IC-MSB Datasheet, PDF (22/29 Pages) IC-Haus GmbH – SIN/COS SIGNAL CONDITIONER WITH 1Vpp DRIVER

iC-MSB^SAFETY, iC-MSB2
SIN/COS SIGNAL CONDITIONER WITH 1Vpp DRIVER
Rev D2, Page 22/29
Offset Calibration CH1, CH2
In order to calibrate the offset the reference source
must first be selected using VOS12. Two fixed voltages
and two dependent sources are available for this pur-
pose. The fixed voltage sources should be selected for
external sensors which provide stable, self-regulating
signals.
So that photosensors can be operated in optical en-
coders iC-MSB tracks changes in offset voltages via
the signal-dependent source VDC when used in con-
junction with the controlled sensor current source for
LED supply (pin ACO). The VDC potential automati-
cally tracks higher DC photocurrents. To this end inter-
mediate potentials VDC1 and VDC2 must be adjusted
to a minimal AC ripple using the selectable k factor (this
calibration must be repeated when the gain setting is
altered).
The feedback of pin voltage V(ACO) fulfills the same
task as source VDC when MR bridge sensors are sup-
plied by the controlled power supply output. In this
instance the VDC intermediate voltages do not need
adjusting.
VOS12
Code
0x0
0x1
0x2
0x3
Adr 0x0E, bit 5:4
Type of source
0.05 · V(ACO)
0.5 V
0.25 V
VDC (ie. VDC1, VDC2)
Table 33: Offset Reference Source CH1, CH2
VDC1
VDC2
Code
0x000
0x001
...
0x3FF
Adr 0x07, bit 4:0; Adr 0x06, bit 7:3
Adr 0x08, bit 6:0; Adr 0x07, bit 7:5
VDC = k · VPi + (1 − k) · VNi
k = 0.33
k = 0.33032
k = 0.33 + MP2 · 0.00032
k = 0.66
The calibration range for the CH1/CH2 offset is depen-
dent on the selected VOS12 source and is set using
OR1 and OR2. Both sine and cosine signals are then
calibrated using factors OF1 and OF2. The calibration
target is reached when the DC fraction of the differen-
tial signals PCHx versus NCHx is zero.
OR1
OR2
Code
0x0
0x1
0x2
0x3
Adr 0x09, bit 0; Adr 0x08, bit 7
Adr 0x0A, bit 5:4
Range
x1
x2
x6
x12
Table 35: Offset Range CH1, CH2
OF1
OF2
Code
0x000
0x001
...
0x3FF
Adr 0xA, bit 3:0; Adr 0x9, bit 7:1
Adr 0xC, bit 0; Adr 0xB, bit 7:0; Adr 0xA, bit 7:6
Factor
Code
Factor
0
0x400
0
0.00098
0x401
−0.00098
0.00098 · OFx ...
−0.00098 · OFx
1
0x7FF
−1
Table 36: Offset Factors CH1, CH2
Phase Correction CH1 vs. CH2
The phase shift between CH1 and CH2 can be ad-
justed using parameter PH12. Following phase cal-
ibration other calibration parameters may have to be
adjusted again (those as amplitude compensation, in-
termediate potentials and offset voltages).
PH12
Code
0x000
0x001
...
0x1FF
Adr 0xD, bit 2:0; Adr 0xC, bit 7:1
Correction angle Code
Correction angle
+0
0x200
−0
+0.0204
0x201
−0.0204
+0.0204 · PH12 ...
−0.0204 · PH12
+10.42
0x3FF
−10.42
Table 34: Intermediate Voltages CH1, CH2
Table 37: Phase Correction CH1 vs. CH2