IC-MR Datasheet, PDF (21/44 Pages) IC-Haus GmbH – 13-BIT S&H SIN/COS INTERPOLATOR WITH CONTROLLER INTERFACES

iC-MR 13-BIT S&H SIN/COS
preliminary
INTERPOLATOR WITH CONTROLLER INTERFACES
Rev A1, Page 21/44
tion with the controlled sensor current source for LED
supply (output ACO). The VDC potential automatically
tracks higher photocurrents. In order to use this func-
tion intermediate potentials SVDC and CVDC have to
be adjusted to a minimal AC ripple using the selectable
k factor of parameters MPS and MPC (see Table 21).
If the gain setting is altered, this calibration has to be
repeated. When single-ended operating mode is se-
lected via register bit INMODE (see Table 12) MPS
and MPC have no impact and the applied voltage at
the negative input replaces the configurable sum volt-
age in the VDC generation.
The feedback of pin voltage V(ACO) fulfills the same
task as source VDC when MR bridge sensors are sup-
plied by the controlled sensor current source. In this
case the justification of intermediate potentials MPS
and MPC is unnecessary.
REFVOS
Code
0x0
0x1, 0x2
0x3
Note
Addr 0x0E, bit 5:4
Source type
Feedback of pin voltage V(ACO): V(ACO)/20
for supply-dependent diff. voltage signals
for Wheatstone measuring bridges
to measure VDDS
Fixed reference:
0x1 = V05 of 500 mV, 0x2 = V025 of 250 mV
for single-ended current or voltage signals
for single-ended or differential stabilized signals
(regulated sensors, frequency generator)
Self-tracking sources VDC1, VDC2 (125...250 mV)
for differential current signals
for differential voltage signals*
*) Requires SELREF = 0x3 and the supply of pin
VREF with the sensor’s reference potential (see
Elec. Char. No. 105 for acceptable input voltage).
Table 20: Offset reference source
MPS
MPC
Code
0x000
0x001
...
0x200
...
0x3FF
Note
Addr 0x06, bit 5:0, Addr 0x05, bit 7:4
Addr 0x08, bit 1:0, Addr 0x07, bit 7:0
VDC = k ∗ VPi + (1 − k) ∗ VNi
k = 0.33
k = 0.33032
...
k = 0.33 + Code · 0.00032
k = 0.50 (center setting)
...
k = 0.66
Adjustment required only if VOSREF = 0x3
Table 21: Intermediate potentials sine, cosine
is reached when the DC rate of the differential signals
V(PSO)-V(NCO) and V(PCO)-V(NCO) is zero.
ORS
ORC
Code
0x0
0x1
0x2
0x3
Note
Addr 0x08, bit 5:4
Addr 0x0A, bit 5:4
Range
maxVOS = 3 * VOSREF
maxVOS = 6 * VOSREF
maxVOS = 18 * VOSREF
maxVOS = 36 * VOSREF
The maximum offset calibration range refers to the
internal calibrated signals (calibration mode Analog
1, see page 18)
Table 22: Offset calibration range sine, cosine
The principle interpolation accuracy of the sine/cosine
signals in dependancy with the selected calibration
range as well as the size of an LSB are exemplarily
illustrated for some values in the following table.
Range
x Source
maxVOS
3 x 0.25 V 750 mV
6 x 0.25 V 1.5 V
6 x 0.5 V 3 V
18 x 0.5 V 9 V
Cal. step
size (LSB)
733 µV
1466 µV
2933 µV
8798 µV
Limitation of
angle precision
@ 100 % (6 Vpp)
@ 50 % (3 Vpp)
none (>13 bit)
none (>13 bit)
0.03°, >13 bit
0.06°, ca. 12 bit
0.06°, ca. 12.5 bit
0.11°, ca. 11.7 bit
0.17°, ca. 11 bit
0.34°, ca. 10 bit
Table 23: Offset calibration and impact on the angle
precision
OFS
OFC
Code
0x000
0x001
...
0x3FF
Addr 0x09, bit 7:0, Addr 0x0A, bit 2:0
Addr 0x0B, bit 7:0, Addr 0x0C, bit 2:0
Factor OF
Code
Factor OF
0
0x400
0
0.00098
0x401
−0.00098
0.00098 ∗ OFx ...
−0.00098 ∗ OFx
1
0x7FF
−1
Table 24: Offset calibration sine, cosine
The calibrated offset is generated through
VOS() = maxVOS ∗ OF
The offset calibration range is dependent on the se-
lected REFVOS source and is adjusted using registers
ORS and ORC. The actual offset calibration happens
through adjusting factors OFS and OFC after having
selected the calibration range. The calibration target
Phase correction SIN vs. COS
The phase shift between sine and cosine can be ad-
justed using register value PH. If the phase error is
too high, some calibration parameters may have to be
adjusted again (those are amplitudes, intermediate po-
tentials and offset voltages).