IC-TW28 Datasheet, PDF (2/80 Pages) IC-Haus GmbH – 10-BIT SIN/COS INTERPOLATOR

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DESCRIPTION
The iC-TW28 is a general purpose 10-bit applica-
tion-specific interpolator for sine/cosine signals with
automatic calibration and adaption of signal path pa-
rameters during operation to maintain minimum an-
gular error and jitter. Angular position is calculated at
a programmable resolution of up to 1024 increments
per input cycle. Automatic calibration and adaption
(correction during operation) of sensor offset, sin/cos
amplitude match, and phase quadrature is provided.
Additionally, automatic calibration of gain, offset and
phase of the zero inputs allows for rapid commission-
ing.
The iC-TW28 accepts 20 mV to 2 V differential Sin/-
Cos input signals directly from magnetic or optical
sensors – no external signal conditioning is required
in most applications. The differential zero input ac-
cepts a wide range of digital and analog index gating
sources such as Hall or MR sensor bridges. The Z
output width, position relative to the sin/cos inputs,
and synchronization to the AB quadrature outputs is
fully programmable.
In addition to industry-standard incremental ABZ
quadrature output, the iC-TW28 provides optional
UVW commutation output modes for 1 to 32 pole-
pair motors and SPI angle and multi-cycle readout for
embedded applications. The incremental ABZ quadra-
ture output can be generated at a frequency of up to
12 MHz (20 ns edge spacing); the maximum output
frequency can also be limited so as not to overwhelm
connected counters or controllers.
In SPI mode, the iC-TW28 provides multi-cycle syn-
chronization and reference mark capture functions
to support absolute position systems. Higher input
signal frequencies are allowed in SPI mode since the
ABZ output frequency limitation is not applicable.
The iC-TW28 offers two configuration modes. Pin con-
figuration mode provides simple, static configuration
that does not require any programming or complicated
calibration. Pin configuration mode uses a subset of
the iC-TW28’s complete capabilities including ABZ
quadrature output, a limited choice of the most com-
monly used interpolation (resolution) and hysteresis
values, and one-button calibration. Eight resistors
set voltage levels at four configuration input pins to
select all operating parameters, simplifying product
assembly. One-button auto calibration sets input gain
and compensates sensor offset and sin/cos channel
gain match and phase with just a few input cycles and
then stores the compensation values to the internal
EEPROM.
In more sophisticated applications, serial configura-
tion mode allows access to all iC-TW28 features.
Complete device configuration using the bi-directional
SPI or Encoder Link ports provides access to all res-
olutions (including fractional interpolation), fully pro-
grammable hysteresis, and advanced noise/jitter filter-
ing, quality monitoring, and fault detection capabilities.
The iC-TW28 requires no external components for op-
eration. An EEPROM for storage of configuration and
calibration data, and RS422 line drivers are already
integrated on-chip. An integrated power-on reset cir-
cuit can be overridden by an external hardware reset
signal if necessary.