IC-TW4 Datasheet, PDF (10/14 Pages) IC-Haus GmbH – PROGRAMMABLE INTERPOLATOR WITH AUTOMATIC OFFSET CORRECTION

iC-TW4 PROGRAMMABLE INTERPOLATOR
WITH AUTOMATIC OFFSET CORRECTION
Test
mode
PGA A
PGA B
Calib 1
Index
cali-
bration
Offset
Vc
[V] at CFG1
0.8 * VDD
0.8 * VDD
0.87 * VDD
0.87 * VDD
0.87 * VDD
0.87 * VDD
Z at CFG1
< 3 kΩ
> 75 kΩ
> 75 kΩ
< 3 kΩ
< 3 kΩ
> 75 kΩ
[V] at CFG2
Refer to table 8
Refer to table 8
Refer to table 8
Refer to table 8
Refer to table 8
Refer to table 8
Z at CFG2
> 75 kΩ
> 75 kΩ
< 3 kΩ
< 3 kΩ
> 75 kΩ
> 75 kΩ
Table 9: Test modes
Rev D1, Page 10/14
INDEX GATING
The iC-TW4 can interface to a wide range of index gat-
ing sources. Most commonly used are the digital Hall
sensor and the MR sensor bridge. The digital Hall sen-
sor provides a large swing input signal to the iC-TW4.
Depending on the polarity of the Hall it is either con-
nected to pin NINZ or PINZ. Most Hall sensors use an
open drain stage pulling the output low in the presence
of a magnetic field. The unused terminal NINZ or PINZ
should be biased to an adequate mid voltage level to
guarantee good noise margin. Refer to Figure 5 for
sample configurations.
VDD
VDD
Digital Hall
active low
PINZ
iC-TW4
NINZ
VDD
MR index
sensor
PINZ
NINZ
iC-TW4
VDD
PINZ
iC-TW4
NINZ
Index gating using
Hall sensor
Index gating
using MR bridge
no Index
Figure 5: Index configuration
A MR sensor differential bridge can also be used to
gate the index. Typically, the MR sensor provides a
small signal amplitude. In addition, residual side lobes
are present that can trigger double indexing. It might
be necessary to externally adjust the sensor offset in
order to fine-tune the desired threshold. The iC-TW4
provides a calibration mode, which allows the internal
gating window to be observed. This simplifies prod-
uct calibration as variation in sensor offset can be eas-
ily compensated for. Figure 6 shows a correctly set
threshold when using an MR gating sensor. The side
lobes are below the threshold line and no parasitic trig-
gering occurs.