IC-MN_16 Datasheet, PDF (24/62 Pages) IC-Haus GmbH – 25-BIT NONIUS ENCODER WITH 3-CH. SAMPLING 13-BIT Sin/D INTERPOLATION

iC-MN 25-BIT NONIUS ENCODER
WITH 3-CH. SAMPLING 13-BIT Sin/D INTERPOLATION
Rev F2, Page 24/62
to finely adjust the gain of the cosine track. In the
final stage of the process the amplitude of the sine
track is adapted to suit the cosine track using regis-
ter GFS_x (10:0). With differential input signals the
overall sine gain of one track is thus calculated as
GAINS_x = GR_x * GFS_x; the total cosine gain is then
GAINC_x = GR_x * GFC_x.
ables the offset calibration to be automatically tracked
dependent on the DC level of the input signal. If ACO is
chosen as the offset reference the voltage at pin ACOx,
divided into ¹/₂₀, acts as a reference. This enables the
offset to be calibrated dependent on the supply voltage
of the sensor.
GR_M
GR_S
GR_N
Code
0
1
2
3
4
5
6
7
Addr. 0x00; bit 2:0
Addr. 0x10; bit 2:0
Addr. 0x20; bit 2:0
Coarse gain
6.0
12.4
16.2
20.2
26.0
31.6
39.5
48.0
Table 16: Gain range sine/cosine
GFC_M
GFC_S
GFC_N
Code k
0x00
0x01
0x02
...
0x1F
Addr. 0x00; bit 7:3
Addr. 0x10; bit 7:3
Addr. 0x20; bit 7:3
k
Fine gain GFC = 6.25 31
1
1.07
1.13
...
6.25
Table 17: Gain factor cosine
GFS_M
GFS_S
GFS_N
Code k
0x000
0x001
0x002
...
0x7FF
Addr. 0x02; bit 2:0
Addr. 0x01; bit 7:0
Addr. 0x12; bit 2:0
Addr. 0x11; bit 7:0
Addr. 0x22; bit 2:0
Addr. 0x21; bit 7:0
k
Fine gain GFS = 6.25 1984
1
1.0009
1.0018
...
6.6245
Table 18: Gain factor sine
Figure 9: Principle offset calibration circuit with se-
lectable reference sources.
REFVOS
Code
0
1
2
3
Addr. 0x0A; bit 5:4
Type of source
Feedback of pin ACO REFVOS = V(ACOx)/20
Reference V05
REFVOS = 0.5 V
Reference V025
REFVOS = 0.25 V
Tracked source VDC
REFVOS = SVDCx,
CVDCx
Table 19: Offset reference source
Source VDC is to be used as reference for current
inputs. The average potentials of sine (SVDCx) and
cosine (CVDCx) are determined by:
SVDCx = (1 − k_s) · V(PSi) + k_s · V(NSi)
Offset Calibration
When calibrating the offset the offset reference source
must first be selected using REFVOS (1:0). This setting
is valid for all three tracks. If VDC is selected as the
offset reference SVDCx is the reference for the sine
track and CVDCx for the cosine. The VDC reference en-
and
CVDCx = (1 − k_c) · V(PCi) + k_c · V(NCi)
Using MPS_x (9:0) and MPC_x (9:0) k_s and k_c should