IC-TW28 Datasheet, PDF (56/80 Pages) IC-Haus GmbH – 10-BIT SIN/COS INTERPOLATOR

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Rev D2, Page 56/80
OUTPUT MODES, DIRECTIONS, AND POLARITIES
The iC-TW28 is capable of operating in six different
output modes, as shown below.
OUTPUT
.uvwen .abzen
0
0
0
1
0
1
1
0
1
0
1
1
iC-TW28 Output Modes
MAIN_CFG
Output
.rs422
Mode
Format
X
SPI Only —
0
ABZ
Differential
1
ABZLD Differential
0
UVW
Differential
1
UVWLD Differential
X
ABZUVW Single-ended
Driver
Hi-Z
CMOS
RS422
CMOS
RS422
CMOS
Table 120: iC-TW28 Output Modes
SPI Only
In SPI Only output mode, all six output drivers are dis-
abled and the output pins are in a high impedance state.
In this mode, position (angle) must be read via the SPI
interface. See SPI Only Output Mode on page 71 for
more information.
The ABZ outputs should be tied low as shown in Figure
29 to minimize noise pickup and to avoid accidentally
enabling the Encoder Link interface.
ABZ and ABZLD
In ABZ and ABZLD output modes, the apol, bpol, zpol,
and abzdir bits in the OUTPUT register can be used
to set the output polarities and directions to match the
application requirements. Note that setting apol or bpol
(but not both) also reverses the counting direction of
the AB outputs. In this case, set the abzdir bit to restore
the original AB output counting direction. Setting both
apol and bpol does not change the AB output counting
direction. See Figure 17 on page 22 for ABZ output
connections.
iC-TW28
A+
A–
B+
B–
Z+
Z–
UVW and UVWLD
In UVW and UVWLD output modes, the uvwpol and
uvwdir bits in the OUTPUT register can be used to set
the output polarity and phase sequence direction of the
UVW outputs to match the application requirements.
Note that setting uvwpol shifts the phase of the UVW
outputs by 180^◦.
In UVWLD mode, connect the ABZ outputs as shown
in Figure 30.
Figure 29: SPI Only Output Connections
SPI Only output mode allows higher sensor input
frequencies because the AB output frequency limit
(ABLIMIT) is no longer in effect. The input frequency
alarm (STAT_VAL.falarm), however, is still in effect in
SPI Only output mode. FALARM should be set to 128
to allow maximum input frequency. Other FALARM set-
tings can be used according to the application require-
ments. STAT_IE.inclim and STAT_HIZ.inclim should be
set to 0 to avoid spurious interrupt requests. Finally, IN-
TER must be set to 0 (interpolation of 256) to allow
the multi-cycle counter to be used.
iC-TW28
A+
A–
B+
B–
Z+
Z–
U+
120 Ω
U–
V+
120 Ω
V–
W+
120 Ω
W–
Figure 30: UVW Output Connections
Position is updated every 20 ns in SPI Only output The three signal pairs should be terminated with a 120 Ω
mode, compared to 320 ns in other modes.
resistor at the far (receiving) end of the cable as shown.