ams AS5306A Integrated hall ics for linear and off-axis rotary motion detection Datasheet

AS5304 / AS5306
Integrated Hall ICs for
Linear and Off-Axis Rotary Motion Detection
1
General Description
PRELIMINARY DATA SHEET
2
The AS5304/AS5306 are single-chip IC’s with integrated
Hall elements for measuring linear or rotary motion using
multi-pole magnetic strips or rings.
This allows the usage of the AS5304/AS5306 in
applications where the Sensor IC cannot be mounted at the
end of a rotating device (e.g. at hollow shafts). Instead, the
AS5304/AS5306 are mounted off-axis underneath a multipole magnetized ring or strip and provides a quadrature
incremental output with 40 pulses per pole period at
speeds of up to 20 meters/sec (AS5304) or 12 meters/sec
(AS5306).
Benefits
•
Complete system-on-chip
•
High reliability due to non-contact sensing
•
Suitable for the use in harsh environments
•
Robust against external magnetic stray fields
3
Key Features
•
High speed, up to 20m/s (AS5304)
12m/s (AS5306)
•
Magnetic pole pair length: 4mm (AS5304) or
2.4mm (AS5306)
•
Resolution: 25µm (AS5304) or 15µm (AS5306)
Using, for example, a 32pole-pair magnetic ring, the
AS5304/AS5306 can provide a resolution of 1280
pulses/rev, which is equivalent to 5120 positions/rev or
12.3bit. The maximum speed at this configuration is 9375
rpm.
•
40 pulses / 160 positions per magnetic period.
•
1 index pulse per pole pair
•
Linear movement
magnetic strips
The pole pair length is 4mm (2mm north pole / 2mm south
pole) for the AS5304, and 2.4mm (1.2mm north pole /
1.2mm south pole) for the AS5306. The chip accepts a
magnetic field strength down to 5mT (peak).
•
Circular off-axis movement measurement using multipole magnetic rings
•
4.5 to 5.5V operating voltage
•
Magnetic field strength indicator, magnetic field alarm
for end-of-strip or missing magnet
A single index pulse is generated once for every pole pair
at the Index output.
Both chips are available with push-pull outputs
(AS530xA) or with open drain outputs (AS530xB).
The AS5304/AS5306 are available in a small 20-pin
TSSOP package and specified for an operating ambient
temperature of -40° to +125°C.
Figure 1:
Revision 1.5
AS5304 (AS5306) with multi-pole ring magnet.
4
measurement
using
multi-pole
Applications
The AS5304/AS5306 are ideal for high speed linear motion
and off-axis rotation measurement in applications such as
•
electrical motors
•
X-Y-stages
•
rotation knobs
•
industrial drives
Figure 2:
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AS5306 (AS5304) with magnetic multi-pole strip magnet
for linear motion measurement
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AS5304/AS5306 Integrated Hall IC for linear and off-axis rotary motion detection
5
Functional Description
The AS5304/AS5306 require a multi-pole magnetic strip or ring with a pole length of 2mm (4mm pole pair length) on the
AS5304, and a pole length of 1.2mm (2.4mm pole pair length) on the AS5306. The magnetic field strength of the multi-pole
magnet should be in the range of 5 to 60mT at the chip surface.
The Hall elements on the AS5304/AS5306 are arranged in a linear array.
By moving the multi-pole magnet over the Hall array, a sinusoidal signal (SIN) is generated internally. With proper configuration
of the Hall elements, a second 90° phase shifted sinusoidal signal (COS) is obtained. Using an interpolation circuit, the length
of a pole pair is divided into 160 positions and further decoded into 40 quadrature pulses.
An Automatic Gain Control provides a large dynamic input range of the magnetic field.
An Analog output pin (AO) provides an analog voltage that changes with the strength of the magnetic field (see chapter 8).
Figure 3:
6
AS5304 / AS5306 block diagram
Sensor Placement in Package
1.02
TSSOP20 / 0.65mm pin pitch
Die C/L
0.2299±0.100
3.200±0.235
0.2341±0.100
Package
Outline
0.7701±0.150
3.0475±0.235
Figure 4:
Sensor in package
Die Tilt Tolerance ±1º
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AS5304/AS5306 Integrated Hall IC for linear and off-axis rotary motion detection
6.1
Pin Description
Pin
Pin Name
Pin Type
1
VSS
S
2
A
DO_OD
3
VDDP
S
4
B
DO_OD
5,12,13,
14,17,18,19
TEST
AIO
test pins, must be left open
6
AO
AO
AGC Analogue Output. (Used to detect low magnetic field strength)
7
VDD
S
8
Index
DO_OD
9,10,11
TEST
AIO
15
TEST_GND
S
test pin, must be connected to VSS
16
VDDA Hall
S
Hall Bias Supply Support (connected to VDD)
20
ZPZmskdis
DI
Test input, connect to VSS during operation
PIN Types:
6.2
S
AIO
DO_OD
Notes
Supply ground
Incremental quadrature position output A. Short circuit current limitation
Peripheral supply pin, connect to VDD
Incremental quadrature position output B. Short Circuit Current Limitation
Positive supply pin
Index output, active HIGH. Short Circuit Current Limitation
test pins, must be left open
supply pin
AO
analogue output
analog input / output
DI
digital input
digital output push pull or open drain (programmable)
Package Drawings and Markings
20 Lead Thin Shrink Small Outline Package – TSSOP20
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AS5304/AS5306 Integrated Hall IC for linear and off-axis rotary motion detection
Dimensions
Symbol
mm
inch
Min
Typ
Max
Min
Typ
Max
A
-
-
1.20
-
-
0.047
A1
0.05
-
0.15
0.002
-
0.006
A2
0.80
1.00
1.05
0.031
0.039
0.041
b
0.19
-
0.30
0.007
-
0.012
c
0.09
-
0.20
0.004
-
0.008
D
6.40
6.50
6.60
0.252
0.256
0.260
E
6.40
E1
4.30
e
6.3
Marking: AYWWIZZ
4.40
0.252
4.50
0.169
0.65
0.173
0.177
0.0256
K
0°
-
8°
0°
-
8°
L
0.45
0.60
0.75
0.018
0.024
0.030
A: Pb-Free Identifier
Y: Last Digit of Manufacturing Year
WW: Manufacturing Week
I: Plant Identifier
ZZ: Traceability Code
JEDEC Package Outline Standard:
MO-153-AC
Thermal Resistance R th(j-a) :
89 K/W in still air, soldered on PCB.
IC's marked with a white dot or the letters "ES" denote
Engineering Samples
Electrical Connection
The supply pins VDD, VDDP and VDDA are connected to +5V. Pins VSS and TEST_GND are connected to the supply ground. A
100nF decoupling capacitor close to the device is recommended.
Figure 5:
Revision 1.5
Electrical connection of the AS5304/AS5306
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AS5304/AS5306 Integrated Hall IC for linear and off-axis rotary motion detection
7
Incremental Quadrature AB Output
The digital output is compatible to optical incremental
encoder outputs. Direction of rotation is encoded into
two signals A and B that are phase-shifted by 90º.
Depending on the direction of rotation, A leads B
(CW) or B leads A (CCW).
7.1.1
S
N
40
Index Pulse
1
N
2
40
1
S
2
A
A single index pulse is generated once for every pole
pair. One pole pair is interpolated to 40 quadrature
pulses (160 steps), so one index pulse is generated
after every 40 quadrature pulses (see Figure 6)
The Index output is switched to Index = high, when a
magnet is placed over the Hall array as shown in
Figure 7, top graph: the north pole of the magnet is
placed over the left side of the IC (top view, pin#1 at
bottom left) and the south pole is placed over the
right side of the IC.
The index output will switch back to Index = low,
when the magnet is moved by one LSB from position
X=0 to X=X1, as shown in Figure 7, bottom graph.
One LSB is 25µm for AS5304 and 15µm for AS5306.
Note: Since the small step size of 1 LSB is hardly
recognizable in a correctly scaled graph it is shown as an
exaggerated step in the bottom graph of Figure 7.
40
1
2
40
1
2
B
Index
Detail:
A
B
Index
Step #
157 158 159
Figure 6:
7.1.2
S
0
1
2
3
4
5
Quadrature A / B and Index output
Magnetic Field Warning Indicator
The AS5304 can also provide a low magnetic field warning to indicate a missing magnet or when the end of the magnetic strip
has been reached. This condition is indicated by using a combination of A, B and Index, that does not occur in normal
operation:
A low magnetic field is indicated with:
Index = high
A=B=low
7.1.3
Vertical Distance between Magnet and IC
The recommended vertical distance between magnet and IC depends on the strength of the magnet and the length of the
magnetic pole.
Typically, the vertical distance between magnet and chip surface should not exceed ½ of the pole length.
That means for AS5304, having a pole length of 2.0mm, the maximum vertical gap should be 1.0mm,
For the AS5306, having a pole length of 1.2mm, the maximum vertical gap should be 0.6mm
These figures refer to the chip surface. Given a typical distance of 0.2mm between chip surface and IC package surface,
the recommended vertical distances between magnet and IC surface are therefore:
AS 5304: ≤ 0.8mm
AS 5306: ≤ 0.4mm
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X=0
AS5304/AS5306 Integrated Hall IC for linear and off-axis rotary motion detection
Magnet drawn at
index position X=0
X
CW magnet
movement direction
N
S
4.220±0.235
Hall Array Center Line
Index = High
Pin 1
Chip Top view
3.0475±0.235
X=X1
X=0
25µm (AS5304)
15µm (AS5306)
X
Magnet drawn at
position X1
(exaggerated)
CW magnet
movement direction
N
S
4.220±0.235
Hall Array Center Line
Index = Low
Pin 1
Chip Top view
3.0475±0.235
Figure 7:
7.1.4
Magnet placement for index pulse generation
Soft Stop Feature for Linear Movement Measurement
When using long multi-pole strips, it may often be necessary to start from a defined home (or zero) position and obtain absolute
position information by counting the steps from the defined home position. The AS5304/AS5306 provide a soft stop feature that
eliminates the need for a separate electro-mechanical home position switch or an optical light barrier switch to indicate the
home position.
The magnetic field warning indicator (see 7.1.2) together with the index pulse can be used to indicate a unique home position
on a magnetic strip:
1.
First the AS5304/AS5306 move to the end of the strip, until a magnetic field warning is displayed (Index = high,
A=B=low)
2.
Then, the AS5304/AS5306 move back towards the strip until the first index position is reached (note: an index position
is generated once for every pole pair, it is indicated with: Index = high, A=B= high). Depending on the polarity of the
strip magnet, the first index position may be generated when the end of the magnet strip only covers one half of the
Hall array. This position is not recommended as a defined home position, as the accuracy of the AS5304/AS5306 are
reduced as long as the multi-pole strip does not fully cover the Hall array.
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AS5304/AS5306 Integrated Hall IC for linear and off-axis rotary motion detection
3.
7.2
It is therefore recommended to continue to the next (second) index position from the end of the strip (Index = high,
A=B= high). This position can now be used as a defined home position.
Incremental Hysteresis
I ncrem en tal
o ut put
If the magnet is sitting right at the transition point between two steps, the
noise in the system may cause the incremental outputs to jitter back and
forth between these two steps, especially when the magnetic field is
weak.
H ys teres is:
1 LS B
X +4
X +3
X +2
X +1
M agnet po sition
X
X
X+1
X+2
X+ 3
X+4
Note: 1LSB = 25µm for AS5304, 15µm for AS5306
Mov ement d ir ection: +X
M ovem ent direc tion: -X
Figure 8:
7.3
To avoid this unwanted jitter, a hysteresis has been implemented. The
hysteresis lies between 1 and 2 LSB, depending on device scattering.
Figure 8 shows an example of 1LSB hysteresis: the horizontal axis is the
lateral position of the magnet as it scans across the IC, the vertical axis
is the change of the incremental outputs, as they step forward (blue line)
with movement in +X direction and backward (red line) in –X direction.
Hysteresis of the incremental output
Integral Non-Linearity (INL)
The INL (integral non-linearity) is the deviation between indicated position and actual position. It is better than 1LSB for both
AS5304 and AS5306, assuming an ideal magnet. Pole length variations and imperfections of the magnet material, which lead to
a non-sinusoidal magnetic field will attribute to additional linearity errors.
7.3.1
Error Caused by Pole Length Variations
Error [µm]
AS5304 Systematic Linearity Error caused by Pole
Length Deviation
140
120
100
80
60
40
20
0
1500
Figure 9 and Figure 10 show the error caused by a non-ideal
pole length of the multi-pole strip or ring.
Error [µm]
This is less of an issue with strip magnets, as they can be
manufactured exactly to specification using the proper
magnetization tooling.
1700
1900
2100
2300
2500
Pole Length [μm]
Figure 9:
Additional error caused by pole length variation: AS5304
Error [µm]
AS5306 Systematic Linearity Error caused by Pole
Length Deviation
140
120
100
80
60
40
20
0
However, when using a ring magnet (see Figure 1) the pole
length differs depending on the measurement radius. For
optimum performance it is therefore essential to mount the
IC such that the Hall sensors are exactly underneath the
magnet at the radius where the pole length is 2.0mm
(AS5304) or 1.2mm (AS5306), see also 8.1.2.
Error [µm]
900
1000
1100
1200
1300
1400
1500
Note that this is an additional error, which must be added to
the intrinsic errors INL (see 7.3) and DNL (see 7.4).
Pole Length [μm]
Figure 10:
Revision 1.5
Additional error caused by pole length variation: AS5306
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Page 7 of 13
AS5304/AS5306 Integrated Hall IC for linear and off-axis rotary motion detection
7.4
Dynamic Non-Linearity (DNL)
incremental output steps
AS5304:
DNL (dynamic non-linearity)
1 LSB - DNL
12.5 µm
1 LSB
25 µm
incremental output steps
The DNL (dynamic non-linearity) describes the non-linearity of the incremental outputs from one step to the next. In an ideal
system, every change of the incremental outputs would occur after exactly one LSB (e.g. 25µm on AS5304). In practice
however, this step size is not ideal, the output state will change after 1LSB +/-DNL. The DNL must be <+/- ½ LSB to avoid a
missing code. Consequently, the incremental outputs will change when the magnet movement over the IC is
minimum 0.5 LSB and maximum 1.5 LSB’s.
AS5306:
DNL (dynamic non-linearity)
1 LSB + DNL
37.5 µm
1 LSB - DNL
7.5 µm
1 LSB
15 µm
1 LSB + DNL
22.5 µm
lateral magnet movement
Figure 11:
8
lateral magnet movement
DNL of AS5304 (left) and AS5306 (right)
The AO Output
The Analog Output (AO) provides an analog output voltage that represents the Automatic Gain Control (AGC) of the Hall
sensors signal control loop.
This voltage can be used to monitor the magnetic field strength and hence the gap between magnet and chip surface:
•
Short distance between magnet and IC → strong magnetic field → low loop gain → low AO voltage
•
Long distance between magnet and IC → weak magnetic field → high loop gain → high AO voltage
For ideal operation, the AO voltage should be between 1.0 and 4.0V (typical; see 9.5).
Figure 12:
Revision 1.5
AO output versus AGC, magnetic field strength, magnet-to-IC gap
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AS5304/AS5306 Integrated Hall IC for linear and off-axis rotary motion detection
8.1
Resolution and Maximum Rotating Speed
When using the AS5304/AS5306 in an off-axis rotary application, a multi-pole ring magnet must be used. Resolution, diameter
and maximum speed depend on the number of pole pairs on the ring.
8.1.1
Resolution
The angular resolution increases linearly with the number of pole pairs. One pole pair has a resolution (= interpolation factor) of
160 steps or 40 quadrature pulses.
Resolution [steps] = [interpolation factor] x [number of pole pairs]
Resolution [bit] = log (resolution[steps]) / log (2)
Example: multi-pole ring with 22 pole pairs
Resolution
= 160x22 = 3520 steps per revolution
= 40x22 = 880 quadrature pulses / revolution
= 11.78 bits per revolution = 0.1023° per step
8.1.2
Multi-pole Ring Diameter
The length of a pole pair across the median of the multi-pole ring must remain fixed at either 4mm (AS5304) or 2.4mm
(AS5306). Hence, with increasing pole pair count, the diameter increases linearly with the number of pole pairs on the magnetic
ring.
Magnetic ring diameter = [pole length] * [number of pole pairs] / π
for AS5304: d = 4.0mm * number of pole pairs / π
for AS5306: d = 2.4mm * number of pole pairs / π
Example: same as above: multi-pole ring with 22 pole pairs for AS5304
Ring diameter =
4 * 22 / 3.14 = 28.01mm (this number represents the median diameter of the ring, this is where the
Hall elements of the AS5304/AS5306 should be placed; see Figure 4)
For the AS5306, the same ring would have a diameter of: 2.4 * 22 / 3.14 = 16.8mm
8.1.3
Maximum Rotation Speed
The AS5304/AS5306 use a fast interpolation technique allowing an input frequency of 5kHz. This means, it can process
magnetic field changes in the order of 5000 pole pairs per second or 300,000 revolutions per minute. However, since a magnetic
ring consists of more than one pole pair, the above figure must be divided by the number of pole pairs to get the maximum
rotation speed:
Maximum rotation speed = 300,000 rpm / [number of pole pairs]
Example: same as above: multi-pole ring with 22 pole pairs:
Max. speed = 300,000 / 22 = 13,636 rpm (this is independent of the pole length)
8.1.4
Maximum Linear Travelling Speed
For linear motion sensing, a multi-pole strip using equally spaced north and south poles is used. The pole length is again fixed
at 2.0mm for the AS5304 and 1.2mm for the AS5306. As shown in 8.1.3 above, the sensors can process up to 5000 pole pairs
per second, so the maximum travelling speed is:
Maximum linear travelling speed = 5000 * [pole pair length]
Example: linear multi-pole strip:
Max. linear travelling speed = 4mm * 5000 1/sec = 20,000mm/sec = 20m/sec
for AS5304
Max. linear travelling speed = 2.4mm * 5000 1/sec = 12,000mm/sec = 12m/sec
for AS5306
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AS5304/AS5306 Integrated Hall IC for linear and off-axis rotary motion detection
9
9.1
GENERAL DEVICE SPECIFICATIONS
Absolute Maximum Ratings (Non Operating)
Stresses beyond those listed under “Absolute Maximum Ratings“ may cause permanent damage to the device.
Parameter
Symbol
Min
Max
Unit
VDD
-0.3
7
V
Input pin voltage
V in
VSS-0.5
VDD+0.5
V
Input current (latchup immunity)
I scr
-100
100
mA
Norm: Jedec 18
kV
Norm: MIL 883 E method 3015
114.5
°C /W
Still Air / Single Layer PCB
150
°C
260
°C
5
85
%
Min
Typ
Max
Unit
4.5
5.0
5.5
V
0.0
0.0
0.0
V
Supply
ESD
+/-2
Package thermal resistance
Θ JA
Storage temperature
T strg
Soldering conditions
T body
-55
Humidity non-condensing
9.2
Note
Norm: IPC/JEDEC J-STD-020C
Operating Conditions
Parameter
Symbol
Positive supply voltage
AVDD
Digital supply voltage
DVDD
Negative supply voltage
Power supply current, AS5304
Power supply current, AS5306
VSS
IDD
25
35
20
30
mA
Ambient temperature
T amb
-40
125
°C
Junction temperature
TJ
-40
150
°C
Resolution
LSB
Integral nonlinearity
INL
1
LSB
Differential nonlinearity
DNL
±0.5
LSB
Hysteresis
Hyst
1
2
LSB
Parameter
Symbol
Min
Power up time
Propagation delay
9.3
25
15
µm
1.5
Note
A/B/Index, AO unloaded!
AS5304
AS5306
Ideal input signal
(ErrMax - ErrMin) / 2
No missing pulses.
optimum alignment
System Parameters
Revision 1.5
Max
Unit
Note
T PwrUp
500
µs
Amplitude within valid range /
Interpolator locked, A B Index enabled
T Prop
20
µs
Time between change of input signal to
output signal
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AS5304/AS5306 Integrated Hall IC for linear and off-axis rotary motion detection
9.4
A / B / C Push/Pull or Open Drain Output
Push Pull Mode is set for AS530xA, Open Drain Mode is set for AS530xB versions.
Parameter
Symbol
Min
Typ
Max
High level output voltage
V OH
0.8 VDD
Low level output voltage
V OL
Current source capability
I LOH
12
14
mA
Current sink capability
I LOL
13
15
mA
Short circuit limitation current
I Short
25
Capacitive load
CL
Load resistance
RL
Rise time
tR
Fall time
tF
0.4 + VSS
Unit
Note
V
Push/Pull mode
V
Push/Pull mode
mA
Reduces maximum
operating temperature
20
pF
See Figure 13
820
Ω
See Figure 13
1.2
µs
Push/Pull mode
1.2
µs
39
VDD = 5V
RL = 820Ω
A/B/Index
from
AS5304/6
TTL
74LS00
CL = 20pF
Figure 13:
9.5
Typical digital load
CAO Analogue Output Buffer
Parameter
Symbol
Min
Typ
Max
Unit
Note
Minimum output voltage
V OutRange
0.5
1
1.2
V
Strong field, min.
AGC
Maximum output voltage
V OutRange
3.45
4
4.3
V
Weak field, max.
AGC
±10
mV
Offset
Current sink / source capability
Average short circuit current
V Offs
IL
5
I Short
6
mA
40
mA
Capacitive load
CL
10
pF
Bandwidth
BW
5
KHz
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Reduces maximum
Operating
Temperature
Page 11 of 13
AS5304/AS5306 Integrated Hall IC for linear and off-axis rotary motion detection
9.6
Magnetic Input
Parameter
Symbol
Magnetic pole length
Min
T FP
Magnetic amplitude
A mag
Magnetic temperature drift
Input frequency
Table 1:
4.0
AS5304
AS5306
AS5304
5
60
1:12
1:24
mT
Off mag
±0.5
mT
T dmag
-0.2
%/K
5
kHz
0
AS5306
AS5304 ordering guide
Resolution
Magnet Pole Length
Digital Outputs
AS5304A
25µm
2mm
Push Pull
AS5304B
25µm
2mm
Open Drain
Resolution
Magnet Pole Length
Digital Outputs
AS5306A
15µm
1.2mm
Push Pull
AS5306B
15µm
1.2mm
Open Drain
AS5306 ordering guide
Device
Revision 1.5
Note
mm
2.4
f mag
Device
Table 2:
Unit
mm
1.2
Operating dynamic input range
Magnetic offset
Max
2.0
L P_FP
Magnetic pole pair length
Typ
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AS5304/AS5306 Integrated Hall IC for linear and off-axis rotary motion detection
Contact
Headquarters
austriamicrosystems AG
A 8141 Schloss Premstätten, Austria
Phone:
+43 3136 500 0
Fax:
+43 3136 525 01
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