IC-TW28 Datasheet, PDF (66/80 Pages) IC-Haus GmbH – 10-BIT SIN/COS INTERPOLATOR

SIN
COS
W^iCIT^-H^TA^WU³⁶²T^0°O⁸-C1A0L-BIBITRSATINIO/CNOASNINDTLEINREPODLRAIVTp^{OERrReliminary}
Sensor
Input
Angle
Rev D2, Page 66/80
zthreshold – ^za^pl^oo^sng with the form of the ZERO input
signal – determ⁰in^° es the width of the internal Z gating
window (gat^Ze^Gw^ai^tdⁱⁿt^gh). To guarantee one and only one Z
output pulse p^Se^igr^nare^l volution, gatewidth must be at least
as wide as the^OUd^Te^Zsired width^zwo^idf^ththe Z output pulse and
no longer than^OUtw^TAo input cycles minus the width of the
Z output pulse_OUu_Tn_Bder all operating conditions as shown
in Figure 37.
zpos
1 Input Cycle
SIN
COS
0° 90° 180° 270° 360°
zthreshold
Z
Gating
Window
Z Output
zwidth
zphase
Figure 37: Z Gating Window Requirements
Internal
Th_Ze_PZ_ulsg_e ating window transitions may occur anywhere
in the gray area shown. Specifically,
zwidth[^◦] < gatewidth^◦ < 720^◦ − zwidth[^◦]
where zwidth[^◦] is the width of the Z output pulse and
gatewidth[^◦] is the width of the internal Z gating window,
both in input cycle degrees. Note that the width of the Z
output pulse is configured in AB edges in the iC-TW28
and must be converted to input cycle degrees for use
in the formula above.
zwidth[^◦] =
90^◦
zwidth
inter
To ensure that the internal Z gating window is the proper
width, it can be observed on the B outputs using Z test
mode. Invoke Z test mode by setting TEST.z = 1 using
the SPI port or the Encoder Link interface. Adjust the
ZERO0.threshold value for the desired gatewidth[^◦] and
then run auto calibration for the Z channel again and
verify that the Z output pulse is centered in the Z gating
window. It is important to always run Z channel auto cal-
ibration after making any changes to ZERO0.threshold
to guarantee proper centering of the Z output pulse in
the Z gating window. Terminate Z test mode by setting
TEST.z = 0. See TEST on page 40 for more information.
When a zero or index sensor is not used and a Z output
once per input cycle is required, connect ZERO+ to
3.3 V and ZERO- to ground. This is useful in on-axis
applications where one input revolution produces only
one input cycle. In this case, the z gating window is
always high (gatewidth = 360°), automatic Z calibration
cannot be used, and zphase must be set manually to
place the Z output in the desired relationship to the sin
and cos inputs. See PHASE_LSB on page 44 for more
information on zphase.
In same phase or absolute burst startup modes, the
state of the AB outputs when the Z output is active is
determined by the polarity bits OUTPUT.apol and OUT-
PUT.bpol. The polarity of the Z output is determined
by OUTPUT.zpol. See Startup Modes on page 58 and
Output Modes, Directions, and Polarities on page 56
for more information.