as5140 austriamicrosystems, as5140 Datasheet - Page 5

• 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
The absolute angular output is always set to a resolution
of 10 bit. Placing the magnet above the chip, angular
values increase in clockwise direction by default.
Data D9:D0 is valid, when the status bits have the
following configurations:
The absolute angular position is sampled at a rate of
10kHz (0.1ms). This allows reading of all 1024 positions
per 360 degrees within 0.1 seconds = 9.76Hz (~10Hz)
without skipping any position. Multiplying 10Hz by 60,
results the corresponding maximum rotational speed of
600 rpm.
Readout of every second angular position allows for
rotational speeds of up to 1200rpm.
Consequently, increasing the rotational speed reduces
the number of absolute angular positions per revolution
(see Table 8). Regardless of the rotational speed or the
number of positions to be read out, the absolute angular
value is always given at the highest resolution of 10 bit.
The incremental outputs are not affected by rotational
speed restrictions due to the implemented interpolator.
The incremental output signals may be used for high-
speed applications with rotational speeds of up to 10,000
rpm without missing pulses.
Revision 1.1, 02-03-2007
OCF
1
COF
0
LIN
Table 4: Status bit outputs
0
Mag
INCn
0
0
1
µC
Data IN
Mag
DECn
CLK
CSn
0
1
0
Figure 5: Daisy Chain hardware configuration
Parity
checksum of
bits 1:15
DO
even
AS5140H
1
CSn
st
Device
Prog
CLK
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DO
AS5140H
2
4.2
The Daisy Chain mode allows connection of several
AS5140H’s in series, while still keeping just one digital
input for data transfer (see “Data IN” in Figure 5 below).
This mode is accomplished by connecting the data output
(DO; pin 9) to the data input (Prog; pin 8) of the
subsequent device. The serial data of all connected
devices is read from the DO pin of the first device in the
chain. The Prog pin of the last device in the chain should
be connected to VSS. The length of the serial bit stream
increases with every connected device, it is
n * (16+1) bits:
The last data bit of the first device (Parity) is followed by
a logic low bit and the first data bit of the second device
(D9), etc… (see Figure 6).
4.2.1
In Daisy Chain mode, the Prog pin is connected directly
to the DO pin of the subsequent device in the chain (see
Figure 5). During programming (see section 9), a
programming voltage of 7.5V must be applied to pin
Prog. This voltage level exceeds the limits for pin DO, so
one of the following precautions must be made during
programming:
Due to the parallel connection of CLK and CSn, all
connected devices may be programmed simultaneously.
e.g. 34 bit for two devices, 51 bit for three devices, etc…
CSn
nd
Device
•
•
Prog
Daisy Chain Mode
CLK
Programming Daisy Chained Devices
open
programming or
add a Schottky diode between DO and Prog
(Anode = DO, Cathode = Prog)
DO
the
AS5140H
last Device
CSn
connection
Prog
CLK
DO
Prog
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