IC-TW11 Datasheet, PDF (10/25 Pages) IC-Haus GmbH – 10-BIT ULTRA LOW POWER MAGNETIC ABSOLUTE ROTARY ENCODER

iC-TW11 10-BIT ULTRA LOW POWER^preliminary
MAGNETIC ABSOLUTE ROTARY ENCODER
Rev B1, Page 10/25
the three Hall voltages, calculates the angle, adjusts
the gain and offset values (for the next measurement)
as required, signals that the conversion is complete by
asserting an interrupt request on the IRQ_OUT pin, and
then powers down the Hall array and analog circuitry.
By default, the interrupt input (IRQ_IN) and output
(IRQ_OUT) pins are active-low and the interrupt logic
is AND. This means that the IRQ_IN pin must be active
(low) AND the sampling complete to assert the interrupt
output (IRQ_OUT low). The sense of the interrupt logic
can be changed to OR via SPI commands.
HALL SENSORS
iC-TW11 has three Hall sensors which convert the mag-
netic field into measurable Hall voltages. The arrange-
ment of the array has been specifically selected to allow
a very tolerant assembly of iC-TW11 to the magnet axis.
Solely the magnetic field’s z-component is evaluated at
which the field lines pass through the sensors.
A diametrically magnetized, cylindrical permanent mag-
net made of Neodymium Iron Boron (NdFeB) or Samar-
ium Cobalt (SmCo) generates optimum sensor signals.
The magnet cylinder’s diameter should be in the range
of 3 mm to 6 mm.
The three Hall sensors are placed in the center of the
QFN16 package on a circle of 2 mm in diameter and
have a 120 ° angle distance to one another (Figure 3).
The diametric magnet is to be placed centrically above
the device package.
NS
HALL0
0°
positive
counting
direction
30°
Figure 3: Position of the Hall sensors in the QFN
package (top view); counting direction vs.
magnet rotation