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AS5304 / AS5306 Integrated Hall ICs for Linear and Off-Axis Rotary Motion Detection
PRELIMINARY DATA SHEET
1
General Description
2
* * * *
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
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). A single index pulse is generated once for every pole pair at the Index output. 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. 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). 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 +125C.
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* * * * * * * * *
Key Features
High speed, up to 20m/s (AS5304) 12m/s (AS5306) Magnetic pole pair length: 4mm (AS5304) or 2.4mm (AS5306) Resolution: 25m (AS5304) or 15m (AS5306) 40 pulses / 160 positions per magnetic period. 1 index pulse per pole pair Linear movement magnetic strips measurement using multi-pole
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
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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 1: Revision 1.5
AS5304 (AS5306) with multi-pole ring magnet.
Figure 2:
AS5306 (AS5304) with magnetic multi-pole strip magnet for linear motion measurement Page 1 of 13
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AS5304/AS5306 Integrated Hall IC for linear and off-axis rotary motion detection
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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:
AS5304 / AS5306 block diagram
6
Sensor Placement in Package
TSSOP20 / 0.65mm pin pitch
Die C/L
1.02
0.22990.100
0.23410.100 3.2000.235
Package Outline
0.77010.150 3.04750.235
Figure 4:
Sensor in package
Die Tilt Tolerance 1
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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 Notes
1 2 3 4 5,12,13, 14,17,18,19 6 7 8 9,10,11 15 16 20 PIN Types:
VSS A VDDP B TEST AO VDD Index TEST TEST_GND VDDA Hall ZPZmskdis S AIO DO_OD
S DO_OD S DO_OD AIO AO S DO_OD AIO S S DI
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 test pins, must be left open AGC Analogue Output. (Used to detect low magnetic field strength) Positive supply pin Index output, active HIGH. Short Circuit Current Limitation test pins, must be left open test pin, must be connected to VSS Hall Bias Supply Support (connected to VDD) Test input, connect to VSS during operation
supply pin AO analogue output analog input / output DI digital input digital output push pull or open drain (programmable)
6.2
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 A A1 A2 b c D E E1 e K L 0 0.45 4.30 mm Min 0.05 0.80 0.19 0.09 6.40 Typ 1.00 6.50 6.40 4.40 0.65 0.60 8 0.75 0 0.018 4.50 0.169 Max 1.20 0.15 1.05 0.30 0.20 6.60 Min 0.002 0.031 0.007 0.004 0.252 inch Typ 0.039 0.256 0.252 0.173 0.0256 0.024 8 0.030 0.177 Max 0.047 0.006 0.041 0.012 0.008 0.260
Marking: AYWWIZZ
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 Rth(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
6.3
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:
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
S N S N S
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 90. Depending on the direction of rotation, A leads B (CW) or B leads A (CCW).
7.1.1
Index Pulse
40
1
2
40
1
2
A
40 1 2 40 1 2
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 25m for AS5304 and 15m 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.
B
Index
Detail: A B Index Step #
157 158 159 0 1 2 3 4 5
Figure 6:
Quadrature A / B and Index output
7.1.2
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 1/2 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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AS5304/AS5306 Integrated Hall IC for linear and off-axis rotary motion detection
X=0
X
Magnet drawn at index position X=0 CW magnet movement direction
Hall Array Center Line
N
4.2200.235
S
Index = High
Pin 1 Chip Top view
3.04750.235
25m (AS5304) 15m (AS5306)
X=0
X=X1
X
Magnet drawn at position X1 (exaggerated) CW magnet movement direction
Hall Array Center Line
N
4.2200.235
S
Index = Low
Pin 1 Chip Top view
3.04750.235
Figure 7:
Magnet placement for index pulse generation
7.1.4
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. 2. First the AS5304/AS5306 move to the end of the strip, until a magnetic field warning is displayed (Index = high, A=B=low) 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.
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.
7.2
Incremental Hysteresis
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. 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. Note: 1LSB = 25m for AS5304, 15m for AS5306
I ncrem en tal o ut put X +4 X +3 X +2 X +1
H ys teres is: 1 LS B
M agnet po sition
X
X
X+1
X+2
X+ 3
X+4
Mov ement d ir ection: +X M ovem ent direc tion: -X
Figure 8: Hysteresis of the incremental output
7.3
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
AS5304 Systematic Linearity Error caused by Pole Length Deviation
140 120 100 80 60 40 20 0 1500
Error [m]
Figure 9 and Figure 10 show the error caused by a non-ideal pole length of the multi-pole strip or ring. This is less of an issue with strip magnets, as they can be manufactured exactly to specification using the proper magnetization tooling.
Error [m]
1700
1900
2100
2300
2500
Pole Length [m]
Figure 9:
Additional error caused by pole length variation: AS5304
AS5306 Systematic Linearity Error caused by Pole Length Deviation
140 120 100 80 60 40 20 0 900 1000 1100 1200 1300 Pole Length [m]
Error [m]
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. Note that this is an additional error, which must be added to the intrinsic errors INL (see 7.3) and DNL (see 7.4).
Error [m]
1400
1500
Figure 10:
Additional error caused by pole length variation: AS5306
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AS5304/AS5306 Integrated Hall IC for linear and off-axis rotary motion detection
7.4
Dynamic Non-Linearity (DNL)
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. 25m on AS5304). In practice however, this step size is not ideal, the output state will change after 1LSB +/-DNL. The DNL must be <+/- 1/2 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.
incremental output steps
1 LSB - DNL 12.5 m 1 LSB 25 m 1 LSB + DNL 37.5 m
incremental output steps
AS5304: DNL (dynamic non-linearity)
AS5306: DNL (dynamic non-linearity) 1 LSB - DNL 7.5 m 1 LSB 15 m 1 LSB + DNL 22.5 m
lateral magnet movement
Figure 11:
lateral magnet movement
DNL of AS5304 (left) and AS5306 (right)
8
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:
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] / for AS5304: d = 4.0mm * number of pole pairs / for AS5306: d = 2.4mm * number of pole pairs / 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 Max. linear travelling speed = 2.4mm * 5000 1/sec = 12,000mm/sec = 12m/sec for AS5304 for AS5306
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AS5304/AS5306 Integrated Hall IC for linear and off-axis rotary motion detection
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9.1
GENERAL DEVICE SPECIFICATIONS
Absolute Maximum Ratings (Non Operating)
Symbol VDD Vin Iscr Min -0.3 VSS-0.5 -100 +/-2 JA Tstrg Tbody 5 -55 114.5 150 260 85 Max 7 VDD+0.5 100 Unit V V mA kV C /W C C % Norm: IPC/JEDEC J-STD-020C Norm: Jedec 18 Norm: MIL 883 E method 3015 Still Air / Single Layer PCB Note
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. Parameter Supply Input pin voltage Input current (latchup immunity) ESD Package thermal resistance Storage temperature Soldering conditions Humidity non-condensing
9.2
Operating Conditions
Symbol AVDD DVDD VSS IDD Tamb TJ LSB INL DNL Hyst 1 1.5 Min 4.5 0.0 25 20 -40 -40 25 15 1 0.5 2 Typ 5.0 0.0 Max 5.5 0.0 35 30 125 150 Unit V V mA C C m LSB LSB LSB AS5304 AS5306 Ideal input signal (ErrMax - ErrMin) / 2 No missing pulses. optimum alignment A/B/Index, AO unloaded! Note
Parameter Positive supply voltage Digital supply voltage Negative supply voltage Power supply current, AS5304 Power supply current, AS5306 Ambient temperature Junction temperature Resolution Integral nonlinearity Differential nonlinearity Hysteresis
9.3
System Parameters
Symbol TPwrUp TProp Min Max 500 20 Unit s s Note Amplitude within valid range / Interpolator locked, A B Index enabled Time between change of input signal to output signal
Parameter Power up time Propagation delay
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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
Symbol VOH VOL ILOH ILOL IShort CL RL tR tF 12 13 14 15 25 20 820 1.2 1.2 39 Min 0.8 VDD 0.4 + VSS Typ Max Unit V V mA mA mA pF s s Reduces maximum operating temperature See Figure 13 See Figure 13 Push/Pull mode Push/Pull mode Note Push/Pull mode
Push Pull Mode is set for AS530xA, Open Drain Mode is set for AS530xB versions. Parameter High level output voltage Low level output voltage Current source capability Current sink capability Short circuit limitation current Capacitive load Load resistance Rise time Fall time
VDD = 5V RL = 820
A/B/Index from AS5304/6
TTL 74LS00
CL = 20pF
Figure 13:
Typical digital load
9.5
CAO Analogue Output Buffer
Symbol VOutRange VOutRange VOffs IL IShort CL BW 5 6 10 5 40 Min 0.5 3.45 Typ 1 4 Max 1.2 4.3 10 Unit V V mV mA mA pF KHz Reduces maximum Operating Temperature Note Strong field, min. AGC Weak field, max. AGC
Parameter Minimum output voltage Maximum output voltage Offset Current sink / source capability Average short circuit current Capacitive load Bandwidth
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AS5304/AS5306 Integrated Hall IC for linear and off-axis rotary motion detection
9.6
Magnetic Input
Symbol LP_FP Min Typ 2.0 1.2 4.0 2.4 5 1:12 Offmag Tdmag fmag 0 60 1:24 0.5 -0.2 5 mT %/K kHz Max Unit mm Note AS5304 AS5306 AS5304 AS5306
Parameter Magnetic pole length
Magnetic pole pair length Magnetic amplitude Operating dynamic input range Magnetic offset Magnetic temperature drift Input frequency
TFP Amag
mm mT
Table 1:
AS5304 ordering guide
Device AS5304A AS5304B
Resolution 25m 25m
Magnet Pole Length 2mm 2mm
Digital Outputs Push Pull Open Drain
Table 2:
AS5306 ordering guide
Device AS5306A AS5306B
Resolution 15m 15m
Magnet Pole Length 1.2mm 1.2mm
Digital Outputs Push Pull Open Drain
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AS5304/AS5306 Integrated Hall IC for linear and off-axis rotary motion detection
Contact
Headquarters
austriamicrosystems AG A 8141 Schloss Premstatten, Austria Phone: +43 3136 500 0 Fax: +43 3136 525 01 www.austriamicrosystems.com
Copyright
Devices sold by austriamicrosystems are covered by the warranty and patent indemnification provisions appearing in its Term of Sale. austriamicrosystems makes no warranty, express, statutory, implied, or by description regarding the information set forth herein or regarding the freedom of the described devices from patent infringement. austriamicrosystems reserves the right to change specifications and prices at any time and without notice. Therefore, prior to designing this product into a system, it is necessary to check with austriamicrosystems for current information. This product is intended for use in normal commercial applications. Copyright (c) 2008 austriamicrosystems. Trademarks registered (R). All rights reserved. The material herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. To the best of its knowledge, austriamicrosystems asserts that the information contained in this publication is accurate and correct. However, austriamicrosystems shall not be liable to recipient or any third party for any damages, including but not limited to personal injury, property damage, loss of profits, loss of use, interruption of business or indirect, special, incidental or consequential damages, of any kind, in connection with or arising out of the furnishing, performance or use of the technical data herein. No obligation or liability to recipient or any third party shall arise or flow out of austriamicrosystems rendering of technical or other services.
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