as5140 austriamicrosystems, as5140 Datasheet - Page 3

• Manufacturer Part Number: as5140
• Description: 10-bit 360? Programmable Magnetic Rotary Encoder For High Ambient Temperatures Up To 150?c
• Manufacturer: austriamicrosystems

AS5140H 10-BIT PROGRAMMABLE MAGNETIC ROTARY ENCODER
Pin 8 (Prog) is also used to program the different
incremental interface modes, the incremental resolution
and the zero position into the OTP (see page 11).
This pin is also used as digital input to shift serial data
through the device in Daisy Chain configuration,
(see page 5).
Pin 11 Chip Select (CSn; active low) selects a device
within a network of AS5140H encoders and initiates
serial data transfer. A logic high at CSn puts the data
output pin (DO) to tri-state and terminates serial data
transfer. This pin is also used for alignment mode (page
12) and programming mode (page 9).
Pin 12 allows a single wire output of the 10-bit absolute
position value. The value is encoded into a pulse width
modulated signal with 1µs pulse width per step (1µs to
1024µs over a full turn). By using an external low pass
filter, the digital PWM signal is converted into an analog
voltage, allowing a direct replacement of potentiometers.
3
The AS5140H 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 around the
center of the device and deliver a voltage representation
of the magnetic field at the surface of the IC.
Through Sigma-Delta Analog / Digital Conversion and
Digital Signal-Processing (DSP) algorithms, the AS5140H
provides accurate high-resolution absolute angular
Revision 1.1, 02-03-2007
Functional Description
VDD5V
Hall Array
Frontend
Amplifier
LDO 3.3V
&
Cos
VDDV3V
Sin
Figure 3: AS5140H block diagram
Programming
Parameters
Register
DSP
www.austriamicrosystems.com
OTP
Rotation Digital Computer (CORDIC) calculates the angle
and the magnitude of the Hall array signals.
The DSP is also used to provide digital information at the
outputs
movements of the used magnet towards or away from the
device’s surface.
A small low cost diametrically magnetized (two-pole)
standard
information (see Figure 17).
The AS5140H 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, an absolute angular representation is given by a
Pulse Width Modulated signal at pin 12 (PWM).
Besides the absolute angular position information the
device
signals. The various incremental output modes can be
selected by programming the OTP mode register bits
(see page 11). 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
turned off. To make the setting permanent, the OTP
register must be programmed (see page 9 ff.). The
default setting is a quadrature A/B mode including the
Index signal with a pulse width of 1 LSB. The Index
signal is logic high at the user programmable zero
position.
The AS5140H is tolerant to magnet misalignment and
magnetic stray fields due to differential measurement
technique and Hall sensor conditioning circuitry.
position information. For this purpose a Coordinate
Ang
Mag
simultaneously
M a g I N C n
magnet
Incremental
Interface
Absolute
Interface
Interface
PWM
(SSI)
provides
and
provides
M a g D E C n
the
PWM_LSB
DO
CSn
MagINCn
MagDECn
CLK
A_LSB_U
B_Dir_V
Index_W
Prog
incremental
angular
that
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indicate
position
output