
tW(REV)
tW(FWD) or
tW(REV)
Opposite
North Pole
Opposite
N→S Boundary
ICC
Opposite
South Pole
Opposite
S→N Boundary
tW(FWD)
tW(FWD)
tW(FWD)
t
Device Location at Power-On
Figure 7: Startup Position Effect on First Device Output Switching
Normal Target Rotation
N
S
Normal Target Rotation
Vibration
N
S
N
S
N
S
N
S
Target
Differential
Magnetic
Profile
tW(REV)
tW(FWD)
tW(FWD)
[or tW(REV)]
[or tW(REV)]
[or tW(FWD)]
tW(FWD) / tW(REV)
tW(FWD)
tW(FWD)
[or tW(REV)]
[or tW(REV)]
Figure 8: Output Functionality in the Presence of Running Mode Target Vibration
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115 Northeast Cutoff
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1.508.853.5000; www.allegromicro.com
10
Two-Wire, True Zero-Speed, High Accuracy
Sensor IC with Speed and Direction Output
A1698
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 MicroSystems 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 or PD), can
be estimated. The following formulas represent the fundamental
relationships used to estimate TJ, at PD. 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.
Example: Reliability for VCC at TA = 150°C, package UB, using
minimum-K PCB.
Observe the worst-case ratings for the device, specifically: RθJA = 213°C/W, TJ(max) = 165°C, VCC(max) = 24 V, and
ICC(AVG) = 14.66 mA. ICC(AVG) is computed using ICC(HIGH)(max)
and ICC(LOW)(max), with a duty cycle of 73% computed from
tw(REV)(max) on-time and tw(FW)(min) off-time (pulse width protocol). This condition happens at a select limiting frequency.
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 ÷ 213 °C/W = 70.4 mW
PD = VIN × IIN (1)
ΔT = PD × RθJA (2)
VCC(est) = PD(max) ÷ ICC(AVG) = 70.4 mW ÷ 14.6 mA = 4.8 V
TJ = TA + ΔT
(3)
The result indicates that, at TA, the application and device can
dissipate adequate amounts of heat at voltages ≤VCC(est).
For example, given common conditions such as: TA= 25°C,
VCC = 12 V, ICC = 14 mA, and RθJA = 213 °C/W, then:
PD = VCC × ICC = 12 V × 7 mA = 84 mW
ΔT = PD × RθJA = 84 mW × 213 °C/W = 17.9°C
Finally, invert equation 1 with respect to voltage:
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.
TJ = TA + ΔT = 25°C + 17.9°C = 42.9°C
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
11
Two-Wire, True Zero-Speed, High Accuracy
Sensor IC with Speed and Direction Output
A1698
PACKAGE OUTLINE DRAWING
For Reference Only – Not for Tooling Use
(Reference DWG-9070)
Dimensions in millimeters – NOT TO SCALE
Dimensions exclusive of mold flash, gate burs, and dambar protrusions
Exact case and lead configuration at supplier discretion within limits shown
4.00 ±0.05
B
4X10°
E 1.45
1.50 ±0.10
1.45 E
C
0.55 E
1.41 E
4.00 ±0.05
E E1
Mold Ejector
Pin Indent
E3 E
E2 E
A
4 X 2.50 REF
0.25 REF
0.30 REF
45°
Branded
Face
NNN
YYWW
LLLL
0.85 ±0.05
0.42 ±0.10
2.54 REF
4 X 0.85 REF
D Standard Branding Reference View
1
N
Y
W
L
2
1.00 ±0.10
= Supplier emblem
= Last three digits of device part number
= Last 2 digits of year of manufacture
= Week of manufacture
= Lot number
12.20 ±0.10
4 X 7.37 REF
+0.05
0.25 –0.03
1.80 REF
A Dambar removal protrusion (8×)
B Gate and tie burr area
C Active Area Depth, 0.38 mm REF
0.38 REF
D Branding scale and appearance at supplier discretion
0.25 REF
4 X 0.85 REF
E Hall elements (E1, E2, and E3); not to scale
0.85 ±0.05
F Molded Lead Bar for preventing damage to leads during shipment
1.80 ±0.05
F
4.00 ±0.05
1.50 ±0.10
Figure 9: Package UB, 2-Pin SIP
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
12
Two-Wire, True Zero-Speed, High Accuracy
Sensor IC with Speed and Direction Output
A1698
Revision History
Revision
Current
Revision Date
–
March 24, 2015
1
May 6, 2015
2
March 2, 2016
Description of Revision
Initial release.
Corrected typo in Selection Guide.
Updated Package Outline Drawing molded lead bar footnote, Internal Discrete Capacitor Ratings
table, and miscellaneous editorial changes.
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
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115 Northeast Cutoff
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1.508.853.5000; www.allegromicro.com
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