IC-MHL200 Datasheet, PDF (14/33 Pages) IC-Haus GmbH – 12-BIT LINEAR / ROTARY POSITION HALL ENCODER

iC-MHL200
12-BIT LINEAR / ROTARY POSITION HALL ENCODER
BASIC OPERATION
Rev C1, Page 14/33
The iC-MHL200 uses an array of hall sensors to detect
the local variation of the magnetic field emerging from
a magnetic target. The target could be a magnetic tape
with periodic varying polarity and a pitch (NS spacing)
of 2 mm to match the iC-MHL200 sensor period P of
4 mm. An example for linear position sensing is shown
in Figure 5.
P = 4 mm
moving magnetic target
NSNS
B
4 mm
φ
x
MHL200
V_cos(φ)
V_sin(φ)
Figure 5: Typical arrangement of a magnetic tape to
iC-MHL200
φ
interpolaton
A
From the periodic magnetic field delivered by the target,
the hall sensor array generates internal sensor signals
which are then further processed and passed to the
interpolator to generate incremental position data, as
shown in Figure 6.
B
φ
Figure 6: Signal generation and position data output
HALL SENSORS: Position and Analog Signals
The magnetic sensor array is placed in a line at the
upper edge of the chip as shown in Figure 7. Each
of the four sensor location (NCOS, PSIN, PCOS and
NSIN) are equally spaced apart and are based on a
pair of Hall sensors. Each Hall sensor pair provides
a Hall output signal from the mean value of the two
single sensors a pair consists of, thus representing the
magnetic field strength at the center of each pair.
When a magnetic target is placed on top of the
iC-MHL200 package, the resulting magnetic field gen-
erates corresponding Hall voltages. If a magnetic south
pole is on top of a Hall sensor pair, the resulting Hall
voltage is positive, whereas a magnetic north pole pro-
vides a negative one.
To provide accurate sensor signals, the magnetic target
must consist of a periodic arrangement of north and
south poles with a pitch (spacing NS) of 2 mm. The
magnetic field distribution thus has a periodic variation
of 4 mm, matching the Hall sensor array period exactly.
Usually, a magnetic tape with magnetized north-south
pattern is used together with the iC-MHL200.