AS5043 Programmable 360 Magnetic Angle Encoder
Revision 1.4, 04-Apr-06
www.austriamicrosystems.com
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1
General Description
The AS5043 is a contactless magnetic angle encoder for accurate
measurement up to 360.
It is a system-on-chip, combining integrated Hall elements,
analog front end and digital signal processing in a single device.
The AS5043 provides a digital 10-bit as well as a programmable
analog output that is directly proportional to the angle of a
magnet, rotating over the chip.
The analog output can be configured in many ways, including
user programmable angular range, adjustable output voltage
range, voltage or current output, etc..
An internal voltage regulator allows operation of the AS5043 from
3.3V or 5.0V supplies.
Figure 1: Typical arrangement of AS5043 and magnet
2
Benefits
Complete system-on-chip
-
Flexible system solution provides absolute output, both digital
and analog
-
Angle measurement with software programmable range up to
360
-
High reliability due to non-contact magnetic sensing
-
Ideal for applications in harsh environments
-
Robust system, tolerant to magnet misalignment, airgap
variations, temperature variations and external magnetic fields
-
No calibration required
3
Key Features
360 contactless high resolution angular position encoding
User programmable zero position
Two 10-bit absolute outputs:
Serial digital interface and
Versatile analog output
programmable angular range up to 360
programmable ratiometric output voltage range
Failure detection mode for magnet field strength and loss of
power supply
Serial read-out of multiple interconnected AS5043 devices
using daisy chain mode
Mode input for optimizing noise vs. speed
Alignment mode for magnet placement guidance
Wide temperature range: - 40C to + 125C
Small package: SSOP 16 (5.3mm x 6.2mm)
4
Applications
The AS5043 is ideal for applications with an angular
travel range from a few degrees up to a full turn of
360, such as
-
Industrial applications:
- Contactless rotary position sensing
- Robotics
- Valve Controls
-
Automotive applications:
- Throttle position sensors
- Gas / brake pedal position sensing
- Headlight position control
Front panel rotary switches
Replacement of potentiometers
DATA SHEET
AS5043
PROGRAMMABLE 360 MAGNETIC ANGLE ENCODER
WITH ABSOLUTE SSI AND ANALOG OUTPUTS
PRELIMINARY DATA SHEET
AS5043 Programmable 360 Magnetic Angle Encoder
Revision 1.4, 04-Apr-06
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5
Pin Configuration
AS5043
Figure 2: AS5043 pin configuration SSOP16
Package = SSOP16 (16 lead Shrink Small Outline Package)
Pin
Symbol
Type
Description
1
MagRngn DO_OD
Magnet Field Magnitude RaNGe warning;
active low, indicates that the magnetic
field strength is outside of the
recommended limits.
2 Mode
DI_PD,
ST
Mode input. Select between low noise
(open, low) and high speed (high) mode.
Internal pull-down resistor
3 CSn
DI_PU,
ST
Chip Select, active low; Schmitt-Trigger
input, internal pull-up resistor (~50k
)
4 CLK DI,ST
Clock Input of Synchronous Serial
Interface; Schmitt-Trigger input
5
NC
-
must be left unconnected
6 DO
DO_T
Data Output of Synchronous Serial
Interface
7
VSS
S
Negative Supply Voltage (GND)
8 Prog_DI
DI_PD
OTP Programming Input and Data Input
for Daisy Chain mode. Internal pull-down
resistor (~74k
).
Should be connected to VSS if
programming is not used
9 DACref AI
DAC Reference voltage input for external
reference
10 DACout AO
DAC output (unbuffered, Ri ~8k
)
11 FB
AI
Feedback, OPAMP inverting input
12 Vout
AO
OPAMP output
13
NC
-
Must be left unconnected
14
NC
-
Must be left unconnected
15 VDD3V3 S
3V-Regulator Output for internal core,
regulated from VDD5V.Connect to
VDD5V for 3V supply voltage. Do not
load externally.
16
VDD5V
S
Positive Supply Voltage, 3.0 to 5.5 V
Table 1: Pin description SSOP16
DO_OD digital output open drain S
supply pin
DI_PD
digital input pull-down
DO_T digital output /tri-
state
DI_PU
digital input pull-up
ST schmitt-trigger
input
AI
analog input
AO analog output
DI digital
input
5.1
Pin Description
Pins 7, 15 and 16 are supply pins, pins 5, 13 and 14
are for internal use and must be left open.
Pin 1 is the magnetic field strength indicator,
MagRNGn. It is an open-drain output that is pulled to
VSS when the magnetic field is out of the
recommended range (45mT to 75mT). The chip will
still continue to operate, but with reduced
performance, when the magnetic field is out of range.
When this pin is low, the analog output at pins #10
and #12 will be 0V to indicate the out-of-range
condition.
Pin 2 MODE allows switching between filtered (slow)
and unfiltered (fast mode). See section 9.
Pin 3 Chip Select (CSn; active low) selects a device
for serial data transmission over the SSI interface. A
"logic high" at CSn forces output DO to digital tri-
state.
Pin 4 CLK is the clock input for serial data
transmission over the SSI interface (see section 8)
Pin 6 DO (Data Out) is the serial data output during
data transmission over the SSI interface (see section
8)
Pin 8 PROG_DI is used to program the different
operation modes, as well as the zero-position in the
OTP register.
This pin is also used as a digital input to shift serial
data through the device in Daisy Chain Configuration,
(see page 6).
Pin 9 DACref is the external voltage reference input
for the Digital-to-Analog Converter (DAC). If selected,
the analog output voltage on pin 12 (V
out
) will be
ratiometric to the voltage on this pin.
Pin10 DACout is the unbuffered output of the DAC.
This pin may be used to connect an external OPAMP,
etc. to the DAC.
Pin 11 FB (Feedback) is the inverting input of the
OPAMP buffer stage.
AS5043 Programmable 360 Magnetic Angle Encoder
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Access to this pin allows various OPAMP configurations.
Pin 12 Vout is the analog output pin. The analog output is a DC
voltage, ratiometric to VDD5V (3.0 5.5V) or an external voltage
source and proportional to the angle.
6
Functional Description
The AS5043 is manufactured in a CMOS standard process and
uses a spinning current Hall technology for sensing the magnetic
field distribution across the surface of the chip.
The integrated Hall elements are placed in a circle around the
center of the device and deliver a voltage representation of the
magnetic field perpendicular to the surface of the IC.
Through Sigma-Delta Analog / Digital Conversion and Digital
Signal-Processing (DSP) algorithms, the AS5043 provides
accurate high-resolution absolute angular position information.
For this purpose a Coordinate Rotation Digital Computer
(CORDIC) calculates the angle and the magnitude of the Hall
array signals.
The DSP is also used indicate movements of the magnet towards
or away from the chip and to indicate, when the magnetic field is
outside of the recommended range (status bits = MagInc,
MagDec; hardware pin = MagRngn).
A small low cost diametrically magnetized (two-pole) standard
magnet, centered over the chip, is used as the input device.
The AS5043 senses the orientation of the magnetic field and
calculates a 10-bit binary code. This code can be accessed via a
Synchronous Serial Interface (SSI). In addition, the absolute
angular representation is converted to an analog
signal, ratiometric to the supply voltage.
The analog output can be configured in many ways,
such as 360/180/90 or 45 angular range, external
or internal DAC reference voltage, 0-100%*VDD or 10-
90% *VDD analog output range, external or internal
amplifier gain setting.
The various output modes as well as a user
programmable zero position can be programmed in an
OTP register. As long as no programming voltage is
applied to pin PROG, the new setting may be
overwritten at any time and will be reset to default
when power is cycled. To make the setting permanent,
the OTP register must be programmed by applying a
programming voltage.
The AS5043 is tolerant to magnet misalignment and
unwanted external magnetic fields due to differential
measurement technique and Hall sensor conditioning
circuitry.
It is also tolerant to airgap and temperature variations
due to Sin-/Cos- signal evaluation.
Sin
Cos
Ang
Mag
MagRNGn
Mode
DO
CLK
FB
Vout
Prog_DI
CSn
+
-
10
DACout
DACref
Figure 3: AS5043 block diagram
AS5043 Programmable 360 Magnetic Angle Encoder
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7
3.3V / 5V Operation
The AS5043 operates either at 3.3V 10% or at 5V
10%. This is made possible by an internal 3.3V Low-
Dropout (LDO) Voltage regulator. The core supply
voltage is always taken from the LDO output, as the
internal blocks are always operating at 3.3V.
For 3.3V operation, the LDO must be bypassed by
connecting VDD3V3 with VDD5V (see Figure 4 ).
For 5V operation, the 5V supply is connected to pin
VDD5V, while VDD3V3 (LDO output) must be buffered by
a 1...10F capacitor, which should be placed close to the
supply pin (see).
The VDD3V3 output is intended for internal use only It
should not be loaded with an external load.
The voltage levels of the digital interface I/O's
correspond to the voltage at pin VDD5V, as the I/O
buffers are supplied from this pin (see Figure 4).
Figure 4: Connections for 5V / 3.3V supply voltages
A buffer capacitor of 100nF is recommended in both
cases close to pin VDD5V.
8
10-bit Absolute Synchronous
Serial Interface (SSI)
The serial data transmission timing is outlined in Figure
5: if CSn changes to logic low, Data Out (DO) will change
from high impedance (tri-state) to logic high and the
read-out sequence will be initiated.
After a minimum time t
CLK FE,
data is latched into the
output shift register with the first falling edge of CLK.
Each subsequent rising CLK edge shifts out one bit of
data.
The serial word contains 16 bits, the first 10 bits are the
angular information D[9:0], the subsequent 6 bits contain
system information, about the validity of data such as
OCF, COF, LIN, Parity and Magnetic Field status
(increase / decrease / out of range) .
A subsequent measurement is initiated by a logic "high"
pulse at CSn with a minimum duration of t
CSn.
Data transmission may be terminated at any time by
pulling CSn = high.
8.1
Serial Data Contents:
D9:D0 absolute angular position data (MSB is clocked
out first).
OCF (Offset Compensation Finished), logic high
indicates that the Offset Compensation Algorithm has
finished and data is valid.
COF (Cordic Overflow), logic high indicates an out of
range error in the CORDIC part. When this bit is set, the
data at D9:D0 is invalid. The absolute output maintains
the last valid angular value.
This alarm may be resolved by bringing the magnet
within the X-Y-Z tolerance limits.
LIN (Linearity Alarm), logic high indicates that the input
field generates a critical output linearity.
When this bit is set, the data at D9:D0 may still be used,
but may contain invalid data. This warning may be
resolved by bringing the magnet within the X-Y-Z
tolerance limits.
Data D9:D0 is valid, when the status bits have the
following configurations:
OCF
COF
LIN
Mag
INC
Mag
DEC
Parity
0 0
0 1
1 0 0
1 0
even
checksum
of bits 1:15
Table 2: Status bit outputs
AS5043 Programmable 360 Magnetic Angle Encoder
Revision 1.4, 04-Apr-06
www.austriamicrosystems.com
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MagInc, (Magnitude Increase) becomes HIGH, when the
magnet is pushed towards the IC, thus the magnetic field
strength is increasing.
MagDec, (Magnitude Decrease) becomes HIGH, when
the magnet is pulled away from the IC, thus the magnetic
field strength is decreasing.
Both signals HIGH indicate a magnetic field that is out of
the allowed range (see Table 3).
Note: Pin 1 (MagRngn) is a combination of MagInc and
MagDec. It is active low via an open drain output and
requires an external pull-up resistor. If the magnetic field
is in range, this output is turned off. (logic "high").
Even Parity bit for transmission error detection of bits
1...15 (D9...D0, OCF, COF, LIN, MagInc, MagDec)
The absolute angular output is always set to a resolution
of 10 bit / 360. Placing the magnet above the chip,
angular values increase in clockwise direction by default.
Even
PAR
CSn
CLK
DO
D9
D8
D7
D6
D5
D4
D3
D2
D1
D0
1
8
16
COF
LIN
OCF
M a g
IN C
M a g
D EC
t
DO active
t
DO Tristate
1
D9
t
CLK FE
t
DO valid
t
CLK FE
t
CSn
T
CLK / 2
Angular Position Data
Status Bits
Figure 5: Synchronous serial interface with absolute angular position data
8.2
Z-Axis Range Indication (Push Button Feature, Red/Yellow/Green Indicator)
The AS5043 provides several options of detecting
movement and distance of the magnet in the vertical (Z-)
direction. Signal indicators MagINC, MagDEC and LIN
are available as status bits in the serial data stream,
while MagRngn is an open-drain output that indicates an
out-of range status (on in YELLOW or RED range).
Additionally, the analog output provides a safety feature
in the form that it will be turned off when the magnetic
field is too strong or too weak (RED range).
The serial data is always available, the red/yellow/green
status is indicated by the status bits as shown below:
SSI Status bits
Hardware Pins
Mag
INC
Mag
DEC
LIN
Mag
Rngn
Analog
output
Description
0 0 0 Off enabled
No distance change
Magnetic Input Field OK (GREEN range, ~45...75mT)
0 1 0 Off enabled
Distance increase, GREEN range; Pull-function. This state is dynamic and only active while the magnet is
moving away from the chip.
1 0 0 Off enabled
Distance decrease, GREEN range; Push- function. This state is dynamic and only active while the magnet is
moving towards the chip.
1 1 0 On enabled
YELLOW Range: Magnetic field is ~ 25...45mT or ~75...135mT. The AS5043 may still be operated in this
range, but with slightly reduced accuracy.
1 1 1 On disabled
RED Range: Magnetic field is ~<25mT or >~135mT. The analog output will be turned off in this range by
default. It can be enabled permanently by OTP programming (see 11.1.2).
It is still possible to use the absolute serial interface in the red range, but not recommended.
Table 3: Magnetic field strength indicators
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