AS5510 AppNote Noise Reduction

Application Note – AN5510-10 Noise Reduction
AS5510
10-bit Linear Incremental Position
Sensor with Digital Angle output
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Revision 1.0 / 2013/01/30
AN5510-10 Noise Reduction
Table of Contents
1.
General Description ............................................................................................................... 2
2.
Input Related Noise ............................................................................................................... 2
3.
On Chip Noise Reduction ...................................................................................................... 3
4.
External Noise Reduction ...................................................................................................... 3
5.
Ordering Information .............................................................................................................. 5
Copyright ....................................................................................................................................... 6
Disclaimer ..................................................................................................................................... 6
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AN5510-10 Noise Reduction
1. General Description
The AS5510 is a linear Hall sensor with 10 bit resolution and I²C interface. It can measure
absolute position of lateral movement of a simple 2-pole magnet. The typical arrangement is
shown below in Figure 1.
Figure 1:
Linear Position Sensor AS5510 + Magnet
magnet
N
S
AS5510
PCB
Depending on the magnet size, a lateral stroke of 0.5~2mm can be measured with air gaps
around 1.0mm. To conserve power, the AS5510 may be switched to a power down state when it
is not used.
Find more information on our webpage:
https://www.ams.com/eng/Products/Magnetic-Position-Sensors/Linear-Incremental-MagneticPosition-Sensors/AS5510
2. Input Related Noise
Input related noise is given in the datasheet of the AS5510 and in Table 1 below. Depending on
the selcted sensitivity option and on the sampling frequency this noise leads to a signal jitter at
the output and is shown in Table 2
Table 1:
AS5510 Input related noise
Mode
fs
tdelay
Maximum Noise (Equivalent to 8*rms)
Fast (default)
50 KHz
20 µs
0.8 mTpp
Slow
12.5 KHz
50 µs
0.5 mTpp
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AN5510-10 Noise Reduction
Table 2:
AS5510 Output jitter
Sensitivity
Step Size
Max. Fast Mode Jitter
Max.Slow Mode Jitter
+/- 50 mT
96.66 µT/LSB
9 LSB
6 LSB
+/- 25 mT
48.83 µT/LSB
17 LSB
11 LSB
+/- 12.5 mT
24.41 µT/LSB
35 LSB
22 LSB
+/- 18.75 mT
36.62 µT/LSB
22 LSB
14 LSB
3. On Chip Noise Reduction
In some applications it may be nessecary to activate the slow mode to reduce the jitter at the
outputs. The AS5510 offers the option to switch to a slow mode that lowers the sampling
frequency to decrease the output jitter.
The Slow Mode is activated by setting the bit 2 (Fast / Slow mode) of register 02h in the AS5510
control register.
Example:
I2C_Write8(0x56, 0x02, 0x04); // Slow Mode
4. External Noise Reduction
If the application should require less jitter than offered by the slow mode, an external averageing
will reduce the jitter to the desired noise level.
In the best case situation the noise reduces with the square root of the number of samples.
Example:
   0.5  0.05;   10
   = 102 = 100
 =
 =
12500 
= 125 
100
1

= 8
Equation 1:
Number of Samples
Equation 2:
Frequency Averaged Output
2

 = (
)
 
 =
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AN5510-10 Noise Reduction
Example:
#define average 100
for (count = average; count; count--)
{
Data1 = I2C_Read8(I2C_ADDR, 0x00);
Data2 = I2C_Read8(I2C_ADDR, 0x01);
position += ((Data2 & 0x03)<<8) + Data1;
}
position = position / average;
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AN5510-10 Noise Reduction
5. Ordering Information
Table 3:
Ordering Information
Ordering Code
Description
comments
AS5510-AB
AS5510 Adapterboard
For rapid evaluation and prototyping
AS5510-DB
AS5510 Demoboard
For functional demonstration
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AN5510-10 Noise Reduction
Copyright
Copyright © 1997-2013, ams AG, Tobelbader Strasse 30, 8141 Unterpremstaetten, Austria-Europe.
Trademarks Registered ®. 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.
All products and companies mentioned are trademarks or registered trademarks of their respective companies.
Disclaimer
Devices sold by ams AG are covered by the warranty and patent indemnification provisions appearing in its
Term of Sale. ams AG 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. ams
AG 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 ams AG for current information.
This product is intended for use in normal commercial applications. Applications requiring extended
temperature range, unusual environmental requirements, or high reliability applications, such as military,
medical life-support or lifesustaining equipment are specifically not recommended without additional
processing by ams AG for each application. For shipments of less than 100 parts the manufacturing flow might
show deviations from the standard production flow, such as test flow or test location.
The information furnished here by ams AG is believed to be correct and accurate. However, ams AG 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 ams AG rendering of
technical or other services.
Contact Information
Headquarters
ams AG
Tobelbader Strasse 30
8141 Unterpremstaetten
Austria
T. +43 (0) 3136 500 0
For Sales Offices, Distributors and Representatives, please visit:
http://www.ams.com/contact
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