IC-MU_17 Datasheet, PDF (20/66 Pages) IC-Haus GmbH – MAGNETIC OFF-AXIS POSITION ENCODER - POLE WIDTH 1.28MM

iC-MU MAGNETIC OFF-AXIS
POSITION ENCODER - POLE WIDTH 1.28MM
SIGNAL CONDITIONING FOR MASTER AND NONIUS CHANNELS: x = M,N
Rev D1, Page 20/66
Bias current source
The calibration of the bias current source in test mode
TEST=0x1F is prerequisite for adherence to the given
electrical characteristics and also instrumental in the
determination of the chip timing (e.g. SCL clock fre-
quency). For the calibration the current out of pin PB2
into VNA must be measured, and register bits CIBM
changed until the current is calibrated to 200 µA.
GF_M(5:0)
GF_N(5:0)
Code
0x00
0x01
...
0x3F
Addr. 0x00; bit 5:0
Addr. 0x06; bit 5:0
Fine gain
1.000
1.048
exp(
ln(20)
64
· GF_x)
19.08
Table 16: Hall signal amplification
VOSS_x
CIBM(3:0)
Code
0x0
...
0x8
0x9
...
0xF
Addr. 0x05; bit 3:0
Description
-40 %
...
0%
+5 %
...
+35 %
Table 14: Calibrating the bias current
HALL _X
X
+
ENAC ^GC_x
GF_x
+
GX_x
PH_x
X
HALL _X
X
+
VOSC_x
PSIN_x
PCOS_x
Gain settings
iC-MU has signal conditioning features that can com-
pensate for signal and adjustment errors. The Hall
signals are amplified in two stages. The gain of both
amplification stages is automatically controlled when
the bit ENAC is set to ’1’. The register bits GC_x and
GF_x have no effect. In the case of a deactivated au-
tomatic gain control (ENAC=’0’) the gain must be set
manually. First, the approximate field strength range
must be selected in which the Hall sensor is to be oper-
ated. The first amplifier stage can be programmed in
the following ranges:
GC_M(1:0)
GC_N(1:0)
Code
0x0
0x1
0x2
0x3
Addr. 0x00; bit 7:6
Addr. 0x06; bit 7:6
Coarse gain
4.4
7.8
12.4
20.7
Table 15: Selection of the Hall signal amplification
range
The second amplifier stage can be varied within a wide
range.
Figure 11: Conditioning of hall voltages
Register GX_x enables the sensitivity of the sine chan-
nel in relation to the cosine channel to be corrected.
The amplitude of the cosine channel is adapted to the
amplitude of the sine channel. The cosine amplitude
can be corrected within a range of approx. ±10 %.
GX_M(6:0)
GX_N(6:0)
Code
0x00
0x01
...
0x3F
0x40
...
0x7F
Addr. 0x01; bit 6:0
Addr. 0x07; bit 6:0
Description
1.000
1.0015
exp(
ln(20)
2048
· GX _x)
1.0965
0.9106
exp(−
ln(20)
2048
· (128
− GX _x))
0.9985
Table 17: Cosine gain adjustment
The integrated amplitude control unit can be activated
using bit ENAC. In this case the differential signal am-
plitude is regulated to 2 Vpp; the values of GF_x have
no effect here.